Pictures: Prehistoric American Skull Found in Sea Cave?

Mastodon Leftovers?

Photograph courtesy Daniel Riordan-Araujo

Diver Alex Alvarez examines the remains of a mastodon, found about 20 feet (6 meters) from the human skull during the 2007 Hoyo Negro cave expedition. Other animal bones were found nearby, including the remains of a likely prehistoric bear, according to Alvarez's teammate Alberto Nava.

(Related: "Mastodons Driven to Extinction by Tuberculosis, Fossils Suggest.")

There are no openings in the cave big enough for a grown mastodon—a smaller, less hairy cousin of the woolly mammoth—to have entered. One possibility, the team says, is that the animal had been hunted and butchered by Paleo-Indian hunters, then carried into the cave in chunks.

Evidence from other sites do seem to confirm that humans once hunted mastodons in North America, according to anthropologist David Meltzer, who wasn't involved in the study.

Overall, the discoveries in Hoyo Negro are "exciting," said Meltzer, a Paleo-Indian expert at Southern Methodist University in Texas.

But, he added, the team's ideas about the bones being 10,000 years old are still "hypotheses to test, rather than conclusions to accept, at this point."

(Also see "Portal to Maya Underworld Found in Mexico?")

Published March 9, 2011

Eater of Light

Photograph courtesy Daniel Riordan-Araujo

During the 2007 expedition, divers descend into Hoyo Negro—"black hole" in Spanish.

"The name comes from the black holes in space," Nava explained. "When we first entered the place, it was just pitch black everywhere. We almost felt like it was absorbing our light.

"I think most people think of caves as something scary," he added.

"For us, it's a beautiful place. The caves are wide and decorated with stalactites. And the water is so crystal clear that when you look at your hand or your equipment, it looks like you're floating in air."

(See pictures of the Bahamas' deadly 'blue hole' caves.)

Published March 9, 2011

Rocket to the Crypt

Photograph courtesy Daniel Riordan-Araujo

Motorized "scooters" pull divers toward the Hoyo Negro cave during the expedition that uncovered the ancient skull—a journey of more than 4,000 feet (1,200 meters) through tortuous underwater passages.

About 200 feet (60 meters) tall and 120 feet (36 meters) wide, Hoyo Negro may have been a valuable source of fresh water before it was inundated with seawater, the team says.

"In the entrance of one of the tunnels, we can see vertical indentations that we think are rope marks," Nava explained.

This suggests "someone was getting water there, or they were jumping in and needed ropes to get out."

(See more pictures of Mexican underwater caves.)

Published March 9, 2011

Head-to-Head

Photograph courtesy Daniel Riordan-Araujo

Alex Alvarez swims toward the human skull (lower right) his team discovered in the Hoyo Negro cave.

The skull's shape  could offer new insights into where the first Americans migrated from, said Dominique Rissolo, an archaeologist at the Waitt Institute in La Jolla, California. (Waitt and National Geographic collaborate on a grant program.)

"By doing these kinds of analyses, we're able to get a better understanding of which Old World populations these individuals most closely resembled," said Rissolo, who's helping to organize a broader investigation of Hoyo Negro with Mexico's National Institute of Anthropology and History.

For now, though, the skull is still in the upside down position it was found in—the team hasn't touched or moved the remains.

Nava, the cave diver, said, "In any archaeological scene, the context that you find something in is key."

The team hopes at some point to extract a skull sample for testing, but that won't happen until a clear plan is in place.

"Right now our main objective is to protect what is there," Nava said,
"and to do the least amount of damage until we can figure out what we're going to do."

(Related: "Undersea Cave Yields One of Oldest Skeletons in Americas.")

Published March 9, 2011