Oldest Footprints Identified

["Richard W. Travsky" <rtravsky@uwyo.edu>]

Yahoo news link, these do not last forever, but this will undoubtedly 
appear elsewhere

http://news.yahoo.com/s/livescience/20070912/sc_livescience/oldestidentifiablefootprintsfound

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 
trackways.

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."