Evolutionary patterns of the intraoral food process in notosuchian crocodyliforms

POL, D.

Punta del Este

Congreso; IX International Congress of Vertebrate Morphology; 2010

Facultad de Ciencias

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:ES-TRAD;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-size:10.0pt; mso-ansi-font-size:10.0pt; mso-bidi-font-size:10.0pt;} @page WordSection1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.WordSection1 {page:WordSection1;} --> Notosuchia the most diverse group of Crocodyliformes from the Cretaceous of Gondwana and is characterized, among other features, by the presence of a heterodont dentition (with incisiviform, caniniform, and molariform teeth). Notosuchians have a broad range of dental morphologies in their posterior molariform teeth, including diverse types of multicusped crowns. Most taxa also have extensive wear facets in posterior molariform teeth indicative of tooth-tooth occlusion, the shape and orientation of which provide valuable information to infer the pattern of jaw movements during occlusion. New information on the tooth morphology and their wear facets for a diverse array of notosuchian taxa is interpreted within a phylogenetic framework to understand the evolution of these features. This analysis shows that the pattern of character acquisition shows that multicusped morphology appeared first in the evolutionary history of the group, in forms (e.g., Simosuchus, Candidodon, Malawisuchus) that lack extensive wear facets and probably also lacked extensive fore-aft movements of the lower jaw during occlusion. A second stage is recognized in more advanced forms (e.g., Mariliasuchus) that have extensive wear facets oriented subparallel to the longitudinal axis of the skull. The orientation of these facets, coupled with modifications in the craniomandibular joint, indicates extensive fore-aft movements were present in these taxa. Finally, a third stage is recognized for highly derived taxa (e.g., Notosuchus, Sphagesaurus) in which the extensive wear facets are obliquely oriented, suggesting the presence of a marked lateral component in the fore-aft jaw motion as well as the presence of alternated unilateral occlusion pattern.