| Protopyknosia | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauromorpha |
| Clade: | Archosauriformes |
| Clade: | † Protopyknosia Nesbitt et al., 2021 |
| Genera | |
| |
Protopyknosia is an extinct clade of archosauriform reptiles from the Late Triassic of India and the United States. First identified by Sterling Nesbitt et al. in 2021, [1] the clade contains two genera: Kranosaura and Triopticus . Members of Protopyknosia characteristically have an unusually domed head reminiscent of the later pachycephalosaurian dinosaurs in an example of convergent evolution. [2] The clade was defined by Nesbitt et al. 2021 as the "most inclusive clade containing Triopticus primus , but not Passer domesticus (the house sparrow), Triceratops horridus , Alligator mississippiensis (the American alligator), Sphenodon punctatus (the tuatara), Heloderma suspectum (the Gila monster), or Chrysemys picta (the painted turtle)"
