I’ve already written about the Hoyo Negro fossil site located in Yucatan, Mexico twice (See: https://markgelbart.wordpress.com/2015/08/08/the-hoyo-negro-fossil-site-in-yucatan-mexico/ and https://markgelbart.wordpress.com/2017/09/13/new-species-of-late-pleistocene-ground-sloth-and-peccary-discovered-on-yucatan-peninsula/ ), but new and interesting discoveries keep happening inside this underwater cave. Scuba divers previously found a 13,000 year old human skeleton, the bones of 30 species of large mammals, and bat guano, containing valuable paleoecological evidence at this site. Included among the mammal specimens were 3 extinct animals new to science–2 species of ground sloth (Xibalbaonyx oviceps and Nahochichak xibalbahakah) and 1 species of peccary (Mucknalia minimas). Recently, scuba divers found another human skeleton here, this 1 dated to 12,000 years BP; and scientists identified the bones of 2 species of extinct carnivores previously thought to have been restricted to South America.
A team of paleontologists looking through bones excavated from Hoyo Negro realized 1 labeled as coyote had been misidentified. The remains actually belonged to Protocyon troglodytes, an extinct wolf-like animal. Subfossils of this species have been excavated from sites located in 6 South American countries, but this is the first time a specimen has ever been found in North America. This team of paleontologists also recognized a bear skull misidentified as belonging to a spectacled bear was actually the skull of an Arctotherium wingei. This species of extinct bear was known from fossil sites in 3 South American countries, and this specimen is also a first from North America. Photos of bear fossils from other sites in the Yucatan peninsula indicate these also are Arctotherium. These discoveries extend the known northern range limits of these species by over 1200 miles.
I think this photo is the Arctotherium skull found in the Hoyo Negro. This specimen is preserved better than any previously known.
The Yucatan peninsula supported a unique fauna during the last Ice Age. Paleontologists recently named a new species of extinct jaguar (Panthera balamoides) from a few bones found at another site in the region. This means there were 4 species of large mammals living on the Yucatan that may not have been found anywhere else. Moreover, both North and South American species had ranges that overlapped here and possibly nowhere else. For example dire wolves co-existed here with protocyon, another predatory canid. It seems likely a vast desert grassland isolated the Yucatan peninsula during Ice Ages. However, the proximity of the Caribbean Sea allowed for more precipitation on the peninsula than farther inland. This fostered the growth of jungles and wetlands that supported a greater variety of fauna, and new species that were different from populations on the other side of the desert evolved in this isolated paleoenvironment.
Reference:
Schubert, Blaine; et. al.
“Yucatan Carnivores Shed Light on Great Biotic Interchange”
Biology Letters May 2019
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