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. 2026 Apr 10;16:16872. doi: 10.1038/s41598-026-48164-4

A new lungfish (Ceratodontoidei, Dipnoi) from the Early Jurassic of Chongqing, China

Bo Luo 1, Guang-Hui Xu 2,✉, Ting-Cong Ren 1, Xin-Ying Ma 3, Qing-Dong Wang 1, Tuo Qiao 2, Feng-Ting Tan 2,4, Ying Tan 1, Guang-Biao Wei 5
PMCID: PMC13230970  PMID: 41963493

Abstract

Dipnoi (lungfishes) are a group of air-breathing sarcopterygian fishes that survived over hundreds of millions of years and their crown members (Neoceratodus, Lepidosiren and Protopterus) are among the closest living relatives of the tetrapods. After the end-Triassic mass extinction, dipnoan diversity was supposedly low, and all Early Jurassic remains were once ascribed to a single genus, Ceratodus on the basis of isolated tooth plates. Later studies indicate that Ceratodus might be an assemblage of forms with disparate cranial morphology. Here, we report the discovery of a new lungfish, Sinoceratodus fortunus gen. et sp. nov., based on three articulated specimens from the Early Jurassic (Sinemurian, ~ 199–193 Ma) lacustrine deposits of Chongqing, China. The new finding represents the best-preserved lungfish known so far from the Jurassic with a unique combination of features (e.g., anterior skull bone marked by sensory lines and presence of supraorbital bone) previously unknown in any genera among Mesozoic lungfishes, and significantly adds to our knowledge regarding the morphological diversity of this clade. Results of phylogenetic studies recover Sinoceratodus as a sister taxon to gnathorhizids within the Dipnoi crown and provide new insights into the origin of modern African and South American lungfishes.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-026-48164-4.

Subject terms: Ecology, Ecology, Evolution, Zoology

Introduction

Lungfishes (Dipnoi) are air-breathing sarcopterygians that are generally regarded as the closest living relatives of tetrapods1,2. They are important in evolutionary biology, frequently used as extant models for exploring the fin-to-limb transition3. Although represented by only three living genera in two ceratodontoid families, i.e., the African Protopterus and South American Lepidosiren in the Lepidosirenidae, and the Australian Neoceratodus in the Neoceratodontidae, this group was much more diverse in fossil record and had a global distribution during the Paleozoic and Mesozoic4–11. A shift from marine to freshwater habitats of this group occurred from the Middle Devonian to Early Carboniferous, and since then dipnoans have been generally freshwater, although some occurrences may come from nearshore environments12,13.

Early primitive dipnoans are generally heavily ossified with cosmine-covered thick scales, but Mesozoic and Cenozoic taxa possess only thin dermal skull bones with the cosmine layer disappeared14. For this reason, Mesozoic dipnoans were mostly represented by isolated tooth plates and jaw bones (with some exceptions mainly in the Triassic), and the estimate of post-Triassic diversity of this clade was heavily biased by sampling15,16. Until recently, all dipnoan remains in the Early Jurassic were mainly tooth plates17 and no articulated taxa were described. These tooth plates were once ascribed to a single genus Ceratodus, the type species of which was erected on the basis of tooth plates from the Triassic of Europe18. Similar to the type species, most species of Ceratodus are represented only by tooth plates, and our knowledge on the skull of the genus is known only in C. sturii from the Late Triassic of Australia19.

Here, we report the discovery of a new genus and species of ceratodontoids based on three articulated specimens from the Early Jurassic Yuzhou Biota in northern Chongqing, China20(Fig. 1). The holotype (Fig. 2a), with both cranium and part of post-cranium preserved, represents the best-preserved ceratodontoid from the Jurassic so far. The skull roof, well-preserved in all three type specimens (Figs. 2 and 3), shows a pattern unique among the Mesozoic dipnoans and significantly adds to our knowledge regarding the morphological diversity of this clade. The new ceratodontoid has been illustrated in a recent publication for reviewing the whole Yuzhou Biota but has not previously been described20. In this contribution, we present a comparative description of this new taxon and resolve its phylogenetic position using a cladistic approach.

Fig. 1.

Fig. 1

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Geological context and outcrop of Sinoceratodus fortunus gen. et sp. nov. (A-C), Early Jurassic and present-day locations of the Yuzhou Biota. The Early Jurassic palaeogeographic map (A) was modified from ref. 41 (https://www.earthbyte.org/). The maps B and C are created using Baidu Map (https://map.baidu.com) and Adobe CS (https://www.adobe.com/). (D), Stratigraphic division of Late Triassic to Early Jurassic deposits in northern Chongqing. Figure created by G.-H. Xu and Q.-D. Wang.

