A 365-million-year-old arm bone fossil found in the eastern
state of Pennsylvania came from one of the first creatures able
to do push-ups, an evolutionary step that was necessary for
animals to move from the sea to dry land. When the animal lived,
there were no vertebrates on dry land, and the oceans were a
place of fierce, toothy meat eaters living a predatory life of
eat or be eaten. It was into this hostile environment that a
two-foot-long animal that was more than a fish and less than a
true amphibian made its brief appearance in the fossil record,
said researcher Neil Shubin. The four-legged creature had a
humerus, or upper arm bone. Such a bone, far different from the
flipper bones of fish, gave the creature an important new
ability - it could raise its upper body like an athlete doing
push-ups. "This animal was there for just a brief moment in
time," said Shubin, a paleontologist at the University of
Chicago. "It was only later that we start seeing in the fossil
record things that commonly walked on l