A new dinosaur species discovered in western China is helping scientists understand how one group of “terrifying lizards” came to look like birds—independent of birds.
George Washington University paleontologist Jonah Choiniere describes the new species Haplocheirus sollers, or “simple, skillful hand,” in today’s Science. The 160-million-year-old specimen is a member of the bird-like Alvarezsauridae family, which was previously thought to be a flightless derivative of ancient birds due to their skeletal similarities.
“What Haplocheirus definitively shows is that alvarezsauroids aren’t birds,” said Choiniere (Scientific American). The earliest diverging member of Alvarezsauridae, Haplocheirus evolved in parallel to birds, confirming their “extreme morphological convergence”.
The new species shows some of the earliest evolutionary stages in the development of a short, powerful arm with a single functional claw typical of alvarezsauroids, but its arms are longer and the claw is a little shorter than the later, Cretaceous species. “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,” Choiniere said (news release).
Haplocheirus is 10 million years older than what is believed to be the world’s first known bird, Archaeopteryx. The find also extends the fossil record of its group by 63 million years. Until now, there has been no direct evidence that these types of dinosaurs lived during the Late Jurassic. “It’s like finding a great, great grandfather in your family which doubles the age of your family tree,” Choiniere said (BBC News).
In 2004, the international expedition found the ten-foot long, nearly complete 3D skeleton in orange mudstone beds in a region known for its fossils from the Late Jurassic—likely the period when birds evolved from the three-toed theropod, or bird-footed, dinosaurs.
But scientists are still trying to pin down exactly when birds first emerged. “Many dinosaurs are very bird-like and early birds are dinosaur-like,” co-author Xing Xu told Discovery News. “It is more or less depending on what you call a bird a bird, which is somewhat an arbitrary procedure.”