Researchers: Earlier study breaking T. rex into 3 different species was wrong

July 26 (UPI) -- A new study of the world's most famous dinosaur refutes a claim made by an earlier fossil examination that claimed the Tyrannosaurus rex roamed the Earth as three separate species.

In the journal Evolutionary Biology, researchers from the American Museum of Natural History and Carthage College said in the study, published this week in the journal Evolutionary Biology, that there is no conclusive evidence confirming the separate giant dinosaur species.

The authors of a study of T. rex fossils published in the same journal in March argued that the dinosaur needed to be reclassified because of three different sizes found. That group of researchers said the T. rex should be broken down into regular size, slim and jumbo sized.

"Recently, a bold theory was announced to much fanfare: what we call T.rex was actually multiple species," Steve Brusatte, co-author on the new study, said in a press release from the museum.

It is true that the fossils we have are somewhat variable in size and shape, but as we show in our new study, that variation is minor and cannot be used to neatly separate the fossils into easily defined clusters," said Brusatte, a paleontologist at the University of Edinburgh who conducted his doctoral studies at AMNH.

Brussatte said that when all T. rex fossils that are available are reviewed, "T. rex stands alone as the single giant apex predator from the end of the Age of Dinosaurs in North America."

The authors of the new study said species identity has always been worth "testing and re-testing," in the past revealing how species have been erroneously lumped into one in the past.

They found, though, that T. rex is not one of them.

"However, the destabilization of taxonomy has serious implications for science and society and should be avoided if not backed up by rigorous empirical and replicable evidence," the authors wrote in the new Evolutionary Biology report.