Life and death of the ground sloth Xibalbaonyx oviceps from the Yucatán Peninsula, Mexico

ABSTRACT

Ongoing investigations in submerged cave systems of Quintana Roo in south-eastern Mexico reveal a rich Late Pleistocene megafaunal assemblage, among them the megalonychid ground sloth Xibalbaonyx oviceps. The taxon has been described based on a complete skull and mandible from El Zapote cenote west of Puerto Morelos. We here add hitherto unreported postcranial material from El Zapote, attributed to the holotype. This new material allows us to reconstruct unexpected locomotion capabilities for Xibalbaonyx oviceps including steep slope and rock climbing. This may have enabled the ground sloth to use the sinkholes and underground caverns as water resource and shelter. The Late Pleistocene age of the fossil allows for a co-existence with early human settlers on the Yucatán Peninsula.

KEYWORDS:

• Ground sloths
• megafauna
• Late Pleistocene
• Mexico

Acknowledgments

We are grateful to the owners of the El Zapote Ecoparque, Mrs. Rosario Fátima González Alcocer and Mr. Santos Zuñiga Roque, for their long-time trust in our work and collaboration during the past years. The Zapote sinkhole was first explored by technical diving instructor Vicente Fito, who also discovered the ground sloth Xibalbaonyx oviceps. Eugenio Acevez Nuñez, Valentina Cucchiara, Alejandro Martinez, Vincenzo Biroli, Luz María Guzman Fernandez, Luis Alberto Sanchez Navarro and David Orozco Pizano assisted in the documentation, adding to site mapping and collection. We also thank CINDAQ volunteers for their underwater cave survey and cartography. The INAH Tulum supported the project ‘Estudios de los grupos humanos precerámicos de la costa oriental de Quintana Roo, México, a través de los contextos actualmente inundados’. The ground sloth material presented here has been part of an INAH rescue campaign (Oficio 401. tf(4) | 9.2014/36/0601). Carmen Rojas Sandoval from the INAH Tulum, headed the collection and is acknowledged for her thoughtful discussions about palaeontological research. We are also thankful to our supporters and sponsors: Miguel Quintana Pali, Grupo Experiencias Xcaret, Ben Mcgiver, Dive-Xtras, Biol. Karla Peregrina, Biol. Roberto Rojo, Dr. Milagros Varguez and the Red the Planetarios de Quintana Roo. Two anonymous reviewers, as well as journal editor Dr. Gareth Dyke, are gratefully acknowledged for their many helpful comments and corrections to this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We gratefully acknowledge financial support by the Federal Ministry of Education and Research (BMBF Projects 01DN119), the German Research Foundation (DFG Project STI128/28; FR1314/26) and the German Exchange Service (DAAD, Kurzreisestipendium für Doktoranden 91683941).