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Rebecca...meet Allosaurus. Now these are the lions of the Jurassic. The top predators of their age.
— Allen, about Allosaurus
in Time of the Titans

Allosaurus (al-oh-saw-us; name meaning "Other Reptile") was a large carnivorous theropod dinosaur that lived originated during the Late Jurassic period in North America. It was of a more primitive line of theropods than the later Tyrannosaurs for example, and this group declined with their rise.

Allosaurus was one of the largest predatory dinosaurs of the Late Jurassic period, on average, measuring 9.2–10 meters long, 4–4.5 meters tall, and weighing 3-4 tons. Its maximum size was 11.6 meters long, max height of 4.9 meters tall, and a max weight of 5 tons. However, one specimen of Allosaurus (the largest ever discovered), grew to 13.8 meter long, 5 meters tall, and weighed up to 6 tons, making it one of the largest known theropods.

Nevertheless, for its day, it was top of the line in a general context, and a deadly carnivore rivaled by few other theropods on Earth in the Late Jurassic period, outclassing the more primitive Coelophysis. In short, the Allosaurus were strong carnivores. They were after all, the 'Lions of the Jurassic'.

Allosaurus gave its family their name, and the Allosaurs lasted for tens of millions of years, only being replaced in importance during the Cretaceous. Torvosaurus may have been a rival, one could speculate, as it was just as fearsome. Allosaurus was one of the most successful predators of its day.

FactsEdit

Era & DiscoveryEdit

Allosaurus was the apex predator of the Late Jurassic Period from 156–145 million years ago, ruling Western North America for 11 million years. Said to be the king or "lion of the Jurassic", it was the largest carnivorous dinosaur of its time. It shared its environment with other creatures like Ornitholestes, Anurognathus, Brachiosaurus, Diplodocus, Apatosaurus, Stegosaurus, Dryosaurus, and Othnielia. Allosaurus was first discovered by Othniel Charles Marsh in 1877. Allosaurus was among the largest predatory dinosaurs of the Late Jurassic and was also among the largest predators until the Tyrannosaurs appeared over 50 million years later.

Physical AttributesEdit

As the largest carnivorous dinosaur of its time and the first giant predatory dinosaur ever to walk North America, Allosaurus was a large carnivorous dinosaur, in fact one of the largest predatory dinosaurs that ever walked Planet Earth, on average, measuring 30–40 feet (9.3–12.3 m) long, standing 13–16 feet (4.2–4.9 m) tall, and weighing up to 3–5 tons (6,000–10,000 lbs). However, the largest Allosaurus ever discovered stood about 16.5 feet (5 m) tall, measured 45 feet (13.8 m) in length, and weighed up to 6.5 tons (13,000 lbs.), making it a huge carnivorous dinosaur almost as large as Tyrannosaurus rex.

Even at that large, Allosaurus were such massive predators, but they were just as fast, quick, and agile as their two little ancestors: Coelophysis and Liliensternus. Allosaurus had to eat their own weight in food every month, which is equivalent to about as much as over 40 humans. From the moment they hatch from their eggs, an individual of Allosaurus could reach their full adult size in just seven short years, give or take.

Allosaurus had a skull that measured three feet long, with a pair of blunt crests just above its eyes, in the orbital region. Allosaurus also had large, powerful jaws with long, sharp, serrated teeth that were 2–4 inches long. Movable joints and elastic ligaments in Allosaurus jaw and skull flexed to help the teeth tear and slice through the prey. The flexible jaws stretched widely to allow the creature to swallow large mouthfuls of flesh. These teeth were curved inward, shaped like a "D" to help secure its prey. 

Allosaurus had a bulky body, a massive tail and thick bones. It had a strong S-shaped neck, and had vertebrae that was different from those of other dinosaurs, hence its name. Running on two muscular, bird-like legs at speeds as fast as 20 mph, Allosaurus preyed upon the large herbivores of the period, including large sauropods, and smaller plant eaters. The forelimbs were short but muscular and had three fingered tipped hands with a sharp curved claw up to 15–25cm (6–10 inches) long for holding prey. The powerful jaws were lined with over 70 sharp 8cm (3 inch) long teeth. 

Behavior & TraitsEdit

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Allosaurus pair

Like many large predators, Allosaurus was a pack hunter, possibly lying in wait to ambush prey. It could hunt in pairs, packs of three (which was their most common number), groups, or even numbers of over half a dozen individuals. But when hunting a herd of larger prey, such as Diplodocus, the Allosaurus pack would split up in between a Diplodocus herd, literately running through and around the herd, break it up, and eventually isolate the young, old, weak, sick, and injured members of the herd.

When the hatchlings of female Allosaurus were born, smell was important to Allosaurus and from the moment the mother and hatchling Allosaurus smelled each other, they formed a bond that was crucial to the hatchlings early survival. Hatchling Allosaurus ate insects and other small animals.

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As young Allosaurus reached their first to second year of life, they grew to almost 10 feet (3 m) and, by then, would no longer be hunting insects, but hunting other, smaller herbivorous dinosaurs, such as Dryosaurus and Othnielia. Despite that, they were still small Allosaurus and they were not a match for almost all other dinosaurs on their environment, such as an overprotective female Ornitholestes.

By the time a juvenile Allosaurus was five years of age, they already reached about 30 feet (9 m) long, however they were not yet fully grown. However, even then, they would be old enough and large enough to hunt larger dinosaurs, such as Stegosaurus and even the large sauropod dinosaurs like Diplodocus.

When Allosaurus lived to be six years old, as a sign of age, the crests over their eyes would gain a darker shade of red. Sexual maturity was dependent on an Allosaurus's size and at 33 feet (10 m) long, young Allosaurus were well on their way to be big enough. But by that time, they were actually mature adolescents rather than full sized adults.

Upon Allosaurus reaching their full size, they quickly established their dominance over predatory dinosaurs, especially other Allosaurs. When gigantic predators get to the size of a fully grown Allosaurus, most of those predators rarely had to bring down their own food. They just scavenged other kills.

Journal EntryEdit

Called the "Lions of the Jurassic", Allosaurus, or "Other Reptile", was the apex predator of the Late Jurassic Era. Measuring 38 ft. in length and weighing more than 4500 kilograms, this carnivore was one of the largest predatory dinosaurs that ever walked Planet Earth.

Equipped with serrated teeth, sharp claws, and powerful arms and legs, Allosaurus was a deadly, fast, and powerful carnivore that could run at a speed of 20 mph.

Allosaurus was also a pack hunter, in which case, allowed it to bring down the heavily-armored Stegosaurus and even the large sauropod dinosaurs of its environment, whereas alone, it hunted smaller prey such as the ornithopods. When hunting a herd of sauropods, the Allosaurus pack would run in between the members of the herd, separate them, and isolate the sick, old, weak, and injured members.

Like all animals, female Allosaurus also cared for their young. From the moment their are born, the hatchling and mother smell each other and then form a bond that was important to the hatchlings survival in life. An individual Allosaurus could reach its full size in just seven years.

— Allen, in his Journal, about Allosaurus

GalleryEdit