Skip to main content
NCBI home page
Springer logoLink to Springer
. 2024 Mar 4;143(1):11. doi: 10.1186/s13358-024-00308-7

The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten

Christian Klug 1,✉, Stephan N F Spiekman 2, Dylan Bastiaans 1, Beat Scheffold 1, Torsten M Scheyer 1
PMCID: PMC10912274  PMID: 38450287

Abstract

Marine conservation deposits (‘Konservat-Lagerstätten’) are characterized by their mode of fossil preservation, faunal composition and sedimentary facies. Here, we review these characteristics with respect to the famous conservation deposit of the Besano Formation (formerly Grenzbitumenzone; including the Anisian–Ladinian boundary), and the successively younger fossil-bearing units Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio (Switzerland and Italy). We compare these units to a selection of important black shale-type Lagerstätten of the global Phanerozoic plus the Ediacaran in order to detect commonalities in their facies, genesis, and fossil content using principal component and hierarchical cluster analyses. Further, we put the Monte San Giorgio type Fossillagerstätten into the context of other comparable Triassic deposits worldwide based on their fossil content. The results of the principal component and cluster analyses allow a subdivision of the 45 analysed Lagerstätten into four groups, for which we suggest the use of the corresponding pioneering localities: Burgess type for the early Palaeozoic black shales, Monte San Giorgio type for the Triassic black shales, Holzmaden type for the pyrite-rich black shales and Solnhofen type for platy limestones.

Keywords: Konservat-Lagerstätten, Taphonomy, Marine reptiles, Exceptional preservation

Introduction

Since the pioneering work of Bernhard Peyer, who began his excavations in the Swiss canton of Ticino in 1924 (Lanz & Felber, 2020; Peyer, 1934), many books and articles have appeared about the conservation deposit of the Middle Triassic of Monte San Giorgio (for the dating of the section see Furrer et al., 2008); the latest comprehensive works are the volumes by Olivier Rieppel (2019) and by Heinz Lanz and Markus Felber (2020). Classically, the monographs (mostly published in the ‘Schweizerische Paläontologische Abhandlungen’, now the Swiss Journal of Palaeontology) on the vertebrates of this locality comprised the most important pioneering work. The rich fauna of fossil vertebrates provides a unique insight into the recovery of shallow marine ecosystems following the devastation of the largest mass extinction event in Earth history, the Permian–Triassic boundary mass extinction (Chen & Benton, 2012; Scheyer et al., 2014a). This fauna includes a broad array of remarkable marine reptiles (Figs. 1, 2), for which this Lagerstätte is arguably best known (e.g., Bürgin et al., 1989; Rieppel, 2019). In particular, the fascinating reptile Tanystropheus contributed to the fame of the Besano Formation (Fig. 1A). Originally known from fragmentary remains, mostly comprising highly elongated and hollow bones, these remarkable yet poorly understood remains led researchers to erroneous ideas about their systematic assignment (e.g., v. Meyer 1847–1855; Nopsca, 1923; Edinger, 1924). Only with the discovery of the spectacular skeletons excavated by Peyer at Monte San Giorgio did their correct identification become a possibility. Today, these elongate bones are known to be hyper-elongated cervical vertebrae that belonged to an extremely long necked, likely aquatic to semi-aquatic archosauromorph reptile (e.g., Beardmore & Furrer, 2017; Jaquier & Scheyer, 2017; Kuhn-Schnyder, 1959; Nosotti, 2007; Peyer, 1930, 1931a; Renesto, 2005; Spiekman & Mujal, 2023; Spiekman & Scheyer, 2019; Spiekman et al., 2020a, 2020b; Tschanz, 1986, 1988; Wild, 1973, 1980). Its terrestrial relative Macrocnemus was also studied by various authors (Herbst et al., 2021; Jaquier et al., 2017; Kuhn-Schnyder, 1962; Miedema et al., 2020; Nopcsa, 1930; Peyer, 1937; Premru, 1991; Renesto & Avanzini, 2002; Rieppel, 1989a; Saller, 2016).

Fig. 1.

Fig. 1

Open in a new tab

Three important marine reptiles from the Middle Triassic of Monte San Giorgio with their reconstructions, recently crafted by Beat Scheffold. A Tanystropheus, PIMUZ T 2817. B Cyamodus, PIMUZ T58. C, Mixosaurus, PIMUZ T 4923 (top) and PIMUZ T 4376 (bottom)

Fig. 2.

Fig. 2

Open in a new tab

Fossilized foetuses inside the mother, examples from the Middle Triassic of Monte San Giorgio. A Mixosaurus, PIMUZ T 4830 (e.g., Brinkmann, 1996; Miedema et al., 2023). B Saurichthys, PIMUZ T 3917 (e.g., Maxwell et al., 2018)

To date, the fossil localities of Monte San Giorgio still represent the best-studied record of a Middle Triassic marine ecosystem worldwide, rich in marine reptiles, fishes, invertebrates, and plants (Fig. 3), which led to its recognition as a UNESCO World Heritage site in 2003 (Felber et al., 2004; https://whc.unesco.org/uploads/nominations/1090.pdf). Despite its long history, the relevance of the site is still increasing, both through continuing studies of the historical collections, and through comparisons to new abundant fossil material, especially also of marine reptiles, from contemporaneous sites on the eastern Tethys margin in what is now southern China (e.g., Benton et al., 2014).

Fig. 3.

Fig. 3

Open in a new tab

Fossilized mollusks from the Middle Triassic of Monte San Giorgio (see Rieber, 1969, 1970, 1973; Pieroni, 2022). A, Proarcestes extralabiatus, internal mould. B, Repossia acutenodosa, silicified internal mould. C, Proarcestes extralabiatus, external mould. D, Phragmoteuthis ticinensis with complete arm crown, cephalic cartilage, oesophagus and ink sac. E, Daonella caudata. F, Pleuronautilus sp., internal mould

Besides Tanystropheus, there are of course other vertebrate fossils of scientific importance known from Monte San Giorgio (Figs. 1, 2, 4). These comprise, for example, the following vertebrate groups (for a more complete bibliography, see Albisetti & Furrer, 2022):

Fig. 4.

Fig. 4

Open in a new tab

Reconstructions of some animals from Monte San Giorgio by Beat Scheffold. Note that not all of the depicted taxa may have co-occurred in time or in space (habitat depth, etc.). At Monte San Giorgio, the water depth was likely greater then shown in these images. A Meride Limestone (Ladinian). B Besano Formation (Anisian)

Fig. 5.

Fig. 5

Open in a new tab

Exceptionally preserved ichthyosaur Mixosaurus cornalianus (Bassani, 1886). PIMUZ T 1839, Besano Formation, Monte San Giorgio (A). The skull of the specimen (C) is covered by a thin pyrite crust and in the pelvic region (B), some phosphatized soft-tissue remains are discernible. Mixosaurus belongs together with Neusticosaurus to the most common reptile fossils of the Besano Formation. This specimen was excavated in 1931 and prepared in 2019 by Christian Obrist

These materials gain increasing attention because of their usefulness for comparisons with related taxa from other Triassic localities. Especially in China, several localities have produced articulated skeletons, mostly of vertebrates, that resemble the Monte San Giorgio specimens not only morphologically, but also with respect to preservation and facies of the sedimentary matrix (e.g., Hu et al., 2011; Jiang et al., 2005, 2009, 2020; Li, 2006; Lu et al., 2018; Rieppel et al., 2000; Sun et al., 2016; Wang et al., 2008). This has revealed that there are numerous Triassic localities worldwide with more or less similar depositional conditions and thus fossil preservation as at Monte San Giorgio. Consequently, Monte San Giorgio has become a reference in research on this type of conservation deposits (cf. Arif et al., 2019; Benton et al., 2013, 2022; Frey et al., 2019; Seilacher, 1970, 1990; Seilacher et al., 1985).

Accordingly, we briefly outline the properties of the Besano Formation, Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio. We compare these to those of other Triassic conservation deposits worldwide. For this purpose, we characterized the six Swiss Triassic conservation deposits and 39 other globally important Phanerozoic Lagerstätten including Ediacara using various sedimentological and palaeontological traits. These were then evaluated using multivariate analyses. The aims were (1) to identify similarities and differences of these Lagerstätten; (2) to identify the palaeoecological conditions in order (3) to better understand under which circumstances the various types of Lagerstätten have formed.

Methods

Here, we follow the approach of Frey et al. (2019) in using the questionnaire published by Seilacher et al. (1985) to compare marine conservation deposits starting with the Ediacaran through a variance–covariance principal component analysis. The variables included information (often absence/presence) on marine basin size, sedimentary facies, palaeolatitude (Fig. 6), thickness of the succession, duration of the time interval in which the exceptionally preserved fossils formed, sea level, sediment structures, pyrite in sediment, faunal composition, trace fossils, infauna, epibenthos, pelagic macrofossils, death marches, landing marks, soft parts, cuticles, roll marks, current alignment, aragonite, internal moulds (pyritic or other), concretions, deformation, carbonization, soft part preservation mode (phosphatization, pyritization, silicification or in clay minerals), and preservation by obrution, stagnation or microbial mats. For the analyses, we omitted ‘life position’, because this was uniformly coded as 0. The original dataset of Frey et al. (2019) included only 21 Lagerstätten.

Fig. 6.

Fig. 6

Open in a new tab

Palaeogeographic map (modified after Scotese, 1997) with data from Brinkmann et al. (2010) and Benton et al. (2013). Note that most of the conservation deposits included here lie in tropical or moderate latitudes, while occurrences of disarticulated materials are also known from boreal to arctic regions (not differentiated here)

For this study, we added data of 34 localities to allow a global comparison of Triassic conservation deposits, which represents an incomplete but representative sample of known Lagerstätten (Tables 1, 2). Our list is not intended to be all inclusive for global Lagerstätten but was assembled with the intention of assessing the characteristics of the Triassic Monte San Giorgio in a global framework. For the Early Triassic, we included the Paris biota (Thaynes Fm) from Idaho, USA (Brayard et al., 2017; Doguzhaeva et al., 2018), the fauna from Kap Stosch, Greenland (Wordie Creek Fm; Brinkmann et al., 2010; Kear et al., 2016), the famous fish nodules from the Middle Sakamena Formation of Madagascar (Beltan, 1996; Brinkmann et al., 2010; Kogan & Romano, 2016), the ichthyosaur- and thalattosaur-bearing faunas of the Sulphur Mountain Formation from British Columbia and Alberta, Canada (Bastiaans et al., 2023a, 2023b; Neuman, 1992, 2015) and of the Vikinghøgda Formation in Svalbard (Hurum et al., 2018).

Table 1.

Coding for the comparison of conservation deposits based on characteristics supposed by Seilacher et al. (1985), using data and modifications by Frey et al. (2019)

Name Country, region Age (not coded) Marine basin size Facies Palaeolatitude Thickness Duration Sea level Sediment structures Pyrite Fauna Traces Infauna Epibenthos Pelagics (macro)
Ediacara Australia Proterozoic 1 1 1 1 1 0 1 0 0 0 0 1 0
Maotianshan Shales S China Cambrian 1 1 0 1 0.5 0.5 1 1 0 0 0 1 1
Burgess Shale Canada Cambrian 1 1 0 1 0.5 1 0 0 0 0 1 1 1
Fezouata Fm Morocco Ordovician 1 1 1 1 1 0.5 1 1 0 0 0 1 1
Hunsrück Shale Germany Devonian 1 1 0 1 0.5 1 0 1 0 1 0 1 0
Gogo Fm Australia Devonian 1 1 0 1 0.5 0.5 0 0 1 0 0 1 1
Thylacoceph. Layer Morocco Devonian 1 1 1 0.5 0.5 1 0 1 1 1 0 1 0
Madene HBS Morocco Devonian 1 1 1 0 0 0.5 0 0 0 1 0 1 0
Bear Gulch Lst Montana Carboniferous 1 0 0 1 0.5 0 0 0 1 0 0 1 0
Francis Creek Shale Illinois Carboniferous 1 1 0 0.5 0.5 0 0 1 0 1 0 1 0
Thaynes Gp Nevada Early Triassic 1 1 0 1 0 0.5 0 1 0 0 0 1 1
Wordie Creek Fm Greenland Early Triassic 1 1 1 1 0.5 0.5 0 0 0 0 0 1 1
Sakamena Gp Madagascar Early Triassic 1 1 1 0.5 0.5 0.5 0 0 1 0 0 0 1
Candelaria Fm Nevada Early Triassic 1 1 0 1 0 0.5 0 0 0 0 0 1 0
Osawa Fm Japan Early Triassic 1 1 0 1 0.5 1 0 0 0 0 0 1 1
Nanlinghu Fm S China Early Triassic 1 0 0 1 0.5 0.5 0 1 1 0 0 0 1
Jialingjiang Fm S China Early Triassic 1 0 0 1 0 0.5 0 0 1 0 0 0 1
Sulphur Mt Fm Alberta, Can Early Triassic? 1 1 0 1 0.5 0.5 0 0 1 0 0 1 1
Vikinghøgda Fm Svalbard Early Triassic? 1 1 1 1 0.5 0.5 0 0 0 1 0.5 1 1
Besano Fm Switzerl Mid Triassic 1 1 0 1 0.5 0.5 0 1 1 0.5 0 0 1
Cava inferiore Switzerl Mid Triassic 1 0 0 0 0 0.5 0 0 1 0 0 0 1
Cava superiore Switzerl Mid Triassic 1 0 0 0.5 0 0.5 0 0 1 0 0 0 1
Cassina Switzerl Mid Triassic 1 0 0 0 0 0.5 0 1 1 0 0 0 1
Kalkschieferz Switzerl Mid Triassic 1 0 0 1 0 0.5 0 0 0 0.5 0 0.5 1
Prosanto Fm Switzerl Mid Triassic 1 1 0 1 0.5 0.5 0 0 1 0 0 1 1
Partnach Fm Austria Mid Triassic 1 0 0 0.5 0.5 0.5 0 0 1 0 0 1 0
Prida Fm Nevada Mid Triassic 1 0 0 1 0.5 0.5 0 0 0 0 0 1 1
Botneheia Fm Svalbard Mid Triassic 1 1 1 1 0.5 0.5 0 1 1 0 0 1 1
Guanling Fm Luop S China Mid Triassic 1 0 0 1 0 0.5 0 1 0 0 0 1 1
Guanling Fm Panx S China Mid Triassic 1 0 0 0.5 0 0.5 0 0 1 0 0 0 0
Falang Fm Xingyi S China Mid Triassic 1 0 0 0.5 0.5 0.5 0 0 1 0 0 0 0
Xiaowa Fm S China Late Triassic 1 0 0 0.5 0 0.5 0 0 1 0 0 1 1
Calcare di Zorzino Italy Late Triassic 1 0 0 0.5 0 1 0 1 1 0 0 1 1
Lunz Fm Austria Late Triassic 1 1 0 0.5 0 0.5 0 1 0 0 0 1 1
Seefeld Mb Austria Late Triassic 1 0 0 0.5 0 0.5 0 1 1 0 0 0 1
Psilonotenton Fm Germany Jurassic 0 1 0 0 0 0 1 0 0 0 0 1 0
Posidoniensch. Fm Germany Jurassic 1 1 0 1 0.5 0.5 0 1 1 1 0 1 0
Oxford Clay Fm UK Jurassic 1 1 0 0.5 0.5 1 0 1 0 0 0 1 0
Terre noires France Jurassic 1 1 0 0.5 0.5 0.5 0 1 0 0 0 1 0
Altmühltal Fm Germany Jurassic 1 0 0 1 0.5 0.5 0 0 1 1 0 1 0
Painten Fm Germany Jurassic 0.5 0 0 1 0.5 0.5 0 0 1 1 0 1 0
Nusplingen Fm Germany Jurassic 0.5 0 0 0.5 0.5 0.5 0 0 1 1 0 1 0
Aitou Fm Lebanon Cretaceous 1 0 0 0.5 0.5 0.5 0 0 1 0 0 1 0
Milna Fm, Hvar Croatia Cretaceous 1 0 0 0.5 0.5 0 0 0 1 0 0 1 0
Fm Mte Post-Pesc Italy Palaeog 0.5 0 0 1 0 0.5 0 0 1 0 0 1 0
Open in a new tab

