Ben Creisler
A new paper:
Willian A.F. Dias, Fabiano V. Iori, Aline M. Ghilardi & Marcelo A. Fernandes (2019)
Highlights
The pterygoid region of C. montealtensis and C. paulistanus is better described
There is variation in the pterygoid of C. montealtensis specimens
A composite pterygoid chamber system was observed in some individuals
The pterygoid chambers of some specimens are connected to the airways
We show the first anatomical evidence for vocal capacity in fossil Crocodylomorpha
Abstract
Caipirasuchus are notosuchians found in the Adamantina Formation, Bauru Basin, Upper Cretaceous of Brazil. Until the present date, four species within the genus have been described. Caipirasuchus montealtensis and Caipirasuchus paulistanus are sister taxa which differ from each other by the presence of a chamber in the pterygoid of the former. Doubts about the validity of these species were raised due to their extreme similarity. In the present study, computed tomography was used to explore the pterygoid region and airways of both forms. The pterygoid region of specimens attributed to C. montealtensis was also compared in detail. It was possible to reinforce previously observed differences between C. montealtensis and C. paulistanus, while variation between individuals assigned to C. montealtensis was identified. Differences in pterygoid shape and sutures are described, plus a composite chamber system in the pterygoid of C. montealtensis paratype. The later shows a secondary pterygoid chamber communicating with its nasopharyngeal system. This additional chamber is not present in the holotype, although it is also recognized in the juvenile with some differences. Comparisons with the modern gharial bulla suggest this additional chamber seen in C. montealtensis referred specimen may have had acoustic implications resulting in enhanced vocalization ability. This is the first anatomical evidence for vocal capacity in fossil Crocodylomorpha. New observations here made contribute to the anatomical knowledge about C. montealtensis and C. paulistanus and bring new information about the genus paleoecology. We also raise new taxonomical questions that will only be solved with further research and analyses.