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Levi bernardo, CC BY-SA 3.0, via Wikimedia Commons

Type: Sauropod
Lived: Mid Jurassic, 169 – 159 million years ago
Weight: 9,800kg
Length 20.2m / 66ft
Diet: Herbivorous

Omeisaurus (oh-mee-sore-us) was a huge sauropod dinosaur that lived in the Bathonian – Callovian Ages during the Late Jurassic Period of what is now China, around 169 – 159 million years ago. Its name comes from Mount Emei, where it was discovered.

Omeisaurus measured 20 feet in length, 12 feet (4 metres) in height and weighed 9,800kgs. It had a bulky body and a very long neck which contained several more neck vertebrae that were larger than most other sauropods. Unlike other sauropods, its nostrils were located close to the end of its snout.

Omeisaurus had 4 thick legs, a long tail and a very small head. The back of the Omeisaurus was higher at the hips than at the shoulders.

The closest relative of Omeisaurus appears to have been the even longer-necked sauropod Mamenchisaurus, which had 19 neck vertebrae compared to the 17 of Omeisaurus.

Omeisaurus was a herbivore and must have eaten huge amounts of plant materal to sustain itself.



FunkMonk (Michael B. H.), CC BY-SA 3.0, via Wikimedia Commons

Type: Sauropod
Lived: Late Cretaceous, 72 – 68 million years ago
Weight: 8,400 – 25,400kgs
Length 11.4m – 13m / 37 – 43ft
Diet: Herbivorous


Opisthocoelicaudia (Oh-pis-tho-see-lih-caw-dee-ah) is a combination of the Greek words ‘opisthen’ and ‘koilos,’ which mean ‘hollow’ or ‘cavity,’ and the Latin term ‘cauda,’ which means ‘tail’ (tail with posterior cavity).

This is a Late Cretaceous sauropod dinosaur genus discovered in Mongolia’s Gobi Desert around 70 million years ago. The formation is considered to date from 83.6-66 million years ago, from the late Campanian to the early to middle Maastrichtian period. Opisthocoelicaudia skarzynskii is the type species in the Opisthocoelicaudia genus. Opisthocoelicaudia is one of the best-known Late Cretaceous sauropods, thanks to a well-preserved skeleton missing only the head and neck discovered in 1965 by Polish and Mongolian scientists. These Late Cretaceous sauropods favored terrestrial environments. This Saurischia clade dinosaur is thought to have lived in a warm, humid climate.

This dinosaur has an odd trait in the vertebrae (bones of the spine) from the front part of the tail. The side of the vertebra facing the tail’s end bent deeply inside (it was concave), whereas the side facing the specimen’s front curved profoundly outward (it was convex). When the dinosaur reached for taller plants and trees, it may have been able to utilize its tail as a prop, similar to the third leg of a tripod. This would have helped the dinosaur balance by shifting some of its weight away from its back legs. It also had an extra vertebra in the pelvic area to strengthen the hips, and the hip socket was sturdy enough to support the dinosaur’s massive weight on two legs. Opisthocoelicaudia may have been a specialized eater because no other sauropod has these characteristics. When the animal stood on its four feet, the hips and tail were also odd (quadrupedal).

Its body was practically straight from its neck to the commencement of its tail when viewed from the side. The majority of sauropods had a rounded profile. This shape was most likely the result of the tail’s specializations. Except for a few bones, the majority of the neck was missing. They reveal that Opisthocoelicaudia held its neck straight out in front of the body when moving. Scavengers may have ripped Opisthocoelicaudia’s neck and head apart, leaving grooves on the pelvis and a bone in its leg where their teeth dug into the bone.

Another trait that distinguishes the Opisthocoelicaudia skarzynskii from other titanosaurs is its back vertebrae. The spinous processes of the back vertebrae are bifurcated, resulting in two rows of bony projections going down the spine. These characteristics distinguished this Mongolian reptile from others. It walked with its tail well off the ground and, like most sauropods, required hundreds of kilograms of feed every day to meet its dietary requirements. It weighed an estimated 30 tons and was 12 meters in length, despite its great size. Despite the absence of both the head and neck of this species, later reconstructions of the sauropod’s nuchal ligament have shown that it had a medium-length neck that grew to around 16.4 feet (5 m) in length.

They lived on Earth for roughly 66 million years before becoming extinct due to predation effects from other dinosaurs.



PaleoNeolitic, CC BY-SA 4.0, via Wikimedia Commons

Type: Small theropod
Lived: Late Jurassic, 156 – 145 million years ago
Weight: 12.6kgs / 27Ibs
Length 2.08m / 6.82ft
Diet: Carnivorous

Ornitholestes (Or-nith-oh-LES-teez) was a small theropod dinosaur who lived during the Late Jurassic period in the forests of North America around 156 – 145 million years ago.