For the literature sources, see text and Table 2. Coding: Marine basin size—0: < 1 km2; 0.5: 1 to 10 km2; 1: > 10 km2. Facies—0: limestone; 1: clastics. Palaeolatitude—0: tropical; 1: moderate. Thickness—0: < 1 m; 0.5: 1 to 10 m; 1: > 10 m. Duration—0: < 1 Ma; 1: 0.5 to 10 Ma; 1: > 10 Ma. Sea level—0: < 10 m; 0.5: 10 to 100 m; 1: > 100 m. Sediment structures—0: lamination; 1: ripple marks. Pyrite—0: absent; 1: present. Fauna—0: invert. 1: vert. (common). Traces- 0: absent; 1: present. Infauna—0: absent; 1: present. Epibenthos—0: absent; 1: present. Pelagics (macro)—0: nekton; 1: plankton (dominant). Death marches—0: absent; 1: present. Landing marks—0: absent; 1: present

Thylacoc. L Thylacocephalan Layer, Famennian, Morocco, HBS Hangenberg Black Shale, end Devonian, Palaeog Palaeogene

Table 2.

Coding for the comparison of conservation deposits based on characteristics supposed by Seilacher et al. (1985), using data and modifications by Frey et al. (2019)

Name Death marches Landing marks Soft parts Cuticles Articulation Life position Roll marks Alignmennt Aragonite Pyrite steinkerns Concretions Deformation Carbonization Phosphatization
Ediacara 0 0 0 0 0 0 0 1 0 0 0 0 0 0
Maotianshan Shales 0 0 1 1 1 0 0 0 0 0 0 1 0 0
Burgess Shale 0 0 1 1 1 0 0 1 0 0 0 1 0 0
Fezouata Fm 0 0 1 1 1 0 0 0 0 0 0 1 0 0
Hunsrück Shale 1 0 1 1 1 0 0 1 0 1 0 1 0 1
Gogo Fm 0 0 1 1 1 0 0 0 0 0 1 0 0 1
Thylacoceph. Layer 0 0 1 1 1 0 0 0 0 1 1 1 0 1
Madene HBS 0 0 1 1 1 0 0 0 0 0 0 1 1 1
Bear Gulch Lst 0 0 1 1 1 0 0 0 0 0 0 1 1 1
Francis Creek Shale 1 0 1 1 1 0 0 0 0 0 1 1 1 1
Lower lst, Thaynes Gp 0 0 1 1 1 0 0 0 0 0 0 1 1 1
Wordie Creek Fm 0 0 0 0 1 0 0 0 0 0 1 1 0 0
Middle Sakamena Fm 0 0 0 0 1 0 0 0 0 0 1 1 0 0
Candelaria Fm 0 0 0 0 1 0 0 0 0 0 1 1 0 0
Osawa Fm 0 0 0 1 1 0 0 0 0 0 0 1 0 0
Nanlinghu Fm 0 0 0 0 1 0 0 0 0 0 0 1 0 0
Jialingjiang Fm 0 0 0 0 1 0 0 0 0 0 0 1 0 0
Sulphur Mt. Fm 0 0 0 0 1 0 0 0 0 0 0 1 0 0
Vikinghøgda Fm 0 0 0 0 1 0 0 0 0 0 1 0 0 0
MSG, Besano Fm 0 0 1 1 1 0 0 0 0 0 0 1 1 1
MSG, Cava inferiore 0 0 0 0 1 0 0 0 0 0 0 1 0 0
MSG, Cava superiore 0 0 1 1 1 0 0 0 0 0 0 1 1 1
MSG, Cassina 0 0 0 1 1 0 0 0 0 0 0 1 1 0
Kalkschieferzone 0 0 0 1 1 0 0 0 0 0 0 1 1 0
Prosanto Fm 0 0 0 1 1 0 0 0 0 0 0 1 0 0
Partnach Fm 0 0 1 0 1 0 0 0 0 0 0 1 0 0
Prida Fm 0 0 0 0 1 0 0 0 0 0 1 1 0 0
Botneheia Fm 0 0 0 0 1 0 0 0 0 0 0 1 0 0
Guanling Fm Luoping 0 0 0 1 1 0 0 0 0 0 1 1 1 0
Guanling Fm Panxian 0 0 0 0 1 0 0 0 0 0 1 1 0 0
Falang Fm Xingyi 0 0 0 0 1 0 0 0 0 0 0 1 0 0
Xiaowa Fm Guanling 0 0 0 0 1 0 0 0 0 0 0 1 1 0
Calcare di Zorzino 0 0 0 1 1 0 0 0 0 0 0 1 0 0
Lunz Fm 0 0 1 1 1 0 0 0 1 0 0 1 1 1
Seefeld Mb 0 0 1 1 1 0 0 1 0 0 0 1 1 1
Psilonotenton Fm 0 0 0 0 1 0 0 0 0 0 0 0 0 0
Posidonienschiefer Fm 0 0 1 1 1 0 0 1 0 1 1 1 1 1
Oxford Clay Fm 0 0 1 1 1 0 0 0 1 0 0 1 0 1
Terres noires, La Voulte 0 0 1 1 1 0 0 0 0 1 1 1 0 1
Altmühltal Fm 1 1 1 1 1 0 1 1 0 0 0 1 0 1
Painten Fm 1 1 1 1 1 0 1 1 0 0 0 1 1 1
Nusplingen Fm 1 1 1 1 1 0 0 1 0 0 0 1 1 1
Aitou Fm 0 0 1 1 1 0 0 1 0 0 0 1 1 1
Milna Fm, Hvar 0 0 1 1 1 0 0 1 0 0 0 1 1 1
Fm del Monte Postale-Pesciara 0 0 1 1 1 0 0 0 0 0 0 1 1 1
Name Pyritization Clay minerals Silicification Obrution Stagnation Bacterial/algal Source
Ediacara 0 0 0 0 0 1 Selden & Nudds, 2012
Maotianshan Shales 1 1 0 0 1 0 Xian-Guang et al. 2003
Burgess Shale 0 0 0 1 1 0 Briggs et al., 1994
Fezouata Fm 1 1 0 1 0 0 van Roy et al., 2010, Martin et al., 2016
Hunsrück Shale 1 0 0 1 1 0 Bartels et al., 1998
Gogo Fm 1 0 0 0 1 0 Long & Trinajstic, 1982
Thylacoceph. Layer 1 0 1 0 1 0 This paper
Madene HBS 0 0 0 0 1 0 This paper
Bear Gulch Lst 0 0 0 1 0 0 Grogan & Lund, 2002
Francis Creek Shale 0 0 0 1 1 0 Selden & Nudds, 2012
Lower lst, Thaynes Gp 0 0 0 0 1 0 Brayard et al., 2017
Wordie Creek Fm 0 0 0 0 1 0 Brinkmann et al., 2010
Middle Sakamena Fm 0 0 0 0 1 0 Kogan & Romano, 2016
Candelaria Fm 0 0 0 0 1 0 Ware et al., 2011
Osawa Fm 0 0 0 0 1 0 Ehiro, 2022
Nanlinghu Fm 0 0 0 0 1 0 Du et al., 2023
Jialingjiang Fm 0 0 0 0 1 0 Li & Liu, 2020
Sulphur Mt. Fm 0 0 0 0 1 0 Neuman, 2015
Vikinghøgda Fm 0 0 1 0 1 0 Hurum et al., 2018
MSG, Besano Fm 1 0 0 0 1 0 Etter, 2002a
MSG, Cava inferiore 0 0 0 0 1 0 Furrer, 2003
MSG, Cava superiore 0 0 0 0 1 0 Furrer, 2003
MSG, Cassina 0 0 0 0 1 0 Stockar, 2010
Kalkschieferzone 0 0 0 0 1 0 Furrer, 2003
Prosanto Fm 0 0 0 0 1 0 Scheyer et al., 2017
Partnach Fm 0 0 0 0 1 0 Tichy, 1998
Prida Fm 0 0 0 0 1 0 Sander et al., 1994, 2021
Botneheia Fm 1 0 0 0 1 0 Engelschiøn et al., 2023
Guanling Fm Luoping 0 0 0 0 1 1 Hu et al., 2011
Guanling Fm Panxian 0 0 0 0 1 0 Jiang et al., 2009
Falang Fm Xingyi 0 0 0 0 1 0 Lu et al., 2018
Xiaowa Fm Guanling 0 0 0 0 1 0 Wang et al., 2008
Calcare di Zorzino 0 0 0 0 1 0 Tintori, 1992
Lunz Fm 0 0 0 0 1 0 Lukeneder & Lukeneder, 2021, 2022, 2023
Seefeld Mb 0 0 0 0 1 0 Hornung et al., 2019
Psilonotenton Fm 0 0 0 1 0 0 Seilacher et al., 1985
Posidonienschiefer Fm 1 0 0 0 1 0 Röhl et al., 2001, 2002
Oxford Clay Fm 0 0 0 0 1 0 Wilby et al., 2008
Terres noires, La Voulte 1 0 0 1 1 0 Etter, 2002b; Charbonnier, 2009
Altmühltal Fm 0 0 0 0 1 1 Arratia et al., 2015
Painten Fm 0 0 0 0 1 1 Arratia et al., 2015
Nusplingen Fm 0 0 0 0 1 1 Dietl & Schweigert, 2001
Aitou Fm 0 0 0 0 1 1 Forey et al., 2003
Milna Fm, Hvar 0 0 0 0 0 1 Hemleben & Freels, 1977
Fm del Monte Postale-Pesciara 0 0 0 0 1 0 Tang, 2002
Open in a new tab

Coding: for all characteristics 0: absent and 1: present

Since the various subunits of the Anisian and Ladinian strata at Monte San Giorgio bear different faunas, we discriminated between the Besano Formation, and the younger units Cava inferiore, Cava superiore, Cassina beds as well as the Kalkschieferzone (e.g., Stockar, 2010). For the Middle Triassic, we added several Chinese localities, which were highlighted as Konservat-Lagerstätten by Benton et al. (2013), being aware that there are several other important localities with articulated vertebrates in China. We assembled data for the localities Luoping, Yunnan (Guanling Fm; Hu et al., 2011), Panxian, Guizhou (Guanling Fm; Jiang et al., 2009), and Xingyi, Guizhou (Falang Fm; Lu et al., 2018). We complemented that list with some European Lagerstätten such as the Swiss Ducanfurgga (Prosanto Fm; Scheyer et al., 2017), which yielded some amazing vertebrate fossils recently (Cavin et al., 2017a, 2017b; Ferrante et al., 2023; Scheyer et al., 2017). Furthermore, we included data from the conservation deposits of the Prida Formation of Fossil Hill, Nevada (Kelley et al., 2016; Sander et al., 1994, 2021), Edgeøya, Svalbard (Botneheia Fm; Engelschiøn et al., 2023; Kear et al., 2016) and the Eosauropterygia-rich strata of the Gailtal in Carinthia (Partnach Fm; e.g., Rieppel, 1994; Tichy, 1998; Zapfe & König, 1980).

As far as the Late Triassic is concerned, we now included the Xiaowa Formation of Guanling, China (Jiang et al., 2005) as well as three European Lagerstätten. Austria has important conservation deposits of Late Triassic age, which received more attention recently. These are the Lunz Formation with the Polzberg biota (Lukeneder & Lukeneder, 2021, 2022, 2023) and the Seefeld Member of Wiestal (Hornung et al., 2019). From Italy, we included the Calcare di Zorzino (Tintori, 1992), which is renowned for the oldest pterosaurs and its splendid fish fauna. Of course, there are numerous more Triassic localities worldwide that yielded excellent fossils; a more comprehensive list was assembled by Brinkmann et al. (2010), but even this list needs an update.

As in Frey et al. (2019), we included the data of these 45 Lagerstätten listed in Tables 1 and 2 in principal component analyses on the variance–covariance matrix in PAST (Hammer et al., 2001). Eigenvalues are listed in Table 3. We then assembled data of the faunal composition and rough abundance estimates of the Triassic Lagerstätten in Table 4 with the eigenvalues in Table 5. We included rough estimates of relative abundances of most organism groups with a focus on eukaryotes, i.e. invertebrates are also included (for cephalopods, see, e.g., Airaghi, 1911; Rieber, 1969, 1970, 1973, 1974; Pieroni, 2022; Pohle et al. in press). Finer estimates of abundances can currently not be made since quantitative data are not available at the same precision for all localities and strata included in this analysis. We then ran another principal component analysis in PAST to compare the relative faunal composition of the Triassic sites (eigenvalues in Table 5). Additionally, we carried out hierarchical cluster analyses (paired group, Ward’s method) using the same datasets. The layout of all biplots was made with CorelDraw X8.

Table 3.

