Developments in Brief : Iowa Yields Fossils That May Help Tell When Creatures First Left the Sea

Paleontologists believe that rare 340-million-year-old fossils found in southeastern Iowa could cast new light on the period when animals first left the sea and crawled onto dry land.

The more than 500 specimens of long-extinct animals called tetrapods found at a site near Delta, Iowa, are “the best tetrapods found in North America in terms of the quality and the abundance of specimens,” according to John Bolt of the Field Museum in Chicago.

He said the tetrapods, some as long as five feet, probably looked like large salamanders.

“It’s unheard of to find bones of this sort in this part of the country,” said Robert McKay, who found the fossils last year with Patrick McAdams. The two men, both geologists for the Iowa Geological Survey, were mapping rock formations in a quarry near Delta.

“I had a pretty good rush of adrenalin going through me as I kept cracking rocks and finding bones,” McKay said. They sent some of the specimens to Bolt.

Bolt said the only other tetrapod fossils of comparable age came from finds in Scotland and West Virginia.

“They are very, very rare, and any chance you have to get this window into the past, you have to seize it,” he said. The fossils may include at least three separate species, Bolt said, adding that most of them appear to have been amphibians, but one may have been a reptile--which would be one of the earliest reptiles ever found.