Table 1.
List of characters accompanied by a description, to elucidate the various carinal/serration morphologies in Thalattosuchia. (This table is an updated version of table 1 presented in Young et al. [13].)
| denticle size | denticles contiguous | denticle definition | description | examples |
|---|---|---|---|---|
| non-ziphodont | n.a. | n.a. | carinae present, but formed solely by a keel (raised ridge). No enamel ornamentation extending onto the carina, and no discrete denticles present |
Metriorhynchus superciliosus Gracilineustes leedsi |
| macroziphodont | yes | well defined | carinae homogeneous, with a long, contiguous series of repetitive isolated and isomorphic true denticles that are visible macroscopically. Dimensions typically exceed 300 μm |
Dakosaurus andiniensis Dakosaurus maximus |
| microziphodont | yes | well defined | carinae homogeneous, with a long, contiguous series of repetitive isolated and isomorphic true denticles that are microscopic; whose dimensions typically do not exceed 300 μm |
Plesiosuchus manselii Geosaurus giganteus Geosaurus grandis Geosaurinae indet. (NHMUK PV R486) |
| yes | poorly defined and hard to discern | carinae homogeneous, with a long, contiguous series of repetitive isolated and isomorphic true denticles that are microscopic; whose dimensions typically do not exceed 300 μm. The denticles themselves are poorly defined and difficult to distinguish even under SEM (although this could be due to the enamel ornamentation extending onto the carina, especially in the apical region) | Torvoneustes carpenteria | |
| no | poorly defined and hard to discern | carinae heterogeneous, with a series of non-contiguous repetitive isolated and isomorphic true denticles that are microscopic. Series can be short (2) or moderate (approx. 10), but are widely separate from one another, i.e. no contiguous series along the carina. Dimensions typically do not exceed 300 μm. In labial or lingual view, the height of the denticles rarely influences the height of the keel (i.e. little or no serrated edge). The denticles themselves are poorly defined and difficult to distinguish even under SEM |
Machimosaurus buffetautia Machimosaurus hugiia ‘Steneosaurus’ obtusidensa ‘Metriorhynchus’ brachyrhynchus Tyrannoneustes lythrodectikos |
aIn these taxa the superficial enamel ornamentation extends onto the carina, especially in the apical region. In the absence of denticles this constitutes the false denticulated (false ziphodont) condition.