Cave divers Sam Meacham and Alex Alvarez returned from a dive and reported that they had seen what they believed to be footprints in solidified mud on the cave floor; I was skeptical. There was a fair amount of jovial banter and good-natured ribbing between friends. I had to eat my words when Sam produced a GoPro from his pocket and played a video on the tiny screen. He seemed to have something and I was excited.
To visit the cave at a time when it was dry enough to have a muddy floor on which to record animal footsteps would be to visit the cave not hundreds of years ago, but thousands. The Mexican caves of the Yucatan Peninsula were dry during the last ice age of the Pleistocene when global sea level was lower. When the glaciers melted they released their trapped water into the ocean and flooded the caves.
In the book Mammals of the Yucatan Peninsula (2009) the paca is described as having “four toes on each forepaw, and five on each hindpaw. Generally, its tracks show only three toes, with non-retractile claws.”1
From the number of tracks now recorded, I assume that there was considerable traffic by animals around the cave. While I don’t know what the animals were doing in there, I do know that these were not the only animals to make their way through the tunnels. Skeletal remains of gomphothere, sabertooth cats, giant ground sloths, bears, tapirs and other animals have been documented from inside the cave systems of the area. The most famous remains are those of Naia, a human skeleton found in the submerged collapse chamber of Hoyo Negro and dated to be between 12,000 and 13,000 years old.2
Deep horizontal cave penetration may not be as sexy as deep ocean exploration. It doesn’t involve submersibles and complex space-age-like gadgetry, and there are few living creatures (monsters of the deep) with which to ignite the public imagination. But locked inside water-filled underground chambers are prehistoric clues to ancient civilisations and if cave divers can be alert to these signs and conscious not to disturb the evidence, we can bring these new discoveries into the light for all to see.
1. Biol. Carlos Alcerreca A., Biol. Rafael Robles de B., Biol. Luis Pereira Lara, Biol. Diana Antochew Alonzo, Dr. Fiona Reid. (2009) Mammals of the Yucatan Peninsula. Mexico: Editorial Dante S.A. de C.V., pp. 228-229.
2. James C. Chatters, Douglas J. Kennett, Yemane Asmerom, Brian M. Kemp, Victor Polyak, Alberto Nava Blank, Patricia A. Beddows, Eduard Reinhardt, Joaquin Arroyo-Cabrales, Deborah A. Bolnick, Ripan S. Malhi, Brendan J. Culleton, Pilar Luna Erreguerena, Dominique Rissolo, Shanti Morell-Hart, Thomas W. Stafford Jr. (2014) Late Pleistocene Human Skeleton and mtDNA Link Paleoamericans and Modern Native Americans. Science, 344(6185), pp. 750-754.