Colobops : a juvenile rhynchocephalian reptile (Lepidosauromorpha), not a diminutive archosauromorph with an unusually strong bite

SCHEYER, TORSTEN M.; SPIEKMAN, STEPHAN N. F.; SUES, HANS-DIETER; EZCURRA, MARTÍN D.; BUTLER, RICHARD J.; JONES, MARC E. H.

Royal Society Open Science

Royal Society

Año: 2020 vol. 7

2054-5703

Correctly identifying taxa at the root of major clades or the oldestclade-representatives is critical for meaningful interpretations ofevolution. A small, partially crushed skull from the Late Triassic(Norian) of Connecticut, USA, originally described as anindeterminate rhynchocephalian saurian, was recently namedColobops noviportensis and reinterpreted as sister to all remainingRhynchosauria, one of the earliest and globally distributedgroups of herbivorous reptiles. It was also interpreted as havingan exceptionally reinforced snout and powerful bite based on anespecially large supratemporal fenestra. Here, after a re-analysisof the original scan data, we show that the skull was stronglydorsoventrally compressed post-mortem, with most bones out oflife position. The cranial anatomy is consistent with that ofother rhynchocephalian lepidosauromorphs, not rhynchosaurs.The ?reinforced snout? region and the ?exceptionally enlargedtemporal region? are preservational artefacts and not exceptionalamong clevosaurid rhynchocephalians. Colobops is thus not a keytaxon for understanding diapsid feeding apparatus evolution.