A New Genus of Megalonychid Ground Sloth (Mammalia, Xenarthra) from the Late Pleistocene of Quintana Roo, Mexico

  title={A New Genus of Megalonychid Ground Sloth (Mammalia, Xenarthra) from the Late Pleistocene of Quintana Roo, Mexico},
  author={H. Gregory McDonald and James C. Chatters and Timothy J. Gaudin},
  journal={Journal of Vertebrate Paleontology},
ABSTRACT A new genus and species of late Pleistocene megalonychid sloth, Nohochichak xibalbahkah, gen. et sp. nov., is described from Hoyo Negro, a chamber in the Sac Actun cave system, Quintana Roo, Mexico. Phylogenetic analysis indicates that this new sloth is most closely related to Meizonyx salvadorensis from the middle Pleistocene of El Salvador, and that these two genera in turn are the sister clade to Megistonyx and Ahytherium in South America and not the other North American… 

Two new megalonychid sloths (Mammalia: Xenarthra) from the Urumaco Formation (late Miocene), and their phylogenetic affinities

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Panthera balamoides and other Pleistocene felids from the submerged caves of Tulum, Quintana Roo, Mexico

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Phylogenetic analysis places the new genus and species of nothrotheriine sloth from riverbank deposits of the Río Acre region of Peru in western Amazonia as sister group to the (Pronothrotherium (NothroTheriops + Nothratherium)) clade.

New Pleistocene remains of megalonychid ground sloths (Xenarthra: Pilosa) from the intertropical Brazilian region

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Premaxillae of the Extinct Megalonychid Sloths Acratocnus, Neocnus, and Megalonyx, and their Phylogenetic Implications (Mammalia, Xenarthra)

Morphological evidence suggests that a broadened, plate-like premaxilla constitutes a synapomorphy for the entire clade Megalonychidae, and the loss of this process may unite late Miocene to Recent megalonychids.

Nothrotheriops shastensis (Sinclair) from Actun Lak: First Record of Nothrotheriidae (Mammalia, Xenarthra, Pilosa) from Belize

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The results imply that the split between the two extant sloth genera is ancient, dating back perhaps as much as 40 Myr, and that the similarities between these two taxa present one of the most dramatic examples of convergent evolution known among mammals.

The ear region of edentates and the phylogeny of the Tardigrada (Mammalia, Xenarthra)

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The Edentata of North America

  • E. Cope
  • Geology
    The American Naturalist
  • 1889
Of these divisions it is evident hat the Nomarthra are the least specialized, and must be regarded as ancestral to the Xenarthra, which are now exclusively Old World, while the Xexartkra are confined to the New World.