The Jurassic (200 to 145 million years ago) marked the period when the dinosaurs firmly established themselves as the dominant lineage on land. Nimble early theropods and large sauropodomorphs appeared during the Triassic, but it was during the Jurassic that dinosaurs would show what they were truly capable of.
Fans of the iconic Jurassic Park franchise might be disappointed to learn that some of the most prominent dinosaurs featured in the film are not actually from the Jurassic period. These include T. rex, velociraptor, and tricerotops, all of which appeared much later in the Cretaceous. Nevertheless, the Jurassic landscape features enormous predators, distinct armored dinosaurs, and colossal sauropods. Here’s a rundown of the most interesting Jurassic dinosaurs.
1. Allosaurus: “Different Lizard”
| Family | Allosauridae |
| Found in | Morrison Formation, Colorado |
| Diet | Carnivorous |
| Lived | 150–144 mya |
| Length | 12 m |
| Height | 4.5 m |
| Weight estimate | 1500 kg |
Probably the most famous Jurassic predator, Allosaurus was prevalent around 150 to 144 million years ago. This dinosaur was a bipedal carnivore, reaching up to 12 meters in length. Its diet most likely included ornithischians, smaller sauropods, and scavenged remains. Equipped with robust hind limbs and a strong tail, Allosaurus was adept in maintaining balance and maneuverability. The ancient predator may have hunted in packs, while other paleontologists think it may have been more like a lone wolf.
2. Apatosaurus: “Deceptive Lizard”
| Family | Diplodocidae |
| Found in | Morrison Formation, Colorado |
| Diet | Herbivorous |
| Lived | 152-151 mya |
| Length | 23 m |
| Height | 18 m |
| Weight estimate | 41,000 kg |
Apatosaurus, a “deceptive” Jurassic sauropod, roamed Earth approximately 150 million years ago. The animal featured an impressive length of 23 meters and was estimated to weigh 41 tons. Its elongated neck enabled it to feed on high vegetation while its strong legs provided stability for its massive frame. Apatosaurus‘s whip tail might have served as a sensory organ and even as a defensive weapon against predators. Despite its size, this herbivore’s skeletal structure suggests it was surprisingly mobile for its size. Apatosaurus was subject to controversy as early descriptions of the animal often mistook it for Brontosaurus, but a 2015 consensus finally separated them into two distinct species.
3. Brachiosaurus: “Arm Lizard”
| Family | Brachiosauridae |
| Found in | Colorado River Valley, Colorado |
| Diet | Herbivorous |
| Lived | 150–130 mya |
| Length | 26 m |
| Height | 13 m |
| Weight estimate | 36,000 kg |
Another icon of the Jurassic is the colossal Brachiosaurus. This huge dinosaurs stood up to 13 meters tall and extended 26 meters in length from head to tail. It weighed around 36 tons. Brachiosaurus has an unusually long neck, positioned vertically rather than horizontally, which facilitated grazing on the high canopy. This allowed it to reach food untapped by other herbivores. The name “Arm Lizard” comes from its longer front limbs which contributed to its almost vertical posture. The well-structured and sturdy skeleton of Brachiosaurus suggests a life spent primarily in terrestrial settings, despite previous speculation of a semi-aquatic lifestyle.
4. Diplodocus: “Double Beam”
| Family | Diplodocidae |
| Found in | Morrison Formation, Colorado |
| Diet | Herbivorous |
| Lived | 161-146 mya |
| Length | 26 m |
| Height | 8 m |
| Weight estimate | 30,000 kg |
Diplodocus, one of the longest and largest land animals to ever walk the Earth traced its existence back to approximately 161-146 million years ago during the Late Jurassic period. The name, derived from the Greek words “diploos” and “dokos,” meaning “double beam”, aptly describes the pair of elongated bones found beneath its tail vertebrae. These distinctive chevron bones may have played a role in supporting the tail muscles, contributing to the dinosaur’s notable length and potentially serving as a defensive apparatus or balance aid. As a sauropod, Diplodocus was endowed with an extensive neck, facilitating a versatile diet of vegetation at various heights.
5. Stegosaurus: “Roof Lizard”
| Family | Stegosauridae |
| Found in | Morrison Formation, Colorado |
| Diet | Herbivorous |
| Lived | 159–144 mya |
| Length | 9 m |
| Height | 3 m |
| Weight estimate | 3800 kg |
The herbivorous Stegosaurus is instantly recognizable thanks to its bony back plates and a spiked tail. This famous dinosaur was notable not just for its distinctive armor but also for the small size of its brain, thought to be only the size of a walnut. This has sparked much debate about its intelligence and sensory capabilities. At one point, scientists speculated the existence of an auxiliary “brain” — not a true brain but a bundle of nerves — in its hip area to aid limb control. This hypothesis, though intriguing, has been met with skepticism. The purpose of Stegosaurus’ back plates has also been a subject of speculation. While once thought to serve as armor, modern theories suggest they might have been used primarily for display or thermoregulation. The spiked tail, or thagomizer, is widely accepted as a defensive weapon against predators.