Fig. 2.

Fig. 2

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Sinoceratodus fortunus gen. et sp. nov. (A-C), SSGT L01-HY-661, holotype; photo (A) and line-drawing (B) of the whole specimen; (C), closeup of the circumorbital and XYZ bones. photo (D) and line-drawing (E) of SSGT L01-HY-855. (F), reconstruction of the skull in dorsal view. Cr, cranial rib; dra, dorsal radial; d.ry, dorsal fin ray; ha + hs, haemal arch and spine; iha. interhaemal; na + ns, neural arch and spine; Op, opercle; Pas, parasphenoid; Ri, rib; ‘su’, ‘supraneural’.

Fig. 3.

Fig. 3

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Sinoceratodus fortunus gen. et sp. nov., SSGT THS2715. photo (a) and line-drawing (b) of the whole specimen. photo (c) and line-drawing (d) of the prearticular tooth plate, right is anterior. Ang, Angular; Ano, Antopercle; Ch, ceratohyal; Cla, Clavicle; Cle, Cleithrum; Op, opercle; Par, prearticular; Sop, subopercle.

Geological setting

The fossil locality was located at the eastern margin of the Sichuan Basin (Fig. 1), where coal-swamp to lacustrine-fluvial deposits were developed during the Triassic-Jurassic transition21. The specimens were found from the basal unit (Dongyuemiao Member) of the Early Jurassic Ziliujing Formation, characterized by gray–black shales intercalated shell limestones and argillaceous limestones. Besides the ceratodontoid described here, other fossils recovered from the Yuzhou Biota include rich plants, bivalves, ostracods, conchostracans, gastropods, hybodontiforms, actinopterygians, pliosauroids and an ornithischian dinosaur22–24. The age of the fossil beds has been constrained to Sinemurian (~ 199–193 Ma) by both biostratigraphic and chemostratigraphic correlations25. The whole biota represents one of the rare trophically complex lacustrine ecosystems from the Early Jurassic and provides valuable information on the biological recovery in the aftermath of the end-Triassic mass extinction26,27.

Results

Systematic palaeontology

Osteichthyes Huxley, 1880.

Sarcopterygii Romer, 1955.

Dipnoi Müller, 1845.

Ceratodontiformes Berg, 1940.

Ceratodontoidei Nikolski, 1954.

Sinoceratodus fortunus Xu, Luo, Ren, Ma, Wang, Qiao, Tan, Tan et Wei gen. et sp. nov.

Etymology. The generic epithet ‘Sino’ refers to China, and the specific epithet ‘fortunus’ means lucky.

Holotype. SSGT L01-HY-661. A dorsally exposed skull associated with laterally compressed axial skeleton and dorsal fin rays.

Paratype. SSGT L01-HY-855, THS2715.

Locality and Horizon. Chongqing, China; Dongyuemiao Member of the Ziliujing Formation, Sinemurian, Early Jurassic20.

Diagnosis. A new species of Ceratodontoidei distinguished from other members of this group by the following features: calvarium with two bones in medial series, two bones in mediolateral series and single bone in lateral series; EFQ-bone shield-like, slightly protruding anteriorly and receiving supraorbital sensory canals from medial margins of KLM-bones; AB-bone equal to EFQ-bone in length; presence of 3 + 4- and 5 + 6-bones; prearticular tooth plate with five ridges originating medially, and medial edge slightly longer than lingual edge; first and last ridges of prearticular tooth plate forming blunt angle of about 110º; and first and second ridges widely spaced, with fourth and last ridges closely spaced.

Description. The skull roof is well-preserved in all three type specimens (Figs. 2 and 3). It is roughly circular and slightly wider than long. The skull roof is composed of eight bony elements, i.e., two medial elements (EFQ-bone and AB-bone), two pairs of mediolateral elements (KLM-bones and IJ-bones) and a pair of lateral elements (XYZ-bones). The surface of the skull roofing bears shallow grooves radiating from the ossification centers, and lacks tubercles (or coarse ridges) found in Ceratodus sturii and Mioceratodus19. Sensory canals are clearly indicated by distinct grooves. The length from the anterior tip of the EFQ-bone to the posterior extremity of the AB-bone is 86 mm and 93 mm in the holotype (Fig. 2a) and SSGT THS2715 (the largest known specimen; Fig. 3a), respectively. From the holotype, the lungfish has an estimated body length of at least 500 mm.