Eigenvalues and variance of the principal components used for the comparison of conservation deposits

PC Eigenvalue % Variance
1 0.964394 22.386
2 0.698364 16.211
3 0.470158 10.913
4 0.324177 7.5249
5 0.252938 5.8713
6 0.239602 5.5617
7 0.189823 4.4062
8 0.163697 3.7998
9 0.144394 3.3517
10 0.123463 2.8658
Open in a new tab

For the matrix, see Tables 1 and 2

Table 4.

Standardized coding for the comparison of Triassic conservation deposits based on faunal composition

Name Other organisms Algae Higher plants Ammonoids Other cephalopods Bivalves Other benthic molluscs Arthropods Crinoids Other echinoderms Agnathans and conodonts Chondrichthyans Actinopterygians Sarcopterygians
Lower lst, Thaynes Gp 1 1 0 0.5 1 0.5 1 1 0.5 1 0.5 0.5 0.5 0

Wordie Creek

Fm

 0 0 0 1 0 1 0 0 0 0 0.5 0.5 1 1

Middle

Sakamena Fm

 0 0 0 0.5 0 0.5 0 0.5 0 0 0 0.5 1 1
Candelaria Fm 0 0 0 1 0.5 1 0 0 0 0 0.5 0 0.5 0
Osawa Fm 0 0 0.5 1 0.5 0 0 0.5 0 0 0.5 0.5 0.5 0
Nanlinghu Fm 0.5 0 1 0.5 0 0.5 0.5 0.5 0 0 0.5 0 1 0
Sulphur Mt. Fm 0 0 0 0.5 0 0.5 0 0 0 0 0.5 0.5 1 1

Jialing-

jiang Fm

 0 0 0 1 0 1 0 0 0 0 0.5 0 1 0

Viking-

høgda Fm

 0 0.5 0.5 1 0 1 1 0 0 0 1 1 1 1
MSG, Besano Fm 0 0.5 0.5 0.5 1 0.5 1 0.5 0.5 1 0.5 0.5 1 1
MSG, Cava inferiore 0 0.5 0 0 0 0.5 0.5 0 0 0 0 0 1 0
MSG, Cava superiore 0 0.5 0 0.5 0 0.5 0.5 0 0 0.5 0 0 1 0
MSG, Cassina 0.5 0.5 1 0 0 0 0 0 0 0 0.5 0 1 0
Kalkschieferzone 0.5 0.5 0.5 0 0 0 0.5 1 0 0 0 0 1 0
Prosanto Fm 0 0 0.5 0 0 0 0 0 0 0 0.5 0 1 1
Partnach Fm 0 0 0 0.5 0.5 0.5 0 0 0 0 0 0 0 0
Prida Fm 0 0 0 0 1 1 0 0 0 0 1 0.5 0.5 1
Botneheia Fm 0 0 0 0.5 0 1 0 0 0 0 0.5 1 1 1
Guanling Fm Luoping 1 0 0.5 0.5 1 1 1 1 0.5 0 1 0 1 1
Guanling Fm Panxian 0 0 0.5 0.5 0 1 0 0 0 0 0.5 0 1 0
Falang Fm Xingyi 1 0 0.5 1 0 0.5 0 1 0 0 0.5 0 1 0
Xiaowa Fm Guanling 1 0 1 1 1 1 1 0.5 1 0 0.5 0.5 0.5 0
Calcare di Zorzino 0.5 0 0.5 0 0 1 0.5 0.5 0.5 0.5 0 0.5 1 0
Lunz Fm 1 1 0.5 1 1 1 1 0.5 0 1 0.5 0.5 1 1
Seefeld Mb 0 0 0 0 0 0 0 0.5 0 0 0 0 1 1
Name Ichthyosaurs Thalattosaurs Eosauropterygians Placodonts Tanystrophaeids s.l Other vertebrates
Lower lst, Thaynes Gp 0 0 0 0 0 0 Brayard et al., 2017

Wordie Creek

Fm

 0 0 0 0 0 0 Brinkmann et al., 2010; Kear et al., 2016

Middle

Sakamena Fm

 0 0 0 0 0 1 Kogan & Romano, 2016
Candelaria Fm 0 0 0 0 0 0 Ware et al., 2011
Osawa Fm 0.5 0 0 0 0 0 Ehiro, 2022
Nanlinghu Fm 1 0 0.5 0 0 0 Du et al., 2023
Sulphur Mt. Fm 1 0.5 0 0 0 0 Neuman, 2015

Jialing-

jiang Fm

 0 0 0.5 0 0 1 Li & Liu, 2020

Viking-

høgda Fm

 1 0 0 0 0 0.5 Hurum et al., 2018
MSG, Besano Fm 1 0.5 1 0.5 0.5 0.5 Etter, 2002a
MSG, Cava inferiore 0 0 0.5 0 0.5 0 Furrer, 2003
MSG, Cava superiore 0 0 0.5 0 0 0 Furrer, 2003
MSG, Cassina 0 0 0.5 0 0.5 0 Stockar, 2010
Kalkschieferzone 0 0 0.5 0 0 0 Furrer, 1995, 2003
Prosanto Fm 0 0 0.5 0 0.5 0 Scheyer et al., 2017
Partnach Fm 0 0 1 0 0.5 0 Tichy, 1998
Prida Fm 1 0 0 0 0 0 Sander et al., 1994
Botneheia Fm 1 0 0 0 0 0 Brinkmann et al., 2010; Kear et al., 2016
Guanling Fm Luoping 1 0 1 0 0 1 Benton et al. 2013
Guanling Fm Panxian 1 0 1 0.5 0.5 1 Benton et al. 2013
Falang Fm Xingyi 0.5 0.5 1 0.5 0.5 0 Benton et al. 2013
Xiaowa Fm Guanling 1 1 0 0.5 0 0.5 Benton et al. 2013
Calcare di Zorzino 0 0.5 0 0.5 0.5 0.5 Tintori, 1992
Lunz Fm 0 0 0 0 0 0 Lukeneder and Lukeneder 2021, 2022, 2023
Seefeld Mb 0 0 0 0 0 0 Hornung et al., 2019
Open in a new tab

For the literature sources, see text and Table 2. Coding: 0: absent or rare; 0.5: moderately common; 1: relatively abundant. For abbreviations see caption of Table 2

Table 5.

Eigenvalues and variance of the principal components used for the comparison of Triassic conservation deposits based on faunal composition

PC Eigenvalue % Variance
1 0.643425 24.364
2 0.470369 17.811
3 0.33971 12.864
4 0.233635 8.847
5 0.178979 6.7774
6 0.160213 6.0667
7 0.134371 5.0882
8 0.125886 4.7669
9 0.0854462 3.2356
10 0.0731675 2.7706
Open in a new tab

Results

Characteristics of the Konservatlagerstätten of Monte San Giorgio

Like several other Triassic conservation deposits, today’s Monte San Giorgio was located at the margin of the Tethys in a tropical latitude during the Middle Triassic (Fig. 6; see, e.g., Lu et al., 2018; Benton et al., 2013). Lithologically, the Besano Formation is dominated by light grey to dark grey dolomitized limestones and black shales (e.g., Arif et al., 2019; Bassani, 1886; Baumgartner et al., 2001; Bernasconi, 1994; Felber, 2006; Furrer, 1995, 2003, 2004; Röhl et al., 2001; Stockar et al., 2012). Most of the strata that yielded articulated vertebrate skeletons (sometimes with embryos or soft-tissue remains: Figs. 2B, 5) are thin-bedded and laminated black shales. In these respects, this Lagerstätte is quite similar to several of those from China (Guanling Fm of Luoping and Panxian, Falang Fm of Xingyi, Xiaowa Fm of Guanling; Benton et al., 2013). The fossiliferous Besano Formation is about 16 m thick and overlies the Salvatore Dolomite (Stockar, 2010). Above, the San Giorgio Dolomite and the Ladinian Meride Limestone follow; the latter contains further beds of Lagerstätten quality such as the Cava inferiore and superiore as well as the Cassina beds and the Kalkschieferzone (Stockar et al., 2010). Except for the somewhat more carbonatic Kalkschieferzone (hence the name), the other four units are dominated by finely laminated limestones and black shales (Stockar, 2010). Depending on the clay content, the fossils (including the bones) are flattened to varying degrees. This applies particularly to the articulated skeletons, although those preserved in carbonatic strata display three-dimensionally preserved bones, occasionally even undeformed. For a recent account of the fossil content with a focus on vertebrates, see Rieppel (2019).

Interestingly, the Besano Formation of Monte San Giorgio plotted somewhat separately from the other black shale deposits compared to the analysis of Frey et al. (2019) and in a different region than the other fossiliferous units at Monte San Giorgio (Fig. 7). In one of the cluster analyses (Fig. 8B), the Besano Formation formed a cluster with the Seefeld Member of Wiestal and the Cava superiore, while the other three units of Monte San Giorgio fell in a different place. In the PCA, the data points of all the Chinese Lagerstätten plot in the vicinity of the Cava inferiore and superiore, the Cassina beds and the Kalkschieferzone; this pattern was also found in the cluster analyses of Fig. 8. The data points of the classic black shales such as Holzmaden (Posidonia shale, Toarcian, Jurassic; Röhl et al., 2002), Bundenbach (Hunsrück slate, Emsian, Devonian; Bartels et al., 1998; De Baets et al., 2013) or Christian Malford (Oxford Clay, Jurassic; Wilby et al., 2008) lie in their own cluster (grey in Figs. 7, 8). In the PCA, the data point of the Besano Formation plots at the margin of the field of the Monte San Giorgio type conservation deposits and more or less between the fields occupied by Solnhofen type and the Holzmaden type Lagerstätten. This was expected considering that in all these deposits, flattened but articulated vertebrate skeletons are common, phosphatized soft-tissues are preserved, and pyritization occurs, albeit to differing extends (very common in the Hunsrück slate and the Posidonia shale while relatively rare in the Besano Formation: Fig. 5). Importantly, the facies of Monte San Giorgio is intermediate given the fact that it contains both laminated limestones and black shales. Accordingly, the Kalkschieferzone and Cava inferiore plot closer to the Solnhofen type in Fig. 7B. Fossil preservation, faunal composition (lack or scarcity of benthos), sedimentary facies, and the palaeogeographical setting suggest at least episodically anoxic conditions (Röhl et al., 2001; Stockar et al., 2012).

Fig. 7.

Fig. 7

Open in a new tab

Classification of marine conservation deposits using a variation–covariation principal components analysis and the characterization of the Besano Formation of Monte San Giorgio (red margin). Data are listed in Tables 1 and 2. Modified after Frey et al. (2019). Note that among Triassic deposits, Monte San Giorgio, the Paris biota (Thaynes Fm) and Polzberg (Lunz Fm) are the only ones plotting close to the classic Black Shale Lagerstätten in A. A PCA 1 and 2; B PCA 2 and 3

Fig. 8.

Fig. 8

Open in a new tab

Classification of marine conservation deposits using cluster analyses. A paired groups. B Ward’s method. Note how in both cases, the Solnhofen and Holzmaden type Lagerstätten cluster well

Triassic marine conservation deposits worldwide

As mentioned above, numerous Triassic localities with preservation modes similar to those known from the fossiliferous beds at Monte San Giorgio have been discovered in South China in the last decades (e.g., Benton et al., 2013; Li, 2006; Lu et al., 2018). Some are from the Early Triassic (Chaoxian, Nanzhang, Wuming, Yuan’an), several from the Middle Triassic (Dingxiao, Guiyang, Fuyuan, Luoping, Luxi, Panxian, Qingzhen, Renhuai, Xingyi) and at least three from the Late Triassic (Guanling, Nylamu, Tingri). Although fossil preservation surprisingly often resembles that of the Besano Formation of Monte San Giorgio (Xiaowa Fm of Guanling, Daye Fm of Guiyang, Guanling Fm of Panxian, Falang Fm of Xingyi), the overall taxonomic composition is similar but differs in key aspects (Table 4, Figs. 9, 10). Also, the respective abundances of the various vertebrate groups are not identical (Benton et al., 2013). The upper part of the Besano Formation yielded many fishes, Neusticosaurus (a pachypleurosaurid eosauropterygian) and Mixosaurus (an ichthyosaur), while some of the Chinese localities like the Xiaowa Fm of Guanling (Benton et al., 2013; Liu et al., 2013; Rieppel, 2019; Wang et al., 2008) are, e.g., rich in thalattosaurs. Furthermore, the huge pseudoplanktonic crinoid colonies of Traumatocrinus present at Guanling (Hagdorn et al., 2007) are unknown from the Alpine occurrences but are comparable to the driftwood crinoid colonies of Moroccocrinus of Late Devonian age from Morocco (Frey et al., 2018, 2019; Klug et al., 2003) and Seirocrinus found in the Jurassic Posidonia shale (e.g., Hess, 1999).

Fig. 9.

Fig. 9

Open in a new tab

Classification of Triassic marine conservation deposits based on abundances of fossil groups using a variation–covariation principal components analysis and the characterization of the fossiliferous units of Monte San Giorgio (red margin). Data are listed in Table 4. Note the similarity in faunal composition of Monte San Giorgio and the Chinese Lagerstätten. The Paris biota (Thaynes Fm) and Polzberg (Lunz Fm) are special in being more invertebrate dominated. The fish localities overlap with those with abundant reptiles (e.g., Ducan). A PCA 1 and 2; B PCA 2 and 3. Reptiles in the graph stands for other reptile groups

Fig. 10.

Fig. 10

Open in a new tab

Classification of Triassic marine conservation deposits based on abundances of fossil groups using a hierarchical cluster analysis and the characterization of the fossiliferous units of Monte San Giorgio (red margin). Data are listed in Table 4

In addition to the Chinese occurrences, well comparable conservation deposits of Triassic age with black shale characteristics in a broad sense (i.e. dark sediment, complete skeletons, poor in benthos, rich in clay) have been recognized in many other places. Examples for such deposits have been documented from Europe (eastern Switzerland, Ducan: Furrer, 2004; western Austria: Zapfe & König, 1980; Wachtler & Perner, 2018; Italy: Stefani et al., 1991; Slovakia: Čerňanský et al., 2018; Slovenia: Hitij et al., 2010), Asia (Spiti, India: Romano et al., 2016; Myanmar: San et al., 2019), and North America (Idaho: Brayard et al., 2017; Nevada: Romano et al., 2019).

