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Dinosaurs copied the body, skull shapes of distant relatives

Researchers say the latest findings offer evidence of convergence across an unexpectedly large swath of time.

By
Brooks Hays
Researcher Michelle Stocker shows of the thick upper skull of the Triassic reptile species Triopticus primus, which translates to first of three eyes. Photo by Virginia Tech
Researcher Michelle Stocker shows of the thick upper skull of the Triassic reptile species Triopticus primus, which translates to "first of three eyes." Photo by Virginia Tech

BLACKSBURG, Va., Sept. 22 (UPI) -- The body and skull shapes of the most iconic dinosaurs weren't entirely original. Dinosaurs took on shapes that were easily recognized in the proportions of their distant relatives.

Analysis of a new species of extinct reptile has revealed a creature with a dino-like skull structure and appearance.

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Triopticus primus lived 230 million years ago, predating dinosaurs by at least 100 million years. Yet, its thickened upper skull and an eye-like pit in the top of its head recalls the appearance of distantly related pachycephalosaur dinosaurs.

What's more, many of the animals recovered from the excavation that yielded Triopticus also recall the shapes of dinosaurs.

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"Triopticus is an extraordinary example of evolutionary convergence between the relatives of dinosaurs and crocodylians and later dinosaurs that is much more common than anyone ever expected," Michelle Stocker, a paleontologist at Virginia Tech, said in a news release. "What we thought were unique body shapes in many dinosaurs actually evolved millions of years before in the Triassic Period, about 225 million years ago."

When two distantly related species evolve a similar body shape and appearance, scientists call it convergence. It a surprisingly common evolutionary phenomenon.

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Even so, researchers say the latest findings offer evidence of convergence across an unexpectedly large swath of time and among a diverse group of reptiles and dinosaurs from the Triassic and Jurassic periods.

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"The Otis Chalk fauna is an amazing single snapshot of geologic time where you have this extraordinary range of animal body plans all present at the same time living together," Stocker said. "Among the animals preserved in the Otis Chalk fauna, Triopticus exemplifies this phenomenon of body-shape convergence because its skull shape was repeated by very distantly related dome-headed dinosaurs more than 100 million years later."

CT scans have revealed a number of other examples of convergence among Otis Chalk reptiles, including the elongated snouts of Spinosaurus, toothless beaks of ornithomimids, and armored plates of ankylosaurs.

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