|“||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; meaning "Other Reptile") was a large carnivorous dinosaur of the Late Jurassic Period. It was also the largest predator of the Late Jurassic period predators. It was of a more primitive line of Theropods than the later Tyrannosaurs for example, and this group declined with their rise.
Allosaurus was 10-11 meters on average, 4.5 meters high, and weighing 3-5 tonnes. It's max size is 12 meters long and a max weight of 5 tonnes. One Allosaurus grew to over 13 meters long, over 5 meters tall, and weighed up to 6 tonnes, making it one of the largest known theropods. Allosaurus name means 'Strange Lizard' or 'Other Lizard'.
Nevertheless, for its day, it was top of the line in a general context, and a deadly carnivore rivaled by no other Theropods on Earth in the Late Jurassic Period, outclassing the more primitive Coelophysis. They were after all, the 'Lions of the Jurassic'. Allosaurus was also one of the most successful predators of its day.
Allosaurus was the top predator of the Late Jurassic Period from 156–145 million years ago, ruling Western North America for 11 million years. It was the biggest carnivore of its time and the King of the Jurassic. It shared its environment with other creatures like Ornitholestes, Anurognathus, Brachiosaurus, Diplodocus, Apatosaurus, Stegosaurus, Dryosaurus, and Othnielia.
As the biggest carnivorous dinosaur of its time and the first giant predatory dinosaur ever to walk North America, Allosaurus was one of the largest predatory dinosaurs that ever walked Planet Earth, on average, measuring 30–40 feet (9.14–12.3 m) long, standing 13–16 feet (3.96–4.88 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 (5.03 m) tall, measured 45 feet (13.7 m) in length, and weighed up to 6–7 tons (12,000–14,000 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 seven short years.
Running on two muscular, bird-like legs at speeds as fast as 20 miles an hour, Allosaurus preyed upon the large herbivores of the period, including large sauropods, and smaller plant eaters. The forelimbs were short but muscular, each of the three fingers tipped with a sharp curved claw up to 25cm (10 inches) long for holding prey. The powerful jaws were lined with over 70 sharp 8cm (3 inch) long teeth. 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.
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 larger prey, such as Diplodocus, an Allosaurus pack would split between a Diplodocus herd, break up the herd, and isolate the weak, sick, and injured Diplodocus.
For female Allosaurus, when they were mothers, 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.
As young Allosaurus reached their first to second year of life, they grew to measure almost three-meters and insects would no longer be on the menu. By then, they would have already been looking for dinosaurs. 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 nine meters long, yet they would be nearly, but not yet, fully grown.
When Allosaurus lived to be six years old, as a sign of age, the crests over their eyes would begin to start reddening. Sexual maturity was dependent on an Allosaurus size and at 10 meters long, young Allosaurus were well on the way to be big enough. But by that time, they were more like mature adolescents instead of full sized adults.
When Allosaurus reached at least 11 meters long, they could quickly establish their dominance over predatory dinosaurs, especially other Allosaurs. When predators get to the size of a fully grown Allosaurus, about 11-13 meters, most of those predators rarely had to bring down their own food. They just scavenged other kills.