Xibalbaonyx

Xibalbaonyx is an extinct genus of megalonychid ground sloth known from the Late Pleistocene of Mexico. Three species are known: "X. oviceps" and "X. exiniferis" from the Yucatan peninsula and "X. microcaninus" from Jalisco. The genus is named after Xibalba, the underworld in Maya mythology.
Discovery and taxonomy.
The holotype of "X. oviceps" is a mostly complete skeleton discovered in an underwater cave system, while "X. microcaninus" being known from a complete skull and mandible from the sediments of the former paleolake of lake Jalisco. The overlapping remains of the skull and mandibles have notable differences between them, enough to call them distinct species. A third species "X. exiniferis" was described in 2020, also from an underwater cave in the Yucatan Peninsula, it is known from a "fragmentary left mandibular ramus, an atlas, and a left humerus". In 2020, a description of the postcranial remains of the holotype "X. oviceps" was published, suggesting that the taxon had climbing capabilities.