Troodon is a genus of relatively small, bird-like, meat-eating dinosaurs, from the later part of the Cretaceous period, 75–65 million years ago. The alternate spelling Troödon show that the 'o's are pronounced separately, as in 'zoology'
Discovered in central Montana in 1855, it was among the first dinosaurs found in North America. Its species ranged widely, with fossil remains recovered from as far north as Alaska, and the Judith River formation of Alberta, and as far south as Wyoming and even possibly Texas and New Mexico.
Troodon had a large brain in proportion to its body weight, and was very smart. It had a sickle claw, an enlarged and retractable second toe claw bone. Troodon had 122 teeth. The size and shape of the leg bones show that the Troodon would have been a fast runner. Troodon is thought to have been a predator like other theropods. This view is supported by its sickle claw on the foot and apparently good binocular vision.
Troodon's size ranged widely. In general, individuals that lived further North were larger than those that lived in more Southern areas. Troodons in Alaska were especially large, up to 12 feet long, 5 feet tall, and weighing up to 175 pounds. Meanwhile, Troodons that lived in more Southern locations were only around 7 feet long, 3 feet tall, and weighed up to 50 pounds, about the size of a Velociraptor.
One of Troodon's closest known relatives was a dinosaur called the Anchiornis. When palaeontologists first found its fossil, they saw that it had been covered in feathers, just like a modern bird. Because Troodon is believed to have been the direct descendant of Anchiornis, there is a possibility that it might also have had feathers. However, no fossil evidence for feathers in Troodon has been found, yet. If Troodon did have feathers, as some scientists believe, then, they probably resembled fur more than feathers. There is a modern bird, called the Kiwi, that has feathers which are very similar, in appearance, to those of extinct raptor dinosaurs, such as Troodon.
The genus now includes specimens previously classified as Stenonychosaurus.
Troodon nests full of eggs have been found in Montana. When scientists CAT-scanned them, they found baby Troodon skeleton embryos inside of them. They found skeletons of a small plant-eating dinosaur named Orodromeus with the eggs, as well as a skeleton of an adult Troodon. At first, it was believed that the eggs had belonged to the Orodromeus, and that the Troodon was there intending to rob the nest.
However, it was later discovered that the eggs belonged to the Troodon when baby Troodon embryos were found inside the eggs. It is now believed that the adult Troodons had killed the Orodromeus and brought them back to feed their babies. Troodons laid up to 24 eggs in their nests which were earth mounds. They were able to lay two eggs at a time, so large clutches would take two weeks to lay.
References[change | edit source]
- "Troodontidae from Encyclopedia of Dinosaurs". credoreference.com. 2011 [last update]. http://www.credoreference.com/entry/estdino/troodontidae. Retrieved May 15, 2011. "Saurornithoides"
- Horner, John R. 1984. "The nesting behavior of dinosaurs". Scientific American, 250:130-137.
- Varricchio, David J.; Horner, John J.; Jackson, Frankie D. (2002). "Embryos and eggs for the Cretaceous theropod dinosaur Troodon formosus". Journal of Vertebrate Paleontology 22 (3): 564–576. doi:10.1671/0272-4634(2002)022[0564:EAEFTC]2.0.CO;2.