New dinosaur species early member of odd family

A newly discovered dinosaur species is helping paleontologists figure out how bird-like characteristics evolved in dinosaurs that aren't related to birds.

A newly discovered dinosaur species is helping paleontologists figure out how bird-like characteristics evolved in dinosaurs that aren't directly related to birds.

This illustration of Haplocheirus shows the short forelimbs and claws put the dinosaur in the alvarezsaur family. ((Portia Sloan))

The dinosaur, Haplocheirus sollers, was three-metres long with short, powerful arms and three claws on each hand. It is an early member of the alvarezsaur family, a strange group of dinosaurs characterized by stubby forelimbs and hands reduced to a single claw.

Haplocheirus is 63 million years older than any other members of its family, helping to clear up the evolution of the meat-eating dinosaurs, the theropods, which includes velociraptors and T. rex.

"Haplocheirus is a transitional fossil, because it shows an early evolutionary step in how the bizarre hands of later alvarezsaurs evolved from earlier predatory dinosaurs," said Jonah Choiniere of George Washington University, in a statement.

"The fossil also confirms our predictions that Alvarezsauridae should have been evolving in the Late Jurassic time period," he said.

The skeletons of the alvarezsaurs have certain bird-like characteristics but Choiniere says his research suggests that they evolved in parallel with the bird-like dinosaurs but didn't descend from them.

Haplocheirus, which lived in the Early Jurassic period, had three fingers, but the middle finger was much long than the other two. In the paper published in Science this week, Choiniere proposed that the three claws could fuse over evolutionary time into the single claw of the later Cretaceous alvarezsaurs.

Paleontologists think the short arms and single claw of the alvarezsaurs could have been used to rip apart termite mounds.

The fossil was found in 2003 in northwestern China, in the Xinjiang region known for its Late Jurassic fossils.