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Description
Adasaurus mongoliensis

Dromaeosaurs, AKA “Raptors” are among the most recognizable of all dinosaurs in the modern era. Thanks to Spielberg’s cinematic masterpiece, Jurassic Park it forever banished the idea that these animals were slow and sluggish. The most iconic feature of the animals being the infamous sickle claw found on all dromaeosaurs. While most genera had large claws proportionate to the other two weight bearing unguals, one species from Cretaceous Mongolia bucks that trend. The dinosaur is called Adasaurus mongoliensis.

History and Discovery:

In 1977, Rinchen Barsbold was conducting an expedition in the Nemegt Formation of Mongolia. When he analyzed the remains he found pelvic material distinct from other theropods in the region. In 1983, he further analyzed the remains in a taxonomic redescription of animals from the Formation. One of the animals he described was a dromaeosaur consisting of a partial skull, pelvis, vertebrae, and most interestingly, a right foot, including digit 2, which had a distinctive killing claw as will be discussed.

The holotype was labeled MPC-D 100/20. Another specimen MPC-D 100/21 was slightly smaller but had a nearly complete right foot. Based on the distinctive ungual and large size of the dromaeosaur, he dubbed the dinosaur Adasaurus mongoliensis. The generic word derived from the Mongolian word: “Ada” which means “evil spirit” in Mongolian and “saurus” the Greek for lizard. The specific word means “Mongolia” in Latin. So “Evil Spirit Lizard of Mongolia”.

In 2004, Dr.Phil Currie and Dr. David J. Varricchio referred 2 more specimens to the genus; IGM 100/22 and IGM 100/23. However, it was found these were from a younger rock layer and could not be confidently attributed to Adasaurus.

Description:

Adasaurus is among the largest of all verified velociraptorines. They would have grown to about 8-11ft long, 2.5-2.9ft tall, and weighed between 75-90lbs. Although it was three times the size of its more famous cousin, the Velociraptor, the most distinctive feature of the Adasaurus would be its sickle claw on digit 2 of its hind feet.

The claw was proportionally tiny while marginally bigger than other weight-bearing toe claws. Less than an inch long compared to Velociraptors 2.5in.

However, compared to the rest of the Velociraptorines, Adasaurus was more robust. With a slightly deeper skull and a bulkier torso. Other than that, it would have had the basic Dromaeosaur body plan.

Furthermore, this dinosaur would’ve been feathered in life. With pennaceous feathers projecting from the arms as its cousin Velociraptor had quill knobs that would’ve been used to support pennaceous feathers. They could also have similar feathers on the tail as close relatives like Microraptor and Zhenyuanlong had them there. However, what shape it was in is up for debate.

Taxonomy:

Adasaurus is a member of the Velociraptorinae subfamily within Dromaeosauridae. As of 2024, they are the largest verified members of the subfamily. According to a 2021 taxonomic evaluation of the group when describing a cousin of Adasaurus, Kuru kulla. In the study by Mark Norrell et al, Adasaurus would’ve been fairly basal within the group. However, according to the study it was a sister genus to Adasaurus.

Hunting Behavior:

Back in the late 60s, when the killing claw of Acheroraptors’ distant cousin, Deinonychus, was found, it was thought the large sickle feet of this animal were used to rip open the sides of prey, slashing it across the belly, throat, and any exposed region. As a modern-day analog, Ostrom used examples of Cassowaries and Ostriches attacking humans and dogs with giant claws.

However, studies from the mid-2000s found that the claw could not cut through flesh and muscle well, given that its curved and dull sides could not slice through flesh. Furthermore, while ratites have killed people using their claws, they usually die because of trauma to their ribcage and internal bleeding, so they are not a good analogy when studying dromaeosaurs.

This has led paleontologists in recent years to look at actual raptors, the birds of prey, suggesting raptors dispatched their prey similarly to eagles and owls.

The victim dying from shock and blood loss. It suggests that raptors would ambush their prey that was smaller or approximately to their size, pin them down under their weight, and then pick at it while they were still alive. They may have also used their arms for balance, flapping their wings to keep themselves stable while on the back of their quarry.

This form of behavior has been dubbed Raptor Prey Restraint (RPR). This is believed to be how dinosaurs like Velociraptor, Dromaeosaurus, and Deinonychus killed their prey. However, the reduced sickle claw poses a question for paleontologists.

