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Description

Allosaurus fragilis
Dinosaurs during the Jurassic have no shortage of iconic animals, from Brachiosaurus to Stegosaurus to the first dinosaur, Megalosaurus. This was the era when dinosaurs came into their own. However, no other Jurassic dinosaurs are more iconic than Allosaurus. Specifically, the species in this profile: Allosaurus fragilis.
History and Discovery:
In 1869, fossils discovered by Ferdinand Hayden found what appeared to be "petrified horse hooves." When he sent the remains to Joseph Leidy, he identified it as a fragment of tail vertebrae. Specifically to dinosaur tail vertebrae.
He assigned it to Poekilopleuron a genus of a theropod from Europe. Later on, he thought this would deserve its own genus, Antrodemus.
Othniel Charles Marsh, one of the foremost paleontologists of Yale, sent material in 1876 consisting of a fairly decently preserved remains of a theropod dinosaur. Consisting of:
-teeth
-3 vertebra
-A toe bone
-A rib fragment
When examining the vertebrae, he settled on a name. He dubbed it Allosaurus fragilis. It was derived from the Greek "Allos," meaning strange/different, and "sauros," meaning lizard, for reptile. "Fragilis" is a Latinized word for fragile, given the state of the fossils.
He dubbed its generic name mainly because it looked different to other theropod dinosaurs.
During the Bone Wars with Marsh's rival, ED Cope, they named multiple dinosaurs from various finds, but many of them are dubious. Marsh described Labrosaurus and Creosaurus, and cope described a massive carnosaur Epantarias.
Many of those are believed to be those of Allosaurus or maybe Saurophaganax.
In 1920, paleontologist Charles W. Gilmore found Antrodemus and Allosaurus remains indistinguishable; this should be the primary name for the animal.
It was accepted for nearly 50 years until James Henry Madsen examined the fossils and found that since the fossils of Antrodemus are very fragmentary, had poor distinguishing features. Above all, the locality where it was unearthed could not be located.
Thus, Allosaurus was deemed valid as a species and Antrodemus was deemed a nomen nudum; a naked name as is the case with most, if not all species attributed to Allosaurus. Except one, which will be elaborated upon in the next section.
Taxonomy:
Allosaurus is the type species for the Allosauridae family and the broader superfamily Allosauroidea. Commonly referred to as "carnosaurs." While the term "carnosaur" has primarily been used in the past to describe every large-bodied carnivorous dinosaur, and some paleontologists even disregard the term altogether, some use it to describe any non-coelurosaurian dinosaur such as Allosaurus, Carcharodontosaurus, Megalosaurus or Spinosaurus.
The superfamily Allosauroidea today includes various families such as Metriacanthosaurids and Carcharodontosaurids. The latter include Giganotosaurines and Neovenatorids.
Allosaurus is a more derived member of Allosauroids compared to animals like Metriacanthosaurs; however, it is also the sister lineage of Carcharodontosaurs.
It should be noted there are three Allosaurus species found across the planet.
-Allosaurus europeaus: As the specific name implies, this animal is found in Europe, namely Portugal. This was a slightly smaller animal. However, it still would have been an apex predator from the region.
-Allosaurus jimmadseni. This dinosaur may have overlapped a little with A. fragilis, but most paleontologists think it lived in the earlier region of the Morrison called the Salty Wash member of the Morrison, whereas A. fragilis is found in the Brushy Basin and later. Compared to A. fragilis, A. jimmadseni had a narrower, less boxy skull, a straight jugal (jaw) bone, and less developed crests. In terms of size, these dinosaurs were relatively comparable in size.
It should be noted that some believe Allosaurus to be the only genus within Allosauridae.
However, there is one questionable exception would be Saurophaganax maximus. This massive 5-6 ton Allosaur would have been the largest apex predator in the region. Today, some paleontologists classify it as a distinct genus, others a species of Allosaurus, or just a large A.fragilis.
The distinction keeping it this would be the shape of the vertebra. With various growth stages of different specimens examined, there is no evidence that Allosaurus changed its vertebral structure as it aged.
Description:
Allosaurus fragilis is a theropod dinosaur. It was one of the largest predators in the Jurassic at the time. Roughly 25-29ft long, 6.8-7.5ft tall, and 2.2-3 tons in weight. Not in the same league as dinosaurs like Giganotosaurus or the legendary Tyrannosaurus, they were the most successful apex predators in the region.
