Sunday, July 5, 2015

Masiakasaurus: Beast of the Week

This week we shall be looking at an awesome little dinosaur with teeth unlike any other!  Check out Masiakasaurus knopfleriMasiakasaurus was a meat-eating (probably) dinosaur that lived in what is now Madagascar during the late Cretaceous, about 70 million years ago.  From snout to tail, an adult would have measured roughly between six and seven feet long.  The genus name, Masiakasaurus, translates to "Vicious lizard/reptile" and the species name, knopfleri, is in honor of singer/songwriter/guitarist, Mark Knopfler, who's music the paleontologists who found this dinosaur's fossils were listening to during their time in the field.

Masiakasaurus life reconstruction by Christopher DiPiazza.

Masiakasaurus belonged to the family of dinosaurs called noasauridae.  Noasaurids, were generally smaller theropods that lived in the southern hemisphere during the Cretaceous.  They are a branch of the broader group of theropods, called ceratosaurs, which also includes the larger, more well known, Ceratosaurus and Carnotaurus, to name just a few.

The most prominent feature about Masiakasaurus, however, is definitely its teeth and jaws.  Unlike the teeth of most other theropods, which angle perpendicular to the jaw, the teeth of Masiakasaurus were angled forward int he front of the mouth.  This striking appearance was what earned its name as "vicious".  Despite its appearance, however, was Masiakasaurus really all that dangerous?  Probably not unless you were a small mammal or an insect.  Having teeth pointing forward would have made it difficult for Masiakasaurus to have dealt much damage to any animal close to its size or larger.  However, its teeth do make a great adaptation for grasping small, fast moving prey, like a moveable cage.  The environment Masiakasaurus lived in did have many small animals in it at the time, thanks to a great fossil record from Cretaceous Madagascar, including frogs, mammals, small crocodilians, and even small birdlike dinosaurs.  Another idea that some people have proposed is that Masiakasaurus was a fisher.  In fact, we see similar, unrelated examples of teeth like this in many marine reptiles, like Plesiosaurus, which paleontologists are almost positive was a fish-eater in life.  The teeth in the back of Masiakasaurus' mouth were more similar to those of other theropods, and would have been for cutting food to be swallowed. 

Masiakasaurus skull, featuring the unique teeth and jaws.  CLEARLY it lived during a time before orthodontists.

In addition to its teeth, some other notable features about Masiakasaurus would be its neck, which was long and actually not very flexible, which is not the norm compared to other kinds of long-necked theropods.  Its hands each had four fingers, but only the first three digits on each had claws.

Masiakasaurus skeleton on display at the Royal Ontario Museum in Toronto, Canada.

Masiakasaurus is a great find by paleontology standards because it is known from more than one specimen, so almost all of its anatomy is known.  Another interesting thing about Masiakasaurus, is that paleontologists were able to study what they think was its growth pattern based on individual specimens of different sizes that have been found.  Based on what the pool of specimens available to work with and by closely examining the kind of bones Masiakasaurus had compared to those of other dinosaurs, it is hypothesized that Masiakasaurus was actually a relatively slow-grower, and would have attained adult size by the time it was about eight years old.  This is indeed pretty slow compared to other non-avian dinosaurs that have been studied in the same way and even modern animals that are related to it, like birds, which reach adulthood, in general, much more rapidly.  (Anyone who has ever raised a baby chick knows exactly what I'm talking about.  Seriously, one minute they are fluffy yellow peeps... blink once and BAM...adult chicken.)

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

References

Carrano, M.T.; Sampson, S.D.; Forster, C.A. (2002). "The osteology of Masiakasaurus knopfleri, a small abelisauroid (Dinosauria: Theropoda) from the Late Cretaceous of Madagascar". Journal of Vertebrate Paleontology 22 (3): 510–534.

Carrano, M.T.; Loewen, M.A.; Sertic, J.J.W. (2011). "New materials of Masiakasaurus knopfleri Sampson, Carrano, and Forster, 2001, and implications for the morphology of the Noasauridae (Theropoda: Ceratosauria)". Smithsonian Contributions to Paleobiology 95: 53pp.

Andrew H. Lee & Patrick M. O’Connor (2013) Bone histology confirms determinate growth and small body size in the noasaurid theropod Masiakasaurus knopfleri. Journal of Vertebrate Paleontology 33(4): 865-876.

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