Mesozoic Era Late Jurassic Period Dinosaurs Allosaurus


Quick Facts
Name Meaning:Different Lizard
Distribution:Utah, Colorado, Montana, New Mexico, Montana, USA
Time Period:Late Jurassic, 156-130 Ma
Length:36 ft (11m)
Weight:2 tons
Linnaean Classification
Cladistic Classification
  • Dinosauria
    • Saurischia
      • Theropoda
        • Tetanurae
          • Avetheropoda
            • Carnosauria
              • Allosauroidea
                • Allosauridae


Allosaurus talons
Allosaurus talons.
The Allosaurus was first discovered in 1877 in Colorado and named by Othniel Charles Marsh. However, these were just a few fragments of the dinosaur and Marsh went on to name other specimens, which, with time, were discovered to also be part of the Allosaurus creating a little confusion for Paleontologists. A more complete skeleton was discovered in 1879 by H. F. Hubbell but was never unpacked. After Hubbell's death the specimen was unpacked in 1908 and was discovered to be one of the most complete theropod skeletons to date. Later, in the Cleveland-Lloyd quarry in Utah over 10,000 bones from approximately 46 specimens were found, making the Allosaurus the most commonly discovered fossil in Utah. Allosaurus was later named the state fossil.


The Allosaurus was one of the greatest carnivores of the Jurassic period, the Tyrannosaurus of its time. It had a larg e heavy body with a long tail to balance its body. The arms had three clawed fingers, and each foot also had three clawed toes. The neck was S-shaped to support its head. The head was the most distinguishing feature of the Allosaurus. It was actually a lot lighter than it appears. The jaws had the ability of opening wide and then expanding in order to bite a huge chunk of meat.


The Allosaurus probably spent time lurking in the undergrowth waiting for an unsuspecting herbivore to pass by. They may have also hunt in packs, preying on the stragglers in a large herd of herbivores, like the young, old, and wounded. They may have also been hostile towards each other. Bone marrow was discovered in an Allosaurus that died at about the age of 10. This particular bone marrow is known to exist in modern female birds to produce calcium to lay eggs. This implies that the Allosaurus were sexually developed long before complete growth. The younger Allosaurus also have been known to have longer legs making them perhaps faster while running.

ScienceViews Writer: Jason Hamilton.

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