Our principal components analysis shown in Fig. 9 allows a classification according to the abundance of (i) more pelagic groups such as ammonoids, fishes and ichthyosaurs; (ii) more neritic groups such as eosauropterygians or tanystrophaeids or (iii) generally invertebrates. Remarkably, the data points of Cava inferiore, Cava superiore, Cassina Beds and the Kalkschieferzone again plotted closer to each other than to the point of the Besano Formation. This pattern is also seen in the cluster analysis in Fig. 10. When regarding the PC1/PC2-plot, the Besano Formation-point is in the field of Lagerstätten with abundant invertebrates, while when regarding PC2 and PC3, it falls quite central in the neritic groups/ reptile-dominated field, possibly due to the abundance of eosauropterygians, thalattosaurs and placodonts. The other four units of Monte San Giorgio fall in their own field in the PC2/PC3-plot with other neritic animal-dominated Lagerstätten.

Discussion

In our principal component analysis presented in Fig. 7, it is remarkable how well especially the platy limestones (Solnhofen type) separate from all other marine Lagerstätten, at least in PC1 and PC2. The German localities plot even closer together within this field (lower right corner in Fig. 7A). They formed their own cluster in both cluster analyses (Fig. 8). The Palaeozoic localities of the Cambrian and Ordovician also fell in a quite well delineated field, which comprises all of the Burgess type both in the PCA and in one of the cluster analyses (Fig. 8A). Likewise, the classic black shale occurrences (Holzmaden type) plot close to each other in the PCA and in both cluster analyses (Fig. 8), while the Monte San Giorgio type organic-rich deposits are somewhat scattered in the PCA (Fig. 7), occupying a large but separate field, thus suggesting a somewhat variable palaeoenvironment. Remarkably, this includes occurrences of Early, Middle and Late Triassic age. It is worth mentioning that this pattern remained stable even after several changes in the matrix. Unsurprisingly, the localities of the Chinese Triassic included here lie quite close to each other in the PCA and the cluster analyses. It is also noteworthy that, in the PC2/PC3-plot (Fig. 7B), the field of the Triassic Monte San Giorgio type Lagerstätten overlaps the fields comprising the black shales deposits of the Holzmaden and the Burgess type as well as the platy limestones of the Solnhofen type. The data points of the only Proterozoic Lagerstätten Ediacara and the obrution deposit Gmünd (Psilonotenton) usually fall more or less separate from the other points both in the PCAs and the cluster analyses.

The peculiar grouping of Monte San Giorgio type Lagerstätten (Figs. 7A, 8A, 9B), is remarkable. We suggest that the highly unusual palaeoecological conditions needed to produce the sedimentary facies of these fossiliferous beds can be explained by the long-term effects of the Permian–Triassic boundary mass extinction (Benton, 2016; Burgess et al., 2014). This created a palaeoenvironment with low oxygen conditions, euxinia, and acidification (Galfetti et al., 2007; Goudemand et al., 2019; Payne et al., 2004, 2012; Romano et al., 2013) and other special conditions, that were unusually widespread throughout much of the Triassic. In turn, this is linked with low diversity benthos in many basins including a slow reef recovery (Benton, 2016).

In our second analysis, we focused on the faunal composition of the Monte San Giorgio type Lagerstätten. The Paris (Idaho; Thaynes Fm) and Polzberg biota (Austria; Lunz Fm) yield abundant and diverse invertebrates and plot near each other in both the PCA (Fig. 9) and the cluster analyses (Fig. 10). The other localities are distributed over the PCA-biplots according to whether their fauna is rather dominated by pelagic or neritic animals. A similar result was found in the cluster analyses, although the grouping differs somewhat (Fig. 10). In the PC1–PC2 plot, the Besano Formation of Monte San Giorgio is nested between the invertebrate dominated localities, while in the PC2–PC3 plot, it falls in the field with abundant thalattosaurs, placodonts and other more neritic animals, similar to some Chinese localities.

To some degree, the groupings correspond to our expectations, i.e. we knew that the localities of Madagascar (Sakamena Fm) and Ducanfurgga (Prosanto Fm) are fish-dominated while invertebrates are very common in the biotas of Polzberg (Lunz Fm) and Paris (Thaynes Fm). The question arises to what extent the results depend on the sampling effort and the quality of the documentation of discoveries. Particularly, the discovery of larger vertebrates may depend on larger excavations over longer time spans. Future excavations in other localities should optimally be bed-by-bed like many excavations at Monte San Giorgio and should document abundance data (specimen counts per bed per surface area or rock volume). Although the Besano Formation at Monte San Giorgio has become one Triassic marine conservation deposit out of many, it is the pioneer of this kind of deposit in the Triassic and will remain an important reference in the future. Accordingly, we consider it adequate to name this kind of Triassic conservation deposits ‘Monte San Giorgio type Lagerstätten’.

Conclusions

The conservation deposits of Anisian and Ladinian age of Monte San Giorgio, comprising the Besano Formation, Cava inferiore, Cava superiore, Cassina Beds, and the Kalkschieferzone, represent some of the first black shale conservation deposits of Triassic age that were thoroughly studied. Now, after a century of excavations and more than a century of research, these deposits begin to enjoy global scientific recognition (e.g., Etter, 2002a; Rieppel, 2019), and continue to produce valuable new information about the palaeobiology and evolution of Triassic vertebrates today.

With this paper, we want to highlight the key role of the conservation deposits of Monte San Giorgio: comparable to the pioneer role of the Burgess Shale for the Cambrian Lagerstätten or Solnhofen for the Mesozoic platy limestones, we highlight the pioneer role of the Besano Formation in particular as the prototype for Triassic Lagerstätten. Our simple comparison of 45 Fossillagerstätten worldwide employing principal component and hierarchical cluster analyses of 32 traits based on the list of Seilacher et al. (1985) confirm that the Besano Formation of Monte San Giorgio Lagerstätte is remarkably similar to other Triassic black shale deposits including, e.g., those of the Swiss Ducanfurgga and the South China block. The Triassic black shale deposits demonstrably occupy their own field separate from the Burgess type black shales, Solnhofen type platy limestones or Holzmaden type black shales. Accordingly, we introduce the term Monte San Giorgio type black shales.

The separate position of the Monte San Giorgio type organic-rich sediments can be explained by the mix of laminated limestones and black shales and the scarcity of benthics, as well as the rise of several new groups such as important clades of marine reptiles. This is to some extent very likely an effect of the long-term ecological impact of the Permian–Triassic boundary mass extinction and the recovery of marine biotas.

Concerning the fossil content of the Monte San Giorgio type Lagerstätten, we found the three main groups ‘pelagic dominated’, ‘neritic dominated’ and ‘invertebrate dominated’. For some of the included Lagerstätten, the position in the PCA-plots and the cluster analyses was expected, for some others we suspect that over the years, more vertebrates and particularly reptiles may be discovered with longer or increased collecting/sampling activities. Accordingly, the respective position might change in the future.

Acknowledgements

Christian Obrist (Rickenbach) prepared the specimen in Fig. 5. We thank Adriana Lopez-Arbarello (Munich) and two anonymous reviewers for their constructive criticism, which helped to significantly improve the manuscript. Merle Greif (Zürich) kindly took the photo of the phragmoteuthid.

Author contributions

CK, BS and TMS had the idea for this study. BS made the models in Fig. 1 and the illustrations in Fig. 4. Data were collected by CK, DB, SNFS and TMS. The photos and other figures were made by CK. Parts of the text were written by all authors. All authors agreed on the final version of the text.

Funding

DB and TMS were supported by the Swiss National Science Foundation SNSF (project no. 31003A_179401). SNFS is funded by the Deutsche Forschungsgemeinschaft DFG (project no. SCHO 791/7-1 to Rainer Schoch).

Availability of data and materials

Specimens with PIMUZ numbers  are kept in the collection of the Palaeontological Institute of the University of Zurich. All data included in our analyses have been published previously and the sources are provided in Tables 2 and 4.

Declarations

Competing interests

We have no competing interests.

