Ice Age Predators Found Alongside Oldest Human in Americas
The well-preserved remains offer a glimpse into the rapidly shifting world that surrounded Naia, a girl who died around 13,000 years ago.
bigger than a modern grizzly.
Photograph by Paul Nicklen, National Geographic Creative
Photograph by Paul Nicklen, National Geographic Creative
Like the saber-toothed cats, giant sloths, and other wild creatures
trapped in the cave, Naia most likely wandered in looking for fresh
water and took a fatal fall into the 90-foot-deep pit. Later, rising
seas brought on by melting glaciers raised the Yucatán Peninsula’s water
table by hundreds of feet, flooding the caves and entombing the
skeletons.
Cave divers first came across Hoyo Negro—Spanish for “black hole”—in
2007, and were stunned to find a massive water-filled chamber rife with
articulated animal remains and the skeleton of Naia. Expeditions through
the years have mapped at least 28 animal skeletons within the pit, only
a handful of which have been fully excavated.
Carnivore Complexity
Now some of those bones have been recovered, and the latest fossil
examinations are giving paleontologists crucial new insight into the
Great American Interchange, a dizzying migration of ancient animals
between North and South America.
After the Isthmus of Panama tectonically rose from the sea some 3 to 5
million years ago, the ecosystems that existed on the two
continents—left to stew in their own evolutionary juices for tens of
millions of years—were at last able to mix and mingle.
This complex exchange of life settled into the Americas’ modern
ecosystems: South America gave North America armadillos, and North
America gave South America llamas. But paleontologists still know very
little about this massive interchange, since fossils are notoriously
hard to come by in the tropical forests that cover the region.
By contrast, Hoyo Negro is a fossil bonanza. The underwater cave
preserved entire animals, because the carcasses had nowhere to go, and
the low-oxygen waters ensured that the remains laid undisturbed for more
than ten thousand years.
Paleontologists and cave divers have found the remains of
saber-toothed cats, peccaries, mountain lions, tapirs, and elephant-like
animals called gomphotheres within Hoyo Negro’s depths. Some parts of
the underwater cave even preserved the footprints of ancient bears,
crusted over in a film of calcite.
Earlier this year, the joint U.S.-Mexico team identified a new species of ground sloth in the cave, which they named Nohochichak xibalbahkah, Mayan for “great-clawed dweller of the underworld.” (Read about another ancient sloth found elsewhere in the Yucatán.)
At the paleontology meeting, Schubert revealed that bears also
entered these caves—and, in the case of Hoyo Negro, sometimes never
exited. Divers have found three exquisitely preserved skulls of the
extinct bear species Arctotherium wingei. A cousin of the Andean spectacled bear, the ancient species was slightly smaller than today’s grizzly bear. (Read more about its sister species—the biggest bear that ever lived.)
The skulls are so well-preserved, Schubert says, that visitors to his
lab often mistake them for high-quality reconstructions. Divers also
found the skull of a stocky, coyote-like canid previously only known
from South America.
Together, the remains represent the first hard evidence of carnivores
leaving North America for South America, diversifying into new South
American species, and then returning northward—adding greater complexity
to the Great American Interchange.
It’s likely that Hoyo Negro will turn up yet more surprises: Schubert
recently received a National Geographic grant for further fieldwork at
the site. The team hopes to collect more bones—and venture deeper into
the darkness.
“When you start out with a little bit of data, it’s easy to spin a
simple scenario,” says Greg McDonald, a U.S. Bureau of Land Management
paleontologist and a member of the Hoyo Negro team. “We are now
recognizing that it is much more complicated, and this is the real fun
of paleontology.”
Like the saber-toothed cats, giant sloths, and other wild creatures
trapped in the cave, Naia most likely wandered in looking for fresh
water and took a fatal fall into the 90-foot-deep pit. Later, rising
seas brought on by melting glaciers raised the Yucatán Peninsula’s water
table by hundreds of feet, flooding the caves and entombing the
skeletons.
Cave divers first came across Hoyo Negro—Spanish for “black hole”—in
2007, and were stunned to find a massive water-filled chamber rife with
articulated animal remains and the skeleton of Naia. Expeditions through
the years have mapped at least 28 animal skeletons within the pit, only
a handful of which have been fully excavated.
Carnivore Complexity
Now some of those bones have been recovered, and the latest fossil
examinations are giving paleontologists crucial new insight into the
Great American Interchange, a dizzying migration of ancient animals
between North and South America.
After the Isthmus of Panama tectonically rose from the sea some 3 to 5
million years ago, the ecosystems that existed on the two
continents—left to stew in their own evolutionary juices for tens of
millions of years—were at last able to mix and mingle.
This complex exchange of life settled into the Americas’ modern
ecosystems: South America gave North America armadillos, and North
America gave South America llamas. But paleontologists still know very
little about this massive interchange, since fossils are notoriously
hard to come by in the tropical forests that cover the region.
By contrast, Hoyo Negro is a fossil bonanza. The underwater cave
preserved entire animals, because the carcasses had nowhere to go, and
the low-oxygen waters ensured that the remains laid undisturbed for more
than ten thousand years.
Paleontologists and cave divers have found the remains of
saber-toothed cats, peccaries, mountain lions, tapirs, and elephant-like
animals called gomphotheres within Hoyo Negro’s depths. Some parts of
the underwater cave even preserved the footprints of ancient bears,
crusted over in a film of calcite.
Earlier this year, the joint U.S.-Mexico team identified a new species of ground sloth in the cave, which they named Nohochichak xibalbahkah, Mayan for “great-clawed dweller of the underworld.” (Read about another ancient sloth found elsewhere in the Yucatán.)
At the paleontology meeting, Schubert revealed that bears also
entered these caves—and, in the case of Hoyo Negro, sometimes never
exited. Divers have found three exquisitely preserved skulls of the
extinct bear species Arctotherium wingei. A cousin of the Andean spectacled bear, the ancient species was slightly smaller than today’s grizzly bear. (Read more about its sister species—the biggest bear that ever lived.)
The skulls are so well-preserved, Schubert says, that visitors to his
lab often mistake them for high-quality reconstructions. Divers also
found the skull of a stocky, coyote-like canid previously only known
from South America.
Together, the remains represent the first hard evidence of carnivores
leaving North America for South America, diversifying into new South
American species, and then returning northward—adding greater complexity
to the Great American Interchange.
It’s likely that Hoyo Negro will turn up yet more surprises: Schubert
recently received a National Geographic grant for further fieldwork at
the site. The team hopes to collect more bones—and venture deeper into
the darkness.
“When you start out with a little bit of data, it’s easy to spin a
simple scenario,” says Greg McDonald, a U.S. Bureau of Land Management
paleontologist and a member of the Hoyo Negro team. “We are now
recognizing that it is much more complicated, and this is the real fun
of paleontology.”
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