Hayashibara Museum of Natural Sciences and Witmer Lab/Ohio University (fossil); Raúl Martín (inset)

ScienceShot: T. rex as a Kid

Even the most terrifying meat-eating dinosaurs were children once, and now scientists have uncovered one of Tyrannosaurs rex's most immature relatives—a 2 or 3 year old (7 or 8 in equivalent human years) whose skeleton is nearly intact. According to a paper published today in The Journal of Vertebrate Paleontology, the 70 million year old fossil belongs to Tarbosaurus bataar, an enormous carnivorous dinosaur of the tyrannosaurid family that was the length of a four-story building from head to tail. Following an exhaustive anatomical analysis (see video of skull), the researchers say this juvenile, which was about the size of an adult human, was not able to crush bone or exert strong bite and twisting forces with its jaw like its parents. Thus, unlike adults who probably did not travel with them and dined on other large dinosaurs, young Tarbosaurus likely hunted small reptiles. Such large dietary differences between a juvenile well past infancy and an adult are rare in the animal kingdom and unprecedented in the world of dinosaurs, the researchers say. If paleontoloists didn't know as much as they do about Tarbosaurus, say the authors, they would think this youngster belonged to a separate species.

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Posted in Paleontology