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

--- up 5 weeks, 1 day, 1 hour, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)