Camptosaurus: Beast of the Week

Camptosaurus dispar was a plant-eating dinosaur that lived in what is now South Dakota, USA, during the late Jurassic Period, roughly 150 million years ago.  Adults measured about 25 feet long from beak to tail, although there is observed variation among individuals.  The genus name, Camptosaurus, translates from Greek to "Bent Lizard/Reptile" in reference to the fact that paleontologists at the time of its discovery predicted its vertebra would have allowed for greater flexibility than what they had observed in other dinosaurs thus far. Camptosaurus was an ornithopod dinosaur, who's lineage would later give rise to the more widespread iguanodontids, and the even more derived hadrosaurids.

Camptosaurus dispar hunkers down during a rainstorm in what is now western North America during the late Jurassic.  Watercolor reconstruction by Christopher DiPiazza.

Camptosaurus was a heavily-built dinosaur, possessing powerful legs, which were longer than its arms.  Its arms, although shorter, would have been powerful and flexible and its fingers, of which it had five of on each hand, would have been somewhat dexterous and able to grasp things, like branches while feeding.  This is in contrast to later forms of ornithopod dinosaurs, like the hadrosauroids, who's fingers were fused together, an adaptation for weight bearing.  Since Camptosaurus lacks this feature, paired with the fact that its front limbs were proportionally shorter, it is likely that this dinosaur was more comfortable as a biped than a quadruped, although it was also capable of four-limbed locomotion if need be.  

Camptosaurus skeletal mount on display at the American Museum of Natural History in New York.  This specimen might represent a juvenile.

Camptosaurus possessed a proportionally small skull on the end of a long, flexible neck.  Its snout was narrow and ended in a slightly downturned beak.  Inside the jaws, Camptosaurus and many small, tightly packed teeth which were ideal for processing plants.  The amount of wear that paleontologists observe on Camptosaurus teeth suggests it was capable of eating tougher plants than many other plant-eating dinosaurs it shared its environment with.  Camptosaurus also had large eye sockets with small ridges over them, which would have given it a superficial "angry expression" on its face in life.  This is possible an adaptation for protecting its eyes from sun glare.  You can observe similar adaptations in some bird species alive today.  Because of this it is possible that Camptosaurus had relatively good vision, and could have been most active during the daytime.  

Mount of an Adult Camptosaurus on display at the National Museum of Natural History in Washington D.C.  

When alive, Camptosaurus would have coexisted with many large sauropod dinosaurs as well as some of the armored stegosaurs in life.  Its ability to easily transition between bipedal and quadrupedal postures while feeding may have helped it carve out a niche in a world that was already so dense with herbivores.  At the same time it could have relied on its sharp vision and longer hind legs for running to avoid predators, like Allosaurus, Ceratosaurus, and Torvosaurus.  

References

Carpenter, K.; Wilson, Y. (2008). "A new species of Camptosaurus (Ornithopoda: Dinosauria) from the Morrison Formation (Upper Jurassic) of Dinosaur National Moument, Utah, and a biomechanical analysis of its forelimb". Annals of the Carnegie Museum. 76 (4): 227–263.

Gilmore, C.W. (1909). "Osteology of the Jurassic reptile Camptosaurus, with a revision of the species of the genus, and descriptions of two new species". Proceedings of the United States National Museum. 36 (1666): 197–332.

Foster, J. (2007). "Camptosaurus dispar." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 219-221.

Marsh, O.C. (1879). "Notice of new Jurassic reptiles". American Journal of Science and Arts. 18 (108): 501–505.