Troodon formosus TROH-oh-don

"Wounding tooth"

Troodon silhouette — silhouette · Cy Marchant (CC-BY) via PhyloPic

Length: 2.4 m (7.9 ft) — About 2.4 m long, ~50 kg — emu-sized.
Period: Late Cretaceous (77–66 Mya)
Place: North America · Alaska · Montana · Alberta
Food: Omnivore — Small prey, eggs, and possibly plants — generalist diet.
Clade: Troodontidae Dinosauria Saurischia Theropoda Coelurosauria Small, brainy, feathered theropods.

A small bird-like predator whose "wounding teeth" hint at a surprising omnivorous diet.

Troodon reconstruction by ABelov2014 — Reconstruction · ABelov2014 (CC-BY)

Troodon had one of the largest brains for its body size of any dinosaur. Big eyes facing forward gave it strong binocular vision, suited to hunting at night or in low light. Troodon fossils have even been found inside the Arctic Circle, where it survived months of winter darkness — possibly the only dinosaur known to have lived under those conditions.

More about Troodon

Discovery

· 1855 · Montana

The type species T. formosus was discovered in October 1855 and was among the first dinosaurs found in North America. The find was thought to be a lizard until 1877.

The name comes from Ancient Greek and means "wounding tooth", a reference to its teeth, which differed from those of most other theropods known at the time of its discovery.

What did Troodon actually eat?

Wear patterns on a large sample of teeth suggest a diet of soft foods, inconsistent with chewing bone, invertebrate exoskeletons, or tough plants. One study hypothesizes a diet primarily of meat, and a pellet possibly belonging to Troodon suggests it hunted early mammals such as Alphadon. Yet the serrations resemble those of herbivorous reptiles, so an omnivorous diet remains possible.

For the curious → Did Troodon have the famous raptor-style killing claw?

Related derived troodontids such as Linhevenator had an enlarged second pedal claw similar to that of dromaeosaurids, apparently evolved convergently as a predation adaptation. The authors suggested this may also apply to Troodon, but they noted this is currently uncertain because too few remains of the genus are known.

What we know

One of the largest brain-to-body ratios among dinosaurs.
Large forward-facing eyes — strong binocular vision and good low-light hunting.
Fossils found above the Arctic Circle, in regions that had long polar nights.
Eggs found in nests, brooded in the same posture used by modern birds.

What we guess

Whether the genus name 'Troodon' is still valid — some scientists argue the type tooth is too fragmentary to define a genus.
Diet: generalist omnivore is the best guess but specifics depend on the season and habitat.
Whether the Arctic populations migrated south for winter or stayed and endured the dark.