An Ultimate Guide to Inostrancevia: The Strange Creature

Leave a comment / / Updated on: 25th September 2023

Name MeaningStrange CreatureHeight1.3-1.4 meters (4.3-4.6 feet)
PronunciationIn-oh-stran-sey-vee-ahLength3-3.5 meters (9.8-11.5 feet)
EraPaleozoicLate PermianWeight0.30 tons (661 lbs)
ClassificationSynapsida, Therapsida, GorgonopsiaLocationEuropean Russia, South Africa

Inostrancevia Pictures

Inostrancevia was a gorgonopsid, often referred to as "mammal-like reptiles"
Inostrancevia was a gorgonopsid, often referred to as “mammal-like reptiles” | Ninjakingofhearts via Dinocrisis Fandom

The Inostrancevia

Gage Beasley Prehistoric's Inostrancevia Concept
Gage Beasley Prehistoric’s Inostrancevia Concept

Inostrancevia was a gargonopsian therapsid.

It was an inhabitant of prehistoric European Russia and South Africa and lived approximately 259-251 million years ago during the Late Permian.

The strange creature may have been the largest of its kind. It was also an apex predator. 

By far the most distinctive characteristics of the genus are the large canines, which served as an efficient aid in subduing prey.

Inostrancevia is thought to have been fully terrestrial and roamed through the cold desert of prehistoric Russia. 

Since its skull was quite large, Inostrancevia had a relatively long, robust neck that supported the massive head while walking. 

Are you eager to discover more? Keep reading!

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Physical Characteristics

Inostrancevia was a carnivorous cat-like dinosaur that lived in Russia during the Permian Period
Inostrancevia was a carnivorous cat-like dinosaur that lived in Russia during the Permian Period | CoreyFord via iStock

The Inostrancevia was a highly robust non-mammalian therapsid, especially at the limb level. 

It had a broad skull at the back and a raised elongated snout.

The snout was lower and wider in Inostrancevia laiforns, and its skull was much larger than the skull of Inostrancevia alexandri.

The eye sockets were small, while the powerful jaws featured strong teeth adapted for holding and tearing skin. 

The teeth were finely serrated at the front and rear edges. Additionally, they were laterally compressed.

It has been estimated that the upper canines, which moved to the sides of the mandible when the mouth was closed, could have reached 12-15 centimeters (4.7-5.9 inches) long, being the largest canines known in non-mammalian therapsids!

Inostrancevia head in a white background
Inostrancevia head in a white background | CoreyFord via iStock

The neck of the Inostrancevia was probably quite long, being able to support the large head. It likely consisted of seven cervical vertebrae.

The hands and feet had five digits. The fifth digits were not attached to the carpus or tarsus, respectively. Instead, they grew from the ulna and the heel bone.

The pelvis had a reptilian form. The femur (thigh bone) had a unique, curved, S-form and was longer than the humerus. The tail was relatively short.

Inostrancevia is one of the largest discovered gorgonopsians. The I. alexandri specimens measure 3 meters (9.8 feet) in length. Imagine that their skulls alone measured 50 centimeters (20 inches) long!

The Inostrancevia latifrons, as mentioned, may have been larger, although this hasn’t been fully confirmed due to the fragmentary nature of the discovered fossils.

Since its skull measured 60 centimeters (23.6 inches) long, scientists estimate a total length of 3.5 meters (11.5 feet) and a weight of 300 kilograms (661 pounds).

Gage Beasley Prehistoric's Inostrancevia Size Comparison Chart
Gage Beasley Prehistoric’s Inostrancevia Size Comparison Chart

Inostrancevia uralensis was likely smaller than Inostrancevia latifrons.

The height of Inostrancevia is estimated at 1.3–1.4 meters (4.3–4.6 feet) at the shoulder.

Another gorgonopsian therapsid known from Russia, Pravoslavlevia, was much smaller, reaching only 1.4 meters (4.6 feet) long and having a skull of 22 centimeters (8.7 inches) long.

An African genus of gorgonopsian therapsid had approximately the same size. 

Its skull was 30 centimeters (11.8 inches) long, while the total length would have been 2 meters (6.6 feet).

Habitat and Distribution

Inostrancevia lived in the territories we now call Russia and South Africa roughly 259-251 million years ago during the Late Permian. Its fossils were unearthed at the following locations:

  • Northern Dvina, Arkhangelsk Oblast, Russia
  • Zavrazhye, Vladimir Oblast, Russia
  • Orenburg Oblast, Russia
  • Nooitgedacht farm, Karoo Basin, South Africa

During the Late Permian, the Russian territory inhabited by Inostrancevia was a cold desert

This means it likely had hot, dry summers and cold, dry winters with little snow. The habitat likely features rivers and lakes.

At the time, European Russia was dominated by plants in the Peltaspermaceae family. 

Ginkgophytes and conifers were quite common, while ferns and sphenophytes were present but rare.

Although multiple Inostrancevia portrayals show it swimming while chasing prey, the Inostrancevia was likely a fully terrestrial carnivore that enjoyed the lands of European Russia and South Africa.

