Monday, March 2, 2015

Eryops: Prehistoric Animal of the Week

Eryops megacephalus was a large amphibian that lived in what is now the United States during the Early Permian, between 310 and 295 million years ago.  It measured almost seven feet long in some cases and would have been a predator, snapping up any smaller animal that could have fit in it's huge mouth.  The genus name, Eryops, translates to "Drawn-out Face" and the species name, megacephalus, translates to "Big Head".  Guess what!  It had a huge noggin.  No, seriously, look at it.  The skull was almost a third of the total body length.  Inside this skull, Eryops was armed with many sharp, cone-shaped teeth.

Eryops snaps up its relative, Cacops in the Permian undergrowth.  Reconstruction by Christopher DiPiazza.

Eryops belonged to an extremely successful group of amphibians, called temnospondyli.  Temnospondyls existed on the planet for over 210 million years before finally going extinct, making them the most successful kind of tetrapod (animal with four limbs) in history.  Eryops was one of the larger temnospondyls and likely didn't have too many predators to worry about during the time it was alive other than Dimetrodon.

Check out those teeth!

Eryops is often depicted as being semi-aquatic, hunting in the water much like a modern alligator.  I don't personally see this as a likely lifestyle for Eryops, however.  For one thing, Eryops' tail was very short, and wouldn't have really helped the animal propel in the water like alligators, and its modern relatives, the newtsEryops also had a very robust skeleton, with well-developed limbs that were designed for supporting weight that were in a sprawled posture, jutting out at an almost ninety degree angle from the body.  The vertebrae of Eryops had relatively tall neural arches which could have helped anchor muscle.  It would not have been able to run very fast with this limb design, but it would have still been a sturdy and powerful walker.  Like most amphibians, however, it still would have needed a body of water in order to reproduce.


Eryops skeletal mount on display at the American Museum of Natural History in New York.

I cannot help but make connections between Eryops and one of my all time favorite living ampbibians, its relative, the Tiger Salamander. (Ambystoma tigrinum)  Tiger salamanders, like Eryops, have large, flat heads with wide mouths.  They do not hesitate to devour any creature smaller than themselves and, despite being reliant on water to drink and reproduce, prefer to spend their adult lives on land. 




Another interesting feature of Eryops is that it had well-developed ribs.  This is not typical for amphibians, which normally have very short ribs or no ribs at all!  Most amphibians, like salamanders and frogs, respire through their skin, and don't need ribs.  This method of breathing was not an option for Eryops, however, which was was significantly larger, and had a much higher mass to surface area ratio of its body, and therefore wouldn't have been able to effectively breathe through its skin.  It may have breathed by rhythmically moving the floor of its mouth to help pump air into the lungs.  This method of breathing, called buccal pumping, can easily be observed in modern amphibians, as well.


That is all for this week!  As always feel free to comment below or on our facebook page.

References

Brainerd, E. L. (1998) Mechanics of lung ventilation in a larval salamander, Ambystoma tigrinum. J. Exp. Biol. 201:2891–2901

Miner, Roy Waldo. The Pectoral Limb of Eryops and Other Primitive Tetrapods. New York: Published by Order of the Trustees, the American Museum of Natural History, 1925. Print.

Pawley, Kat, and Anne Warren. "The Appendicular Skeleton Of Eryops Megacephalus Cope, 1877 (Temnospondyli: Eryopoidea) From The Lower Permian Of North America." Journal of Paleontology 80.3 (2006): 561-80. Web.

Sawin, Horace John. The Cranial Anatomy of Eryops Megacephalus. N.p.: n.p., n.d. Print.

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