Alejandro Terrazas Mata

Xibalbaonyx oviceps, a new megalonychid ground sloth (Folivora, Xenarthra) from the Late Pleistocene of the Yucatán Peninsula, Mexico, and its paleobiogeographic significance

Here we describe a new genus and species of giant ground sloth, Xibalbaonyx oviceps (Megalonychidae, Xenarthra), from the drowned cave system of the northeastern Yucatán Peninsula. The specimen is Late Pleistocene in age and was discovered in the Zapote sinkhole (cenote) near Puerto Morelos in the Mexican state of Quintana Roo. Xibalbaonyx oviceps differs significantly from all hitherto known Megalonychidae including those from the Greater Antilles and South America. The new taxon suggests a local Caribbean radiation of ground sloths during the Late Pleistocene, which is consistent with the dispersal of the group along a Mexican corridor.KurzfassungDie Unterwasserhöhlen auf der nordöstlichen Halbinsel Yukatan zeigen eine artenreiche Ansammlung von Großsäugern aus dem späten Pleistozän und frühen Holozän. Hier beschreiben wir die neue Gattung und Art eines Riesenfaultiers, Xibalbaonyx oviceps (Megalonychidae, Xenarthra), aus der Zapote Doline (Cenote) in der Nähe von Puerto Morelos im mexikanischen Bundesstaat Quintana Roo. Das Exemplar unterscheidet sich signifikant von allen bisher dokumentierten Megalonychidae einschließlich derjenigen von den Großen Antillen und aus Südamerika. Das neue Taxon deutet auf eine lokale karibische Radiation von Bodenfaultieren währen des Spätpleistozäns hin, die mit der Ausbreitung der Gruppe entlang des mexikanischen Korridors übereinstimmt.

The earliest settlers of Mesoamerica date back to the late Pleistocene

Preceramic human skeletal remains preserved in submerged caves near Tulum in the Mexican state of Quintana Roo, Mexico, reveal conflicting results regarding 14C dating. Here we use U-series techniques for dating a stalagmite overgrowing the pelvis of a human skeleton discovered in the submerged Chan Hol cave. The oldest closed system U/Th age comes from around 21 mm above the pelvis defining the terminus ante quem for the pelvis to 11311±370 y BP. However, the skeleton might be considerable older, probably as old as 13 ky BP as indicated by the speleothem stable isotope data. The Chan Hol individual confirms a late Pleistocene settling of Mesoamerica and represents one of the oldest human osteological remains in America.

The Muknal cave near Tulum, Mexico: An early-Holocene funeral site on the Yucatán peninsula

Here, we report on an incomplete human skeleton, soot patches related to anthropogenic fireplaces, and cut marks on the mandible of an extinct peccary, from the submerged Muknal cave southwest of Tulum on the Mexican Yucatán peninsula. The human individual, here named ‘Muknal Grandfather’, was identified as a male based on cranial parameters. The age at the time of death was estimated to be between 40 and 45 years. We propose that the human bones have been brought to the cave during the latest Pleistocene or early Holocene, but not later than 8600 14C yr BP (ca. 9600 cal BP), as a secondary burial of a partial skeleton. The peccary mandible was placed close to the burial site, possibly as part of the same ritual. The Muknal cave therefore served as a place for funeral rituals.