( A University of Florida-led study has d...)'Terror bird' arrived in North America before land bridge, study finds

UF paleontologist Bruce MacFadden said his team used an established geochemical technique that analyzes rare earth elements in a new application to revise the ages of terror bird fossils in Texas and Florida, the only places in North America where the species has been found. Rare earth elements are a group of naturally occurring metallic elements that share similar chemical and physical properties.

"It was previously thought that Titanis immigrated to Texas across the Panamanian land bridge that formed about 3 million years ago connecting North and South America," said MacFadden, a curator of vertebrate paleontology at the Florida Museum of Natural History at UF. "But the rare earth element analysis of a fossil Titanis bone from Texas determines its age to be 5 million years old. This shows that the bird arrived 2 million years before the land bridge formed, probably across islands that formed what today is the Isthmus of Panama."

The study will be published Jan. 23 in the online version of the journal Geology and featured in its February print edition.

The terror bird was carnivorous, weighed about 330 pounds, had powerful feet and a head larger than a man's. It is known in the fossil record from a single toe bone in Texas, and in Florida by about 40 bone fragments from different skeletal regions. MacFadden's team also analyzed six specimens from the Santa Fe River in north Central Florida.

"We found that the Titanis fossils were 2 million years old and not 10,000 years old as had been suggested," MacFadden said. "This also shows the last known occurrence of Titanis in the fossil record and reflects its extinction."

When an animal dies, its porous bones absorb groundwater as they fossilize. As
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Source:University of Florida