Behavior and Diet

3D illustration of an inostrancevia hunting a scutosaurus
3D illustration of an inostrancevia hunting a scutosaurus | estt via iStock

As mentioned, the Inostrancevia was likely a fully terrestrial predator that moved with an erect gait. 

Its limbs were likely positioned almost vertically instead of horizontally. However, this therapsid probably could not have moved its limbs too far forward.

It is widely believed that gorgonopsias were nocturnal creatures, and their vision was adapted to low-light conditions. 

Only Clelandina has been confirmed to be strictly diurnal. 

This behavioral trait was not studied in Inostrancevia, but we cannot rule out the possibility that it preferred to hunt during the night.

Gorgonopsians generally had quite a strong bite force, except for those with a less robust skull and longer canines, like Inostrancevia or Smilesaurus

This mammal-like reptile showing its jaw and strong teeth
This mammal-like reptile showing its jaw and strong teeth | CoreyFord via iStock

The members of these genera had a much weaker bite, so they relied on their canines to slash prey.

It has been calculated that Rubidgea, a gorgonopsian similar in size to Inostrancevia had a bite force of only 715 N, so we may assume that the strange creature’s bite force was similar.

The Inostrancevia may have engaged in a bite-and-retreat hunting technique. 

If so, it would ambush its prey and take a huge bite out of it. 

Then, as the prey tried to escape, the predator would follow it and eventually deliver a fatal bite. 

Since Inostrancevia is known to have been able to open its jaws quite wide, it could probably deliver fatal bites.

On the other hand, some studies compare the way Inostrancevia killed prey to the way Smilodon killed prey. 

Illustration of smilodon cat from the Cenozoic era
Illustration of smilodon cat from the Cenozoic era | Corey Ford via GettyImages

This machairodont held prey still with its forelimbs and bit it using its canine teeth. 

It is believed Smilodon delivered quick slashing or stabbing bites instead of slow, suffocating ones.

As such, we still do not know how Inostrancevia killed its prey. 

Did it hold it still while trying to kill it? Did it take breaks? Did it deliver multiple, consecutive bites?

Life Cycle

The reproductive behavior and life cycle of Inostrancevia and other therapsids are poorly studied.

Some sources list that Inostrancevia reproduced by laying eggs, but no evidence supports this theory.

Digital colored illustration of inostrancevia
Digital colored illustration of inostrancevia | Nobu Tamura via Wikimedia Commons

Other scientists tried to guess some reproductive aspects of therapsids by comparing them with mammals.

For example, they have suggested that therapsids may have had anal and urogenital openings, mammal-like facial musculature specialized for suckling, and mammary glands. 

As such, they argued in favor of viviparity.

However, as mentioned, none of these things can be confirmed for Inostrancevia.

Additionally, even if Inostrancevia were viviparous, it remains unknown how long the gestation period was, how developed the babies were when they were born, and how much parental care the adults engaged in.

Besides this, the ontogeny of the genus is also poorly studied, which is why the growth stages of baby and juvenile Inostrancevia remain in the shadows.

Evolution and History

Photo montage of several representatives members of the clade Synapsida
Photo montage of several representatives members of the clade Synapsida | Nobu Tamura et al.,2021 via Wikimedia Commons

The Synapsida group has historically been split between Pelycosauria and Therapsida

While pelycosaurs probably evolved in the Upper Carboniferous, therapsids likely appeared during the Middle Permian.

The six major therapsid groups are the following:

  • Biarmosuchia
  • Dinocephalia
  • Anomodontia
  • Gorgonopsia (which includes Inostrancevia)
  • Therocephalia
  • Cynodontia

It is believed they evolved approximately 265 million years ago. 

The oldest member of their lineage dates from the Wordian, having been discovered in the Karoo Basin. 

Illustration of inostrancevia, a member of the clade synapsida
Illustration of inostrancevia, a member of the clade synapsida | CoreyFord via iStock

Unfortunately, the remains have not been associated with any genera.

So if the earliest gorgonopsian lived in South Africa, how did they reach Russia? Let’s find out!

During the Upper Carboniferous and Lower Permian, the pelycosaurs lived in equatorial forests separated from the temperate regions by an extensive desert.

By the Middle Permian, however, when gorgonopsians evolved, the climate close to the equator shifted to having wet and dry seasons. 

The swamps where pelycosaurs lived were connected to the temperate zones through coastal passages. 

That’s how various prehistoric creatures migrated from South Africa to Russia.

Since therapsids, including gorgonopsians, diversified during this period, they adapted well to the typical humid or dry landscape. 

3D illustration of an inostrancevia on a rocky ground
3D illustration of an inostrancevia on a rocky ground | estt via iStock

Pelycosaurs, on the other hand, did not cope so well with the changes and started disappearing.

When pelycosaurs went extinct, therapsids experienced something called adaptive radiation. 

This means that therapsids diversified rapidly from an ancestral species, therefore filling new environmental niches.

The rise of gorgonopsians occurred after the extinction of gigantic dinocephalians. 

Alongside dicynodonts and small therocephalians, gorgonopsians replaced the dinocephalians in their habitat.