Footnotes

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

  1. Airaghi C. Ammoniti degli scisti bituminosi di Besano in Lombardia. Bollettino Della Società Geologica Italiana. 1911;30:1048–1050. [Google Scholar]
  2. Albisetti D, Furrer H. Bibliografia del Monte San Giorgio. Fondazione del Monte San Giorgio; 2022. p. 27. [Google Scholar]
  3. Argyriou T, Clauss M, Maxwell EE, Furrer H, Sánchez-Villagra MR. Exceptional preservation reveals gastrointestinal anatomy and evolution in early actinopterygian fishes. Scientific Reports. 2016;6:18758. doi: 10.1038/srep18758. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Arif S, Reitner J, Hoppert M. Composition, diversity and functional analysis of the modern microbiome of the Middle Triassic Cava Superiore Beds (Monte San Giorgio, Switzerland) Scientific Reports. 2019;9(1):20394. doi: 10.1038/s41598-019-55955-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Arratia G, Schultze H-P, Tischlinger H, Viohl G. Solnhofen: Ein Fenster in die Jurazeit. Pfeil; 2015. p. 620. [Google Scholar]
  6. Bartels C, Briggs DEG, Brassel G. The Fossils of the Hunsrück Slate. Marine Life in the Devonian. Cambridge Paleobiology Series. 1998;3:1–309. [Google Scholar]
  7. Bassani F. Sui fossili e sull’eta degli schisti bituminosi triasici di Besano in Lombardia. Atti Societa Italiana Di Scienze Naturali. 1886;29:15–72. [Google Scholar]
  8. Bastiaans D, Buffa V, Scheyer TM. To glide or to swim? A reinvestigation of the enigmatic Wapitisaurus problematicus (Reptilia) from the Early Triassic of British Columbia. Canada. Royal Society Open Science. 2023;10(11):231171. doi: 10.1098/rsos.231171. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Bastiaans, D., Herbst, E. C., Van de Kamp, T., Zuber, M., & Scheyer, T. M. (2023). The first 3D cranial and myological reconstruction of the highly flattened remains of Askeptosaurus italicus (Diapsida: Thalattosauriformes). Abstracts of the International Congress of Vertebrate Morphology, 28. July-01. August 2023, Cairns, Australia.
  10. Baumgartner, P. O., Bernoulli, D., & Martire, L. (2001). Mesozoic pelagic facies of the Southern Alps: Paleotectonics and paleoceanography. International Association of Sedimentologists, Davos: Field Trip Guide, Excursion A 1 (pp. 1–19).
  11. Beardmore SR, Furrer H. Preservation of Pachypleurosauridae (Reptilia, Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland. Neues Jahrbuch Für Geologie Und Paläontologie, Abhandlungen. 2016;280:221–240. doi: 10.1127/njgpa/2016/0578. [DOI] [Google Scholar]
  12. Beardmore SR, Furrer H. Land or water: Using taphonomic models to determine the lifestyle of the Triassic protorosaur Tanystropheus (Diapsida, Archosauromorpha) Palaeobiodiversity and Palaeoenvironments. 2017;98:243–258. doi: 10.1007/s12549-017-0299-7. [DOI] [Google Scholar]
  13. Bernasconi SM. Geochemical and microbial controls on dolomite formation in anoxic environments: A case study from the middle Triassic (Ticino, Switzerland) Contributions to Sedimentology. 1994;19:1–109. [Google Scholar]
  14. Beltan L. Overview of systematics, paleobiology, and paleoecology of Triassic fishes of northwestern Madagascar. In: Arratia G, Viohl G, editors. Mesozoic fishes—systematics and paleoecology. Verlag Dr. Friedrich Pfeil; 1996. pp. 479–500. [Google Scholar]
  15. Benton MJ. The Triassic. Current Biology. 2016;26:R1214–R1218. doi: 10.1016/j.cub.2016.10.060. [DOI] [PubMed] [Google Scholar]
  16. Benton M, Hu S, Zhang Q, Xie T, Zhou C, Wen W, Huang J. Establishment of the Luoping Biota National Geopark in Yunnan, China. Geoconservation Research. 2022;5:261–284. [Google Scholar]
  17. Benton MJ, Zhang Q, Hu S, Chen Z-Q, Wen W, Liu J, Huang J, Zhou C, Xie T, Tong J, Choo B. Exceptional vertebrate biotas from the Triassic of China, and the expansion of marine ecosystems after the Permo-Triassic mass extinction. Earth-Science Reviews. 2013;137:85–128. doi: 10.1016/j.earscirev.2013.05.014. [DOI] [Google Scholar]
  18. Bindellini G, Wolniewicz AS, Miedema F, Scheyer TM, Dal Sasso C. Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: Taxonomic and palaeobiological implications. PeerJ. 2021;9:1–66. doi: 10.7717/peerj.11179. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Brayard A, Krumenacker J, Botting JP, Jenks J, Bylund KG, Fara E, Vennin E, Olivier N, Goudemand N, Saucède T, Charbonnier S, Romano C, Doguzhaeva L, Thuy B, Hautmann M, Stephen DA, Thomazo C, Escarguel G. Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna. Science Advances. 2017;3:e1602159. doi: 10.1126/sciadv.1602159. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Briggs DEG, Erwin DH, Collier FJ. The Fossils of the Burgess Shale. Smithsonian Books; 1994. p. 238. [Google Scholar]
  21. Brinkmann W. Ein Mixosaurier (Reptilia, Ichthyosauria) mit Embryonen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin) Eclogae Geologicae Helvetiae. 1996;89:1321–1344. [Google Scholar]
  22. Brinkmann W. "Sangiorgiosaurus" n.g.-eine neue Mixosaurier-Gattung (Mixosauridae, Ichthyosauria) mit Quetschzähnen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin) Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 1998;207:125–144. doi: 10.1127/njgpa/207/1998/125. [DOI] [Google Scholar]
  23. Brinkmann W. Ichthyosaurus cornalianus Bassani, 1886 (currently Mixosaurus cornalianus; Reptilia, Ichthyosauria): Proposed designation of a neotype. Case 3122. Bulletin of Zoological Nomenclature. 1999;56:247–249. doi: 10.5962/bhl.part.23086. [DOI] [Google Scholar]
  24. Brinkmann W. Mixosaurier (Reptilia, Ichthyosauria) mit Quetschzähnen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin) Schweizerische Paläontologische Abhandlungen. 2004;124:1–84. [Google Scholar]
  25. Brinkmann W, Romano C, Bucher H, Ware D, Jenks J. Palaeobiogeography and stratigraphy of advanced gnathostomian fishes (Chondrichthyes and Osteichthyes) in the Early Triassic and from selected Anisian localities (Report 1863–2009) Zentralblatt Für Geologie Und Paläontologie. 2010;2:765–812. [Google Scholar]
  26. Burgess SD, Bowring S, Shen S. High-precision timeline for Earth’s most severe extinction. Proceedings of the National Academy of Sciences. 2014;111:3316–3321. doi: 10.1073/pnas.1317692111. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Bürgin T. Der Schuppenpanzer von Habroichthys minimus, einem ungewöhnlichen Strahlenflosser (Actinopterygii; Peltopleuriformes) aus der Mittleren Trias der Südalpen. Neues Jahrbuch Für Geologie Und Paläontologie, Abhandlungen. 1990;1990(11):647–658. doi: 10.1127/njgpm/1990/1990/647. [DOI] [Google Scholar]
  28. Bürgin T. Reproduction in Middle Triassic actinopterygians; complex fin structures and evidence of viviparity in fossil fishes. Zoological Journal of the Linnean Society. 1990;100:379–391. doi: 10.1111/j.1096-3642.1990.tb01866.x. [DOI] [Google Scholar]
  29. Bürgin T. Basal ray-finned fishes (Osteichthyes; Actinopterygii) from the middle Triassic of Monte San Giorgio (Canton Tessin, Switzerland): Systematic palaeontology with notes on functional morphology and palaeoecology. Schweizerische Paläontologische Abhandlungen. 1992;114:1–164. [Google Scholar]
  30. Bürgin T. Actinopterygian fishes (Osteichthyes; Actinopterygii) from the Kalkschieferzone (Uppermost Ladinian) near Meride (Canton Ticino, Southern Switzerland) Eclogae Geologicae Helvetiae. 1995;88:803–826. [Google Scholar]
  31. Bürgin T. Middle Triassic marine fish faunas from Switzerland. Mesozoic Fishes. 1999;2:481–494. [Google Scholar]
  32. Bürgin, T. (1999b). New actinopterygian fishes (Osteichthyes) from the lower Meride Limestones (Lower Ladinan) of Acqua del Ghiffo (Monte San Giorgio, Southern Switzerland). In: 3rd International symposium on lithographic limestones. Rivista Museo civico Scienze Naturali “Enrico Caffi“, Suppl. al Vol. 20, 57–62.
  33. Bürgin T, Rieppel O, Sander PM, Tschanz K. The fossils of Monte San Giorgio. Scientific American. 1989;260:74–81. doi: 10.1038/scientificamerican0689-74. [DOI] [Google Scholar]
  34. Carroll RL, Gaskill P. The nothosaur Pachypleurosaurus and the origin of plesiosaurs. Philosophical Transactions of the Royal Society of London B: Biological Sciences. 1985;309(1139):343–393. doi: 10.1098/rstb.1985.0091. [DOI] [Google Scholar]
  35. Cavin L, Furrer H, Obrist C. New coelacanth material from the Middle Triassic of eastern Switzerland, and comments on the taxic diversity of actinistians. Swiss Journal of Geosciences. 2013;106:161–177. doi: 10.1007/s00015-013-0143-7. [DOI] [Google Scholar]
  36. Cavin L, Mennecart B, Obrist C, Costeur L, Furrer H. Heterochronic evolution explains unusual body shape in a Triassic coelacanth from Switzerland. Scientific Reports. 2017;7(13695):1–7. doi: 10.1038/s41598-017-13796-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Cavin L, Mennecart B, Obrist C, Costeur L, Furrer H. Heterochronic evolution explains novel body shape in a Triassic coelacanth from Switzerland. Scientific Reports. 2017;7:13695. doi: 10.1038/s41598-017-13796-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Čerňanský A, Klein N, Soták J, Olšavský M, Šurka J, Herich P. A Middle Triassic pachypleurosaur (Diapsida: Eosauropterygia) from a restricted carbonate ramp in the Western Carpathians (Gutenstein Formation, Fatric Unit): Paleogeographic implications. Geologica Carpathica. 2018;69:3–16. doi: 10.1515/geoca-2018-0001. [DOI] [Google Scholar]
  39. Charbonnier S. Le Lagerstätte de La Voulte: Un environnement bathyal au Jurassique. Publications scientifiques du Muséum Paris; 2009. p. 272. [Google Scholar]
  40. Chen Z-Q, Benton MJ. The timing and pattern of biotic recovery following the end-Permian mass extinction. Nature Geoscience. 2012;5:375–383. doi: 10.1038/ngeo1475. [DOI] [Google Scholar]
  41. Cornalia E. Notizie zoologiche sul Pachypleura edwardsii Cor. Nuovo sauro acrodonte degli strati triasici di Lombardia. Giornale Dell’istituto Lombardo Di Scienze, Lettere Ed Arti. 1854;6:45–56. [Google Scholar]
  42. Dal Sasso C, Pinna G. Besanosaurus leptorhynchus n. gen. n. sp., a new shastasaurid ichthyosaur from the Middle Triassic of Besano (Lombardy, N. Italy) Paleontologia Lombarda, Ns. 1996;4:1–23. [Google Scholar]
  43. De Baets K, Klug C, Korn D, Bartels C, Poschmann M. Emsian Ammonoidea and the age of the Hunsrück Slate (Rhenish Mountains, Western Germany) Palaeontographica A. 2013;299:1–114. doi: 10.1127/pala/299/2013/1. [DOI] [Google Scholar]
  44. Dietl G, Schweigert G. Im Reich der Meerengel. Pfeil Verlag; 2001. [Google Scholar]
  45. Doguzhaeva LA, Brayard A, Goudemand N, Krumenacker LJ, Jenks JF, Bylund KG, Fara E, Olivier N, Vennin E, Escarguel G. An Early Triassic gladius associated with soft tissue remains from Idaho, USA—a squid-like coleoid cephalopod at the onset of Mesozoic Era. Acta Palaeontologica Polonica. 2018;63:341–355. doi: 10.4202/app.00393.2017. [DOI] [Google Scholar]
  46. Du Y, Song H, Dal Corso J, Wang Y, Zhu Y, Song H, Tian L, Chu D, Huang J, Tong J. Paleoenvironments of the Lower Triassic Chaohu Fauna, South China. Palaeogeography, Palaeoclimatology, Palaeoecology. 2023;617:1–10. doi: 10.1016/j.palaeo.2023.111497. [DOI] [Google Scholar]
  47. Edinger T. Rückenmark im Wirbelkörper! Anatomischer Anzeiger. 1924;57:515–519. [Google Scholar]
  48. Engelschiøn VS, Roberts AJ, With R, Hammer Ø. Exceptional X-Ray contrast: Radiography imaging of a Middle Triassic mixosaurid from Svalbard. PLoS ONE. 2023;18(5):e0285939. doi: 10.1371/journal.pone.0285939. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Ehiro M. Latest Olenekian (Early Triassic) Ammonoids from the Uppermost Part of the Osawa Formation (Inai Group) in the South Kitakami Belt, Northeast Japan. Paleontological Research. 2022;26:137–157. doi: 10.2517/PR200027. [DOI] [Google Scholar]
  50. Etter W. Monte San Giorgio: Remarkable Triassic marine vertebrates. In: Bottjer DJ, Etter W, Hagadorn JW, Tang CM, editors. Exceptional Fossil Preservation. Columbia University Press; 2002. p. 403. [Google Scholar]
  51. Etter W. La Voulte-sur-Rhône: Exquisite cephalopod preservation. In: Bottjer DJ, Etter W, Hagadorn JW, Tang CM, editors. Exceptional fossil preservation. Columbia University Press; 2002. p. 403. [Google Scholar]
  52. Felber M. Il Monte San Giorgio. Edizioni Casagrande: Dai fossili alla lavorazione artistica della pietra; 2006. p. 222. [Google Scholar]
  53. Felber M, Furrer H, Tintori A. The Triassic of Monte San Giorgio in the World Heritage List of UNESCO: An opportunity for science, the local people and tourism. Eclogae Geologicae Helvetiae. 2004;97:1–2. doi: 10.1007/s00015-004-1118-5. [DOI] [Google Scholar]
  54. Ferrante C, Cavin L. Early Mesozoic burst of morphological disparity in the slow-evolving coelacanth fish lineage. Scientific Reports. 2023;13:11356. doi: 10.1038/s41598-023-37849-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Forey PL, Yi L, Patterson C, Davies CE. Fossil fishes from the Cenomanian (Upper Cretaceous) of Namoura, Lebanon. Journal of Systematic Palaeontology. 2003;1:227–330. doi: 10.1017/S147720190300107X. [DOI] [Google Scholar]
  56. Frey L, Pohle A, Rücklin M, Klug C. Fossil-Lagerstätten and preservation of vertebrates and invertebrates from the Devonian of Morocco (eastern Anti-Atlas) Lethaia. 2019;53:242–266. doi: 10.1111/let.12354. [DOI] [Google Scholar]
  57. Frey L, Rücklin M, Korn D, Klug C. Late Devonian and Early Carboniferous alpha diversity, ecospace occupation, vertebrate assemblages and bio-events of southeastern Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology. 2018;496:1–17. doi: 10.1016/j.palaeo.2017.12.028. [DOI] [Google Scholar]