6. Ceratosaurus: “Horned Lizard”
| Family | Ceratosauridae |
| Found in | Morrison Formation, Colorado |
| Diet | Carnivorous |
| Lived | 156–145 mya |
| Length | 7 m |
| Height | 2 m |
| Weight estimate | 1000 kg |
As a famous theropod, the Late Jurassic Ceratosaurus stood out due to its unique physical features for its time. This carnivore, measuring up to seven meters in length, was equipped with strong jaws and long, blade-like teeth, well-suited for grasping and slicing through flesh. A notable feature was the prominent, ridge-like horn on its snout and a pair of additional horns over its eyes, giving it a fearsome appearance. Despite having short forelimbs, Ceratosaurus made good use of them, with three clawed fingers on each hand. These formidable weapons would have allowed it to grasp or hold onto prey. Its sprinting capability, powered by strong back legs, made it a formidable predator, capable of capturing prey with sudden bursts of speed. It inhabited swamps in southern North America, where its diet included other dinosaurs and fish.
7. Compsognathus: “Pretty Jaw”
| Family | Compsognathidae |
| Found in | Bavaria, Germany |
| Diet | Carnivorous |
| Lived | 150 mya |
| Length | 1 m |
| Height | 0.3 m |
| Weight estimate | 3 kg |
While other contemporary theropods swelled in size, the agile Compsognathus went down a different evolutionary path. Known for its small size, comparable to a modern-day turkey, this dinosaur measured approximately one meter in length and weighed around three kilograms. Despite its stature, Compsognathus was a predator, it’s diet consisting of smaller animals such as insects, lizards, and mammals. Fossil evidence showing a lizard skeleton inside the ribcage of one specimen highlights its predatory lifestyle. Its elongated legs and slender build suggest it was a swift runner, capable of rapid movements for hunting and evasion from larger animals.
8. Dryosaurus: “Oak Lizard”
| Family | Dryosauridae |
| Found in | Albany County, Wyoming |
| Diet | Herbivorous |
| Lived | 147 mya |
| Length | 3 m |
| Height | 1.7 m |
| Weight estimate | 77-90 kg |
Dryosaurus, also known as the “oak lizard,” was a Late Jurassic ornithopod. This small, agile herbivore was approximately three meters long, 1.7 meters tall at the hips, and weighed about 77–90 kilograms. It was characterized by a long neck and stiff tail, which are believed to have provided balance, enabling high-speed movement on its two legs. Its large eyes suggest good vision, potentially aiding in predator detection. Notably, Dryosaurus had a horny beak and cheek teeth but lacked front teeth, indicating a specialized herbivorous diet. Some scientists hypothesize that this dinosaur may have stored food in its cheeks, similar to modern-day hamsters.
9. Ornitholestes: “Bird Robber”
| Family | Maniraptoromorpha |
| Found in | Bone Cabin Quarry, Wyoming |
| Diet | Carnivorous |
| Lived | 161–146 mya |
| Length | 2 m |
| Height | ~0.9 m |
| Weight estimate | 11 kg |
While raptors dominated the Cretaceous scene, their ancestors, Ornitholestes, had humbler beginings during the Late Jurassic. This maniraptoromorph thrived around 161 to 146 million years ago. It was small, agile theropod, measuring approximately two meters in length, that was adept at bipedal running and capable of swift pursuits. Its small head and sharp teeth were suited for a carnivorous diet, possibly including small mammals, lizards, frogs, and juvenile dinosaurs. The dinosaur’s ability to grasp with both hands suggests a refined approach to hunting. Belonging to the maniraptoromorphs, it’s believed that Ornitholestes may have had feathers, a feature typical of its clade, with important implications for its thermoregulation, display, or other behaviors
10. Kentrosaurus: “Sharp Lizard”
| Family | Stegosauridae |
| Found in | Tendaguru Formation, Tanzania |
| Diet | Herbivorous |
| Lived | 156-151 mya |
| Length | 5 m |
| Height | ~1.5 m (to the hip) |
| Weight estimate | 1000 kg |
And finally, Stegosaurus‘ smaller cousin, Kentrosaurus. This medium-sized herbivore, prevalent during the Late Jurassic, measured approximately five meters in length and weighed about one ton. Unlike Stegosaurus‘ dorsal plates, Kentrosaurus bore smaller plates that transitioned into spikes towards the tail, culminating in a menacing thagomizer. Kentrosaurus also featured a pair of side spikes which may have provided protection against predators, deterring attacks from the sides. Its diet consisted mainly of low-lying vegetation, which it grazed peacefully, spending much of its time in search of food across the vast plains of the Late Jurassic.
Now read:
