When did the allosaurus live?
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Allosaurus
Allosaurus, (genus Allosaurus), subsumes Antrodemus, large carnivorous dinosaurs that lived from 150 million to 144 million years ago during the Late Jurassic Period; they are best known from fossils found in the western United States, particularly from the Cleveland-Lloyd Quarry in Utah and the Garden Park Quarry in Colorado.
Allosaurus weighed two tons and grew to 10.5 metres (35 feet) in length, although fossils indicate that some individuals could have reached 12 metres. Half the body length consisted of a well-developed tail, and Allosaurus, like all theropod dinosaurs, was a biped. It had very strong hind limbs and a massive pelvis with strongly forward- (anteriorly) and rearward- (posteriorly) directed projections. The forelimbs were considerably smaller than the hind limbs but not as small as those of tyrannosaurs. The forelimbs had three fingers ending in sharp claws and were probably used for grasping.
The allosaur skull is distinguished by a large roughened ridge just in front of the eye. The skull was large and had sizable laterally compressed teeth, which were sharp and recurved. Allosaurus likely preyed upon ornithischian dinosaurs, small sauropod dinosaurs, and anything else that it could trap and kill. It is possible that Allosaurus was also a scavenger, feeding upon carcasses of dead or dying animals.
The name Allosaurus subsumes Antrodemus, which was named earlier but was based only on an undiagnostic tail vertebra. Descendants of Allosaurus lived from 144 million to 135 million years ago, during the Early Cretaceous Period, and are known from fossils found in North America, Africa, and Australia.
Species
Six species of Allosaurus have been named: A. amplus, A. atrox, A. europaeus, the type species A. fragilis, A. jimmadseni and A. lucasi. Among these, Daniel Chure and Mark Loewen in 2020 only recognized the species A. fragilis, A. europaeus, and the newly-named A. jimmadseni as being valid species.
A. fragilis is the type species and was named by Marsh in 1877. It is known from the remains of at least 60 individuals, all found in the Kimmeridgian–Tithonian Upper Jurassic-age Morrison Formation of the United States, spread across the states of Colorado, Montana, New Mexico, Oklahoma, South Dakota, Utah, and Wyoming. Details of the humerus (upper arm) of A. fragilis have been used as diagnostic among Morrison theropods, but A. jimmadseni indicates that this is no longer the case at the species level.
A. jimmadseni has been scientifically described based on two nearly complete skeletons. The first specimen to wear the identification was unearthed in Dinosaur National Monument in northeastern Utah, with the original “Big Al” individual subsequently recognized as belonging to the same species. This species differs from A. fragilis in several anatomical details, including a jugal or cheekbone with a straight lower margin. Fossils are confined to the Salt Wash Member of the Morrison Formation, with A. fragilis only found in the higher Brushy Basin Member.
A. fragilis, A. jimmadseni, A. amplus, and A. lucasi are all known from remains discovered in the Kimmeridgian–Tithonian Upper Jurassic-age Morrison Formation of the United States, spread across the states of Colorado, Montana, New Mexico, Oklahoma, South Dakota, Utah and Wyoming. A. fragilis is regarded as the most common, known from the remains of at least 60 individuals.
For a while in the late 1980s and early 1990s, it was common to recognize A. fragilis as the short-snouted species, with the long-snouted taxon being A. atrox; however, subsequent analysis of specimens from the Cleveland-Lloyd Dinosaur Quarry, Como Bluff, and Dry Mesa Quarry showed that the differences seen in the Morrison Formation material could be attributed to individual variation.
A study of skull elements from the Cleveland-Lloyd site found wide variation between individuals, calling into question previous species-level distinctions based on such features as the shape of the lacrimal horns, and the proposed differentiation of A. jimmadseni based on the shape of the jugal. A. europaeus was found in the Kimmeridgian-age Porto Novo Member of the Lourinhã Formation, but may be the same as A. fragilis.
Allosaurus material from Portugal was first reported in 1999 on the basis of MHNUL/AND.001, a partial skeleton including a quadrate, vertebrae, ribs, gastralia, chevrons, part of the hips, and hindlimbs. This specimen was assigned to A. fragilis, but the subsequent discovery of a partial skull and neck (ML 415) near Lourinhã, in the Kimmeridgian-age Porto Novo Member of the Lourinhã Formation, spurred the naming of the new species A. europaeus by Octávio Mateus and colleagues. The species appeared earlier in the Jurassic than A. fragilis and differs from other species of Allosaurus in cranial details. However, more material may show it to be A. fragilis, as originally described.
The issue of species and potential synonyms is complicated by the type specimen of Allosaurus fragilis (catalog number YPM 1930); being extremely fragmentary, consisting of a few incomplete vertebrae, limb bone fragments, rib fragments, and a tooth. Because of this, several scientists have interpreted the type specimen as potentially dubious, and thus the genus Allosaurus itself or at least the species A. fragilis would be a nomen dubium (“dubious name”, based on a specimen too incomplete to compare to other specimens or to classify). To address this situation, Gregory S. Paul and Kenneth Carpenter (2010) submitted a petition to the ICZN to have the name “A. fragilis” officially transferred to the more complete specimen USNM4734 (as a neotype).
