Sunday, September 29, 2013

Triceratops: Prehistoric Animal of the Week

It is the end of September and it is time to finally review my favorite animal of all time!  For Prehistoric Animal of the Week some very popular and well known animals have been reviewed.  I try to more often than not do the lesser known animals and sprinkle the popular ones in every once in a while (like today).  Today, however, it's time to take a look at the mighty Triceratops!

Triceratops horridus by Christopher DiPiazza

Triceratops was a plant-eating dinosaur that lived in what is now North America during the late Cretaceous period about 68 to 66 million years ago and could grow to thirty feet long.  There are currently two species of Triceratops known, Triceratops horridus (larger of the two) and Triceratops prorsus (smaller but had a longer nose horn).  It was the largest and most well known member of the Ceratopsid family with many good specimens on the fossil record.  When alive, Triceratops would have coexisted with other well known dinosaurs like Ankylosaurus, Edmontosaurus/Anatotitan, Pachycephalosaurus, Dracorex and of course, Tyrannosaurus rex.  


Triceratops skeletal mount at the National Museum in Washington D.C.  Notice how the front limbs are slightly splayed out.  This is the posture we believe all large ceratopsians had.

The name, Triceratops, translates to "Three Horn Face" which makes sense considering this animal indeed had three horns...on its face; one short one between the nostrils and a long one above each eye.  Triceratops also had a round frill that was made of solid bone.  This is unique to this genus since all other ceratopsians known have holes, or what are known as fenestrae, in their frills to make them lighter.  The exact reason why Triceratops had a solid frill is the subject of some debate.  One such explanation could be for stronger defense against predators.  While the horns and frills of ceratopsians were probably for display purposes, I'm sure they were effective weapons against predators if need be as well.  That being said consider the fact that Triceratops lived alongside Tyrannosaurus.  This may be a result of an evolutionary arms race where the predator and prey keep evolving more advanced weapons and defenses to deal with one another.

In addition to the horns and frill, Triceratops is also known for its curved beak, which it could have used for clipping vegetation.  Beyond the beak, farther into the mouth were batteries of many small teeth perfect for mushing the tough plant material.  

Triceratops specimens baby to adult.

Like I stated above, Triceratops is a well studied animal thanks to a huge amount of fossils that have been found from it over the years.  Amongst these fossils we have massive adults all the way down to a baby with horns no larger than my thumb.  We also have what are believed to be juveniles with upturned brow horns which would grow more forward later in life.

Triceratops with baby by Christopher DiPiazza

Some scientists believe that the animal we call Triceratops was actually only a sub-adult form of a more mature form, which is currently considered a different genus, TorosaurusTorosaurus had a much longer frill that is much thinner than that of Triceratops and possessed two finestrae (holes).  Despite the fact that this hypothesis has been getting a lot of press lately (because Triceratops is such a popular animal) a lot of other paleontologists still don't agree with it.

Triceratops (left) and Torosaurus (right) painting by Christopher DiPiazza

Within the past few years there was even some preserved scaly skin discovered from a Triceratops.  The scales believed to be from the animal's back are all either heptagon, hexagon or pentagon shaped and placed much like mosaic tiles.  They vary in size with larger ones surrounded by smaller ones forming an almost rosette-type pattern.  The larger scales also come up to a shallow point like a Hershey kiss...or a nipple. The scales from the ventral(belly) side of the animal are supposedly rectangular shaped like the belly scales from a crocodile.

Chunk of fossilized Triceratops skin.  Check out those nipple scales.

I suppose we shall stop here.  Hope you enjoyed my birthday as much as I have!  As always you are welcome to comment below or on our facebook page!  Farewell until next time.

References


Dodson, P.; Forster, C.A.; and Sampson, S.D. (2004) Ceratopsidae. In: Weishampel, D. B.; Dodson, P.; and Osmólska, H. (eds.), The Dinosauria (second edition). University of California Press, Berkeley, pp. 494–513. ISBN 0-520-24209-2.

Lehman T.M. (1987). "Late Maastrichtian paleoenvironments and dinosaur biogeography in the Western Interior of North America". Palaeogeography, Palaeoclimatology and Palaeoecology 60 (3): 290. doi:10.1016/0031-0182(87)90032-0.

Longrich NR, Field DJ (2012) Torosaurus Is Not Triceratops: Ontogeny in Chasmosaurine Ceratopsids as a Case Study in Dinosaur Taxonomy. PLoS ONE 7(2): e32623. doi:10.1371/journal.pone.0032623

Ostrom, J. H. (1966). "Functional morphology and evolution of the ceratopsian dinosaurs". Evolution 20 (3): 290–308. doi:10.2307/2406631. JSTOR 2406631.

Rega, E.; Holmes, R.; and Tirabasso, A. (2010). "Habitual locomotor behavior inferred from manual pathology in two Late Cretaceous chasmosaurine ceratopsid dinosaurs, Chasmosaurus irvinensis (CMN 41357) and Chasmosaurus belli (ROM 843)". In Ryan, Michael J.; Chinnery-Allgeier, Brenda J.; and Eberth, David A. (editors.). New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Bloomington and Indianapolis: Indiana University Press. pp. 340–354. ISBN 978-0-253-35358-0.

Scannella, J.; and Horner, J.R. (2010). "Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny". Journal of Vertebrate Paleontology 30 (4): 1157–1168. doi:10.1080/02724634.2010.483632.

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