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Acrocanthosaurus atokensis
"High Spine Lizard"
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These pictures were taken at The Dallas Museum of Natural History in Dallas, TX.
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Acrocanthosaurus atokensis
Stovall & Langston, 1950
Length: 8 to 12 meters
Mass: 2 - 3 tonnes
Time: Aptian to Albanian, 112.2 to 98.9 mya, late Early Cretaceous
Place: Oklahoma, Texas, Utah, Maryland? USA
Remains: Partial skeleton, partial post cranium, elements
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This Cretaceous theropod, while sharing many obvious affinities with allosaurs and carcharodontosaurs, was peculiar in having elongated vertebral spines along its back. These spines probably formed a sort of "sail", making the animal appear to be larger than it actually was. Though most of the largest spines along the neck and back averaged 8 to 12 inches in height, some of the spines toward the tail could have approached 2 feet. It's unlikely that there was a hump or fatty deposit present as some have suggested. This is due to the fact that neck mobility would have been significantly obstructed, living relatives of dinosaurs do not store fat on their backs, but place it at the base of the tail, adding weight to the back of such a large animal would only hamper movement, which is silly, and there is no real evidence for any sort of strong muscle attachments on the spines to begin with. More than likely, as in modern animals with large, odd structures, the elongated vertebral spines were encorporated into a visual device in the form of a "sail", which was used during mating and threat displays. I would even go as far as to say that it's a sexual dimorphic trait; The males supporting the larger spines and "sail", with the females having smaller spines and thus a smaller "sail". Given the lack of a significant amount of material... that is, multiple specimens... my speculation is just that... a speculation... albeit a possibly correct one.
Acrocanthosaurus is the probable track-maker at the Paluxy River tracksite in Glen Rose, Texas.
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Remember! These are low-res photos and collages! Feel free to e-mail me about my high-res photographs.
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Acrocanthosaurus atokensis
Copyright Kristopher J Kripchak 2002
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