A large archosauriform tooth with multiple supernumerary carinae from the Upper Triassic of New Mexico (USA), with comments on carina development and anomalies in the Archosauria

Abstract

Here we report a tooth of a large archosauriform from the Upper Triassic of New Mexico, USA that displays developmental anomalies of carina formation. This tooth has two supernumerary carinae, both on the lingual side of the tooth. Previously, carina anomalies of this sort were primarily known from theropod dinosaurs, but always from the labial surface. Integrating this specimen into a reassessment of the published accounts of carina anomalies in other fossil diapsids reveals that supernumerary carinae are more widespread throughout Archosauriformes than previously reported. Our interpretation of this developmental anomaly highlights the present lack of understanding of tooth development in archosaurs, particularly carina formation, and suggests that crown morphology development in archosauriforms may be constrained differently than it is in mammals. This developmental constraint may explain the differences observed between the complexity found in mammal and archosauriform cusp morphology.

Keywords:

• Archosauriformes
• rauisuchia
• odontogenesis
• paleopathology

Acknowledgements

Reviews by Stephen Brusatte and one anonymous reviewer significantly improved the manuscript. For assistance with specimens studied we would like to thank S. Lucas (NMMNH). D.C. Heckert found the tooth while assisting A.B. Heckert with field work for his M.S. Thesis. The tooth was collected under a permit issued to the NMMNH for vertebrate fossil collection by the Cibola National Forest. D. Ulibarri (NMMNH) expertly moulded and cast the specimen for our analyses.