Allosaurus fragilis
    Late Jurassic - 144-156 million years old
    Grand County, Utah

    Dinosaur bone can fossilize in many ways, but when superheated water passes through layers of rock due to geothermal activity it can deposit silica in the porous marrow of the dinosaur bone leading to complete agatization. These agatized bones are essentially infilled with the mineral quartz or silicon dioxide which can pick-up a variety of colorful minerals that were dissolved in the superheated water - this mechanism is commonly referred to as "hydrothermal deposition". These colorful agatized dinosaur bones are highly prized by collectors who avidly search for them in the remote Utah deserts. The rarest type of agatization is called a "fortification agate"; this occurs when the superheated water blasts the center out of a bone like a high pressure jet, collapsing the bone marrow cell structure and completely infilling the cavity created with mineral-carrying silica or agate. As the agate cools, it forms layers in concentric rings with slightly different mineralogical components, creating the multiple rings or fortifications of "fortification agate". The most prized colors by collectors are red and yellow. Here we have an exceptional blood-red "fortification" specimen of incredible beauty.
    We can definitively identify this bone as coming from Allosaurus because of the large size of the marrow cells near the center of the bone and the concentric layered rind of the bone, which is characteristic of theropod (meat-eating) dinosaurs only. An exquisite example of nature's art measuring 5 x 4 inches by 2 inches thick.

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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, 2008
    8th Sunday
    Bids + Registered Phone Bidders: 1
    Lot Tracking Activity: N/A
    Page Views: 1,679

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