Initially known from only a single tooth, Troodon has progressed over the past 150 years into the poster reptile for dinosaur intelligence. Here are 10 facts you may (or may not) have known about this Cretaceous carnivore.
1. Troodon is pronounced "TRUE-oh-don..."
One of the most frequently mispronounced dinosaurs, Troodon actually comprises three syllables (there used to be an umlaut over the second "o" as a way of alerting the unwary). This genus was named way back in 1856 by the famous American paleontologist Joseph Leidy, who actually thought he was dealing with a small, inoffensive lizard rather than a true dinosaur.
2. ...and was named after a single tooth.
Troodon is Greek for "wounding tooth," a reference to the single incisor by which it was originally known. It wasn't until the early 1930's that the actual bones of this dinosaur were discovered (amounting to fragments of its hand, foot and tail), and even then, the fossils were assigned to the incorrect genus (for more, see the article How Was Troodon Discovered?).
3. For decades, Troodon was known as Stenonychosaurus.
In 1932, Charles R. Sternberg erected the new genus Stenonychosaurus, which he classified as a basal theropod closely related to Coelurus. It was only after the discovery of more complete fossil remains in 1969 that paleontologists redesignated Stenonychosaurus as Troodon, and recognized its close affinity to the Asian theropod Saurornithoides.
4. Troodon had a bigger brain than most dinosaurs...
The most notable feature of Troodon was its unusually large brain, which was much bigger, in proportion to the rest of its body, than the brain matter of comparably sized theropods. According to one analysis, Troodon had an "encephalization quotient" several times that of most other meat-eating dinosaurs, making it a true Albert Einstein of the Cretaceous period.
5. ...and might eventually have evolved a human level of intelligence.
In 1982, the Canadian paleontologist Dale Russell speculated about what might have happened if Troodon had managed to survive the K/T Extinction 65 million years ago. In his "counterfactual" history, Troodon evolved into a large-brained, two-legged, intelligent reptile with big eyes, partially opposable thumbs and three fingers on each hand--and looked much like a modern human being!
6. Unlike most dinosaurs, Troodon flourished in colder climates.
Troodon had larger eyes than most theropod dinosaurs, a hint that it needed to gather in all the available light from its cold, dark climate (another dinosaur that pursued this evolutionary strategy was the Australian Leaellynasaura). Processing more visual information necessarily entails having a bigger brain, which helps to explain this dinosaur's relatively high IQ.
7. Troodon laid clutches of 16 to 24 eggs...
Besides its presumed intelligence, Troodon is famous for being one of the few carnivorous dinosaurs whose parenting routines are known in detail. To judge by the preserved nesting grounds discovered by Jack Horner in Montana's Two Medicine Formation, Troodon females laid two eggs per day over the course of a week or so, resulting in circular clutches of 16 to 24 eggs.
8. ...which were probably brooded by the males of the species.
The evidence is circumstantial at best, but a recent analysis comparing the bone growth of Troodon with that of modern birds and crocodiles concludes that this dinosaur's eggs were brooded by the males of the genus, and not the females. If this sounds unusual, bear in mind that male brooding is standard operating procedure for many species of modern birds!
9. It's unclear how many species Troodon comprised.
Fossil specimens of Troodon have been unearthed across the expanse of North America, as far north as Alaska and (depending on how you interpret the evidence) as far south as New Mexico. When paleontologists are faced with such wide distributions, they're tempted to speculate that the umbrella genus may be too big--and that some "Troodon" species actually belong to their own genera.
10. Troodon was probably covered in feathers.
Except in certain exceptional circumstances--witness the profusion of "dino-birds" that have recently been discovered in China--feathers don't preserve well in the fossil record. Still, considering its evolutionary affinity with raptors and other small theropods, it would be very surprising if Troodon didn't sport at least some feathers, and at least during some point of its life cycle.