A skull is approximately 3ft long, solidly built, and equipped with dagger-like teeth with serrations front and back. The skull was long and narrow and lacked more overall binocular vision having just 20 degrees of overlap, less than today's crocodilians. Most striking were the crests on its head. These were likely just the bony cores and with a lot of pitting, it's suggested that these dinosaurs may have had keratinous sheaths over them and may have been colorfully designed to attract mates or intimidate rivals.
The neck was long compared to other dinosaurs. Being about as long as the ribcage and is designed to support the head atop the skull and support powerful neck muscles atop the head and neck. The torso itself was broad, characteristic of most allosaur theropods.
The forelimbs were heavily muscled, equipped with three-fingered hands and intimidating talons designed to grapple with prey.
The hindlimbs were similar to most theropods at the time. Three-toed with a dewclaw on the foot and more hoof-like nails compared to other dinosaurs. However, they lacked the arctometatarsal seen in Tyrannosaurs, Ornithomimids, or Troodontids. Indicating they were not pursuit predators but ambush specialists. However, juvenile Allosaurus specimens have been found, and they had longer legs than adults proportionally. This suggests that Allosaurus juveniles were geared towards more swift and spry prey and as they got older, shifted their niche to become
A long, powerful tail counterbalanced the front and anchored the hip muscles designed to help propel it forward. Interestingly, the number of the tail vertebra is unknown, with estimates ranging from 45 to 50 bones in the tail.
A brain endocast was made of the dinosaur and it was found that this dinosaur was more in line with crocodilians as opposed to birds, furthermore, the animal held its head nearly vertically.
In terms of integument, there are patches of skin impressions found on Allosaurus. Most of them are scales that resemble the reticula of bird feet. The scales measure 1-2mm in diameter. Integument such as feathers is unknown, with only Concavenator, a more derived relative having circumstantial evidence of having them.
With so few remains of Allosaurus and the fact that these animals diverged from the coelurosaurs and more derived members of dinosaurs, including birds, some 174-178,000,000 years ago, it's possible that this animal could have lost its feathers and been completely scaley. On the other hand, it could have been possible that this dinosaur also possessed feathers. Without better impressions, this is a question open to interpretation.
Habitat:
Allosaurus lived in North America and resided in the Morrison Formation from around 155-145,000,000 years ago. The environment it lived in was savannah-like, but no grass existed at the time. Only horsetail and ferns populated the prairies of the Morrison. There were pronounced wet and dry seasons, ranging from lush floodplains to arid semi-desert environments. Tall conifer trees like Monkey Puzzle and Sequoia trees surrounded these prairies. Taphonomic studies suggest that these dinosaurs lived in drier settings than other animals.
Among the most iconic dinosaurs it lived alongside, Stegosaurus dwelled here. Furthermore, it lived alongside many sauropod dinosaurs like Apatosaurus, Brontosaurus, and Diplodocus. Smaller ornithopods, like Camptosaurus, Dryosaurus, and Nanosaurus, lived in the environment.
Alongside Allosaurus, predators like the horned predator Ceratosaurus have been found here along with smaller dinosaurs. Among the most unique was the basal tyrannosaur Stokesosaurus. While small, its kin would eventually take the spot of top predator during the Cretaceous, but for now, they were small predators. Furthermore, a recently discovered small troodontid called Hesperornithoides existed in this region. Alongside this apex predator, Torvosaurus, a slightly larger carnivorous dinosaur, dwelt alongside Allosaurus.
Dozens upon dozens of specimens of Allosaurus have been described in the Morrison Formation. Alongside a handful of skeletons that are decently complete. It should be noted that Allosaurus was the most common apex predator in the region.
Diet, Feeding, and Predatory Behavior:
Allosaurus was undoubtedly the apex predator in the region. With this predation came both evidence of hunts and injuries. A paper published in 2005 described two separate discoveries detailing a plate from a Stegosaurus with a bite mark taken out of it. This mark fits the snout of an Allosaurus perfectly. Even more intriguing is a vertebra from an Allosaurus detailing an impact wound from a thagomizer. Which amazingly healed from the injury and developed an abscess of scar tissue.
Another find, being the holotype of "Labrosaurus ferox" (now attributed to A. fragilis), shows that this dinosaur had a severely broken jaw likely attributable to a whip tail from a diplodocid sauropod. Although, the severity was far less than was established in the show. As is the case with the vertebra, this individual would survive. A basis for this finding would be utilized for Dinosaur Revolution.
