Reptiles are a cold-blooded vertebrate animal class that regularly sheds their outer layer of skin, yet are also very similar to birds (in fact, the crocodile is more closely related to a bird than to a lizard). Reptiles are not as old as fish, with the earliest reptile on record emerging 315 million years ago, but they were the dominant class during the Mesozoic age until the extinction of the dinosaurs. Like birds, reptiles are an air-breathing class with many of its species laying eggs instead of giving birth to live young. In fact, out of all the reptiles, the only species to give birth to live young are boas and pythons. Being cold-blooded without the ability to regulate their internal temperature, Reptiles become inactive during the cooler times of the year.
Tyrannosaurus Rex (T-Rex) was one of the largest predatory dinosaurs that ever existed. Living during the Cretaceous period (68-66 Mya) in the forested river valleys of today’s western North America, Tyrannosaurus is a carnivore popularly known for its large 5’ | 1.5 m skull, ferocious serrated teeth, small useless arms, strong tail, and powerful bipedal legs. Tyrannosaurus Rex was 40’ | 12.3 m in length, with a head height of 17’ | 5.2 m and hip height of 12’-13’ | 3.7-4 m.
Height (Hips): 12’-13’ | 3.7-4 m
Period: Cretaceous (68-66 million years ago)
Scientific Name: Tyrannosaurus
Tyrannosaurus | T-Rex side elevation, front, back, plan
Stegosaurus was a Late Jurassic (155-150 Mya) herbivorous quadrupedal dinosaur known for its array of upright plates on its back and strong spiked tail. Heavily built with short limbs, a small head, and large body, Stegosaurus was a defensive dinosaur that likely foraged for twigs and low hanging fruits. Stegosaurus has a body length of 30’ | 9.1 m and a height of 14’ | 4.3 m.
Spinosaurus was a large carnivorous Cretaceous period (112-93.5 Mya) dinosaur characterized by its large thin back spikes. A giant predator on both land and water, similar to the present day crocodile, fossils prove that the Spinosaurus was as larger or larger than the Tyrannosaurus Rex. Spinosaurus has a length of 49’-51’ | 15-15.6 m, a head height of 16.5’ | 5 m, and an overall spine height of 21.5’ | 6.5 m.
Height (Head): 16.5’ | 5 m
Period: Cretaceous (112-93.5 million years ago)
Scientific Name: Spinosaurus
Spinosaurus side elevation, front, back, plan
Triceratops were three-horned herbivorous dinosaurs that roamed western North America in the late Cretaceous period (68-66 Mya). Combined with a shield-like head plate, the horns of the Triceratops were likely used to protect them from predators and may have also been used for mating rituals. The Triceratops had a length between 26’-29.5’ | 7.9-9 m and stood 9.5’-10’ | 2.9-3 m tall.
Period: Late Cretaceous (68-66 million years ago)
Scientific Name: Triceratops
Triceratops side elevation, front, back, plan