In a 2019 study by Peter Bishop, he analyzed the effectiveness of Deinonychus and the killing claw in the genera. He found RPR was indeed the likely method to dispatch prey and the forces exerted at the tip of the killing claw was where the force would be at its greatest. The effectiveness and force would’ve varied from species to species. In the study, he also looked at Adasaurus and found that while the claw had been reduced, the function of it being used as a killing weapon and whether or not it’d flex is unknown.

It's possible that Adasaurus could’ve hunted in a manner similar to modern seriemas or secretary birds. This would result in it pinning down small prey with the whole of its foot or grabbing them in the mouth and then slamming them to the ground or on a rock; killing them.

As commonly shown in media, raptors are often depicted hunting in packs.

Although shown to be equivalent to the wolves of the Cretaceous, there is no hard evidence aside from a handful of trackways of 2-toed dinosaurs attributable to dromaeosaurs moving together from the same region as Adasaurus. Even then, those could just be two individuals tolerating each other. Without observing these animals, we will unlikely ever find out what their behavior was like.

Habitat:

Adasaurus was a denizen of the Nemegt Formation in the heart of Mongolia. Adasaurus existed from about 70,000,000 years ago to the end of the dinosaurs’ reign, among the last of the velociraptorines. The Nemegt formation was a lush swamp similar to the Okavango Delta in Botswana or the Bayou of Louisiana. As well as some conifer forests with Araucaria and fern prairies dispersed throughout the environment.

It is this region where Adasaurus would’ve thrived. It would’ve functioned in the region as a predator hunting prey. Animals like the Troodontids such as Zanabazar and Borogovia. They could’ve been easy prey for Adasaurus targeting them, juveniles, or their eggs. As with the myriad of omnivorous oviraptorosaurs like Avimimus, Oksoko, Nemegtomaia, or Rinchenia just to name a few. In competition, there are a handful of dromaeosaurs from the region, including one believed to be like Velociraptor, but these have currently been undescribed. Scampering through the fern prairie would’ve been Gallimimus and Anserimimus, two ostrich-like dinosaurs.

Pachycephalosaurs like Prenocephale and Homalocephale browsed off tougher foliage and cycad in the region. These distinctive thick-headed and barrel-chested ornithischian dinosaurs could’ve also been prey for Adasaurus.

Outsizing Adasaurus would’ve been Sauropod dinosaurs like Nemegtosaurus, Opisthocoelicaudia, and an as-of-now unnamed giant sauropod estimated to be at least 70-90ft long known only from footprints. Beyond the eggs and hatchlings, hunting these sauropods would’ve been out of the question.

Hadrosaurs like Saurolophus and Barsboldia measuring 30-40ft long have been found in the Nemegt Formation. This small-clawed dromaeosaur could also have poached their eggs and juvenile dinosaurs.

Also, there would’ve been the giant-clawed Therizinosaurus. A bizarre herbivorous theropod using its massive arms to bring foliage to its maw. As would the equally giant and clawed Deinocheirus, an ornithomimid with a hadrosaur-esque skull and a sail/humped back.

Predators would’ve been the two species of Alioramus. Two lithe and small-bodied Tyrannosaurs running prey down in forests or the prairies. Finally there would’ve been the apex predator; Tarbosaurus. The Asian Equivalent to T.rex. All these tyrannosaurs would’ve been formidable hunters in the Nemegt and Adasaurus could’ve been prey for them.

Extinction:

Adasaurus, along with other Nemegt Formation residents, would die out 66,000,000 years ago when an asteroid smashed into the earth, marking the end of the non-avian dinosaurs.

While extinct, Adasaurus shows the diversity of Dromaeosaurs at the end of the late cretaceous and also demonstrates that not all raptors were equipped with giant sickle claws on their feet.
___________________________________________________________________________________________
I love PTO.

I had this guy on my backlog of animals I wanted to show and thought it’d be good to show Adasaurus in a profile. So last night I finished up the skin and got this guy ready. Easily one of the most unique of all dromaeosaurs and one of my favorites to make in both blender and photoshop. Since I’ve got a couple days off with my work and I wanted to start New Years off right, what better way than to write out a profile?

Will this be in PMP? Yes, it will. Looking forward to writing the scenes out for this guy.

Credit to Lgcfm and Ulquiorra for making the base model and skins. I basically took their Velociraptor, beefed up the skull and legs, adjusted the tail posture, and of course reduced the sickle claw.

For Past Meets Present (Must have an account to read):
Past Meets Present - The ZT2 Round Table

Original model and skin by Lgcfm and Ulquiorra, modified by me:
Velociraptor (Lgcfm & Ulquiorra) | ZT2 Download Library Wiki | Fandom

Description
Adasaurus mongoliensis

Dromaeosaurs, AKA “Raptors” are among the most recognizable of all dinosaurs in the modern era. Thanks to Spielberg’s cinematic masterpiece, Jurassic Park it forever banished the idea that these animals were slow and sluggish. The most iconic feature of the animals being the infamous sickle claw found on all dromaeosaurs. While most genera had large claws proportionate to the other two weight bearing unguals, one species from Cretaceous Mongolia bucks that trend. The dinosaur is called Adasaurus mongoliensis.

History and Discovery:

In 1977, Rinchen Barsbold was conducting an expedition in the Nemegt Formation of Mongolia. When he analyzed the remains he found pelvic material distinct from other theropods in the region. In 1983, he further analyzed the remains in a taxonomic redescription of animals from the Formation. One of the animals he described was a dromaeosaur consisting of a partial skull, pelvis, vertebrae, and most interestingly, a right foot, including digit 2, which had a distinctive killing claw as will be discussed.

The holotype was labeled MPC-D 100/20. Another specimen MPC-D 100/21 was slightly smaller but had a nearly complete right foot. Based on the distinctive ungual and large size of the dromaeosaur, he dubbed the dinosaur Adasaurus mongoliensis. The generic word derived from the Mongolian word: “Ada” which means “evil spirit” in Mongolian and “saurus” the Greek for lizard. The specific word means “Mongolia” in Latin. So “Evil Spirit Lizard of Mongolia”.

In 2004, Dr.Phil Currie and Dr. David J. Varricchio referred 2 more specimens to the genus; IGM 100/22 and IGM 100/23. However, it was found these were from a younger rock layer and could not be confidently attributed to Adasaurus.

Description:

Adasaurus is among the largest of all verified velociraptorines. They would have grown to about 8-11ft long, 2.5-2.9ft tall, and weighed between 75-90lbs. Although it was three times the size of its more famous cousin, the Velociraptor, the most distinctive feature of the Adasaurus would be its sickle claw on digit 2 of its hind feet.

The claw was proportionally tiny while marginally bigger than other weight-bearing toe claws. Less than an inch long compared to Velociraptors 2.5in.

However, compared to the rest of the Velociraptorines, Adasaurus was more robust. With a slightly deeper skull and a bulkier torso. Other than that, it would have had the basic Dromaeosaur body plan.

Furthermore, this dinosaur would’ve been feathered in life. With pennaceous feathers projecting from the arms as its cousin Velociraptor had quill knobs that would’ve been used to support pennaceous feathers. They could also have similar feathers on the tail as close relatives like Microraptor and Zhenyuanlong had them there. However, what shape it was in is up for debate.

Taxonomy:

Adasaurus is a member of the Velociraptorinae subfamily within Dromaeosauridae. As of 2024, they are the largest verified members of the subfamily. According to a 2021 taxonomic evaluation of the group when describing a cousin of Adasaurus, Kuru kulla. In the study by Mark Norrell et al, Adasaurus would’ve been fairly basal within the group. However, according to the study it was a sister genus to Adasaurus.

Hunting Behavior:

Back in the late 60s, when the killing claw of Acheroraptors’ distant cousin, Deinonychus, was found, it was thought the large sickle feet of this animal were used to rip open the sides of prey, slashing it across the belly, throat, and any exposed region. As a modern-day analog, Ostrom used examples of Cassowaries and Ostriches attacking humans and dogs with giant claws.

However, studies from the mid-2000s found that the claw could not cut through flesh and muscle well, given that its curved and dull sides could not slice through flesh. Furthermore, while ratites have killed people using their claws, they usually die because of trauma to their ribcage and internal bleeding, so they are not a good analogy when studying dromaeosaurs.

This has led paleontologists in recent years to look at actual raptors, the birds of prey, suggesting raptors dispatched their prey similarly to eagles and owls.

The victim dying from shock and blood loss. It suggests that raptors would ambush their prey that was smaller or approximately to their size, pin them down under their weight, and then pick at it while they were still alive. They may have also used their arms for balance, flapping their wings to keep themselves stable while on the back of their quarry.

This form of behavior has been dubbed Raptor Prey Restraint (RPR). This is believed to be how dinosaurs like Velociraptor, Dromaeosaurus, and Deinonychus killed their prey. However, the reduced sickle claw poses a question for paleontologists.

