Xibalbaonyx

Xibalbaonyx
Temporal range: Late Pleistocene (Rancholabrean) ~0.016–0.010 Ma
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pilosa
Suborder: Folivora
Family: †Megalonychidae
Subfamily: †Megalonychinae
Genus: †Xibalbaonyx
Stinnesbeck et al. (2017)
Type species
†Xibalbaonyx oviceps
Stinnesbeck et al 2017
Other species
  • †Xibalbaonyx microcaninus Stinnesbeck et al 2018
  • †Xibalbaonyx exinferis Stinnesbeck et al 2020

Xibalbaonyx is an extinct genus of megalonychid ground sloth known from the Late Pleistocene of Mexico. Three species are recognized: X. oviceps and X. exiniferis from the Yucatán Peninsula and X. microcaninus from Jalisco. The genus name derives from Xibalba, the underworld in Maya mythology.

Discovery and taxonomy

The holotype of X. oviceps consists of a mostly complete skeleton discovered in an underwater cave system, whereas X. microcaninus is known from a complete skull and mandible recovered from sediments deposited by the ancient Lake Jalisco. The overlapping cranial and mandibular remains exhibit notable morphological differences, sufficient to support their recognition as distinct species. A third species, X. exiniferis, was described in 2020 from an underwater cave in the Yucatán Peninsula, it is known from a fragmentary left mandibular ramus, an atlas, and a left humerus. In 2020, the postcranial remains of the X. oviceps holotype were described The following year, remains of a form closely related to Xibalbaonyx were reported from Pleistocene deposits in Cueva de Iglesitas near Caracas, Venezuela.

Description

Xibalbaonyx oviceps was approximately 2 meters (6.6 ft) long and weighed around 200 kilograms (440 lb), with a similar body mass estimated for X. exiniferis. Its robust forelimbs were likely supported by well-developed musculature and possessed a broad range of movement. These features have been interpreted as adaptations for climbing, comparable to the abilities of similarly sized American black bears.

References

  1. ↑ Stinnesbeck, Sarah R.; Frey, Eberhard; Olguín, Jerónimo Avíles; Stinnesbeck, Wolfgang; Zell, Patrick; Mallison, Heinrich; González González, Arturo; Aceves Núñez, Eugenio; Velázquez Morlet, Adriana; Terrazas Mata, Alejandro; Benavente Sanvicente, Martha; Hering, Fabio; Rojas Sandoval, Carmen (2017). "Xibalbaonyx oviceps, a new megalonychid ground sloth (Folivora, Xenarthra) from the Late Pleistocene of the Yucatán Peninsula, Mexico, and its paleobiogeographic significance". PalZ. 91 (2): 245–271. Bibcode:2017PalZ...91..245S. doi:10.1007/s12542-017-0349-5. ISSN 0031-0220. S2CID 134188352.
  2. ↑ Stinnesbeck, Sarah R.; Frey, Eberhard; Stinnesbeck, Wolfgang (2018). "New insights on the paleogeographic distribution of the Late Pleistocene ground sloth genus Xibalbaonyx along the Mesoamerican Corridor". Journal of South American Earth Sciences. 85: 108–120. Bibcode:2018JSAES..85..108S. doi:10.1016/j.jsames.2018.05.004. ISSN 0895-9811. S2CID 134541882.
  3. 1 2 Stinnesbeck, Sarah R.; Stinnesbeck, Wolfgang; Frey, Eberhard; Avilés Olguín, Jerónimo; González, Arturo González (2020-05-12). "Xibalbaonyx exinferis n. sp. (Megalonychidae), a new Pleistocene ground sloth from the Yucatán Peninsula, Mexico". Historical Biology. 33 (10): 1952–1963. Bibcode:2021HBio...33.1952S. doi:10.1080/08912963.2020.1754817. ISSN 0891-2963. S2CID 219425309.
  4. 1 2 3 Stinnesbeck, Sarah R.; Frey, Eberhard; Avilés Olguín, Jerónimo; González, Arturo González; Velázquez Morlet, Adriana; Stinnesbeck, Wolfgang (2020-09-21). "Life and death of the ground sloth Xibalbaonyx oviceps from the Yucatán Peninsula, Mexico". Historical Biology. 33 (11): 2610–2626. doi:10.1080/08912963.2020.1819998. ISSN 0891-2963. S2CID 224987707.
  5. ↑ Rincón, Ascanio D.; Lemoine, Luis A.; McDonald, H. Gregory (2021-10-01). "A new addition to Pleistocene megalonychid sloth diversity in the northern Neotropics". Journal of South American Earth Sciences. 110 103379. Bibcode:2021JSAES.11003379R. doi:10.1016/j.jsames.2021.103379. ISSN 0895-9811.