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Biological communities of Central America, although under threat, retain among the highest levels of medium-to-small animal diversity of any ecosystems on earth. They were formerly even more diverse, including a complex megafaunal assemblage as well.  Paleontological records of such environments tend to be rare, however, because warm temperatures and acid soils lead to rapid destruction of skeletal remains.  The limestone caves of the Yucatan peninsula are proving to be an exception to this pattern, offering an almost unmatched skeletal record of large mammals dating to the time of humans’ first arrival in the Americas.  Most large mammal discoveries are being made underwater in the submerged caves of Belize and the Mexican state of Quintana Roo.  The most spectacular and informative of these is the site of Hoyo Negro.

Located at the confluence of three >600 meter-long tunnels, Hoyo Negro is a 60 meter-diameter collapse chamber that falls 30-45 meters below the tunnel floors and 40-55 meters below the water surface.  Before sea level rose at the end of the last glaciation, it was a perfect natural trap.  At its bottom, among boulders, heaps of calcite raft sediment, and piles of bat guano, lie the remains of 27 large animals.  Others are found in the connecting tunnels. 

At least eight extinct species are included among the almost perfectly-preserved skeletons: saber tooths, highland gomphotheres, three species of giant ground sloth, the south American bear Arctotherium, and a large canid.  One of the sloths is a new genus; the South American carnivores have not been previously documented in Central America.  Along with tapirs, peccaries, pumas, and a coati, which remain in the region today, are bobcats and coyotes, which are far outside their modern ranges.  Additional tunnels contain remains of glyptodont, extinct llama, and horse.  The image is of a highly diverse megafaunal community or closely spaced communities in a complex, dynamic mosaic. 

At least some of these many species were extant after 15,000 years ago, when humans first arrived.  Among their bones on the floor of Hoyo Negro floor are remains of one of those earliest people, Naia, an adolescent girl.  Her nearly complete ~13,000 year-old skeleton is the earliest currently known in the Americas and is providing extraordinary information about the activities, health, and livelihood of the first people of Meso America.

Investigation and, in some cases, recovery of these skeletons from deep under water, in the dark, has posed major technical challenges.  Dating them has been problematic.  However, their study, together with paleoecological analysis of the calcite raft sediment, stalagmites, guano deposits, and abundant sticks and charcoal, offers an unparalleled opportunity to understand the ecosystems of the terminal Pleistocene Yucatan and the initial impact of people on them.

Hoyo Negro: Terminal Pleistocene Megafauna

and the First Human of the Yucatan

Keynote

Dr.  James Chatters

James Chatters is an American forensic anthropologist, archaeologist, and paleontologist. As of 2012, he is the owner of forensics consulting firm, Applied Paleoscience; and serves as a Research Associate in the Office of Graduate Studies, Research, and Continuing Education at Central Washington University; Deputy Coroner of Benton County, Washington; and a consulting scientist on staff with Foster Wheeler Environmental Corporation of Bothell, Washington. In 1996, Chatters was the first scientist to excavate and study the prehistoric (Paleo-Indian) skeletal remains, known as Kennewick Man, which were discovered on the banks of the Columbia River.

Keynote speaker

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