The anterior element in the medial series is interpreted as an EFQ-bone because it receives the supraorbital sensory canals from the KLM-bones, reminiscent of the arrangement found in Gnathorhiza and Microceratodus9,19,28,29. The EFQ-bone is shied-like and slightly protrudes anteriorly (contra Asiatoceratodus sharovi, C. sturii and Potamoceratodus8,15,30,31, having a rounded anterior margin and nearly straight lateral margins. The AB-bone is large and hexagonal, nearly as long as the EFQ-bone with which it articulates with a slightly concave anterior margin (Figs. 2 and 3). The anterolateral and posterolateral margins of the AB-bone are straight or slightly concave and the posterior margin is slightly convex. The maximum width, situated at the junction of the anterolateral margin and the posterolateral margin, is three quarters of the length of the bone. There are no medial C-bone and medial fenestra found in Ptychoceratodus serratus32 and Paraceratodus germaini8. It is probable that the C-bone has been fused with the AB-bone as likely in living lungfishes or with the E-bone as supposed in some fossil taxa (e.g., Arganodus atlantis19 and Ferganoceratodus jurassicus)33.

The elements in the mediolateral series of Sinoceratodus are similar in shape to those in A. atlantis19. The KLM-bone is the longest ossification in the skull roof, being about two-thirds of the length of the skull roof (Figs. 2 and 3). It is pentagonal, having a slightly convex anterior margin, a slightly curved lateral margin, and straight anteromedial, posteromedial and posterior margins. The supraorbital sensory canal extends through the KLM-bone along an inverse sigmoid concavity on the bone, and enters the EFQ-bone anteromedially. The IJ-bone is relatively short and quadrangular, contacting the KLM-bone anteriorly, the AB-bone medially and the XYZ-bone laterally. The IJ-bone slightly widens posteriorly and forms the lateral portion of the posterior margin of skull roof. The middle portion of the IJ-bone transfers the supratemporal commissure medially into the AB-bone.

The XYZ-bone in the lateral series is elongate and irregular in shape, forming the posterolateral margin of the skull roof (Fig. 2a). The bone carries the junction of the temporal sensory canal with the infraorbital sensory canal at its anterior portion, indicating that the X-bone probably has been fused with the YZ-bone19,31(Fig. 2c). In comparison, a separate X-bone or a XK-bone is present in Mioceratodus, Neoceratodus, Paraceratodus and more primitive lungfishes7,19,31. The type specimens are dorsally exposed, and it is unknown if the XYZ-bone of Sinoceratodus has a long descending articular process as in the XYZ-bone of Arganodus atlantis or the YZ-bone of Ferganoceratodus annekempae8,19,31,34. The temporal sensory canal extends longitudinally through the XYZ-bone along a C-shaped curve, and posteromedially connects with the supratemporal commissure in the IJ-bone.

Two bones in the holotype definitely belong to the orbit, including a trapezoid anterodorsal element (3 + 4-bone) and an elongate and slightly curved posteroventral element (5 + 6-bone). The former contacts the KLM-bone laterally and the XYZ-bone posteriorly (Fig. 2a, c). Most of this element is situated at the supraorbital position, reminiscent of the 3-bone in early dipnoans7,8,12. However, the posteroventral part of this element carries the infraorbital sensory canal, resembling the 4-bone. We thus interpret a fused 3 + 4-bone here for Sinoceratodus. The posteroventral element contacts the 3 + 4-bone dorsally and forms the posteroventral margin of the orbit, resembling the 5 + 6 bone in Sagenodus12.