Ornitholestes measured approximately 6.5 feet (2 metres) in length and weighed around 15 kilograms (25 pounds). It was a lightly built, hollow-boned bipedal dinosaur who was a very fast runner. Ornitholestes had a small head and a small bony crest on its snout which may have been used to attract mates. It had many sharp, conical teeth, an ‘s’ shaped, flexible neck and a long tapered stiff tail. The tail would probably have been used to counter-balance when this agile predator was chasing its prey.

Ornitholestes had long legs and was able to change direction very quickly when in pursuit of prey. Its arms were short and strong and it had hands that had 4 clawed fingers, one of which was tiny.



Tom Parker, CC BY-SA 4.0, via Wikimedia Commons

Type: Large theropod
Lived: Late Cretaceous, 74 – 65 million years ago
Weight: 170kgs / 370Ibs
Length 3.8m / 12ft
Diet: Carnivorous


Ornithomimus (NEETH-oh-MY-mus) is a Greek word meaning (bird mimic) was a tiny, bird-like dinosaur with toothless jaws that lived between 65 and 98 million years ago in North America and Asia during the late Cretaceous period.

Ornithomimus belongs to the Ornithomimidae family, which includes ostrich-like dinosaurs with unusually large eyes and brains. Paleontologists acknowledge two Ornithomimus species, one of which lived in Canada, Ornithomimus edmontonicus.

It lived in Alberta between 72.6 and 69.6 million years ago, while specimens as old as 76.5 million years ago have been identified to as that species.

Ornithomimus had feathers that looked down and had wings that it utilized for courting and exhibition. A paleontologist discovered feathers on Ornithomimus in 2008, marking the first time a feathered dinosaur had been identified in the Western Hemisphere. It was first discovered in Colorado in 1889.

During the Cretaceous Period, its fossils have been discovered in Mongolian, European, and North American deposits dating from 125 million to 66 million years old. Ornithomimid dinosaurs were a unique group of theropod dinosaurs that exhibit convergent evolution with ratite birds like ostriches. They weren’t as closely linked to birds as the Dromaeosauridae, but they were still members of the Coelurosauria, which included birds. Ornithomimids are fascinating and useful for the knowledge they may provide about bird evolution.

Its name literally means “bird,” and its speed and size are sometimes compared to those of a modern-day ostrich. It was bipedal, which meant it walked and stood on two legs. The feet had three toes and the legs were long and adapted for sprinting. To balance its weight over its hips, it probably ran with its neck, head, and tail outstretched. The slim arms culminated in grabbing hands with three long clawed fingers.

They were all fast-paced reaching speeds of up to 30 mph (48 km/h) and omnivorous with excellent vision. The brain chamber was vast in the little thin-boned skull. Ornithomimus’ increased grey matter in the brain is most likely due to the fact that it is required to keep its balance at rapid speeds and may have had slightly enhanced smell, sight, and hearing. They ate little animals like lizards, insects, and small mammals because they had no teeth and their heads were too small to devour large things. Eggs, nuts, and plants may have also been part of their diet.

It had a huge braincase despite its small skull and is considered one of the most intelligent dinosaurs. It was up to 3.8 meters long and weighed 170 kg. It possessed a long tail, a long neck that connected to a small head, a huge belly, long muscular hind limbs, and long forelimbs with three digits on each side. Long, straight claws were attached to the fingers of the hand, which could have been utilized to grab branches.

Ornithomimus thrived on a subtropical coastal plain on the western shore of the Western Interior Seaway, this was an inland sea that divided North America in two by connecting the modern-day Arctic Ocean to the Gulf of Mexico. Ornithomimus’ habitats have altered considerably over millions of years as a result of variations in sea levels, drainage conditions, and climate swings. Its natural habitats ranged from warm, humid marshes to dry, chilly forested regions



Tomopteryx, CC BY-SA 3.0, via Wikimedia Commons

Type: Orthithopod
Lived: Late Cretaceous, 74 million years ago
Weight: 170kgs / 370Ibs
Length 2.5m / 8.2ft
Diet: Herbivorous


Orodromeus (or-oh-DROM-ee-us), often known as the ‘mountain runner,’ was a tiny herbivorous dinosaur that lived in North America between 65 and 98 million years ago.

Horner and Weishampel named it in 1988 when Robert Makela discovered a fragmentary skeleton and head in the Egg Mountain site of the Two Medicine Formation in Montana, North America.

A huge number of eggs of a new ornithopod dinosaur were also discovered. The new dinosaur was given the name Orodromeus after the discovery site and the animal’s anticipated speed, which was based on its long hind limbs and slender body.

One full nest had 19 eggs set in a spiral pattern. Paleontologists gently opened one egg and extracted the preserved embryo for further research after a radiographic inspection revealed embryonic bones inside the eggs.

