Apatopus is an ichnogenus, or a name based on footprints, that may have been from a phytosaur. The trackmaker lived in the early Triassic. It was named by Baird in 1957.

Apatopus
Trace fossil classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Phytosauria
Ichnofamily: Aptopodidae
Ichnogenus: Apatopus
Baird, 1957
Type ichnospecies
Apatopus lineatus
Baird, 1957
Synonyms
  • Otozoum (?) lineatus Bock, 1952

Of special relevance in regard to its phytosaurian identity is the fact that the tracks are positioned in a way that indicates that the limbs were held directly under the body, a gait known in true archosaurs like crocodiles and dinosaurs but previously thought absent in phytosaurs. This raises the question of whereas this trait was shared by the last common ancestor between archosaurs and phytosaurs or if it evolved independently between these groups.[1][2]

References

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  1. ^ Padian, K., Li, C., & Pchelnikova, J. 2010. The trackmaker of (Late Triassic, North America): implications for the evolution of archosaur stance and gait. Palaeontology 53, 175-189.
  2. ^ Klein, H. & Lucas, S. G. 2013. The Late Triassic tetrapod ichnotaxon Apatopus lineatus (Bock, 1952) and its distribution. Bulletin of the New Mexico Museum of Natural History 61, 313-324.