The palate is poorly known for Sinoceratodus because the skull is dorsally exposed in available material. The vomers and pterygopalatines are not exposed. The parasphenoid is known only by its posterior shaft that is dorsoventally flat and extends a certain length beyond the skull roof in the holotype (Fig. 2a, b). The lower jaw is known from SSGT THS2715 (Fig. 3a, b), including a left angular and a left prearticular with an ankylosed tooth plate. The tooth plate was partly damaged on the occlusal surfaces of the anterior two ridges. Because the left tooth plate has a certain distance away from the symphysis of the prearticular, it would not contact with the right tooth plate. The angular is long and plate-like, expanded dorsally at midway and tapering towards both ends. The prearticular has a long posterior process that is nearly twice the length of the tooth plate. The lower tooth plate is small, 21 mm long and 12 mm wide (Fig. 3c). The medial edge is slightly longer than the lingual edge, and both are slightly curved. The tooth plate has five ridges that originate medially. The first and second ridges is widely spaced, and the first cleft is deep. The fourth ridge appears the longest, and is closely located to the last ridge. The angle between the first and last ridge of the prearticular tooth plate is about 110º, contrasting a slightly acute angle in Ferganoceratodus jurassicus, Ptychoceratodus serratus and Potamoceratodus30–35.

In the branchial region, the opercle, subopercle and ceratohyal are discernible at the left side of the skull (Fig. 3a, b). The opercle is relatively small and roughly trapezoid, contrasting the large and rounded opercle in many Paleozoic lungfishes1,7,8. The subopercle is elongate and slender. The ceratohyal comprises an elongate shaft and an expanded posterior portion. Both bones are similar to those in Gnathorhiza29,30 and Neoceratodus19. Additionally, three elements are referable to the left side of the pectoral girdle (Fig. 3a, b), including a hatchet-like anocleithrum, a large and curved cleithrum with a trapezoid branchial lamina, and a fan-shaped clavicle.

A pair of cranial ribs, at least eight long and curved pleural ribs, some elements of the axial skeleton and a series of dorsal fin rays are discernible from the holotype (Fig. 2a), showing a similar condition to that in extant ceratodontoids36. The cranial rib has a narrow and rod-like proximal portion and becomes gradually expanded and flatten towards the distal end. There are 18 neural spines (fused with neural arches), 15 ‘supraneurals’, 10 dorsal radials, 14 haemal spines (fused with haemal arches), and several interhaemals preserved in the axial skeleton. Ossified centra are clearly absent. The short paired neural arches form a forked structure that is fused with the base of the long median neural spine, and the haemal spine and arches show a similar condition. The ‘supraneurals’ are rod-like, expanded at both ends and somewhat longer than the corresponding neural spine. The dorsal radials are relatively short and hourglass-shaped with the proximal end more conspicuously expanded. The fin rays are long and slender with their unsegmented proximal portions inserting between the radials. The scales were damaged during preparation and are rather incomplete for description.

Phylogenetic analysis

To assess the phylogenetic affinities of Sinoceratodus, we incorporated it into a dataset from a previous study11(see Methods and Supplementary Information). The phylogenetic analysis resulted in single most parsimonious tree (tree length = 156 steps, consistency index = 0.532, retention index = 0.684). Following ref.11, we incorporated this tree into a dipnoan cladogram resulted from ref.9, and the whole time-scaled composite tree is presented in Fig. 4. The topology is largely consistent with the previous topology11 with slight differences on the positions of Ferganoceratodus and Gnathorhizidae. Paraceratodus is nested at the base of Ceratodontiformes; within the Ceratodontiformes crown (namely Ceratodontoidei herein), the Neoceratodontidae is recovered as the sister group to all other ceratodontoids, including Ferganoceratodus, Gnathorhizidae, Sinoceratodus, Ceratodus, Ptychoceratodus, Gosfordia and Lepidosirenidae. Sinoceratodus is recovered as the sister taxon to Gnathorhizidae, and Gosfordia and Ptychoceratodus form a clade sister to Lepidosirenidae, contrasting the previous recovery of Gnathorhizidae as the sister group to Lepidosirenidae11.

Fig. 4.

Fig. 4

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Time-scaled composite tree including basal dipnoan (black clades) and ceratodontiform (red clade) taxa with mapped fossil record and ghost ranges. The basal dipnoan cladogram is from ref.9 and the skull reconstruction and time-calibration are from refs7,8,11.

