Dinosaur family tree poised for colossal shake-up

By Sid Perkins

The longstanding division of dinosaurs into ‘bird-hipped’ species including Stegosaurus and their ‘lizard-hipped’ counterparts such as Brachiosaurus and Tyrannosaurus rex may no longer be valid, a study published on 22 March in Nature contends1. Among the other proposed changes to the dinosaur family tree, the long-necked herbivorous and often gargantuan sauropods such as Brachiosaurus are no longer as closely related to bipedal, meat-eating theropods such as T. rex as they were under previous schemes.

“This is a textbook changer — if it continues to pan out,” says Thomas Holtz, a vertebrate palaeontologist at the University of Maryland in College Park. “It’s only one analysis, but it’s a thorough one.”

The new study assesses kinship among 74 dinosaur species that span the family tree, on the basis of similarities or differences in more than 450 anatomical features, says Matthew Baron, a vertebrate palaeontologist at the University of Cambridge, UK, who led the study.

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