In a 2019 study by Peter Bishop, he analyzed the effectiveness of Deinonychus and the killing claw in the genera. He found RPR was indeed the likely method to dispatch prey and the forces exerted at the tip of the killing claw was where the force would be at its greatest. The effectiveness and force would’ve varied from species to species. In the study, he also looked at Adasaurus and found that while the claw had been reduced, the function of it being used as a killing weapon and whether or not it’d flex is unknown.

It's possible that Adasaurus could’ve hunted in a manner similar to modern seriemas or secretary birds. This would result in it pinning down small prey with the whole of its foot or grabbing them in the mouth and then slamming them to the ground or on a rock; killing them.

As commonly shown in media, raptors are often depicted hunting in packs.

Although shown to be equivalent to the wolves of the Cretaceous, there is no hard evidence aside from a handful of trackways of 2-toed dinosaurs attributable to dromaeosaurs moving together from the same region as Adasaurus. Even then, those could just be two individuals tolerating each other. Without observing these animals, we will unlikely ever find out what their behavior was like.

Habitat:

Adasaurus was a denizen of the Nemegt Formation in the heart of Mongolia. Adasaurus existed from about 70,000,000 years ago to the end of the dinosaurs’ reign, among the last of the velociraptorines. The Nemegt formation was a lush swamp similar to the Okavango Delta in Botswana or the Bayou of Louisiana. As well as some conifer forests with Araucaria and fern prairies dispersed throughout the environment.

It is this region where Adasaurus would’ve thrived. It would’ve functioned in the region as a predator hunting prey. Animals like the Troodontids such as Zanabazar and Borogovia. They could’ve been easy prey for Adasaurus targeting them, juveniles, or their eggs. As with the myriad of omnivorous oviraptorosaurs like Avimimus, Oksoko, Nemegtomaia, or Rinchenia just to name a few. In competition, there are a handful of dromaeosaurs from the region, including one believed to be like Velociraptor, but these have currently been undescribed. Scampering through the fern prairie would’ve been Gallimimus and Anserimimus, two ostrich-like dinosaurs.

Pachycephalosaurs like Prenocephale and Homalocephale browsed off tougher foliage and cycad in the region. These distinctive thick-headed and barrel-chested ornithischian dinosaurs could’ve also been prey for Adasaurus.

Outsizing Adasaurus would’ve been Sauropod dinosaurs like Nemegtosaurus, Opisthocoelicaudia, and an as-of-now unnamed giant sauropod estimated to be at least 70-90ft long known only from footprints. Beyond the eggs and hatchlings, hunting these sauropods would’ve been out of the question.

Hadrosaurs like Saurolophus and Barsboldia measuring 30-40ft long have been found in the Nemegt Formation. This small-clawed dromaeosaur could also have poached their eggs and juvenile dinosaurs.

Also, there would’ve been the giant-clawed Therizinosaurus. A bizarre herbivorous theropod using its massive arms to bring foliage to its maw. As would the equally giant and clawed Deinocheirus, an ornithomimid with a hadrosaur-esque skull and a sail/humped back.

Predators would’ve been the two species of Alioramus. Two lithe and small-bodied Tyrannosaurs running prey down in forests or the prairies. Finally there would’ve been the apex predator; Tarbosaurus. The Asian Equivalent to T.rex. All these tyrannosaurs would’ve been formidable hunters in the Nemegt and Adasaurus could’ve been prey for them.

Extinction:

Adasaurus, along with other Nemegt Formation residents, would die out 66,000,000 years ago when an asteroid smashed into the earth, marking the end of the non-avian dinosaurs.

While extinct, Adasaurus shows the diversity of Dromaeosaurs at the end of the late cretaceous and also demonstrates that not all raptors were equipped with giant sickle claws on their feet.
___________________________________________________________________________________________
I love PTO.

I had this guy on my backlog of animals I wanted to show and thought it’d be good to show Adasaurus in a profile. So last night I finished up the skin and got this guy ready. Easily one of the most unique of all dromaeosaurs and one of my favorites to make in both blender and photoshop. Since I’ve got a couple days off with my work and I wanted to start New Years off right, what better way than to write out a profile?

Will this be in PMP? Yes, it will. Looking forward to writing the scenes out for this guy.

Credit to Lgcfm and Ulquiorra for making the base model and skins. I basically took their Velociraptor, beefed up the skull and legs, adjusted the tail posture, and of course reduced the sickle claw.

For Past Meets Present (Must have an account to read):
Past Meets Present - The ZT2 Round Table

Original model and skin by Lgcfm and Ulquiorra, modified by me:
Velociraptor (Lgcfm & Ulquiorra) | ZT2 Download Library Wiki | Fandom