Monday, January 15, 2018

Compsognathus: Beast of the Week

This week we will be looking at a popular, but often misunderstood dinosaur.  Let's check out Compsognathus longipes!

Compsognathus was a relatively small, meat-eating dinosaur that lived in what is now Germany, France, and possibly Portugal, during the late Jurassic period, about 150 million years ago.  From snout to tail, an adult measured almost four feet long.  The genus name, Compsognathus, translates to "delicate jaw" and the species name, longipes, translates to "long foot", both in reference to this dinosaur's anatomy.

Compsognathus longipes with Archaeopteryx chick as prey.

The first specimen of Compsognathus discovered back in the mid 1800s was only a little over a foot long, and was considered the smallest known dinosaur.  In addition, there were not many small-ish fossil dinosaurs known yet, either, so Compsognathus became sort of an oxymoron, and therefore quite popular.  It almost always would appear in books about dinosaurs for years to come as "the smallest dinosaur!" often being compared to a chicken in size.  However, during the 1970s, a larger specimen of Compsognathus was unearthed in France that was almost four feet long.  Not huge...but certainly bigger than a chicken, proving the original German specimen was only a juvenile when it died.  Thanks to many more dinosaur discoveries since then, Compsognathus was far from the smallest nonavian dinosaur, but for some reason that stigma hasn't fully shaken even today.

Compsognathus that was discovered in Germany.  This specimen was roughly the size of a small chicken, and was for many years regarded as the smallest kind of dinosaur. (not including birds)

One cool thing about Compsognathus is that we know what it was eating before it died.  Both specimens on the fossil record have the bones of lizards in their body cavities, proving this dinosaur was a meat-eater, and likely quite agile if it was catching lizards in life.  The teeth in the front of Compsognathus' mouth were straight and pointed, while the teeth lining the sides of its jaws were more flattened, and blade-like.  This would have enabled it to capture and process small prey.  Compsognathus had two relatively short arms, each equipped with two long fingers and a third shorter finger.  For a while Compsognathus was believed to have only had two fingers because of the incompleteness of the first uncovered specimen.

Thanks to well-preserved specimens of other closely related dinosaurs that preserved down-like feathers on their fossilized bodies, it is logical to assume Compsognathus also had some sort of feathering in life.  This is despite the fact that no fossils of Compsognathus, itself, provide  fossilized feathers, themselves.The kinds of feathers found on members of Compsognathus' family would have been fine and soft in life, and may not have fossilized under the conditions that Compsognathus, itself, was in.

Compsognathus skeletal mount on display at the Academy of Natural Science in Philadelphia, Pennsylvania.

During the late Jurassic, the parts of Europe that Compsognathus was native to were a chains of small islands in a shallow sea.  The islands would have been relatively dry, sandy, but also would have had inland lagoons.  Some of Compsognathus' neighbors would have included all matter of marine life, small lizards, the pterosaurs, Pterodactylus and Rhamphorhyncus, and fellow feathered dinosaur, Archaeopteryx.  Since no remains from any large land animals have been found from this habitat, it is likely these small islands could only support animals under a certain size threshold due to a lower availability of food and space.  It is very likely that Compsognathus was the top predator of its community.

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

References

Chen, P.; Dong, Z.; Zhen, S. (1998). "An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China". Nature. 391 (6663): 147–152.

Seebacher, F. (2001). "A new method to calculate allometric length-mass relationships of dinosaurs". Journal of Vertebrate Paleontology. 21 (1): 51–60.  

Stromer, E., 1934, "Die Zähne des Compsognathus und Bemerkungen über das Gebiss der Theropoda", Zentralblatt für Mineralalogie, Geologie und Paläontologie, Abteilung B, Jahrgang 1934: 74–85

Therrien, F.; Henderson, D.M. (2007). "My theropod is bigger than yours...or not: estimating body size from skull length in theropods". Journal of Vertebrate Paleontology. 27 (1): 108–115.

 Zinke, J. (1998). "Small theropod teeth from the Upper Jurassic coal mine of Guimarota (Portugal)". Palaontologische Zeitschrift. 72: 179–189. doi:10.1007/bf02987825. Archived from the original on 2007-09-27.

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