Troodontids had some of the highest encephalization quotients (a measure of the ratio between actual brain size and the brain size predicted from body size) among non-avian dinosaurs.
As suggested by their large eye-sockets and well-developed middle-ears, they appear to have had keen senses.
They also had proportionately long legs, which indicates they were agile.
Due to their large brains, possible stereoscopic vision, grasping hands, and enlarged sickle-claws, troodontids were generally assumed to have been predatory.
In 1998, the palaeontologist Thomas R. Holtz and colleagues pointed out that the serrations on the teeth of troodontids were different from those of typical, carnivorous theropods in their large size and wide spacing, which is similar to the condition in herbivorous dinosaurs (including therizinosaurid theropods) and lizards rather than carnivorous dinosaurs.
They suggested that this difference in coarseness may be related to the size and resistance of plant and meat fibres, and that troodontids may have been herbivorous or omnivorous.
They also pointed out that some features that had been interpreted as predatory adaptations in troodontids were also found in herbivorous and omnivorous animals, such as primates and raccoons.

In 2001, the palaeontologists Philip J. Currie and Dong Zhiming rejected the idea that troodontids could have been herbivorous.
They stated that troodontid anatomy was consistent with a carnivorous lifestyle, and pointed out that the structure of their serrations was not much different from those of other theropods.
They noted that troodontid features such as sharply pointed serrations that curved up towards the tip of the teeth, razor sharp enamel between the serrations, and blood grooves at the bases, were not seen in herbivorous dinosaurs, which had simpler, cone shaped serrations.
Lü and colleagues discussed the previous studies of troodontid diet, and suggested that the loss of serrations in the teeth of Xixiasaurus and some other troodontids was related to a change in their diet.
Since the teeth would appear to have lost their typical ability to slice meat, at least these trodontids may therefore have been either herbivorous or omnivorous.
In 2015, the palaeontologist Christophe Hendrickx and colleagues suggested that basal (or "primitive") troodontids with unserrated teeth were herbivorous, whereas more derived troodontids with serrated teeth were carnivorous or omnivorous.
Troodontids had some of the highest encephalization quotients (a measure of the ratio between actual brain size and the brain size predicted from body size) among non-avian dinosaurs. As suggested by their large eye-sockets and well-developed middle-ears, they appear to have had keen senses. They also had proportionately long legs, which indicates they were agile. Due to their large brains, possible stereoscopic vision, grasping hands, and enlarged sickle-claws, troodontids were generally assumed to have been predatory. In 1998, the palaeontologist Thomas R. Holtz and colleagues pointed out that the serrations on the teeth of troodontids were different from those of typical, carnivorous theropods in their large size and wide spacing, which is similar to the condition in herbivorous dinosaurs (including therizinosaurid theropods) and lizards rather than carnivorous dinosaurs. They suggested that this difference in coarseness may be related to the size and resistance of plant and meat fibres, and that troodontids may have been herbivorous or omnivorous. They also pointed out that some features that had been interpreted as predatory adaptations in troodontids were also found in herbivorous and omnivorous animals, such as primates and raccoons.
In 2001, the palaeontologists Philip J. Currie and Dong Zhiming rejected the idea that troodontids could have been herbivorous. They stated that troodontid anatomy was consistent with a carnivorous lifestyle, and pointed out that the structure of their serrations was not much different from those of other theropods. They noted that troodontid features such as sharply pointed serrations that curved up towards the tip of the teeth, razor sharp enamel between the serrations, and blood grooves at the bases, were not seen in herbivorous dinosaurs, which had simpler, cone shaped serrations. Lü and colleagues discussed the previous studies of troodontid diet, and suggested that the loss of serrations in the teeth of Xixiasaurus and some other troodontids was related to a change in their diet. Since the teeth would appear to have lost their typical ability to slice meat, at least these trodontids may therefore have been either herbivorous or omnivorous. In 2015, the palaeontologist Christophe Hendrickx and colleagues suggested that basal (or "primitive") troodontids with unserrated teeth were herbivorous, whereas more derived troodontids with serrated teeth were carnivorous or omnivorous.
Xixiasaurus