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Oldest Footprints Identified
Yahoo news link, these do not last forever, but this will undoubtedly
Two reptile-like animals living 290 million years ago are the oldest
creatures to have their footprints positively identified after a
fortuitous discovery allowed scientists to match fossils to preserved
Fossils of Diadectes absitus and Orobates pabsti were recently found in
the Tambach Formation in central Germany. Nearby and in the same sediment
layer, scientists found well-preserved footprints made by creatures that
plodded through the region's soft sediments long ago. The footprints
turned out to be a match for the fossil animals.
The work, detailed in the latest issue of the Journal of Vertebrate
Paleontology, marks the first footprints of the Paleozoic Era, a time
before the dinosaurs that lasted from 540 to 240 million years ago, to be
associated with the animals that made them. It could also force scientists
to rethink how the ancient creatures moved.
Because of the exceptional preservation of the Tambach skeletons,
scientists were able to match them to the nearby footprints. The two
species were among the first four-legged plant eaters on land and have no
close living relatives.
The work could also lead to a rethinking of how some of the first land
creatures stood and walked. Mammals tend to have legs and limbs that drop
vertically from the pelvis to the ground, while those of reptiles tend to
extend away from the body horizontally before turning back downward. The
new reptiles had a "mammalian" arrangement for their limbs.
"We know from the trackways that these animals had their feet planted
almost under their body," Berman said, "whereas in textbooks, they give
them a sprawling gait as if the limbs are extended out from the body
considerably. This just isn't true. You look at the trackway and you see
that the footprints are very close to the midline of the body."