How long did allosaurus live?
Normally, an average meat eating allosaurus would live for up to 90 – 100 years, just like a normal human.
Fossil finds
The first Allosaurus was discovered in 1877 in Colorado and named by Othniel Charles Marsh. This specimen offered just a few fragments of the dinosaur. Marsh went on to name other, seemingly unique dinosaur specimens, which, with time, were discovered to also be Allosaurus fossils, causing quite a bit of confusion in the early documentation of this dinosaur.
A more complete Allosaurus skeleton was discovered in 1879 by H.F. Hubbell; but was left unpacked at the time. In 1903, after Hubbell’s death, the specimen was finally examined and turned out to be one of the most complete theropod skeletons unearthed to date.
In 1991, a joint team consisting of researchers from the Museum of the Rockies and the University of Wyoming Geological Museum found an Allosaurus fossil near Shell, Wyo. that was 95 percent intact — they dubbed it “Big Al” nd in 1996, the same team discovered “Big Al Two,” the best-preserved Allosaurus skeleton to date.
Interesting Facts About the Allosaurus
You might have heard of these large predators, as they were quite imposing animals in their time. However, these fun facts might just surprise you! Read on to learn more about these massive predators.
- All the Allosaurs – Did you know there are four known species of of this particular dino? That’s just the species that we know about! Who knows what other fossilized dinos are waiting for our discovery? The four known species are: Allosaurus fragilis, Allosaurus europaeus, Allosaurus amplus, and Allosaurus lucasi.
- Big Prey – We have plenty of evidence suggesting that they preyed on other large dinosaurs, particularly Stegosaurus. Some specimens researchers found had puncture wounds matching those of a Stegosaurus tail spike. Conversely, some Stegosaurs had wounds matching the bite of Allosaurus.
- Small Bite – Though their mouths were large, these dinosaurs had relatively small teeth. Allosaurs had small teeth and a relatively low bite force compared to other predators its size. Instead of stabbing with long teeth, it used its jaws almost like saws to inflict slashes.
- Toothy Trouble – These dinosaurs didn’t get away from slashing at prey without losing a few teeth. In fact, they lost and regrow teeth incredibly frequently. There are so many fossilized Allosaur teeth that you can purchase one for only a few hundred dollars!
Habitat of the Allosaurus
These top predators roamed a number of different habitats. Overall, their environment was semiarid, and had wet seasons and dry seasons. Some of the ecosystems that these dinosaurs may have inhabited included floodplains, conifer forests, savannas, gallery forests of large ferns, and more.
It is likely that these creatures lived mostly in open floodplains, and occasionally entered more forested areas, simply because they are so large that forests would have been more inaccessible.
Did Allosaurus Live With Long Neck Dinosaurs?
Ever wonder what the world was like when Allosaurus roamed? Allosaurus is often regarded as the most famous predator from the Jurassic period. Although it has been speculated that the Allosaurus was a scavenger, the majority of paleontologists in this day agree that the dinosaur could hunt down dinosaurs even larger than itself. It makes me wonder, did Allosaurus live with long-necked dinosaurs?
The Allosaurus existed 163 million years ago – 89 million years ago during the Late Jurassic period; and it is famous for being an apex predator during that time.
It is often referred to as the “different lizard” because of its unusual vertebrae and agile body structure, smaller than other carnivorous theropods.
When researching about sauropods that lived in similar geographical areas as the Allosaurus, it became apparent that some sauropod fossils were even found relatively close to the same fossil excavations as the Allosaurus, for instance, in the Morrison formation in North America.
What Long Neck Dinosaurs Lived Where Allosaurus Lived?
It seems that Jurassic dinosaur demographics were alike across North America, Europe, and Africa. For example, you’ll find a balanced ratio of Allosaurus to sauropods across the:
- Morrison Formation (North America)
- Lourinha Formation (Portugal, Europe)
- Tendaguru archeological site (Tanzania, Africa)
The long-necked dinosaurs that lived where Allosaurus lived included:
- Diplodocus – It was one of the biggest dinosaurs during the Late Jurassic. It roamed North America, eating plants and growing up to a length of 175 feet.
- Camarasaurus -This herbivore was one of the smaller sauropods, stretching about 60 feet in length. It made an easier target for Allosaurus compared to adult Diplodocus.
- Apatosaurus: The tail whip of this enormous dinosaur could break the limbs of Allosaurus. This North American long-neck herbivore could grow up to a length of 75 feet.
Long-necked dinosaurs were spread all over the planet and the earliest species from the Early Jurassic period.
They went extinct after hell-fire meteor showers violently ended the Late Cretaceous period.
Herbivorous dinosaurs had puny brains relative to their body mass. Sauropods were long-necked plant-eaters. They also had thick legs to support their massive size.
They could bring down robust tree clusters and swallow treetops without chewing.
The teeth of sauropods were sharp and strong to clear plant matter. The chisel shape was not appropriate for chewing, but it had an elaborate digestion process to break down the vegetation.
