Famennian Devonian Acanthostega gunnari Skull Reconstructed

360 million-year-old tetrapods may have been more like modern crocodiles than previously thought, according to 3D skull reconstruction. The results publish March 11, 2015 in the open-access journal PLOS ONE by Laura Porro from University of Bristol, UK, and colleagues.

Acanthostega gunnari was a 'four-footed' vertebrate, also known as a tetrapod, that invaded land during one of the great evolutionary transitions in Earth's history, 380-360 million years ago. This species is crucial for understanding the anatomy and ecology of the earliest tetrapods; however, after hundreds of millions of years buried in the ground, fossils are often damaged and deformed. To try to reconstruct the skull of this species from numerous skull pieces, the authors of the study applied high-resolution X-ray computed tomography (CT) scanning to several specimens of Acanthostega gunnari from East Greenland.

Researchers found that the reconstructed skull had a longer postorbital region and a more strongly hooked lower jaw than previously thought. They also found clues as to how the species fed. The size and distribution of its teeth and the shape of contacts between individual bones of the skull (called sutures) suggest Acanthostega may have initially seized prey at the front of its jaws using its large front teeth and hook-shaped lower jaw.

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