Troodon formosus

Troodon, a small but highly intelligent theropod dinosaur that lived during the late Cretaceous period, around 75 to 70 million years ago, is often considered one of the most bird-like and cognitively advanced dinosaurs due to its relatively large brain size in proportion to its body, which suggests it had keen sensory abilities, complex behaviors, and possibly even social interactions; measuring about 2 to 2.5 meters in length and weighing roughly 50 kilograms, Troodon possessed a slender, lightweight build, characterized by sharp, serrated teeth suited for an omnivorous diet, as well as long, slender legs indicating a fast and agile predator, likely preying on small vertebrates, insects, and plants; its most distinctive feature, however, was its highly specialized, large eyes, which, in conjunction with its high brain-to-body mass ratio, may have given it excellent vision, particularly in low-light conditions, perhaps aiding in nocturnal or crepuscular hunting; fossil evidence, including well-preserved foot bones, suggests that Troodon had an opposable toe, which could have helped it grasp prey or perch, further supporting theories that it might have been more arboreal or versatile than other theropods; Troodon is often highlighted as a key genus in discussions about the evolutionary link between non-avian dinosaurs and birds, especially considering its highly developed features and complex brain structure that foreshadow the cognitive abilities of modern birds.