such as "Introduction", "Conclusion"..etc
December 4, 2007 — Long before tourists arrived
in the Bahamas, ancient visitors took up residence in this archipelago
off Florida's coast and left remains offering stark evidence that the
arrival of humans can permanently change -- and eliminate -- life on
what had been isolated islands, says a University of Florida researcher.
The unusual discovery of well-preserved fossils in a water-filled
sinkhole called a blue hole revealed the bones of landlubbing
crocodiles and tortoises that did not survive human encroachment, said
David Steadman, a UF ornithologist and the lead author of a paper
published by the Proceedings of the National Academy of Sciences.
"The climate and environmental conditions back then weren't much
different from those of today," said Steadman, who works at the Florida
Museum of Natural History on the UF campus. "The big difference is us.
When people got to the island, there was probably nothing easier to
hunt than tortoises so they cooked and ate them. And they got rid of
the crocodiles because it's tough to have kids playing at the edge of
the village where there are terrestrial crocodiles running around."
The first entire fossilized skeletons of a tortoise and a crocodile
found anywhere in the West Indies were uncovered from Sawmill Sink on
Great Abaco Island in the Bahamas, along with bones of a lizard,
snakes, bats and 25 species of birds, as well as abundant plant fossils.
Radiocarbon analyses date the bones at between 1,000 and 4,200 years
old with the youngest fossil being that of a human tibia, he said. The
fossils are the best preserved of any ever found in the Bahamas because
of their unusual location in the deep saltwater layer of the sinkhole
that contains no oxygen, which normally would feed the bacteria and
fungi that cause bones to decay, Steadman said. Expert diver Brian
Kakuk and other skilled scuba divers retrieved the fossils from various
places along the floor and walls of the blue hole, which contains salt
water covered by a layer of freshwater.
"The fossils from Sawmill Sink open up unparalleled opportunities
for doing much more sophisticated work than ever before in
reconstructing the ancient plant and animal communities of the
Bahamas," Steadman said. "It helps us to understand not only how
individual species evolve on islands, but how these communities changed
with the arrival of people because we know that changes in the
ecosystem are much more dramatic on islands than they are on
There are many blue holes on Abaco and other Bahamian islands, but
this is the first to be the site of a sophisticated fossil excavation,
Steadman said. Although the Bahamian government has gone to great
lengths to protect its coastline, blue holes with their submerged cave
passages have received little attention as a marine resource, he said.
The fossil site is especially valuable because of the presence of
fossilized plants -- leaves, twigs, flowers, fruits and seeds -- pollen
and spores, and vertebrates, giving evidence of both the island's flora
and fauna, Steadman said.
"In a typical vertebrate fossil site, you identify the species of
vertebrates -- reptiles, birds or mammals -- and based on that
identification you speculate what the habitat might have been," he
said. "For the first time here in the West Indies, we have here on
Abaco plant fossils right in with the vertebrates, so we can
reconstruct the habitats in a much more sophisticated way."
For instance, because bracken ferns are one of the first plants to
recolonize after a fire, the presence of their spores would indicate
regular burning in prehistoric times and indicate that an area was
grassland. Evidence for this also comes from the numerous fossils of
burrowing owls or meadow larks, which prefer open habitats, he said.
Among the excavation's findings are that the land-roaming Cuban
crocodile lived in the Bahamas until humans arrived, Steadman said.
"People tend to think of crocodiles as aquatic and certainly most of
them are, but in the Bahamas where there is no fresh water, the
crocodile became a terrestrial predator," he said.
The collaborative project includes Bahamian scientists Nancy Albury,
Keith Tinker and Michael Pateman, as well as paleontologist Gary Morgan
of the New Mexico Museum of Natural History.
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