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Troodon formosus (Joseph Leidy, 1856; Sauvage, 1876)
Not on the poster

Name Means: "Tooth that wounds" Length: 6 feet (3 m)
Pronounced: True-don Weight: 110 pounds (50 kilos)
When it lived: Late Cretaceous - 67 MYA    
Where found: Montana, USA; Alberta, Canada    
Troodon was a small dinosaur, only about 6 feet long, but he had a very large brain compared to his body size.  Some scientists think that the was the smartest of all the dinosaurs.  It's eyes were large suggesting nocturnal activity they faced slightly forward facing, giving it some depth perception.  Troodon had very long, slender limbs suggesting that it was a fast runner. 
    Troodon is Greek for "wounding tooth", and refers to the dinosaur's sharp teeth with serrated edges. Although originally thought to be a predator, there is some evidence that Troodon may either have been an omnivore or an herbivore. The teeth are short but broad, and have  large serrations like those of herbivorous dinosaurs; their sides show signs of wear.  The jaws meet in a broad, U-shaped symphysis similar to that of an iguana.  Its diet may have consisted of smaller animals, including mammals and perhaps a significant amount of plant material.
    Its long arms that folded back like a birds', and its hands possessed partially opposable thumbs. It had large, sickle-shaped claws on its second toes which were raised off the ground when running. This claw is common in the superfamily Maniraptora, to which Troodon belongs. Although no feathers have been found, Troodon was descended from     Sinornithoides who did have them.  Paleontologists believe that Troodon inherited the feature and was covered with them
    Prior to 1983 Troodon was a mystery to paleontologists. The first scientifically studied dinosaurs were discovered in England during the early part of the 19th century. By 1842 (the year Richard Owen first proposed the name Dinosauria) several species of these Mesozoic giants were known from fragmentary fossils.  About a decade later, in 1855, Ferdinand V. Hayden collected some fossils at the confluence of the Judith and Missouri Rivers in Montana while on a geological survey. The fossils, which included an assortment of species, were among the first American dinosaur fossils.  He forwarded them to Joseph Leidy at the Academy of Natural Sciences in Philadelphia.  Leidy was one of the great American scientists of the 19th-Century and is best known as the Father of American Vertebrate Paleontology.  The species contained an interesting tooth.  Leidy though it was from a previously unknown lizard and gave it the name Troodon, possibly because of its worn condition. It was later reclassified as a plant eating dinosaur now known as the stegosaurus, but other scientists assigned to various groups carnivorous dinosaurs.
   In 1983, paleontologist Phil Currie stumbled across a jawbone containing the mystery teeth while walking in the Alberta badlands near the Royal Tyrrell Museum where he works. It was the link he needed to build a theory of what the Troodon looked like when it roamed the earth 75-million years ago.  Currie then determined that the Troodon would have been about 45 kilograms, six feet in length and particularly suited to running.  "The legs were relatively long, and the lower parts of the leg were especially elongated. We walk on the flats of our feet, but troodontids stood on their toes like most other dinosaurs. However only two toes actually touched the ground when this animal was running,"  In fact the Troodon's foot structure, as well as its posture and brain indicate that it was very birdlike. Many scientists believe it was covered in feathers.  Currie published his finding in his book,  A Moment in Time with Troodon
Additional specimens have been found in Montana and Wyoming.  Today
Troodon is one of the most well known dinosaurs, with over 20 known specimens. 
    Fossil nests found at the famous "Egg Mountain" site in Montana contained elongated eggs that were originally attributed to the small plant-eating hypsilophodont Orodromeus.  They have been reidentified as nests belonging to Troodon. Full preparation of an embryo revealed a baby Troodon inside one of them. A recently discovered nest included partial remains of an adult Troodon that may have been brooding the eggs, much in the manner of the meat-eating dinosaur Oviraptor.   Troodon produced two large eggs at a time, perhaps daily
or at longer intervals over a period of weeks, and used and soil and direct body contact to incubate the clutch in an open nest -- there is no evidence of accumulated plant material at the known nest sites.

Courtesy DK Publishing


 

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