The state of the nesting place, as well as the anatomical characteristics of the embryo, provided insight into Orodromeus’s alleged parental habits. The eggs had been trampled less, indicating that the young had departed the place shortly after emerging from their shells. The hatchlings’ joints were fully formed, indicating that they were capable of leaving the spot and fending for themselves right away.

The discovery of fossils and specimens of this ground-dwelling dinosaur at the Egg Mountain site supports the theory that it lived in a terrestrial habitat on mountains and hills.

Orodromeus reached a length of around 8 feet (2.4 meters) and weighed between 3 and 10 kilograms. Its skull was triangular in shape, and its tail was extremely long. It has a small, light head with a beak like a bird. The arms ended in five short, blunt-clawed fingers, while the hind legs were long and slender. Orodromeus was a bipedal creature, standing and walking on two legs. Animals from the same family Orodromeus, like its co-familial, had effective grinding teeth and cheeks that held food during chewing.

According to some evidence, they may have migrated in herds. It was discovered to dig burrows and was a close relative of Orodromeus. It was a low-growing herbivorous dinosaur. It ate luscious fruits and maybe insects, especially when it was young. It was one of the hypsilopods with the longest legs for its size as an adult. The orodromus had a long, straight tail with many braided bone tendons supporting it. When they were running, they relied on its tail for balance.

Their herbivorous diet would have necessitated a lot of plants. Some researchers believe the Orodromeus lived in burrows to avoid predators because their remains were found grouped together rather than scattered.

This dinosaur genus is most likely extinct due to the Cretaceous Paleogene extinction event, which occurred almost 66 million years ago due to the impact of a massive comet or asteroid on Earth’s surface. 



Tim Evanson, CC BY-SA 2.0, via Wikimedia Commons

Type: Ornithopod
Lived: Late Cretaceous, 95 million years ago
Weight: 22 – 32kgs / 48.5 – 70.5Ibs
Length 2.1m / 6.9ft
Diet: Herbivorous


Dr Anthony and his colleagues originally discovered Oryctodromeus (or-ik-tow-drohm-ee-us), which means “digging runner,” in 2007. They discovered, an adult skeleton with an upper beak or premaxillae, a partial braincase, six back vertebrae, three-neck vertebrae, seven hip vertebrae, ribs, 23 vertebrae from the tail, a shoulder girdle, an arm without the hand, an incomplete fibula, both tibiae, and lastly a metatarsal was discovered.

The Oryctodromeus is the first non-avian dinosaur species to display burrowing behavior. Oryctodromeus lived in southern Montana and southwestern Idaho during the Middle Cretaceous period, around 95 million years ago.

The first remains of Oryctodromeus were found in a hole more than 2 meters long, 30 centimetres wide, and approximately 40 centimetres high. The remains of Oryctodromeus within this hole had evidently died of undetermined circumstances. The presence of juveniles among the adults shows that Oryctodromeus offered parental care for a long time. 

Oryctodromeus could reach a size of up to 6.8 feet long with more than half of that being tail and weigh 70 pounds, making him roughly the same size as a modern coyote. 93.3-95 million years ago, the Oryctodromeus dinosaur became extinct.

Oryctodromeus was a burrowing dinosaur, and was able to survive and thrive in a variety of settings, including windy and arid places, polar climates, and high mountains.

Oryctodromeus was the perfect build to dig as it featured a shoulder girdle and a narrow pelvis. It may have pushed the soil with its snout and excavated with its muscular forearms and shoulders. 

It is believed that Oryctodromeus dinosaurs were able to establish a microclimate in their burrows. The microclimate would be influenced by the external environment. The den would have been just over two meters long, with a sharp s-bend that made it difficult for predators to enter and an exit chamber.

The tail of the Oryctodromeus was free of ossified tendons. One thick tendon lattice was present in the sacrum, caudal, and dorsal columns, according to some fossil specimens from the Wayan formation. This suggests that the ossified tendons are more flexible than previously thought.


Othnielia Dinosaur

Image source

Type: Ornithopod
Lived: Late Cretaceous, 95 million years ago
Weight: 10kg / 22Ibs
Length 1.4m / 4.6ft
Diet: Herbivorous

Othnielia (oth-ni-ee-lee-a) was an ornithopod dinosaur, a genus of hypsilophodont, that lived in the Oxfordian – Tithonian stages during the late Jurassic Period, about 156-145 million years ago. Othnielia could be found in Colorado, North America and Utah.

Othnielia measured 4 feet (1.1 metres) in length, 1 foot (30 centimetres) tall at the hips and weighed 22.5 kilograms (50 pounds).

It had a small skull with a beak that contained self-sharpening, chisel-like cheek teeth and large eyes. It may also have had cheek pouches. Othnielia was a bipedal dinosaur and moved around on 2 legs.