Moreover, there is evidence of Allosaurus feeding on Sauropod dinosaurs. Scraping bite marks found on various sauropod bones and teeth found in association show some proof of this.
Whether these carnivores hunted down these animals or just scavenged their remains cannot be known. They could have just brought down juvenile individuals of sauropods. They were far more plentiful than the adults and presented less risk in bringing down their quarry.
A fanciful theory. The bite force of an Allosaurus was less powerful than that of a lion. Noting the weakness in its bite, paleontologists such as Robert T. Bakker proposed these dinosaurs had a skull built like a Samoan War club. This animal would either rip flesh violently from prey or use its jaw like a hatchet. The latter theory was picked up by British paleontologist Emily Rayfield in 2001, who proposed this dinosaur used its strong neck muscles to drive its top jaw into its prey. However, many paleontologists argued against this, given that it could have dislocated its jaw or shed excess teeth in an unsustainable manner.
Dr. Thomas Holtz and his colleagues suggested in 2004 that this animal may have been a "flesh grazer," biting from sauropods' flanks or fleshy parts of the prey and fed upon the parts of the prey that way. This was expanded upon and demonstrated by Paleoartist Mauricio Anton, who posited a similar theory a year earlier with its strong muscles in its neck, it could have pulled flesh more effectively from prey.
A 2013 study by Eric Snively found that Allosaurus would have fed like a kestrel or other birds of prey. Gripping the prey with its arms or, more importantly, its feet and then pulling back chunks of flesh. Many paleontologists now think this is how it fed. Furthermore, many infections have been seen on Allosaurus, especially in the feet. With stress marks and fractures being common there, the fact they were using them as a feeding device makes sense.
Social Behavior:
Robert Bakker first posited grouping behavior. For years, many documentaries such as Walking With Dinosaurs depicted Allosaurus as "a lion of the Jurassic," which, like a lion, hunted in prides. Finds of Allosaurus together had Bakker posit that this was a den site where adults would bring meat back to their young. Moreover, he theorized that Allosaurus could recover from such injuries because it had other members of the pack backing it up as it healed.
It makes sense in some aspects. Many sauropods were massive animals, and hunting in packs could have lessened the risk and even enabled them to bring down an adult sauropod dinosaur.
However, a study published in 2007 by Dan Brinkman and Brian Roach found that theropod dinosaurs such as Allosaurus and even Deinonychus, the iconic pack-hunting raptor indicates that these animals were more likely to have been solitary hunters that occasionally could have formed some close association with one another. In this study, Brinkman and Roach pointed out that modern diapsid carnivores like Eagles, Crocodilians, and varanid lizards don't cooperate to bring down prey and are often very hostile to each other when feeding.
Only the Harris Hawk has demonstrated some cooperation, but this was an exception, not the rule. The authors did note there could have been some predation in the form of mob hunting. This is seen with animals like Crocodiles in Africa gaining up on Zebra Wildebeest or Komodo Dragons hunting Water Buffalo. Often during these encounters, they snap at each other and be very hostile towards each other while feeding.
Conversely, a fossil find of Camarasaurus shows evidence of Allosaurus teeth shed at various ages. Could this be evidence of a kill brought down by a pack or a mob? Impossible to know.
Without going back in time and observing them, we may never know what their social life was like.
Why did so many theropods here get to great size?:
Allosaurus, Torvosaurus, Ceratosaurus, and potentially Saurophaganax were large predators in the Morrison Formation. Many who specialized in this region have asked, "how did 3-4 genera of large theropods evolve in this region and attain large sizes?"
Studies in this region indicate there were two eco-regions. Some had lush environments with conifer forests, and the other had scrubby floodplain environments from season to season. Paleontologists have speculated that a form of niche partitioning was at play, with animals like Ceratosaurus and Torvosaurus inhabiting more forested and underbrush environments where Allosaurus and its kin probably stuck to the outskirts and predated on the floodplains hunting larger prey.
With Torvosaurus being a woodland animal and inhabiting a different environment, it would have been able to achieve larger sizes as selection pressures put on it enabled it to target larger prey in its environment.
However, they still came into contact with their competition for all its partitioning. Fossils of Allosaurus in the Mygatt-Moore quarry in Colorado indicate bite marks on Allosaurus bones left by a large carnivore. This could have been from a Saurophaganax or Torvosaurus. In hard times like the dry season or food scarcity, carnivores will eat just about anything, and they did just that here, right down to the bone.