The most derived, massive, and heavily built gorgonopsians were the rubidgeans. 

They lived until the Late Lopingian and went extinct during the Permian-Triassic extinction event. 

Restoration of inostrancevia
Restoration of inostrancevia | image via Wikipedia CC BY-SA 4.0

The primary thing that caused their extinction was the volcanic activity from the Siberian Traps, which led to multiple climatic disruptions that destroyed their habitats.

Gorgonopsians were subsequently replaced by other terrestrial animals like suaropsids and mammals. 

Some gorgonopsians had disappeared before this, being replaced by large therocephalians. 

Inostrancevia, a gorgonopsian, appeared 259 million years ago and lived for roughly 8 million years. 

The first fossils associated with the genus were discovered in the 1890s in Northern Dvina, European Russia.

Before this discovery, such animals were known only from South Africa and India. 

As such, Inostrancevia remains opened the doors toward new paleontological research and discoveries, as well as toward a different understanding of our planet during the Permian.

Replica of the skeleton of inostrancevia
Replica of the skeleton of inostrancevia | image via Wikimedia Commons CC A-SA 3.0

Fossil excavations at the site continued until 1914 when the beginning of World War I put an end to paleontological discoveries.

Only in 1927 was the description of the genus officially published. At the time, it consisted only of two species – Inostrancevia alexandri and Inostrancevia latifrons.

Inostrancevia uralensis was described in 1974 upon a few remains unearthed from Orenburg Oblast.

The South African fossils were unearthed between 2010 and 2011 in the Karoo Basin. 

In 2023, after thorough research, scientists confirmed that the remains belonged to a new Inostrancevia species, Inostrancevia africana.

It is believed that the Inostrancevia migrated to South Africa after the extinction of rubidgeines and, as such, replaced their ecological niche and became apex predators in the respective African territory. 

Interactions with Other Species

Two Inostrancevia go after a tapinocephalid therapsid on a grassy plain in the Permian Period
Two Inostrancevia go after a tapinocephalid therapsid on a grassy plain in the Permian Period | CoreyFord via iStock

The European Russia of the Middle Permian was rich in terrestrial and shallow freshwater creatures. 

We do not know to what extent Inostrancevia crossed paths with each, but since it was the top predator in the environment, we assume it did interact with some, at least with those that served as prey!

Here are some creatures whose remains were discovered in the same fossil sites:

  • Ostracods, also known as seed shrimp
  • Various fish species
  • Reptiliomorphs, including Kotlassia and Chroniosuchus
  • Temnospondyls (tetrapods, often regarded as primitive amphibians) like Dvinosaurus
  • Pareiasaurs (large, herbivorous parareptiles armored with osteoderms) like Scutosaurus
  • Dicynodonts like (herbivorous non-mammalian therapsid) like Vivaxosaurus
  • Other gorgonopsians like Pravoslavlevia
  • Therocephalian like Annatherpsidus

The Inostrancevia is often portrayed chasing a Scutosaurus, which indicates that pareiasaur may have represented a significant food source.

Inostrancevia life restoration with speculative hair
Inostrancevia life restoration with speculative hair | AnnieI via Wikimedia Commons CC A-SA 4.0

However, the lifestyle of pareiasaurs has been highly debated; some scientists consider them fully terrestrial, while others argue in favor of an aquatic or amphibious lifestyle. 

If it were aquatic, Inostrancevia could not have preyed upon it, as gorgonopsians were probably fully terrestrial.

Inostrancevia lived alongside other grogonopsian and therocephalian predators, but they likely preyed on different species that suited their size and hunting techniques.

Cultural Significance

The discovery of Inostrancevia marks a significant paleontological event, as it was the first evidence of South African megafauna in Russia. 

Since it was an apex predator, studying the appearance and behavior of Inostrancevia helped scientists outline a new perspective on the Russian Late Permian environment.

Needless to say, countless studies have focused on describing this animal, and new findings are still being published, so we’re on the lookout for fresh jaw-dropping facts!

Inostrancevia hunting juvenile scutosaurus
The mammal-like reptile hunting juvenile scutosaurus | DiBgd via Wikimedia Commons CC A-SA 3.0

If you want to watch an Inostrancevia attacking a Scutosaurus, we recommend checking out the last episode of Walking with Monsters

It is also featured in Dinosaur Revolution, Primeval, and Jurassic World: Alive.


Having lived during the Late Permian in Russia and South Africa, Inostrancevia is now a famous prehistoric therapsid!

Its remains were first discovered in the Northern Dvina in Russia and were followed by other major discoveries, some of which occurred in the South African Karoo Basin.

Inostrancevia is now known as the largest gorgonopsian exhibiting a broad skull, large canines, and a large jaw opening angle. 

It was probably an apex predator in its habitat and relied heavily on its canines to subdue prey, although the exact nature of hunting and killing prey remains unconfirmed.

Without a doubt, Inostrancevia is now a major genus in our world’s evolutionary tree. 

We hope that future findings will bring to light more prehistoric details we never even thought we’d discover!


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