Sunday, January 12, 2014

Troodon: Prehistoric Animal of the Week

This week we will be looking at another dinosaur featured in the recent movie, Walking with Dinosaurs 3D.  Check out TroodonTroodon was a smaller, feathered dinosaur that lived in many parts of what is now North America during the Late Cretaceous.  Fossils assigned to the genus, Troodon, range in age from about 77 million years to 66 million years old and have been discovered in Montana, Wyoming, and even up in Alaska.  It is likely that there were more than one species of Troodon that lived within such a large time and space range.  Troodon measured about six feet long from snout to tail and would have eaten meat and possibly some plant material as well when it was alive.  Its genus name translates to "Wounding Tooth".

Troodon inequalis munching the head off an unfortunate constrictor by Christopher DiPiazza

Troodon was somewhat closely related to other theropod dinosaurs like Deinonychus and Velociraptor.  Like them, Troodon would have had feathers when alive and also possessed a retractable "killer" claw on digit two of each of its feet.  However, Troodon was overall more lightly built than dromaeosaurs (family that includes Deinonychus and Velociraptor).  Troodon also had a longer neck and shorter arms.

Troodon tooth

The first Troodon fossil was discovered in 1856 in the form of just a tooth.  Troodon teeth were small, triangular, and had serrations designed for slicing.  They are not consistent with other typical meat-eating dinosaur teeth, however, which lead many scientists to believe Troodon was more of an opportunistic feeder, taking advantage of both meat AND plant food sources.  Many more Troodon remains have been found that gradually painted a more accurate picture of the animal.  Troodon also had large eyes that face forward in the skull.  This suggests that Troodon may have been nocturnal or crepuscular and would have had decent depth perception as well.

Posterior section of a Troodon skull showing the cranium and large eye socket.

Niche, wise.  I always thought of Troodon as being the "coyote of the Cretaceous".  As far as dinosaurs go, Troodon had the largest brain compared to its body.  It isn't likely that it was solving any algebra, however.  Troodon would still have been plenty smart enough to catch small animal prey during the Late Cretaceous, though.  This adaptation combined with its possible omnivorous diet, which allowed it to take advantage of a wide array of food sources, could have been reasons for Troodon's extreme success.

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

References

Currie, P. (1987). "Theropods of the Judith River Formation". Occasional Paper of the Tyrrell Museum of Palaeontology 3: 52–60.

Holtz, Thomas R., Brinkman, Daniel L., Chandler, Chistine L. (1998) Denticle Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15. December 1998. pp. 159-166.

Larsson, H.C.E. 2001. Endocranial anatomy of Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution. pp. 19-33. In: Mesozioc Vertebrate Life. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.

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