Extinction:
Allosaurus would vanish by the end of the Jurassic. The extinction of this theropod is likely down to climate change. Despite these dinosaurs dying off, their successors, the Carcharodontosaurs, would thrive well into the mid-Cretaceous.
Although it's extinct, this dinosaur still lives on in the countless fossil specimens and mounts plastered across the globe. Allosaurus was immortalized in museum halls and on the big screen. Its appearance in Walking With Dinosaurs gave it an iconic color scheme still recognizable today. Moreover, its recent appearance in Jurassic World made it even more well-known.
___________________________________________________________________________________________
Happy New Year’s Eve! Or New Years, because it’s 9:30PM (CST) at night as I finish writing this. I decided to re-do my profile of the most iconic dinosaur.
Here, we have a female resting and a male inspecting his mate. I decided to lean into the more social aspect of Allosaurus that is theorized, and have a more pleasant pose rather than it killing a dinosaur.
I remodeled my old Allosaurus model with a better skull shape, better claw shape to be more consistent with other dinosaurs in the series, and also revamped the juveniles.
Anyways, hope you all have a happy new year and may you all excel and stay swell!
Original model by DinosaurManZT2 :
WWD Allosaurus / Big Al by DinosaurManZT2 on DeviantArt
Base model that I modified:
Allosaurus (HENDRIX) | ZT2 Download Library Wiki | Fandom

For Past Meets Present:
Past Meets Present (Pt4 is Up) - The ZT2 Round Table
I remodeled my old Allosaurus model with a better skull shape, better claw shape to be more consistent with other dinosaurs in the series, and also revamped the juveniles.
Anyways, hope you all have a happy new year and may you all excel and stay swell!
Original model by DinosaurManZT2 :
WWD Allosaurus / Big Al by DinosaurManZT2 on DeviantArt
Base model that I modified:
Allosaurus (HENDRIX) | ZT2 Download Library Wiki | Fandom

For Past Meets Present:
Past Meets Present (Pt4 is Up) - The ZT2 Round Table

Description

Allosaurus fragilis
Dinosaurs during the Jurassic have no shortage of iconic animals, from Brachiosaurus to Stegosaurus to the first dinosaur, Megalosaurus. This was the era when dinosaurs came into their own. However, no other Jurassic dinosaurs are more iconic than Allosaurus. Specifically, the species in this profile: Allosaurus fragilis.
History and Discovery:
In 1869, fossils discovered by Ferdinand Hayden found what appeared to be "petrified horse hooves." When he sent the remains to Joseph Leidy, he identified it as a fragment of tail vertebrae. Specifically to dinosaur tail vertebrae.
He assigned it to Poekilopleuron a genus of a theropod from Europe. Later on, he thought this would deserve its own genus, Antrodemus.
Othniel Charles Marsh, one of the foremost paleontologists of Yale, sent material in 1876 consisting of a fairly decently preserved remains of a theropod dinosaur. Consisting of:
-teeth
-3 vertebra
-A toe bone
-A rib fragment
When examining the vertebrae, he settled on a name. He dubbed it Allosaurus fragilis. It was derived from the Greek "Allos," meaning strange/different, and "sauros," meaning lizard, for reptile. "Fragilis" is a Latinized word for fragile, given the state of the fossils.
He dubbed its generic name mainly because it looked different to other theropod dinosaurs.
During the Bone Wars with Marsh's rival, ED Cope, they named multiple dinosaurs from various finds, but many of them are dubious. Marsh described Labrosaurus and Creosaurus, and cope described a massive carnosaur Epantarias.
Many of those are believed to be those of Allosaurus or maybe Saurophaganax.
In 1920, paleontologist Charles W. Gilmore found Antrodemus and Allosaurus remains indistinguishable; this should be the primary name for the animal.
It was accepted for nearly 50 years until James Henry Madsen examined the fossils and found that since the fossils of Antrodemus are very fragmentary, had poor distinguishing features. Above all, the locality where it was unearthed could not be located.
Thus, Allosaurus was deemed valid as a species and Antrodemus was deemed a nomen nudum; a naked name as is the case with most, if not all species attributed to Allosaurus. Except one, which will be elaborated upon in the next section.
