Crocodilian behaviour: a window to dinosaur behaviour?

Abstract

Modern crocodilians and birds are the only living representatives of the Archosauria, a group that also includes non-avian dinosaurs and pterosaurs. Modern crocodilians originated during the early Cretaceous period and dispersed globally. Examples of physiological similarities between living crocodilians and birds include similar amino acids in β-keratins among crocodiles, turtles and birds; oviduct homologies between crocodilians and birds; similar forelimb structures in crocodiles and other archosaurs and similarities in gene expression in limb development in alligators and chickens. While individual crocodilian species have adapted their behaviours to meet specific strategies for survival in specific habitats, core reproductive behaviours are universal among modern crocodilians and transcend speciation, morphology and geographic distribution. Hard-wired core behaviours include social signals that incorporate chemosensory, auditory and mechanoreception modalities; construction of a temperature-stabilising nest chamber to incubate eggs; and parental care of their young. Parental care may reflect a primitive character for archosaurs, including dinosaurs. Crocodilians use integumentary sense organs (ISOs) during courtship and in parental care, and similar structures may have had similar functions in dinosaurs. The presence of numerous foramina (possible ISOs) in the skulls of saurischians, along with the findings of fossilised nests with adults, may indicate similar complex behaviours, including parental care, in dinosaurs.

Keywords:

• dinosaurs
• crocodilians
• behaviour
• temperature
• reproduction
• integumentary sense organs

Acknowledgements

We wish to express our thanks to David Varricchio, Frankie Jackson, Montana State University, Bozeman, MT, and the National Science Foundation for travel funding to allow our attendance at the 4th International Symposium on Dinosaur Eggs and Babies, and for their hospitality. Special thanks to Frankie Jackson for her assistance in the preparation of the figures used in the manuscript. Thanks also to Gregory Watkins-Colwell and the Yale Peabody Museum of Natural History, Department of Vertebrate Zoology; John White for use of images; Bruce Foster and Bill Holmstrom, NY Wildlife Conservation Society; Joseph Martinez and Harvard University, Museum of Comparative Zoology, Cambridge, MA; Museum of Natural History, University of Kansas, Lawrence, KS; John Brueggen and the St. Augustine Alligator Farm, St. Augustine, FL; Bruce Shwedick and Dr. Kent Vliet.