  58. Furrer H. The Kalkschieferzone (Upper Meride Limestone; Ladinian) near Meride (Canton Ticino, Southern Switzerland) and the evolution of a Middle Triassic intraplatform basin. Eclogae Geologicae Helvetiae. 1995;88:827–852. [Google Scholar]
  59. Furrer H. Der Monte San Giorgio im Südtessin -Vom Berg der Saurier zur Fossil-Lagerstätte internationaler Bedeutung. Neujahrsblatt Der Naturforschenden Gesellschaft Zürich. 2003;206:1–64. [Google Scholar]
  60. Furrer, H. (2004). So kam der Fisch auf den Berg—Eine Broschüre zur Sonderausstellung über die Fossilfunde am Ducan. Bündner Natur-Museum Chur und Paläontologisches Institut und Museum der Universität Zürich. 32.
  61. Furrer H, Schaltegger U, Ovtcharova M, Meister P. U-Pb zircon age of volcaniclastic layers in Middle Triassic platform carbonates of the Austroalpine Silvretta nappe (Switzerland) Swiss Journal of Geosciences. 2008;101:595–603. doi: 10.1007/s00015-008-1295-8. [DOI] [Google Scholar]
  62. Galfetti T, Bucher H, Brayard A, Hochuli PA, Weissert H, Guodun K, Atudorei V, Guex J. Late Early Triassic climate change: Insights from carbonate carbon isotopes, sedimentary evolution and ammonoid paleobiogeography. Palaeogeography, Palaeoclimatology, Palaeoecology. 2007;243:394–411. doi: 10.1016/j.palaeo.2006.08.014. [DOI] [Google Scholar]
  63. Goudemand N, Romano C, Leu M, Bucher H, Trotter JA, Williams IS. Dynamic interplay between climate and marine biodiversity upheavals during the early Triassic Smithian-Spathian biotic crisis. Earth-Science Reviews. 2019;195:169–178. doi: 10.1016/j.earscirev.2019.01.013. [DOI] [Google Scholar]
  64. Grogan ED, Lund R. The geological and biological environment of the Bear Gulch Limestone (Mississippian of Montana, USA) and a model for its deposition. Geodiversitas. 2002;24:295–315. [Google Scholar]
  65. Guttormsen SE. Beitrage zur Kenntnis des Ganoidengebisses, insbesondere des Gebisses von Colobodus. Schweizerische Paläontologische Abhandlungen. 1937;56:1–41. [Google Scholar]
  66. Hagdorn H, Wang X, Wang C. Palaeoecology of the pseudoplanktonic Triassic crinoid Traumatocrinus from Southwest China. Palaeogeography, Palaeoclimatology, Palaeoecology. 2007;247:181–196. doi: 10.1016/j.palaeo.2006.10.020. [DOI] [Google Scholar]
  67. Hammer Ø, Harper DAT, Ryan PD. PAST: Palaeontological statistics software package for education and data analysis. Palaeontologia Electronica. 2001;4:1–9. [Google Scholar]
  68. Hänni, K. (2004). Die Gattung Ceresiosaurus. Ceresiosaurus calgagnii Peyer und Ceresiosaurus lanzi n. sp. (Lariosauridae, Sauropterygia). PhD Thesis. Paläontologisches Institut und Museum, University of Zürich, Zürich. 146.
  69. Hemleben C, Freels D. Algen-laminierte und gradierte Plattenkalke in der Oberkreide Dalmatiens (Jugoslawien) Neues Jahrbuch Für Geologie Und Paläontologie, Abhandlungen. 1977;154:61–93. [Google Scholar]
  70. Herbst EC, Lautenschlager S, Bastiaans D, Miedema F, Scheyer TM. Modeling tooth enamel in FEA comparisons of skulls: comparing common simplifications with biologically realistic models. iScience. 2021;24:103182. doi: 10.1016/j.isci.2021.103182. [DOI] [PMC free article] [PubMed] [Google Scholar]
  71. Hess H. Lower Jurassic Posidonia Shale of Southern Germany. In: Hess H, Ausich WI, Brett CE, Simms MJ, editors. Fossil crinoids. Cambridge University Press; 1999. pp. 183–196. [Google Scholar]
  72. Hitij T, Žalohar J, Celarc B, Križnar M, Renesto S, Tintori A. The kingdom of Tethys: The fossilized world of Triassic vertebrates from the Kamniško-Savinjske Alps. Scopolia. 2010;5:1–212. [Google Scholar]
  73. Hornung T, Kogan I, Moosleitner G, Wolf G, van der Wielen J. The Norian fish deposits of Wiestal (“Seefeld Member”, Northern Calcareous Alps, Salzburg, Austria)—taxonomy and palaeoenvironmental implications. Austrian Journal of Earth Sciences. 2019;112:125–165. doi: 10.17738/ajes.2019.0008. [DOI] [Google Scholar]
  74. Hu S-X, Zhang Q-Y, Chen Z-Q, Zhou C-Y, Lu T, Xie T, Wen W, Huang Y-J, Benton MJ. The Luoping biota: Exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction. Proceedings of the Royal Society B. 2011;278:2274–2282. doi: 10.1098/rspb.2010.2235. [DOI] [PMC free article] [PubMed] [Google Scholar]
  75. Hugi J. The long bone histology of Ceresiosaurus (Sauropterygia, Reptilia) in comparison to other eosauropterygians from the Middle Triassic of Monte San Giorgio (Switzerland/Italy) Swiss Journal of Palaeontology. 2011;130:297–306. doi: 10.1007/s13358-011-0023-6. [DOI] [Google Scholar]
  76. Hugi J, Scheyer TM. Ossification sequences and associated ontogenetic changes in the bone histology of pachypleurosaurids from Monte San Giorgio (Switzerland/Italy) Journal of Vertebrate Paleontology. 2012;32:315–327. doi: 10.1080/02724634.2012.646376. [DOI] [Google Scholar]
  77. Hugi J, Scheyer TM, Sander PM, Klein N, Sánchez-Villagra MR. Long bone microstructure gives new insights into the life of pachypleurosaurids from the Middle Triassic of Monte San Giorgio, Switzerland/Italy. Comptes Rendus Palevol. 2011;10:413–426. doi: 10.1016/j.crpv.2011.03.009. [DOI] [Google Scholar]
  78. Hurum JH, Engelschiøn VS, Økland I, Bratvold J, Ekeheien CP, Roberts AJ, Delsett LL, Hansen BB, Mørk A, Nakrem HA, Druckenmiller PS, Hammer Ø. The history of exploration and stratigraphy of the Early to Middle Triassic vertebrate-bearing strata of Svalbard (Sassendalen Group, Spitsbergen) Norwegian Journal of Geology. 2018;98:165–174. [Google Scholar]
  79. Jaquier VP, Fraser NC, Furrer H, Scheyer TM. Osteology of a new specimen of Macrocnemus aff. M. fuyuanensis (Archosauromorpha, Protorosauria) from the Middle Triassic of Europe: implications for species recognition and paleogeography of tanystropheid protorosaurs. Frontiers in Earth Science. 2017;5:91. doi: 10.3389/feart.2017.00091. [DOI] [Google Scholar]
  80. Jaquier VP, Scheyer TM. Bone histology of the Middle Triassic long-necked reptiles Tanystropheus and Macrocnemus (Archosauromorpha, Protorosauria) Journal of Vertebrate Paleontology. 2017;37:e1296456. doi: 10.1080/02724634.2017.1296456. [DOI] [Google Scholar]
  81. Jiang D, Motani R, Hao W, Rieppel O, Sun Y, Tintori A, Sun Z, Schmitz L. Biodiversity and sequence of the Middle Triassic Panxian marine reptile fauna, Guizhou Province, China. Acta Geologica Sinica, English Edition. 2009;83:451–459. doi: 10.1111/j.1755-6724.2009.00047.x. [DOI] [Google Scholar]
  82. Jiang D, Motani R, Li C, Hao W, Sun Y, Sun Z, Schmitz L. Guanling Biota: A marker of Triassic biotic recovery from the end-Permian extinction in the ancient Guizhou Sea. Acta Geologica Sinica, English Edition. 2005;79:715–859. [Google Scholar]
  83. Jiang D-Y, Motani R, Tintori A, Rieppel O, Ji C, Zhou M, Wang X, Lu H, Li Z-G. Evidence supporting predation of 4-m marine reptile by Triassic megapredator. iScience. 2020 doi: 10.1016/j.isci.2020.101347. [DOI] [PMC free article] [PubMed] [Google Scholar]
  84. Kear BP, Lindgren J, Hurum JH, Milan J, Vajda V. An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories. In: Kear BP, Lindgren J, Hurum JH, Milan J, Vajda V, editors. Mesozoic biotas of Scandinavia and its Arctic territories. Geological Society, Special Publications; 2016. p. 15. [Google Scholar]
  85. Kelley NP, Motani R, Embree P, Orchard MJ. A new Lower Triassic ichthyopterygian assemblage from Fossil Hill, Nevada. PeerJ. 2016;4(e1626):1–16. doi: 10.7717/peerj.1626. [DOI] [PMC free article] [PubMed] [Google Scholar]
  86. Klein N, Sander PM, Liu J, Druckenmiller PS, Metz E, Kelley NP, Scheyer TM. Comparative bone histology of two thalattosaurians (Diapsida: Thalattosauria) Askeptosaurus italicus from the Alpine Triassic (Middle Triassic) and a Thalattosauroidea indet. from the Carnian of Oregon (Late Triassic) Swiss Journal of Palaeontology. 2023;142:1–20. doi: 10.1186/s13358-023-00277-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  87. Krebs B. Ticinosuchus ferox nov. gen. nov. sp. Ein neuer Pseudosuchier aus der Trias des Monte San Giorgio. Schweizerische Paläontologische Abhandlungen. 1965;81:1–140. [Google Scholar]
  88. Klug C, Rücklin M, Meyer-Berthaud B, Soria A. Late Devonian pseudoplanktonic crinoids from Morocco. Neues Jahrbuch für Geologie und Mineralogie, Monatshefte. 2003;2003(3):153–163. doi: 10.1127/njgpm/2003/2003/153. [DOI] [Google Scholar]
  89. Kogan I, Romano C. Redescription of Saurichthys madagascariensis Piveteau, 1945 (Actinopterygii, Early Triassic), with implications for the early saurichthyid morphotype. Journal of Vertebrate Paleontology. 2016;36:1–22. doi: 10.1080/02724634.2016.1151886. [DOI] [Google Scholar]
  90. Kolb C, Sánchez-Villagra MR, Scheyer TM. The palaeohistology of the basal ichthyosaur Mixosaurus (Ichthyopterygia, Mixosauridae) from the Middle Triassic: Palaeobiological implications. Comptes Rendus Palevol. 2011;10:403–411. doi: 10.1016/j.crpv.2010.10.008. [DOI] [Google Scholar]
  91. Kuhn E. Über einen weiteren Fund von Paraplacodus broilii PEYER aus der Trias des Monte San Giorgio. Eclogae Geologicae Helvetiae. 1942;35:174–183. [Google Scholar]
  92. Kuhn E. Der Schädel von Askeptosaurus italicus Nopcsa. Eclogae Geologicae Helvetiae. 1946;39:363. [Google Scholar]
  93. Kuhn E. Über Acrodus-Funde aus dem Grenzbitumenhorizont der anisischen Stufe der Trias des Monte San Giorgio (Kanton Tessin) Ecologae Geologicae Helvetiae. 1946;38:662–673. [Google Scholar]
  94. Kuhn E. Über einen Fund von Birgeria aus der Trias des Monte San Giorgio (Kanton Tessin) Eclogae Geologicae Helvetiae. 1946;39:363–364. [Google Scholar]
  95. Kuhn-Schnyder E. Hand und Fuss von Tanystropheus longobardicus (Bassani) Eclogae Geologicae Helvetiae. 1959;52:921–941. [Google Scholar]
  96. Kuhn-Schnyder E. Über Placodontier. Paläontologische Zeitschrift. 1960;34:91–102. doi: 10.1007/BF02987045. [DOI] [Google Scholar]
  97. Kuhn-Schnyder E. Ein weiterer Schädel von Macrocnemus bassanii Nopcsa aus der anisischen Stufe der Trias des Monte San Giorgio (Kt. Tessin, Schweiz) Paläontologische Zeitschrift. 1962;1962:110–133. doi: 10.1007/BF02987896. [DOI] [Google Scholar]
  98. Kuhn-Schnyder E. Der Schädel von Paranothosaurus amsleri Peyer aus dem Grenzbitumenhorizont der anisisch-ladinischen Stufe der Trias des Monte San Giorgio (Kanton Tessin, Schweiz) Eclogae Geologicae Helvetiae. 1966;59:517–540. [Google Scholar]
  99. Kuhn-Schnyder E. Das Problem der Euryapsida. Mitteilungen aus dem Paläontologischen Institut der Universität Zürich. 1967;49:335–348. [Google Scholar]
  100. Kuhn-Schnyder E. Die Triasfauna der Tessiner Kalkalpen. XXVI. Lariosaurus-lavizzarii new species (Reptiplia; Sauropterygia) Schweizerische Paläontologische Abhandlungen. 1987;110:1–24. [Google Scholar]
  101. Kuhn-Schnyder E. Bemerkungen zur Ordnung der Thalattosauria (Reptilia) Eclogae Geologicae Helvetiae. 1988;81:879–886. [Google Scholar]
  102. Lanz H, Felber M. Wissenschaftliche Grabungen, Landschaften und Menschen im Gebiet des Monte San Giorgio – Aufnahmen 1924–1936. Geologia Insubrica. 2020;14:1–110. [Google Scholar]
  103. Lautenschlager S, Desojo JB. Reassessment of the Middle Triassic rauisuchian archosaurs Ticinosuchus ferox and Stagonosuchus nyassicus. Paläontologische Zeitschrift. 2011;85:357–381. doi: 10.1007/s12542-011-0105-1. [DOI] [Google Scholar]
  104. Li J. A brief summary of the Triassic marine reptiles of China. Vertebrata PalAsiatica. 2006;44:99–108. [Google Scholar]
  105. Li Q, Liu J. An Early Triassic sauropterygian and associated fauna from South China provide insights into Triassic ecosystem health. Communications Biology. 2020;3(63):1–11. doi: 10.1038/s42003-020-0778-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  106. Liu J, Zhao LJ, Li C, He T. Osteology of Concavispina biseridens (Reptilia, Thalattosauria) from the Xiaowa Formation (Carnian), Guanling, Guizhou, China. Journal of Paleontology. 2013;87:341–350. doi: 10.1666/12-059R1.1. [DOI] [Google Scholar]
  107. Lombardo C. Sexual dimorphism in a new species of the actinopterygian Peltopleurus from the Triassic of northern Italy. Palaeontology. 1999;42:741–760. doi: 10.1111/1475-4983.00095. [DOI] [Google Scholar]
  108. Lombardo C. A new basal actinopterygian fish from the Late Ladinian of Monte San Giorgio (Canton Ticino, Switzerland) Swiss Journal of Geosciences. 2013;106:219–230. doi: 10.1007/s00015-013-0125-9. [DOI] [Google Scholar]
  109. Lombardo C, Tintori A. New Perleidiforms from the Triassic of the Southern Alps and the revision of Serrolepis from the Triassic of Wüttemberg (Germany) Mesozoic Fishes. 2004;3:179–196. [Google Scholar]
  110. Lombardo C, Tintori A, Tona D. A new species of Sangiorgioichthys (Actinopterygii, Semionotiformes) from the Kalkschieferzone of Monte San Giorgio (Middle Triassic; Meride, Canton Ticino, Switzerland) Bollettino Della Societa Paleontologica Italiana. 2012;51:203–212. [Google Scholar]
  111. Long J, Trinajstic K. A review of recent discoveries of exceptionally preserved fossil fishes from the Gogo sites (Late Devonian, Western Australia) Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 2018;108:111–117. doi: 10.1017/S1755691018000178. [DOI] [Google Scholar]
  112. López-Arbarello A, Bürgin T, Furrer H, Stockar R. New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland) PeerJ. 2016;4:e2234. doi: 10.7717/peerJ.2234. [DOI] [PMC free article] [PubMed] [Google Scholar]
  113. López-Arbarello A, Bürgin T, Furrer H, Stockar R. Taxonomy and phylogeny of Eosemionotus Stolley, 1920 (Neopterygii: Ginglymodi) from the Middle Triassic of Europe. Palaeontologia Electronica. 2019;22(1):1–64. doi: 10.26879/904. [DOI] [Google Scholar]
