Hesperosaurus (Stegosaurus) mjosi
    Upper Jurassic Period, Kimmeridgian Stage, 155 million years old
    Morrison Formation
    Dana Quarry, Ten Sleep, Washakie County, Wyoming, USA

    The Stegosaurus is another iconic dinosaur; its distinctive appearance having made it a favorite in popular culture; appearing as one of the memorable creatures on "Skull Island" in the original 1933 screen version of King Kong and also present in Disney's 1940 Fantasia. The first Stegosaurus remains were collected by Othniel Charles Marsh during the Bone Wars in 1877, from the Morrison Formation in northern Colorado. The Stegosaurs thrived across North America during the Upper Jurassic, 155-145 million years ago. They are known from three species, S. stenops, S. armatus and S. longispinus, of which over 80 specimens have been collected from the Morrison Formation. The present specimen has been identified as the Hesperosaurus mjosi ("western lizard"), a primitive genus described in 2001 by noted paleontologist Dr. Kenneth Carpenter and other authors from a single almost complete specimen found in stratigraphic zone 1 of the Morrison Formation in Wyoming. It was distinguished from Stegosaurus by having shorter but longer plates on its back, and a shorter, broader skull.

    The name Stegosaurus is derived from "roof lizard" in Greek, as assigned by Marsh, so chosen for the plate-like osteoderms; the alternating plates that lined its back and tail. The purpose of the plates remains unclear; they are not well placed for defense but could possibly have been used for thermoregulation, or just for decoration. More easily identified is the function of the four horizontal spikes that graced the Stegosaur's tail; these spikes could measure up to 3 feet long, and was certainly used as a weapon to defend against predators. The brain of the Stegosaur was quite small; cast of the cavity taken by Marsh indicates a brain weight of around 2.8 oz and a size equivalent to that of a dog.

    Stegosaurs were herbivores; tracks in the Morrison Formation indicate that they lived in multi-age herds. It is posited that they were low-level browsers, feeding on bushes and fruit, and flora such as mosses, ferns, horsetails, cycads and conifers.
    Based on their jaw structures, they had limited chewing capacity; therefore they would swallow gastroliths, stones that sat in the stomach to aid digestion.

    "Fantasia" appears to belong to a more primitive genus Hersperosaurus mjosi. As with the A. jimmadseni, only one other example of the H. mjosi has been documented, a partial skeleton with cranium. "Fantasia" boasts an exceptional skull, completely undistorted. The primitive nature of "Fantasia" is scientifically important to the history and evolution of Stegosaurs. Measuring 18 feet in length and standing over 8 feet tall, "Fantasia" is 75-80% complete and mounted together with a few elements of another skeleton of equal size and quality. The skeleton is accurately mounted in the same manner as the well-known Stegosaurus composite at the American Museum of Natural History in New York.

    This lot will only be offered if lot #49071 is unsold.

    Estimate: $900,000 - up.

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    Condition report available upon request.

    *Heritage Auctions strives to provide as much information as possible but encourages in-person inspection by bidders. Statements regarding the condition of objects are only for general guidance and should not be relied upon as complete statements of fact, and do not constitute a representation, warranty or assumption of liability by Heritage. Please note that we do not de-frame lots estimated at $1,000 or less and may not be able to provide additional details for lots valued under $500. All lots are sold "AS IS" under the Terms & Conditions of Auction.

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    Auction Dates
    June, 2011
    12th Sunday
    Bids + Registered Phone Bidders: 0
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