The Fossil Record of Vertebrate Tracks in Mexico

Abstract

The fossil record of vertebrate tracks in Mexico is taxonomically rich and geographically diverse, and ranges in age from Middle Jurassic to Pleistocene and possibly Holocene. Middle Jurassic saurischian dinosaur tracks from Oaxaca represent the oldest record of vertebrate tracks in Mexico. Tracks attributed to Late Jurassic theropods and ornithopods are known from Michoacán. Theropod tracks of supposed Jurassic age are known from Durango. Lower Cretaceous Saurischian and ornithopod tracks are known from southern Puebla. Central Mexico has yielded Late Cretaceous hadrosaurid and sauropod tracks (Puebla), and tracks belonging to Theropoda and Ornithopoda (El Aguaje, Michoacan). In Coahuila several tracksites occur within the Cerro del Pueblo Formation and include tracks of mesoreptiles, pterosaurs, small to large theropods, bipedal and quadrupedal ornithopods, birds and possibly a mammal. A tracksite in the Olmos Formation includes tracks of turtles, crocodilians, medium-sized theropods, small ornithopods, and birds. Bird tracks of supposed Eocene age are known from Sinaloa. Two important Pleistocene ichnofaunas occur in the states of Puebla (Tepexi de Rodríguez) and Jalisco (San Juan de los Lagos), and include tracks of camelids, artiodactyls, small ungulates, elephants, large felids and birds. Pleistocene human tracks occur in Coahuila and Jalisco. Mexico's track record provides important insights into vertebrate diversity, paleoecology, and paleoenvironments. Given the rate of new discoveries since 1998, there is no doubt that new sites await to be found.

Keywords:

• Paleoichnology
• fossil tracks
• dinosaurs
• vertebrates
• Mexico

ACKNOWLEDGEMENTS

We thank to Miguel A. Lara, Carlos R. Delgado-de Jesús, Ignacio Vallejo, Rufino Rodríguez, José Flores-Ventura, Donald B. Brinkman and Scott D. Sampson for their encouragement and field support. Rich McCrea and Giuseppe Leonardi provided insights and companionship during the 2002 field season. Martin G. Lockley freely shared his data with us. Robert L. Carroll, Jason Anderson and Ingrid Birker provided helpful access to the Redpath Museum data base and collections. Federico Solórzano Barreto, Oscar J. Polaco, Rosario Gómez-Núñez, Arturo H. González-González and the staff at the Museo del Desierto supported many aspects of this research over the years. Finally we thank Neffra Matthews and David Mossman for critical review of the manuscript. Some data were collected with financial assistance from the Parras Basin Dinosaur Project funded by National Geographic Society Grant No. 7171-01 to Scott D. Sampson.