It's stenonychosaurus, it's troodon, no it's latenivenatrix!

Latenivenatrix mcmasterae by Fred Wierum

Latenivenatrix mcmasterae, the "hiding hunter". Is the largest troodontid known with a skull length of 45 centimeters, and and a full body length of 3.5 meters, seemingly small compared to other theropods, but quite big for a troodontid. The animal was originially described in 1969 by Dale Allen Russel, it was described to the genus stenonychosaurus. Then in 1987 is was referred to as troodon (which is now stenonychosaurus again) . and then later referred to its own genus as latenivenatrix.

The animal was originally found in the Dinosaur Park formation in Alberta, Canada. It was one of the two troodontids in that formation, the other being Stenonychosaurus inequalis. Like I said earlier the animal was originally classified to the genus stenonychosaurus, but later on was classified as its own. 

The remains known of this animal are a partial skeleton from the first described specimen, specimen UALVP 55804 had a partial pelvis, specimen TMP 1982.019.0023 had a partial skull, and the specimen TMP 1992.036.575 had a right dentary and several metatarsals. 

Latenivenatrix can be differentiated from Stenonychosaurus by its frontals, and its metatarsals.

It was quite different compared to other troodontids because of its hips. The pubis retroverted which formed a 17° angle, the shaft of the pubis was curved anteriorly, a large muscle scar was visible on on the lateral surface of the pubic shaft, and each frontal bone had a triangular shape.

It belongs to the subfamily troodontinae, which is a subfamily of troodontids first described in 2017 descending from the last ancestors of Gobivenator, and Zanzabazar.

Sources: https://en.wikipedia.org/wiki/Latenivenatrix, https://en.wikipedia.org/wiki/Dinosaur_Park_Formation#Paravians, https://en.wikipedia.org/wiki/Troodontinae, https://blogs.scientificamerican.com/laelaps/paleo-profile-the-hiding-hunter/