  114. López-Arbarello A, Stockar R, Bürgin T. Phylogenetic relationships of the Triassic Archaeosemionotus Deecke (Halecomorphi, Ionoscopiformes) from the ‘Perledo Fauna’. PLoS ONE. 2014;9(10):1–64. doi: 10.1371/journal.pone.0108665. [DOI] [PMC free article] [PubMed] [Google Scholar]
  115. Lu H, Jiang D-Y, Motani R, Ni P-G, Sun Z-Y, Tintori A, Xiao S-Z, Zhou M, Ji C, Fu W-L. Middle Triassic Xingyi Fauna: Showing turnover of marine reptiles from coastal to oceanic environments. Palaeoworld. 2018;27:107–116. doi: 10.1016/j.palwor.2017.05.005. [DOI] [Google Scholar]
  116. Lukeneder A, Lukeneder P. The Upper Triassic Polzberg palaeobiota from a marine Konservat-Lagerstätte deposited during the Carnian Pluvial Episode in Austria. Scientific Reports. 2021;11(16644):1–14. doi: 10.1038/s41598-021-96052-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
  117. Lukeneder A, Lukeneder P. New data on the marine Upper Triassic palaeobiota from the Polzberg Konservat-Lagerstätte in Austria. Swiss Journal of Palaeontology. 2023;142:1–14. doi: 10.1186/s13358-023-00269-3. [DOI] [Google Scholar]
  118. Lukeneder P, Lukeneder A. Mineralized belemnoid cephalic cartilage from the late Triassic Polzberg Konservat-Lagerstätte (Austria) PLoS ONE. 2022;17(4):e0264595. doi: 10.1371/journal.pone.0264595. [DOI] [PMC free article] [PubMed] [Google Scholar]
  119. Maisch MW, Matzke AT. Mikadocephalus gracilirostris n. gen., n. sp., a new ichthyosaur from the Grenzbitumenzone (Anisian-Ladinian) of Monte San Giorgio (Switzerland) Paläontologische Zeitschrift. 1997;71:267–289. doi: 10.1007/BF02988496. [DOI] [Google Scholar]
  120. Maisch MW, Matzke AT. Observations on Triassic ichthyosaurs. Part II: A new ichthyosaur with palatal teeth from Monte San Giorgio. Neues Jahrbuch für Geologie und Paläontologie-Monatshefte. 1998;1998(1):26–41. doi: 10.1127/njgpm/1998/1998/26. [DOI] [Google Scholar]
  121. Maisch MW, Matzke AT, Brinkmann W. The otic capsule of the Middle Triassic ichthyosaur Mixosaurus from Monte San Giorgio (Switzerland): New evidence on the braincase structure of basal ichthyosaurs. Eclogae Geologicae Helvetiae. 2006;99:205–210. doi: 10.1007/s00015-006-1189-6. [DOI] [Google Scholar]
  122. Mariani E. Su un nuovo esemplare di “Lariosaurus balsami, CUR.” Trovato negli scisti di Perledo sopra Varenna (Lago di Como) Atti Della Società Italiana Di Scienze Naturali. 1923;62:1–8. [Google Scholar]
  123. Martin ELO, Pittet B, Gutiérrez-Marco J-C, Vannier J, El Hariri K, Lerosey-Aubril R, Masrour M, Nowak H, Servais T, Vandenbroucke TRA, Van Roy P, Vaucher R, Lefebvre B. The Lower Ordovician Fezouata Konservat-Lagerstätte from Morocco: Age, environment and evolutionary perspectives. Gondwana Research. 2016;34:274–283. doi: 10.1016/j.gr.2015.03.009. [DOI] [Google Scholar]
  124. Maxwell EE, Argyriou T, Stockar R, Furrer H. Re-evaluation of the ontogeny and reproductive biology of the Triassic fish Saurichthys (Actinopterygii: Saurichthyidae) Palaeontology. 2018;18:559–574. doi: 10.1111/pala.12355. [DOI] [Google Scholar]
  125. Maxwell EE, Furrer H, Sánchez-Villagra MR. Exceptional preservation demonstrates a new mode of axial skeleton elongation in early ray-finned fishes. Nature Communications. 2013;4:2570. doi: 10.1038/ncomms357010.1038/ncomms3570. [DOI] [PubMed] [Google Scholar]
  126. Maxwell EE, Romano C, Wu F, Furrer H. Two new species of Saurichthys (Actinopterygii: Saurichthyidae) from the Middle Triassic of Monte San Giorgio, Switzerland, with implications for character evolution in the genus. Zoological Journal of the Linnean Society. 2015;173:887–912. doi: 10.1111/zoj.12224. [DOI] [Google Scholar]
  127. Meyer HV. Die Saurier des Muschelkalkes mit Rücksicht auf die Saurier aus buntem Sandstein und Keuper. In: Keller H, editor. Zur Fauna der Vorwelt, zweite Abtheilung. Heinrich Keller; 1855. pp. 1–167. [Google Scholar]
  128. Miedema F, Klein N, Blackburn DG, Sander PM, Maxwell EE, Griebeler EM, Scheyer TM. Heads or tails first? Evolution of fetal orientation in ichthyosaurs, with a scrutiny of the prevailing hypothesis. BMC Ecology and Evolution. 2023;23(12):1–13. doi: 10.1186/s12862-023-02110-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  129. Miedema F, Spiekman SNF, Fernandez V, Reumer JWF, Scheyer TM. Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography. Scientific Reports. 2020;10(1):12412. doi: 10.1038/s41598-020-68912-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  130. Müller J. The anatomy of Askeptosaurus italicus from the Middle Triassic of Monte San Giorgio and the interrelationships of thalattosaurs (Reptilia, Diapsida) Canadian Journal of Earth Sciences. 2005;42:1347–1367. doi: 10.1139/e05-030. [DOI] [Google Scholar]
  131. Mutter RJ. Tooth variability and reconstruction of dentition in Acrodus sp. (Chondrichthyes, Selachii, Hybodontoidea) from the Grenzbitumenzone (Middle Triassic) of Monte San Giorgio (Ticino, Switzerland) Geologia Insubrica. 1998;3:23–31. [Google Scholar]
  132. Mutter RJ. Zur systematischen Stellung einiger Bezahnungsreste von Acrodus georgii sp. nov. (Selachii, Hybodontoidea) aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz) Eclogae Geologicae Helvetiae. 1998;91:513–519. [Google Scholar]
  133. Mutter RJ. The skull of Colobodontidae sensu Andersson 1916 (emended) (Actinopterygii: Perleidiformes) Geologia Insubrica. 2001;6:65–78. [Google Scholar]
  134. Mutter RJ. The “perleidiform” family Colobodontidae: A review. Mesozoic Fishes. 2004;3:197–208. [Google Scholar]
  135. Mutter RJ, Herzog A. A new genus of Triassic actinopterygian with an evaluation of deepened flank scales in fusiform fossil fishes. Journal of Vertebrate Paleontology. 2004;24:794–801. doi: 10.1671/0272-4634(2004)024[0794:ANGOTA]2.0.CO;2. [DOI] [Google Scholar]
  136. Neenan J, Li C, Rieppel O, Bernardini F, Tuniz C, Muscio G, Scheyer TM. Unique method of tooth replacement in durophagous placodont marine reptiles, with new data on the dentition of Chinese taxa. Journal of Anatomy. 2014;224:603–613. doi: 10.1111/joa.12162. [DOI] [PMC free article] [PubMed] [Google Scholar]
  137. Nesbitt SJ. The early evolution of archosaurs: Relationships and the origin of major clades. American Museum of Natural History, Bulletin. 2011;352(292):1–292. doi: 10.1206/352.1. [DOI] [Google Scholar]
  138. Neuman AG. Lower and Middle Triassic Sulphur Mountain formation, Wapiti Lake, British Columbia. 1. Summary of geology and fauna. Royal British Columbia Museum Contributions to Natural Science. 1992;16:1–12. [Google Scholar]
  139. Neuman AG. Fishes from the Lower Triassic portion of the Sulphur Mountain Formation in Alberta, Canada: geological context and taxonomic composition. Canadian Journal of Earth Sciences. 2015;52:557–568. doi: 10.1139/cjes-2014-0165. [DOI] [Google Scholar]
  140. Nopsca FB. Neubeschreibung des Trias-Pterosauriers Tribelesodon. Paläontologische Zeitschrift. 1923;5:161–181. doi: 10.1007/BF03160365. [DOI] [Google Scholar]
  141. Nopcsa FB. Askeptosaurus, ein neues Reptil der Trias von Besano. Zentralblatt für Mineralogie, Geologie und Paläontologie. 1925;8:265–267. [Google Scholar]
  142. Nopcsa FB. Notizen über Macrocnemus Bassanii nov. gen. et spec. Centralblatt Für Mineralogie, Geologie und Paläontologie B. 1930;1930:252–255. [Google Scholar]
  143. Nosotti S. Tanystropheus longobardicus (Reptilia, Protorosauria): Re-interpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, northern Italy) Memorie Della Società Italiana Di Scienze Naturali e Del Museo Civico Di Storia Naturale Di Milano. 2007;35:1–88. [Google Scholar]
  144. Nosotti S, Rieppel O. “Eusaurosphargis dalsassoi” N. Gen. N. Sp., a new, unusual diapsid reptile from the Middle Triassic of Besano (Lombardy, N Italy) Memorie Societa Italiana Scienze Naturali. 2003;16:1–33. [Google Scholar]
  145. Pardo-Pérez JM, Kear BP, Maxwell EE. Skeletal pathologies track body plan evolution in ichthyosaurs. Scientific Reports. 2020;10(4206):1–7. doi: 10.1038/s41598-020-61070-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  146. Payne JL, Clapham ME. End-Permian mass extinction in the oceans: An ancient analog for the twenty-first century? Annual Review of Earth and Planetary Sciences. 2012;40:89–111. doi: 10.1146/annurev-earth-042711-105329. [DOI] [Google Scholar]
  147. Payne JL, Lehrmann DJ, Wei J, Orchard MJ, Schrag DP, Knoll AH. Large perturbations of the carbon cycle during recovery from the end-Permian extinction. Science. 2004;305:506–509. doi: 10.1126/science.1097023. [DOI] [PubMed] [Google Scholar]
  148. Peyer, B. (1930). Tanystropheus longobardicus Bass. sp. Vorläufige Mitteilung. Centralblatt für Mineralogie etc.,8, 336–337.
  149. Peyer B. Die Triasfauna der Tessiner Kalkalpen II. Tanystropheus longobardicus Bass. Sp. Abhandlungen Der Schweizerischen Paläontologischen Gesellschaft. 1931;50:9–110. [Google Scholar]
  150. Peyer B. Die Triasfauna der Tessiner Kalkalpen III. Placodontia. Schweizerische Paläontologische Abhandlungen. 1931;51:1–25. [Google Scholar]
  151. Peyer B. Die Triasfauna der Tessiner Kalkalpen. IV. Peyer, B. 1931. Ceresiosaurus calcagnii nov. gen. nov. spec. Abhandlungen der Schweizerischen Paläontologischen Gesellschaft. 1931;62:1–87. [Google Scholar]
  152. Peyer B. Paraplacodus broiliinov. gen. nov. sp., ein neuer Placodontier aus der Tessiner Trias: Vorläufige Mitteilung. Centralblatt für Mineralogie und Paläontologie B. 1931;1931:570–573. [Google Scholar]
  153. Peyer B. Zehn Jahre Tessiner Fossiliengrabung des Zoologischen Museums der Universität Zürich. Verhandlungen der Schweizerischen Naturforschenden Gesellschaft. 1934;115:257–261. [Google Scholar]
  154. Peyer B. Die Triasfauna der Tessiner Kalkalpen. X. Clarazia schinzi nov. gen. nov. spec. Schweizerische Paläontologische Abhandlungen. 1936;57:1–61. [Google Scholar]
  155. Peyer B. Die Triasfauna der Tessiner Kalkalpen. XI. Heschleria ruebeli nov. gen. nov. spec. Schweizerische Paläontologische Abhandlungen. 1936;58:1–48. [Google Scholar]
  156. Peyer B. Die Triasfauna der Tessiner Kalkalpen. XII Macrocnemus Bassanii Nopcsa. Schweizerische Paläontologische Abhandlungen. 1937;59:1–140. [Google Scholar]
  157. Pieroni, V. (2022). Middle Triassic Nautilida from the Besano Formation of Monte San Giorgio, Switzerland. Swiss Journal of Palaeontology,141, 21. 10.1186/s13358-022-00263-1
  158. Pinna G. Cyamodus hildegardis Peyer, 1931 (Reptilia, Placodontia) Memorie Della Societa Italiana Di Science Naturali e Del Museo Civico Di Storia Naturale Di Milano. 1992;26:2–21. [Google Scholar]
  159. Pinna G, Arduini P. Un nuovo esemplare di Ticinosuchus ferox Krebs, rinvenuto nel giacimento Triassico di Besano in Lombardia. Natura - Società Italiana Di Scienze Naturali, Museo Civico Di Storia Naturale Di Milano. 1978;69:73–80. [Google Scholar]
  160. Pohle, A. & Klug, C. Orthoceratoid and coleoid cephalopods from the Middle Triassic of Switzerland with an updated taxonomic framework for Triassic Orthoceratoidea. Swiss Journal of Palaeontology, 143, 30 (in press) [DOI] [PMC free article] [PubMed]
  161. Premru E. Beschreibung eines neuen Fundes von Macrocnemus bassanii Nopcsa (Reptilia, Squamata, Prolacertiformes) aus der Grenzbitumenzone (Anis/Ladin) des Monte San Giorgio (Besano, I) Diplomarbeit Universität Zürich; 1991. p. 57. [Google Scholar]
  162. Renesto S. A juvenile Lariosaurus (Reptilia, Sauropterygia) from the Kalkschieferzone (Uppermost Ladinian) near Viggiu (Varese, Northern Italy) Rivista Italiana Di Paleontologia e Stratigrafia. 1993;99:199–212. [Google Scholar]
  163. Renesto S. A new specimen of Tanystropheus (Reptilia Protorosauria) from the Middle Triassic of Switzerland and the ecology of the genus. Rivista Italiana Di Paleontologia e Stratigrafia. 2005;11:377–379. [Google Scholar]
  164. Renesto S, Avanzini M. Skin remains in a juvenile Macrocnemus bassanii Nopcsa (Reptilia, Prolacertiformes) from the Middle Triassic of northern Italy. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen. 2002;224:31–48. doi: 10.1127/njgpa/224/2002/31. [DOI] [Google Scholar]
  165. Renesto S, Dal Sasso C, Fogliazza F, Ragni C. New findings reveal that the Middle Triassic ichthyosaur Mixosaurus cornalianus is the oldest amniote with a dorsal fin. Acta Palaeontologica Polonica. 2020;65:511–522. doi: 10.4202/app.00731.2020. [DOI] [Google Scholar]
  166. Renesto S, Stockar R. First record of a coelacanth fish from the Middle Triassic Meride Limestone of Monte San Giorgio (Canton Ticino, Switzerland) Rivista Italiana Paleontologia e Stratigrafia. 2018;124:639–653. [Google Scholar]
  167. Rieber H. Daonellen aus der Grenzbitumenzone der mittleren Trias des Monte San Giorgio (Kanton Tessin, Schweiz) Eclogae Geologicae Helvetiae. 1969;62:657–683. [Google Scholar]
  168. Rieber H. Phragmoteuthis? ticinensis n. sp., ein Coleoidea-Rest aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz) Paläontologische Zeitschrift. 1970;44:32–40. doi: 10.1007/BF02989793. [DOI] [Google Scholar]
  169. Rieber H. Die Triasfauna der Tessiner Kalkalpen. XXII. Cephalopoden aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz) Schweizerische Paläontologische Abhandlungen. 1973;93:1–96. [Google Scholar]
  170. Rieber H. Breviconoteuthis breviconus Reis, ein Phragmoteuthide aus der Mittleren Trias des Monte San Giorgio, Kanton Tessin, Schweiz. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte. 1974;7:415–421. [Google Scholar]
  171. Rieppel O. A new coelacanth from the Middle Triassic of Monte San Giorgio, Switzerland. Eclogae Geologicae Helvetiae. 1980;73:921–939. [Google Scholar]
