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

    In the spring of 2007, on a ranch located near the foothills of the Big Horn Mountains in Ten Sleep Wyoming, a team from Dinosauria International LLC made an exciting discovery: the beautifully preserved femur of a giant carnivorous dinosaur. As they kept digging, their excitement grew greater; next came toe bones, leg bones, ribs, vertebrae and finally a skull: complete, undistorted and, remarkably, with full dentition. It was an incredible find; one of the best known dinosaurs - Allosaurus, virtually complete, articulated and beautiful preserved. But that was not all; when the field jackets got back to the preparation lab, they discovered another leg bone beneath the Allosaurus skull... There was another dinosaur overlapping the Allosaurus skeleton in the 155 million year-old rock. After more digging and more bones, they realized the enormity of their discovery; the Allosaurus was preserved together with another Jurassic icon, an armored Stegosaurus. It has been hypothesized that the pair got stuck in mud and died in combat; forever locked in death.

    The Allosaurus and Stegosaurus, deadly carnivore and armored herbivore, were often speculated to have fought pitched battles across the savannahs of Upper Jurassic North America but never before had they been found together. Here at last was proof, not only of their co-existence, but possible preservation of their combat. Previously reported finds included a Stegosaurus neck plate with a U-shaped wound corresponding to the bite of an Allosaur, and an Allosaurus tail vertebrae with a puncture wound the exact shape of a Stegosaurus tail spike. The association was undeniable: the humerus of the Stegosaur was found almost inside the mouth of the Allosaur, and given their complete articulation, it is impossible not to imagine the two giants caught in a fight to the death. The Stegosaur was named "Fantasia" after a scene in the classic Disney film. The Allosaurus was named "Dracula" for its bristling mouthful of deadly teeth. This is a unique opportunity to acquire this unprecedented find: two incredibly well-preserved iconic dinosaurs identified as rare species of well-known genera and found in direct association in the oldest and least explored lowest stratigraphic level of the famous and historically important Morrison Formation.

    The Allosaurus, "Dracula", is a full grown adult measuring approximately 21 feet in length. According to famed paleontologist Dr Robert T. Bakker, "Dracula" appears to belong to a relatively new species; the Allosaurus jimmadseni. The lower jugal border of the skull is horizontal, the manus claws less hooked and the skeleton generally more slender in comparison to the well-known Allosaurus fragilis. A.jimmadseni is proposed in an unpublished manuscript, and is regarded as being an earlier version of the A.fragilis, which is known from only one previously documented example. Much has yet to be learned about the species.

    Of all the Allosaur fossils discovered, "Dracula" represents one of the very few with a fully articulated, undistorted skull. Most Allosaur are found with their skulls in fragments and loose piles; but "Dracula" was articulated, allowing a rare look for researchers into the exact position and orientation of Allosaur skull bones. Its full set of teeth is an almost unheard-of characteristic; not only do Allosaur shed teeth during their lifetime, but usually teeth fall out of the jaw bone after death, making this an extremely rare and significant instance of the complete dentary arrangement being preserved. This information is immensely useful to science; so important in fact that the skull was prepped in jacket and un-restored so that further study can be done on the skull in the future. A cast was carefully made from the original skull to use for the mounted skeleton; this way the scientific integrity of the actual skull remains undisturbed.

    Given that the skull represents about 30% of a dinosaur's entire skeleton, "Dracula" is about 70-75% original bone, with part of the tail and several dorsal vertebrae being modeled reproductions. The skeleton is mounted in an attack position and the mount is designed to allow replacement of individual bones; work continues at the Dana Quarry so as new bones are unearthed; they can be reunited with their original skeleton. The original skull is kept separately in a carefully packed crate as part of the mounted skeleton. Hence, a cast of the original skull is mounted on the skeleton.

    The Stegosaurus, "Fantasia", appears to belong to a more primitive genus Hersperosaurus mjosi. As with the Allosaurus 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 is the first time that these two iconic dinosaurs of the Jurassic have been found together, in remarkable condition, and are available for acquisition with a remarkable amount of data to offer. Their early age give insight into the development and evolution of Jurassic dinosaurs in North America and their association gives them historic scientific significance. Both skeletons contain a majority of original bone and are prepared professionally with minimal restoration; the mounts are also professionally made and the bones have been articulated in their osteologically accurate positions.

    An important feature of this pair is that they were professionally collected and documented with full locality and stratigraphic data. The greatest care has been taken from the very start of the process to excavate, preserve and present the bones with their scientific value and significance uncompromised. This is a rare opportunity to own a unique and prestigious discovery.

    This lot is being sold as a pair, however, if this lot does not meet its reserve then each item will be offered separately in the 2 following lots.

    Condition Report*: 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. Some condition issues may not be noted in the condition report but are apparent in the provided photos which are considered part of the condition report. 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. Heritage does not guarantee the condition of frames and shall not be liable for any damage/scratches to frames, glass/acrylic coverings, original boxes, display accessories, or art that has slipped in frames. All lots are sold "AS IS" under the Terms & Conditions of Auction.

    Auction Info

    Auction Dates
    June, 2011
    12th Sunday
    Bids + Registered Phone Bidders: 3
    Lot Tracking Activity: N/A
    Page Views: 107,282

    Buyer's Premium per Lot:
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