• Ichthyosaur's last meal is evidence of T

    From ScienceDaily@1337:3/111 to All on Thu Aug 20 21:30:32 2020
    Ichthyosaur's last meal is evidence of Triassic megapredation

    Date:
    August 20, 2020
    Source:
    University of California - Davis
    Summary:
    Some 240 million years ago, a dolphin-like ichthyosaur ripped to
    pieces and swallowed another marine reptile only a little smaller
    than itself.

    Then it almost immediately died and was fossilized, preserving
    the first evidence of megapredation, or a large animal preying on
    another large animal.



    FULL STORY ==========================================================================
    Some 240 million years ago, a dolphin-like ichthyosaur ripped to
    pieces and swallowed another marine reptile only a little smaller than
    itself. Then it almost immediately died and was fossilized, preserving
    the first evidence of megapredation, or a large animal preying on another
    large animal. The fossil, discovered in 2010 in southwestern China,
    is described in a paper published Aug. 20 in the journal iScience.


    ==========================================================================
    The ichthyosaurs were a group of marine reptiles that appeared in
    the oceans after the Permian mass extinction, about 250 million years
    ago. They had fish- like bodies similar to modern tuna, but breathed
    air like dolphins and whales.

    Like modern orca or great white sharks, they may have been apex predators
    of their ecosystems, but until recently there has been little direct
    evidence of this.

    When a specimen of the ichthyosaur Guizhouichthyosaurus was discovered
    in Guizhou province, China in 2010, researchers noticed a large bulge of
    other bones within the animal's abdomen. On examination, they identified
    the smaller bones as belonging to another marine reptile, Xinpusaurus xingyiensis, which belonged to a group called thalattosaurs. Xinpusaurus
    was more lizard-like in appearance than an ichthyosaur, with four
    paddling limbs.

    "We have never found articulated remains of a large reptile in the stomach
    of gigantic predators from the age of dinosaurs, such as marine reptiles
    and dinosaurs," said Ryosuke Motani, professor of earth and planetary
    sciences at the University of California, Davis, and coauthor on the
    paper. "We always guessed from tooth shape and jaw design that these
    predators must have fed on large prey but now we have direct evidence
    that they did." The Guizhouichthyosaurus was almost five meters (15
    feet) long, while the researchers calculate its prey was about four
    meters (12 feet) long, although thalattosaurs had skinnier bodies than ichythyosaurs. The predator's last meal appears to be the middle section
    of the thalattosaur, from its front to back limbs. Interestingly, a fossil
    of what appears to be the tail section of the animal was found nearby.

    Predators that feed on large animals are often assumed to have large
    teeth adapted for slicing up prey. Guizhouichthyosaurus had relatively
    small, peg- like teeth, which were thought to be adapted for grasping
    soft prey such as the squid-like animals abundant in the oceans at the
    time. However, it's clear that you don't need slicing teeth to be a megapredator, Motani said.

    Guizhouichthyosaurus probably used its teeth to grip the prey, perhaps
    breaking the spine with the force of its bite, then ripped or tore the
    prey apart.

    Modern apex predators such as orca, leopard seals and crocodiles use a
    similar strategy.


    ========================================================================== Story Source: Materials provided by
    University_of_California_-_Davis. Original written by Andy Fell. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Da-Yong Jiang, Ryosuke Motani, Andrea Tintori, Olivier Rieppel,
    Cheng Ji,
    Min Zhou, Xue Wang, Hao Lu, Zhi-Guang Li. Evidence Supporting
    Predation of 4-m Marine Reptile by Triassic Megapredator. iScience,
    2020; 101347 DOI: 10.1016/j.isci.2020.101347 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2020/08/200820112848.htm

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