It had long legs with very long shins and feet with 4 clawed toes. Its arms were small and it had hands with 5 clawed fingers. Othnielia was a fast, agile dinosaur who had a long stiff tail which was used as a counter-balance and balance when running and changing direction.

Othnielia was a herbivore and may have lived in herds. These dinosaurs laid eggs and probably cared for their young.



Audrey.m.horn, CC BY-SA 4.0, via Wikimedia Commons

Type: Ornithopod
Lived: Early Cretaceous, 115 – 100 million years ago
Weight: 4,000kg
Length 7m / 23ft
Diet: Herbivorous


Ouranosaurus (ore-ANN-oh-SORE-us) was a basal hadrosaur herbivore named after the Greek word for “brave lizard.”

It lived on Africa’s terrestrial plains during the Cretaceous. Its fossils have been discovered in places like Tataouine (Tunisia), Niger, and North Kordofan State (Sudan), and it lived between the Aptian and 66 million years ago. Large vast grasslands and woods, especially near Africa, would be typical Ouranosaurus zones.

Ouranosaurus was a huge dinosaur with a length of 23-27 feet (7-8 metres), a height of 18 feet (5.5 metres), and a weight of 5 tonnes (4470.6 kg). The fastest known Ouranosaurus speed was roughly 25mph (40.2 kph).

Rows of spines protruding out vertically from this plant-backbone eater have sparked the hypothesis that it may have had a skin sail. However, other palaeontologists believe Ouranosaurus had a flattened hump, similar to that of a camel, rather than a sail. This dinosaur’s back was characterized by a tall, slender, fin-like crest. This fin is considered to have emitted excess body heat during the day and absorbed heat at night. This sail may have also helped them keep afloat while swimming deep down in rivers or lakes. The fossilized bone had been struck by at least one sharp bullet-like item, implying some sort of hunting behaviour or combat between rival groups.

The Ouranosaurus’ weak point was its weak leg bones, which caused some difficulty in their daily activities. 

Researchers have determined that the Ouranosaurus skeleton had roughly 380 bones after conducting comprehensive research on the fossils discovered. Spines, skulls, hand bones, hump sail bones, backbone, and two feet bones, and many different shaped teeth were among the bones discovered.

It possessed a strong body and a short neck with huge eyes and wide nostrils, as well as low neural spines. This characteristic of Ouranosaurus distinguished it from several other species. As previously discussed above, Ouranosaurus also had a low sail on its back hump, as well as several spines. It is believed that it had strong pointed teeth in its skull for breaking food.

The two feet were additionally pointed to facilitate digging in its surroundings. Each hand had a close distinctive thumb on each hand. 

Ouranosaurus had excellent hearing, which could have helped it communicate with other Ouranosaurus or stay one step ahead of predators such as theropods. In addition to its large hearing organs, this dinosaur had three fenestrae pores in its jawbone that would have made communication simpler. It’s also be hypnotised that the back sail, as well as the teeth, beak, and snout, could have been utilised to communicate with other Ouranosaurus. 

Ouranosaurus were unusual in many respects, including their mating method, which involved male Ouranosaurus courting females until she ultimately accepted his advances.

Female Ouranosaurus would lay eggs in a nest. Female Ouranosaurus were nearly identical to males, but their bones were much more delicate. One reason for this could have been that the males fought each other in the mating season.

According to scientists, this animal may have a lifespan of 50 years or so. An Ouranosaurus was a herbivorous dinosaur that ate mostly plants. It preferred the grasslands because it could graze on the luxuriant plants without fear of predators. 



PaleoNeolitic, CC BY 4.0, via Wikimedia Commons

Type: Small theropod
Lived: Late Cretaceous, 85 – 75 million years ago
Weight: 33 – 40kg / 73 – 88Ibs
Length 1.6m / 5.2ft
Diet: Omnivorous

Oviraptor (OH-vee-RAP-tor) was a small, bird-like dinosaur who lived in the late Campanian stage during the late Cretaceous period, about 88 – 70 million years ago in the deserts of Mongolia, China.

Oviraptor measured 6 – 8 feet (1.8 – 2.5 metres) in length, 2.6 feet (0.8 metres) in height and weighed around 25 – 35 kilograms (55 – 76 pounds). It was a lightly built, bipedal dinosaur that had long legs and was fast moving. Oviraptor had a curved, ‘s’ shaped neck and a strange parrot-like head. It had a toothless beak and powerful jaws built for crushing prey.

Oviraptor had powerful hind legs with 3 clawed toes on each foot and strong short forearms with 3 clawed fingers on each hand. The fingers were long and grasping and the claws measured 3 inches (8 centimetres) in length. A small, stumpy horn-like crest sat on its snout and was probably used for mating displays. The crest could differ between Oviraptor species and for males, females and juveniles.

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Last Updated on 15/07/2022 by