Dinosaurs, arguably the most renowned prehistoric creatures, are incredibly diverse, with many species that remain unfamiliar or seldom heard of.
Velociraptor
Velociraptor is perhaps one of the most famous - and most misunderstood - species among dromaeosaurs (the group of bird-like dinosaurs). In Jurassic Park, these creatures were depicted as highly intelligent human-sized killers that hunted in packs, as described by CNET. However, National Geographic pointed out that Velociraptors were not the wandering predators of Asia during the Cretaceous as portrayed in movies.

First described in 1924 by renowned paleontologist Henry Fairfield Osborn (according to the Natural History Museum of the United Kingdom), Velociraptors were relatively modest in size, weighing about 45kg. They were also covered in feathers and likely solitary hunters, using their large claws to pin down prey similar to modern-day birds of prey.
Velociraptors also possessed highly acute senses of smell and sight, possibly making them nocturnal hunters. They were incredibly fast as well, reaching speeds of 40 km/h, though not as fast as depicted in movies.
If you could reverse the time machine back to the Paleozoic era, perhaps you wouldn't have to worry about the Velociraptor's hunting spree. Their prey mainly consisted of reptiles and small mammals.
Deinonychus
This is also a species of theropod dinosaur similar to birds, inhabiting North America and being twice the size of Velociraptor. Like other meat-eating birds, it also has a long, stiff tail.

Deinonychus was discovered in the 1960s by paleontologist John Ostrom, who also named it, meaning 'terrible claw'. Based on fossil analysis, paleontologists have speculated that Deinonychus hunted in packs. This hypothesis is still hotly debated in the academic community.
Microraptor
Microraptor is a very small genus of meat-eating dinosaur. The Natural History Museum of the United Kingdom suggests they weigh just over 1kg with a body length of about 70cm, making them slightly larger than European kestrels.

The US Natural History Museum explains that it has a feather arrangement similar to that of bird wings in both the forelimbs and hindlimbs. This suggests that this species could fly or at least glide among the trees in the ancient Chinese forests where they lived.
National Geographic informs us that this small meat-eating bird often preys on primitive bird species. Fossil evidence shows that this dinosaur hunted in a manner similar to modern meat-eating birds.
Utahraptor
The largest and perhaps most terrifying meat-eating bird dinosaur ever to exist on our planet is Utahraptor. Discovered in 1991 by paleontologist Jim Kirkland of Utah, this dinosaur resembles Velociraptor or Deinonychus - except it's larger.
Utahraptor weighed up to nearly 300kg and reached lengths of up to 7m. Utahraptor is also one of the earliest dromaeosaurs. Fossils of this species indicate that Utahraptors appeared in the early Cretaceous, 125 million years ago.

In 2001, a series of Utahraptor fossils were found in Moab. These specimens may have been victims of quicksand, providing us with a deeper insight into this prehistoric meat-eating animal. Utahraptors were typically larger than other meat-eating bird dinosaurs, meaning they relied more on muscle strength than agility for hunting.
Rahonavis
Rahonavis is considered one of the earliest precursor birds. Paleontological discoveries tell us that this small dromaeosaur lived in Madagascar, roughly the size of a kestrel, and was capable of flight. Its name originates from Malagasy, the language of Madagascar, meaning 'menacing cloud bird'.

Rahonavis has been compared to the most famous early ancestor of birds, Archaeopteryx. Like Archaeopteryx, Rahonavis had a lizard-like tail and sickle-shaped claws.
However, scholars suggest that Rahonavis appears to be a transitional species between dinosaurs and early birds like Archaeopteryx. While it may have been a more advanced flying bird than Archaeopteryx, it is still considered a primitive bird needing a running start before taking flight.
Bambiraptor
According to Dinosaurs: A Visual Encyclopedia, in 1995, Wes Linster (a 14-year-old boy) was fossil hunting in Montana's Glacier National Park when he stumbled upon a small set of bones.

Paleontological analysis reveals it to be a carnivorous dinosaur, with scientists naming the fossil Bambiraptor. Bambiraptor weighed about 2kg and was slightly over 60cm long.
Interestingly, Bambiraptor had a relatively large brain-to-body size ratio. It is speculated to have possessed intelligence comparable to some of the smartest bird species today.
Sources: Grunge; Britannica; National Geographic; CNET