Taxonomy:
Allosaurus is the type species for the Allosauridae family and the broader superfamily Allosauroidea. Commonly referred to as "carnosaurs." While the term "carnosaur" has primarily been used in the past to describe every large-bodied carnivorous dinosaur, and some paleontologists even disregard the term altogether, some use it to describe any non-coelurosaurian dinosaur such as Allosaurus, Carcharodontosaurus, Megalosaurus or Spinosaurus.
The superfamily Allosauroidea today includes various families such as Metriacanthosaurids and Carcharodontosaurids. The latter include Giganotosaurines and Neovenatorids.
Allosaurus is a more derived member of Allosauroids compared to animals like Metriacanthosaurs; however, it is also the sister lineage of Carcharodontosaurs.
It should be noted there are three Allosaurus species found across the planet.
-Allosaurus europeaus: As the specific name implies, this animal is found in Europe, namely Portugal. This was a slightly smaller animal. However, it still would have been an apex predator from the region.
-Allosaurus jimmadseni. This dinosaur may have overlapped a little with A. fragilis, but most paleontologists think it lived in the earlier region of the Morrison called the Salty Wash member of the Morrison, whereas A. fragilis is found in the Brushy Basin and later. Compared to A. fragilis, A. jimmadseni had a narrower, less boxy skull, a straight jugal (jaw) bone, and less developed crests. In terms of size, these dinosaurs were relatively comparable in size.
It should be noted that some believe Allosaurus to be the only genus within Allosauridae.
However, there is one questionable exception would be Saurophaganax maximus. This massive 5-6 ton Allosaur would have been the largest apex predator in the region. Today, some paleontologists classify it as a distinct genus, others a species of Allosaurus, or just a large A.fragilis.
The distinction keeping it this would be the shape of the vertebra. With various growth stages of different specimens examined, there is no evidence that Allosaurus changed its vertebral structure as it aged.
Description:
Allosaurus fragilis is a theropod dinosaur. It was one of the largest predators in the Jurassic at the time. Roughly 25-29ft long, 6.8-7.5ft tall, and 2.2-3 tons in weight. Not in the same league as dinosaurs like Giganotosaurus or the legendary Tyrannosaurus, they were the most successful apex predators in the region.
A skull is approximately 3ft long, solidly built, and equipped with dagger-like teeth with serrations front and back. The skull was long and narrow and lacked more overall binocular vision having just 20 degrees of overlap, less than today's crocodilians. Most striking were the crests on its head. These were likely just the bony cores and with a lot of pitting, it's suggested that these dinosaurs may have had keratinous sheaths over them and may have been colorfully designed to attract mates or intimidate rivals.
The neck was long compared to other dinosaurs. Being about as long as the ribcage and is designed to support the head atop the skull and support powerful neck muscles atop the head and neck. The torso itself was broad, characteristic of most allosaur theropods.
The forelimbs were heavily muscled, equipped with three-fingered hands and intimidating talons designed to grapple with prey.
The hindlimbs were similar to most theropods at the time. Three-toed with a dewclaw on the foot and more hoof-like nails compared to other dinosaurs. However, they lacked the arctometatarsal seen in Tyrannosaurs, Ornithomimids, or Troodontids. Indicating they were not pursuit predators but ambush specialists. However, juvenile Allosaurus specimens have been found, and they had longer legs than adults proportionally. This suggests that Allosaurus juveniles were geared towards more swift and spry prey and as they got older, shifted their niche to become
A long, powerful tail counterbalanced the front and anchored the hip muscles designed to help propel it forward. Interestingly, the number of the tail vertebra is unknown, with estimates ranging from 45 to 50 bones in the tail.
A brain endocast was made of the dinosaur and it was found that this dinosaur was more in line with crocodilians as opposed to birds, furthermore, the animal held its head nearly vertically.
In terms of integument, there are patches of skin impressions found on Allosaurus. Most of them are scales that resemble the reticula of bird feet. The scales measure 1-2mm in diameter. Integument such as feathers is unknown, with only Concavenator, a more derived relative having circumstantial evidence of having them.
With so few remains of Allosaurus and the fact that these animals diverged from the coelurosaurs and more derived members of dinosaurs, including birds, some 174-178,000,000 years ago, it's possible that this animal could have lost its feathers and been completely scaley. On the other hand, it could have been possible that this dinosaur also possessed feathers. Without better impressions, this is a question open to interpretation.