  172. Rieppel O. The hybodontiform sharks from the Middle Triassic of Monte San Giorgio, Switzerland. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 1981;161:324–353. [Google Scholar]
  173. Rieppel O. A new genus of shark from the Middle Triassic of Monte San Giorgio, Switzerland. Palaeontology. 1982;25:399–412. [Google Scholar]
  174. Rieppel O. Die Triasfauna der Tessiner Kalkalpen. XXV. Die Gattung Saurichthys (Pisces, Actinopterygii) aus der mittleren Trias des Monte San Giorgio, Kanton Tessin. Schweizerische Paläontologische Abhandlungen. 1985;108:1–103. [Google Scholar]
  175. Rieppel O. A second actinistian from the Middle Triassic of Monte San Giorgio, Kanton Tessin, Switzerland. Eclogae Geologicae Helvetiae. 1985;78:707–713. [Google Scholar]
  176. Rieppel O. Clarazia and Hescheleria: A re-investigation of two problematical reptiles from the Middle Triassic of Monte San Giorgio (Switzerland) Palaeontographica Abteilung A. 1987;195:101–129. [Google Scholar]
  177. Rieppel O. The hind limb of Macrocnemus bassanii (Nopcsa) (Reptilia, Diapsida): Development and functional anatomy. Journal of Vertebrate Paleontology. 1989;9:373–387. doi: 10.1080/02724634.1989.10011771. [DOI] [Google Scholar]
  178. Rieppel O. A new pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland. Philosophical Transactions of the Royal Society of London B. 1989;323:1–73. doi: 10.1098/rstb.1989.0001. [DOI] [PubMed] [Google Scholar]
  179. Rieppel O. Lariosaurus balsami Curioni (Reptilia, Sauropterygia) aus den Gailtaler Alpen. Carinthia II. 1994;184:345–356. [Google Scholar]
  180. Rieppel O. Mesozoic sea dragons: Triassic marine life from the ancient tropical lagoon of Monte San Giorgio (Life of the Past) Indiana University Press; 2019. p. 256. [Google Scholar]
  181. Rieppel O, Liu J, Bucher H. The first record of a thalattosaur reptile from the Late Triassic of southern China (Guizhou Province, PR China) Journal of Vertebrate Paleontology. 2000;20:507–514. doi: 10.1671/0272-4634(2000)020[0507:TFROAT]2.0.CO;2. [DOI] [Google Scholar]
  182. Rieppel O, Müller J, Liu J. Rostral structure in Thalattosauria (Reptilia, Diapsida) Canadian Journal of Earth Sciences. 2005;42:2081–2086. doi: 10.1139/e05-076. [DOI] [Google Scholar]
  183. Röhl HJ, Schmid-Röhl A, Furrer H, Frimmel A, Oschmann W, Schwark L. Microfacies, geochemistry and palaeoecology of the Middle Triassic Grenzbitumenzone from Monte San Giorgio (Canton Ticino, Switzerland) Geologia Insubrica. 2001;6:1–13. [Google Scholar]
  184. Röhl A, Schmid-Röhl HJ, Oschmann W, Frimmel A, Schwark L. Palaeoenvironmental reconstruction of Lower Toarcian epicontinental black shales (Posidonia Shale, SW Germany): Global versus regional control. Geobios. 2002;35:13–20. doi: 10.1016/S0016-6995(02)00005-0. [DOI] [Google Scholar]
  185. Romano C, Brinkmann W. Reappraisal of the lower actinopterygian Birgeria stensioei Aldinger, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic of Monte San Giorgio (Switzerland) and Besano (Italy) Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 2009;252:17–31. doi: 10.1127/0077-7749/2009/0252-0017. [DOI] [Google Scholar]
  186. Romano C, Goudemand N, Vennemann TW, Ware D, Schneebeli-Hermann E, Hochuli PA, Brühwiler T, Brinkmann W, Bucher H. Climatic and biotic upheavals following the end-Permian mass extinction. Nature Geoscience. 2013;6:57–60. doi: 10.1038/ngeo1667. [DOI] [Google Scholar]
  187. Romano C, López-Arbarello A, Ware D, Jenks JF, Brinkmann W. Marine Early Triassic Actinopterygii from the Candelaria Hills (Esmeralda County, Nevada, USA) Journal of Paleontology. 2019;93:971–1000. doi: 10.1017/jpa.2019.18. [DOI] [Google Scholar]
  188. Romano C, Ware D, Brühwiler T, Bucher H, Brinkmann W. Marine Early Triassic Osteichthyes from Spiti, Indian Himalayas. Swiss Journal of Palaeontology. 2016;135:275–294. doi: 10.1007/s13358-015-0098-6. [DOI] [Google Scholar]
  189. San KK, Fraser NC, Foffa D, Rieppel O, Brusatte SL. The first Triassic vertebrate fossils from Myanmar: Pachypleurosaurs in a marine limestone. Acta Palaeontologica Polonica. 2019;64:357–362. doi: 10.4202/app.00594.2019. [DOI] [Google Scholar]
  190. Saller, F. (2016). Anatomia, paleobiologia e filogenesi di Macrocnemus bassanii Nopcsa 1930 (Reptilia, Protorosauria). Dottorato di ricerca in Scienze della terra, 27 Ciclo. Università di Bologna. 10.6092/unibo/amsdottorato/7449.
  191. Sander PM. A fossil reptile embryo from the Middle Triassic of the Alps. Science. 1988;239:780–783. doi: 10.1126/science.3340859. [DOI] [PubMed] [Google Scholar]
  192. Sander PM. The large ichthyosaur Cymbospondylus buchseri, sp. nov., from the Middle Triassic of Monte San Giorgio (Switzerland), with a survey of the genus in Europe. Journal of Vertebrate Paleontology. 1989;9:163–173. doi: 10.1080/02724634.1989.10011750. [DOI] [Google Scholar]
  193. Sander PM. The pachypleurosaurids (Reptilia: Nothosauria) from the Middle Triassic of Monte San Giorgio (Switzerland) with the description of a new species. Philosophical Transactions of the Royal Society of London B. 1989;325:561–670. doi: 10.1098/rstb.1989.0103. [DOI] [PubMed] [Google Scholar]
  194. Sander, P. M., Griebeler, E. M., Klein, N., Velez Juarbe, J., Wintrich, T., Revell, L. J. & Schmitz, L. (2021). Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science, 374, 1578, 1–16. [DOI] [PubMed]
  195. Sander PM, Rieppel OC, Bucher H. New marine vertebrate fauna from the Middle Triassic of Nevada. Journal of Paleontology. 1994;68:676–680. doi: 10.1017/S0022336000026020. [DOI] [Google Scholar]
  196. Scheyer TM. New interpretation of the postcranial skeleton and overall body shape of the placodont Cyamodus hildegardis Peyer, 1931 (Reptilia, Sauropterygia) Palaeontologia Electronica. 2010;13(2):15A. [Google Scholar]
  197. Scheyer T, Neenan JM, Bodogan T, Furrer H, Obrist C, Plamondon M. A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny. Scientific Reports. 2017;7(4406):1–22. doi: 10.1038/s41598-017-04514-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  198. Scheyer TM, Romano C, Jenks J, Bucher H. Early Triassic marine biotic recovery: the predators’ perspective. PLoS ONE. 2014;9(3):e88987. doi: 10.1371/journal.pone.0088987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  199. Scheyer TM, Schmid L, Furrer H, Sánchez-Villagra MR. An assessment of age determination in fossil fish: The case of the opercula in the Mesozoic actinopterygian Saurichthys. Swiss Journal of Palaeontology. 2014;133:243–257. doi: 10.1007/s13358-014-0068-4. [DOI] [Google Scholar]
  200. Schwarz W. Die Triasfauna der Tessiner Kalkalpen. XX. Birgeria Stensiöi Aldinger. Schweizerische Paläontologische Abhandlungen. 1970;89:1–93. [Google Scholar]
  201. Scotese CR. Paleogeographic Atlas, PALEOMAP progress report 90–0497. Department of Geology, University of Texas at Arlington; 1997. p. 37. [Google Scholar]
  202. Seilacher A. Begriff und Bedeutung der Fossil-Lagerstätten. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte. 1970;1970:34–39. [Google Scholar]
  203. Seilacher A. Taphonomy of fossil-Lagerstätten. In: Briggs DEG, Crowther PR, editors. Palaeobiology: a synthesis. Blackwell; 1990. pp. 266–270. [Google Scholar]
  204. Seilacher A, Reif W-E, Westphal F. Sedimentological, ecological and temporal patterns of fossil Lagerstätten. Philosophical Transactions of the Royal Society of London B. 1985;311:5–23. doi: 10.1098/rstb.1985.0134. [DOI] [Google Scholar]
  205. Selden P, Nudds J. Evolution of fossil ecosystems. Boca Raton: CRC Press; 2012. p. 304. [Google Scholar]
  206. Spiekman SNF, Mujal E. Decapitation in the long-necked Triassic marine reptile Tanystropheus. Current Biology. 2023;33:R699–R709. doi: 10.1016/j.cub.2023.04.027. [DOI] [PubMed] [Google Scholar]
  207. Spiekman SNF, Neenan JM, Fraser NC, Fernandez V, Rieppel O, Nosotti S, Scheyer TM. Aquatic habits and niche partitioning in the extraordinarily long-necked Triassic reptile Tanystropheus. Current Biology. 2020;30(19):1–7. doi: 10.1016/j.cub.2020.07.025. [DOI] [PubMed] [Google Scholar]
  208. Spiekman SNF, Neenan JM, Fraser NC, Fernandez V, Rieppel O, Nosotti S, Scheyer TM. The cranial morphology of Tanystropheus hydroides (Tanystropheidae, Archosauromorpha) as revealed by synchrotron microtomography. PeerJ. 2020;8(2):e10299. doi: 10.7717/peerj.10299. [DOI] [PMC free article] [PubMed] [Google Scholar]
  209. Spiekman SNF, Scheyer TM. A taxonomic revision of the genus Tanystropheus (Archosauromorpha, Tanystropheidae) Palaeontologia Electronica. 2019;22.3.80:1–46. doi: 10.26879/1038. [DOI] [Google Scholar]
  210. Stefani M, Arduini P, Garassino A, Pinna G, Teruzzi G, Trombetta GL. Palaeoenvironment of extraordinary fossil biotas from the Upper Triassic of Italy. Atti Della Societa Italiana Di Scienze Naturali e Del Museo Civico Di Storia Naturale Di Milano. 1991;132:309–335. [Google Scholar]
  211. Stockar R. Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina beds (Meride Limestone, Monte San Giorgio, Switzerland) Swiss Journal of Geosciences. 2010;103:101–119. doi: 10.1007/s00015-010-0008-2. [DOI] [Google Scholar]
  212. Stockar R, Baumgartner PO, Condon D. Integrated Ladinian bio-chronostratigraphy and geochrononology of Monte San Giorgio (Southern Alps, Switzerland) Swiss Journal of Geosciences. 2012;105:85–108. doi: 10.1007/s00015-012-0093-5. [DOI] [Google Scholar]
  213. Sun Z, Jiang D, Ji C, Hao W. Integrated biochronology for Triassic marine vertebrate faunas of Guizhou Province, South China. Journal of Asian Earth Sciences. 2016;118:101–110. doi: 10.1016/j.jseaes.2016.01.004. [DOI] [Google Scholar]
  214. Tang, C. M. (2002). Monte Bolca: An Eocene fishbowl. In D. J. Bottjer, W. Etter, J. W. Hagadorn, & C. M. Tang (Eds.), Exceptional fossil preservation (pp. 365–377). Columbia University Press.
  215. Tichy K. Ein Neufund von Neusticosaurus toeplitschi (Nopcsa, 1928) (Reptilia, Sauropterygia) aus den Partnachschichten der Gailtaler Alpen, Kärnten. Carinthia II. 1998;188:519–530. [Google Scholar]
  216. Tintori A. Dipteronotus olgiatii n. sp. (Actinopterygii, Perleidiformes) from the Kalkschieferzone of Ca’del Frate (N. Italy) Atti Ticinensi Di Scienze Della Terra. 1990;33:191–197. [Google Scholar]
  217. Tintori A. Fish taphonomy and Triassic anoxic basins from the alps: A case history. Rivista Italiana Paleontologia e Stratigrafia. 1992;97:393–408. [Google Scholar]
  218. Tschanz, K. (1986). Funktionelle Anatomie der Halswirbelsäule von Tanystropheus longobardicus (Bassani) aus der Trias (Anis/Ladin) des Monte San Giorgio (Tessin) auf der Basis vergleichend morphologischer Untersuchungen an der Halsmuskulatur rezenter Echsen. PhD thesis, University of Zurich, Zurich, Switzerland.
  219. Tschanz K. Allometry and heterochrony in the growth of the neck of Triassic prolacertiform reptiles. Palaeontology. 1988;31:997–1011. [Google Scholar]
  220. Van Roy P, Orr PJ, Botting JP, Muir LA, Vinther J, Lefebvre B, el Hariri K, Briggs DEG. Ordovician faunas of Burgess Shale type. Nature. 2010;465:215–218. doi: 10.1038/nature09038. [DOI] [PubMed] [Google Scholar]
  221. Wachtler M, Perner T. Some new and exciting Triassic Archosauria from the Dolomites (Northern Italy) Dolomythos Museum, Oregon Institute of Geological Research; 2018. [Google Scholar]
  222. Wang X, Bachmann GH, Hagdorn H, Sander PM, Cuny G, Chen X, Wang C, Chen L, Cheng L, Meng F, Xu G. The Late Triassic black shales of the Guanling area, Guizhou Province, south-west China: A unique marine reptile and pelagic crinoid fossil lagerstätte. Palaeontology. 2008;51:27–61. doi: 10.1111/j.1475-4983.2007.00735.x. [DOI] [Google Scholar]
  223. Ware D, Jenks JF, Hautmann M, Bucher H. Dienerian (Early Triassic) ammonoids from the Candelaria Hills (Nevada, USA) and their significance for palaeobiogeography and palaeoceanography. Swiss Journal of Geosciences. 2011;104:161–181. doi: 10.1007/s00015-011-0055-3. [DOI] [Google Scholar]
  224. Wilby PR, Duff K, Page K, Martin S. Preserving the unpreservable: A lost world rediscovered at Christian Malford, UK. Geology Today. 2008;24:95–98. doi: 10.1111/j.1365-2451.2008.00666.x. [DOI] [Google Scholar]
  225. Wild R. Die Triasfauna der Tessiner Kalkalpen XXII. Tanystropheus longobardicus (Bassani) (Neue Ergebnisse) Schweizerische Paläontologische Abhandlungen. 1973;95:1–162. [Google Scholar]
  226. Wild R. Die Triasfauna der Tessiner Kalkalpen. XXIV. Neue Funde von Tanystropheus (Reptilia, Squamata) Schweizerische Paläontologische Abhandlungen. 1980;102:1–43. [Google Scholar]
  227. Wilson LAB, Furrer H, Stockar R, Sánchez-Villagra MR. A quantitative evaluation of evolutionary patterns in opercle bone shape in Saurichthys (Actinopterygii: Saurichthyidae) Palaeontology. 2013;56:901–915. doi: 10.1111/pala.12026. [DOI] [Google Scholar]
  228. Xian-Guang, H., Siveter, David J., Siveter, Derek J., Aldridge, R. J., Pei-Yun, C., Gabbott, S. E., Xiao-Ya, M., Purnell, M. A. & Williams, M. (2003). The Cambrian fossils of Chengjiang, China: the flowering of early animal life. Wiley, Hoboken N.J.
  229. Zapfe, H. & König, H. (1980). Neue Reptilienfunde aus der Mitteltrias der Gailtaler Alpen (Kärnten, Österreich). Sitzungsberichte der Österreichischen Akademie der Wissenschaften. Mathematisch-naturwissenschaftliche Klasse, Abt. I, 189, 65–82.

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

Specimens with PIMUZ numbers  are kept in the collection of the Palaeontological Institute of the University of Zurich. All data included in our analyses have been published previously and the sources are provided in Tables 2 and 4.

Articles from Swiss Journal of Palaeontology are provided here courtesy of Springer

RESOURCES