Discussion

Results of our analysis illuminate the phylogenetic position of Sinoceratodus within the Dipnoi. Sinoceratodus is clearly a member of Ceratodontiformes as it possesses five synapomorphies of this order, i.e., presence of a single EFQ- (or equivalent) bone, absence of a separate F-bone, calvarium with no more than two bones in the lateral series, superficial location of the sensory line canals, and mandibular bones unmarked by sensory lines. It further possesses four synapomorphies of Ceratodontoidei: absence of a separate C-bone (reversal in gnathorhizids and Ptychoceratodus), calvarium with no more than two bones in the medial series of (reversal in gnathorhizids and Ptychoceratodus), calvarium with no more than two bones in the mediolateral series, and presence of an oval or elongate opercle (reversal in Persephonichthys). As in almost all non-neoceratodontid ceratodontoids (except Ferganoceratodus), Sinoceratodus lacks a separate XK- (or equivalent) bone. Furthermore, Sinoceratodus shares with gnathorhizids a single derived feature, anterior skull bones marked by sensory lines. This feature is otherwise present in some basal dipnoans and Mioceratodus. Gnathorhizidae thrived in the Paleozoic with only a few relict forms in the Early Triassic11. Sinoceratodus does not possess the features diagnostic for traditional gnathorhizids13. The unexpected sister-taxon relationships between Sinoceratodus and gnathorhizids are weakly supported, but this hypothesis is regarded here as the most likely.

Results of our analysis provide new insights into the origin of Lepidosirenidae. Gosfordia and Ptychoceratodus form a clade which is sister to Lepidosirenidae in our cladogram (Fig. 4), sharing four derived features with the later family, i.e., presence of contiguous lower dentition, a restrictive jaw articulation, slender paired fins, and a reduced scale cover on the body. As such, the Triassic Gosfordia and Ptychoceratodus could be closer to the common ancestor of modern African and South American lungfishes than other lungfish clades. This challenges the previously alleged close affinities of modern lepidosirenids with gnathorhizids, which were supported by a single unambiguous feature (aestivation burrow; unknown in most fossil taxa) and some homoplastic features11. Additionally, another analysis10 based on combined mitogenomic, nuclear gene and fossil data supported the sister-group relationships between modern lepidosirenids and an unnamed clade comprised of Ferganoceratodus and neoceratodontids. Notably, when the Bayesian tip-dated analysis was performed, this analysis recovered all pre-Jurassic lungfishes outsides the Ceratodontoidei based on the same set of morphological data as ref.11.

The discovery of Sinoceratodus significantly enriches our knowledge on the taxonomic diversity of lungfishes in the Early Jurassic. After the end-Triassic mass extinction, ceratodontoid diversity was supposedly low and the lungfish remains in the Early Jurassic were known by several Ceratodus species, e.g., C. stewarti from the Hettangian to Sinemurian of Utah and C. cf. guentheri from the Sinemurian to Pliensbachian of Arizona in the United States17,37. These species have only tooth plates preserved, and differ from Sinoceratodus by having a relatively short medial edge, a shallow first notch and a slightly acute angle formed by the first and last ridges in the prearticular tooth plate. Notably, later studies indicate that the broadly inclusive Ceratodus might be an assemblage of forms with disparate cranial morphologies6,9,11. Pardo et al.33 named the genus Potamoceratodus on the basis of a partial skull from the Late Jurassic of Colorado and ascribed C. guentheri to the genus. In comparison to the pattern of the skull roof, Potamoceratodus is similar to C. sturii but is easily distinguished from Sinoceratodus in having the calvarium with a long anterior process of the anteromedial element (vs. short in Sinoceratodus), a much laterally expanded posteromedial element, and lacking a pair of separate IJ-bones.

The discovery of Sinoceratodus documents the first articulated lungfish known in the Early Jurassic. The presence of articulated cranial bones associated with the prearticular tooth plate in the well-preserved specimens permits more extensive comparisons beyond the simple meristic variation of the dentition and allows for a better assessment on the ceratodontoid diversity in the Jurassic. Besides Potamoceratodus mentioned above, only Ferganoceratodus was previously known about its skull among Jurassic lungfishes15,33,34. Multiple species throughout the Mesozoic have been referred to Ferganoceratodus, and this widens the character range diagnostic for the genus, causing potential taxonomic confusion35,38,39. As such, our comparisons of Sinoceratodus with Ferganoceratodus focus on the type species F. jurassicus from the Middle Jurassic of Kyrgyzstan33. In the prearticular plate, Sinoceratodus differs from the later in having a longer medial edge, five ridges (vs. four in F. jurassicus) and a blunt angle formed by the first and last ridges. In the skull roof, Sinoceratodus differs from F. jurassicus in having grooves for the supraorbital canals in the anteromedial element (EFQ-bone), a longer EFQ-bone, a single element (XYZ-bone) in the lateral series, and a large supraorbital bone (3 + 4-bone) flanking the KLM-bone. The unique combination of features mentioned above also easily distinguish Sinoceratodus from F. martini and F. annekempae based on cranial elements from Thailand15,34. According to the original description34, F. annekempae further differs from F. jurassicus in having a YZ-bone with an elongated and slightly curved anterior process.