Habitat:
Allosaurus lived in North America and resided in the Morrison Formation from around 155-145,000,000 years ago. The environment it lived in was savannah-like, but no grass existed at the time. Only horsetail and ferns populated the prairies of the Morrison. There were pronounced wet and dry seasons, ranging from lush floodplains to arid semi-desert environments. Tall conifer trees like Monkey Puzzle and Sequoia trees surrounded these prairies. Taphonomic studies suggest that these dinosaurs lived in drier settings than other animals.
Among the most iconic dinosaurs it lived alongside, Stegosaurus dwelled here. Furthermore, it lived alongside many sauropod dinosaurs like Apatosaurus, Brontosaurus, and Diplodocus. Smaller ornithopods, like Camptosaurus, Dryosaurus, and Nanosaurus, lived in the environment.
Alongside Allosaurus, predators like the horned predator Ceratosaurus have been found here along with smaller dinosaurs. Among the most unique was the basal tyrannosaur Stokesosaurus. While small, its kin would eventually take the spot of top predator during the Cretaceous, but for now, they were small predators. Furthermore, a recently discovered small troodontid called Hesperornithoides existed in this region. Alongside this apex predator, Torvosaurus, a slightly larger carnivorous dinosaur, dwelt alongside Allosaurus.
Dozens upon dozens of specimens of Allosaurus have been described in the Morrison Formation. Alongside a handful of skeletons that are decently complete. It should be noted that Allosaurus was the most common apex predator in the region.
Diet, Feeding, and Predatory Behavior:
Allosaurus was undoubtedly the apex predator in the region. With this predation came both evidence of hunts and injuries. A paper published in 2005 described two separate discoveries detailing a plate from a Stegosaurus with a bite mark taken out of it. This mark fits the snout of an Allosaurus perfectly. Even more intriguing is a vertebra from an Allosaurus detailing an impact wound from a thagomizer. Which amazingly healed from the injury and developed an abscess of scar tissue.
Another find, being the holotype of "Labrosaurus ferox" (now attributed to A. fragilis), shows that this dinosaur had a severely broken jaw likely attributable to a whip tail from a diplodocid sauropod. Although, the severity was far less than was established in the show. As is the case with the vertebra, this individual would survive. A basis for this finding would be utilized for Dinosaur Revolution.
Moreover, there is evidence of Allosaurus feeding on Sauropod dinosaurs. Scraping bite marks found on various sauropod bones and teeth found in association show some proof of this.
Whether these carnivores hunted down these animals or just scavenged their remains cannot be known. They could have just brought down juvenile individuals of sauropods. They were far more plentiful than the adults and presented less risk in bringing down their quarry.
A fanciful theory. The bite force of an Allosaurus was less powerful than that of a lion. Noting the weakness in its bite, paleontologists such as Robert T. Bakker proposed these dinosaurs had a skull built like a Samoan War club. This animal would either rip flesh violently from prey or use its jaw like a hatchet. The latter theory was picked up by British paleontologist Emily Rayfield in 2001, who proposed this dinosaur used its strong neck muscles to drive its top jaw into its prey. However, many paleontologists argued against this, given that it could have dislocated its jaw or shed excess teeth in an unsustainable manner.
Dr. Thomas Holtz and his colleagues suggested in 2004 that this animal may have been a "flesh grazer," biting from sauropods' flanks or fleshy parts of the prey and fed upon the parts of the prey that way. This was expanded upon and demonstrated by Paleoartist Mauricio Anton, who posited a similar theory a year earlier with its strong muscles in its neck, it could have pulled flesh more effectively from prey.
A 2013 study by Eric Snively found that Allosaurus would have fed like a kestrel or other birds of prey. Gripping the prey with its arms or, more importantly, its feet and then pulling back chunks of flesh. Many paleontologists now think this is how it fed. Furthermore, many infections have been seen on Allosaurus, especially in the feet. With stress marks and fractures being common there, the fact they were using them as a feeding device makes sense.
Social Behavior:
Robert Bakker first posited grouping behavior. For years, many documentaries such as Walking With Dinosaurs depicted Allosaurus as "a lion of the Jurassic," which, like a lion, hunted in prides. Finds of Allosaurus together had Bakker posit that this was a den site where adults would bring meat back to their young. Moreover, he theorized that Allosaurus could recover from such injuries because it had other members of the pack backing it up as it healed.