Lungfishes form an important component of the Early Jurassic Yuzhou Biota. Similar to extant ceratodontoids, they likely preyed upon small-sized invertebrates such as ostracods, conchostracans and gastropods, which are rich from the biota. Meanwhile, inferred from regurgitalites, they could be preyed upon themselves by large pliosauroids from the same biota20. The lungfish remains previously described from the Jurassic of China are only tooth plates that were referred to as five species (e.g., C. szechuanensis and C. youngi) of the genus Ceratodus38,39. Some authors40 considered C. youngi to be a junior synonym of C. szechuanensis and included this species in the genus Ferganoceratodus. The new finding indicates that the lungfishes from the Jurassic of China are more taxonomically diverse than previously thought. Besides Sinoceratodus described here, preliminary studies indicate that the Yuzhou Biota includes two other species of ceratodontiforms with different features in the tooth plates and skull roof bones. Detailed studies of these taxa would provide further information on the evolution of lungfishes and the biological recovery of the Early Jurassic lacustrine ecosystems in Southwest China.

Methods

All specimens described in this study are stored in the fossil collections of the Southeast Sichuan Geological Team (SSGT), Chongqing Bureau of Geology and Minerals Exploration in Chongqing, China. They were mechanically prepared with pneumatic airscribe or sometimes with sharp steel needles, and were photographed with a digital camera (Canon EOS 800D). Illustrations were drawn manually and then prepared using Adobe Photoshop (CS5). Although we recognize the efforts of some authors15,42 to avoid the mire of subjective homology assignments present in post-Paleozoic lungfish research, we have chosen to use the alphabetical nomenclature system for ease of comparison with most existing literature. This follows the apparent development of bones within several series, including a medial series (primitive elements A, B, C, D, E, F), a first lateral series (primitive elements I, J, K, L, M, N, Q), a second lateral series (primitive elements X, Y, Z), and a circumorbital series (numbered). The description of the postcranial skeleton follows the terminology of ref36. The classification of lungfishes is highly unstable, and we follow the classification of ref.4 and consider the Dipnoi as a superorder that includes many Palaeozoic orders and the Ceratodontiformes (living lungfishes and their closely fossil relatives). The Ceratodontiformes crown is here referred to the suborder Ceratodontoidei. Additionally, the African Protopterus and South American Leipdosiren are united in a single family Lepidosirenidae (rather than two separated families), following ref11. The new taxon was incorporated in a phylogenetic analysis based on the data matrix of ref11. This data matrix was selected because it represents the largest and the most recent attempt at resolving post-Devonian lungfish phylogeny based on morphological data. The current data matrix includes 18 taxa scored for 74 characters. All characters were unordered and equally weighted. Tree searches were accomplished with a parsimony analysis of the data set using the branch-and-bound search algorithm in PAUP* 4.0a16943. We divided the original state 1 of Character 11 (lateral series: with two bones or less) into two states (1, two bones; 2 single bone).

Scorings for Sinoceratodus represent 56.8% of the total characters in the matrix: 1,111,111,221,211??????0100011?????1??1010??100?0???0??0?00??11??111?0?????110.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary Material 1 (138.2KB, zip)

Acknowledgements

We thank M.-M. Chang, D.-L. Li, W. Zeng, J. Yu, and J.-H. Wang for constructive suggestions, Y. Chen for helps in fossil collection and M.-N. Lü for specimen preparation.

Author contributions

X.G. designed the research, L.B., W.Q., R.T., W.G. and T.Y. did field work and and provided stratigraphic data, X.G. prepared figures, X.G., L.B., M.X., Q.T., T.F., W.Q. and R.T. collected and analyzed the data, X.G. wrote the main manuscript text and all authors reviewed and approved the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China (42172008, 42202016), Science & Technology Fundamental Resources Investigation Program (Grant No. 2024FY100800), Stable Supporting Fund of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Chongqing Planning and Natural Resources Bureau, and Open Subject Funding of Chongqing Key Laboratory of Resource and Environmental Effects of Major Geological Events (Chongqing Institute of Geology and Mineral Resources) (CKLEMME-202201).

Data availability

The data that support the findings of this study are available in the Supplementary Information.

Declarations

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s note

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

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