It makes sense in some aspects. Many sauropods were massive animals, and hunting in packs could have lessened the risk and even enabled them to bring down an adult sauropod dinosaur.
However, a study published in 2007 by Dan Brinkman and Brian Roach found that theropod dinosaurs such as Allosaurus and even Deinonychus, the iconic pack-hunting raptor indicates that these animals were more likely to have been solitary hunters that occasionally could have formed some close association with one another. In this study, Brinkman and Roach pointed out that modern diapsid carnivores like Eagles, Crocodilians, and varanid lizards don't cooperate to bring down prey and are often very hostile to each other when feeding.
Only the Harris Hawk has demonstrated some cooperation, but this was an exception, not the rule. The authors did note there could have been some predation in the form of mob hunting. This is seen with animals like Crocodiles in Africa gaining up on Zebra Wildebeest or Komodo Dragons hunting Water Buffalo. Often during these encounters, they snap at each other and be very hostile towards each other while feeding.
Conversely, a fossil find of Camarasaurus shows evidence of Allosaurus teeth shed at various ages. Could this be evidence of a kill brought down by a pack or a mob? Impossible to know.
Without going back in time and observing them, we may never know what their social life was like.
Why did so many theropods here get to great size?:
Allosaurus, Torvosaurus, Ceratosaurus, and potentially Saurophaganax were large predators in the Morrison Formation. Many who specialized in this region have asked, "how did 3-4 genera of large theropods evolve in this region and attain large sizes?"
Studies in this region indicate there were two eco-regions. Some had lush environments with conifer forests, and the other had scrubby floodplain environments from season to season. Paleontologists have speculated that a form of niche partitioning was at play, with animals like Ceratosaurus and Torvosaurus inhabiting more forested and underbrush environments where Allosaurus and its kin probably stuck to the outskirts and predated on the floodplains hunting larger prey.
With Torvosaurus being a woodland animal and inhabiting a different environment, it would have been able to achieve larger sizes as selection pressures put on it enabled it to target larger prey in its environment.
However, they still came into contact with their competition for all its partitioning. Fossils of Allosaurus in the Mygatt-Moore quarry in Colorado indicate bite marks on Allosaurus bones left by a large carnivore. This could have been from a Saurophaganax or Torvosaurus. In hard times like the dry season or food scarcity, carnivores will eat just about anything, and they did just that here, right down to the bone.
Extinction:
Allosaurus would vanish by the end of the Jurassic. The extinction of this theropod is likely down to climate change. Despite these dinosaurs dying off, their successors, the Carcharodontosaurs, would thrive well into the mid-Cretaceous.
Although it's extinct, this dinosaur still lives on in the countless fossil specimens and mounts plastered across the globe. Allosaurus was immortalized in museum halls and on the big screen. Its appearance in Walking With Dinosaurs gave it an iconic color scheme still recognizable today. Moreover, its recent appearance in Jurassic World made it even more well-known.
___________________________________________________________________________________________
Happy New Year’s Eve! Or New Years, because it’s 9:30PM (CST) at night as I finish writing this. I decided to re-do my profile of the most iconic dinosaur.
Here, we have a female resting and a male inspecting his mate. I decided to lean into the more social aspect of Allosaurus that is theorized, and have a more pleasant pose rather than it killing a dinosaur.
I remodeled my old Allosaurus model with a better skull shape, better claw shape to be more consistent with other dinosaurs in the series, and also revamped the juveniles.
Anyways, hope you all have a happy new year and may you all excel and stay swell!
Original model by DinosaurManZT2 :
WWD Allosaurus / Big Al by DinosaurManZT2 on DeviantArt
Base model that I modified:
Allosaurus (HENDRIX) | ZT2 Download Library Wiki | Fandom

For Past Meets Present:
Past Meets Present (Pt4 is Up) - The ZT2 Round Table
I remodeled my old Allosaurus model with a better skull shape, better claw shape to be more consistent with other dinosaurs in the series, and also revamped the juveniles.
Anyways, hope you all have a happy new year and may you all excel and stay swell!
Original model by DinosaurManZT2 :
WWD Allosaurus / Big Al by DinosaurManZT2 on DeviantArt
Base model that I modified:
Allosaurus (HENDRIX) | ZT2 Download Library Wiki | Fandom

For Past Meets Present:
Past Meets Present (Pt4 is Up) - The ZT2 Round Table