|Name Meaning||Scythe Lizard||Height||4-5 meters (13-16 feet)|
|Pronunciation||Theri-zino-sore-us||Length||9-10 meters (30-33 feet)|
|Era||Mesozoic – Late Cretaceous||Weight||3-5 tons (3.3-5.5 short tons)|
|Classification||Dinosauria, Saurischia & Theropoda||Location||Mongolia (Asia)|
Scientifically speaking, when discussing therizinosaurs, we should be talking, in fact, about the Therizinosauria clade because its members are all called therizinosaurs.
Today, however, we’ll focus on the clade’s representative genus, the famous Therizinosaurus.
More precisely, the Therizinosaurus cheloniformis species, also called the scythe lizard!
This scythe lizard was a large herbivorous dinosaur renowned for its very large claws.
It roamed the Earth during the Late Cretaceous period, meaning around 70 million years ago, and its first remains were discovered in 1948 in the Gobi Desert in East Asia.
A few years later, in 1954, Evgeny Maleev produced the first written description of this prehistoric animal and mentioned that it was a turtle-like creature.
Only in 1970, a paleontologist suggested that the discovered remains belonged to a theropod, which led to its classification in the Therizinosaurus genus, classified under Theropoda.
Once further research was done, it was established that the Therizinosaurus was the largest representative of its clade, the Therizinosauria.
Numerous discoveries helped specialists confirm and outline the scientific classification, appearance, and behavior of the prehistoric animal called Therizinosaurus.
However, much is yet to be discovered!
As such, this specimen is highly important in paleontological research, and its discovery offered significant insight for evolutionary studies.
Some researchers consider the species to have the most “substantial anatomical evidence of herbivory.”
Although further research is required to outline the appearance of the Therizinosaurus, paleontologists were able to provide approximate characteristics of the species based on available remains as well as on other therizinosaurid descriptions.
Therizinosaurus was a large prehistoric animal.
Paleontologists estimate an approximate length of 9-10 meters (30-33 feet), a height of 4-5 meters (13-16 feet), and a weight of 3-5 tons (3.3-5.5 short tons).
But, naturally, besides its huge size, the Therizinosaurus is most renowned for its three long claws on its forelimbs, measuring around 50 centimeters (20 inches) long – in fact, they’re considered the longest known claws in any terrestrial species!
The claws were straight and side-to-side flattened.
Compared to other dinosaurs in the clade, the species we’re discussing had distinctive claws thanks to their length and the fact that only their tips were sharply curved.
The forelimbs of Therizinosaurus specimens measured approximately 2.4 meters (7.9 feet) long.
As for the hind limbs, they featured four toes, three of which served for weight bearing.
Unlike other theropods, the Therizinosaurus’ first toe was, in fact, a dewclaw and didn’t touch the ground while the animal was standing.
Other distinctive features of the Therizinosaurus included the following:
- A large belly that aided foliage digestion
- A wide pelvis
- Sparse feathering (sometimes thought to have been “organized” into two feather layers)
- A small skull with what scientists call a “rhamphotheca” or a “horny beak.”
Habitat and Distribution
The first remains of the Therizinosaurus were found in the Gobi Desert of Mongolia, more precisely in what we now call the Nemegt Formation, and it’s considered that their range didn’t extend beyond Mongolia.
Sediment research showed that the Therizinosaurus most likely preferred fluvial areas, as they spent their time foraging in riparian regions.
Moreover, it is believed that these animals inhabited woodlands in enclosed canopy-like forests.
Scientists suspect that the climate of the environments that supported animals alike was temperate and featured hot and rainy summers and cold, dry winters.
Behavior and Diet
The Therizinosaurus is believed to have been a herbivore, primarily thanks to its body plan, the form of its skull and teeth, as well as its enormous claws, which were thought to have been used to gather up quantities of vegetation.
Some scientists even believe that these prehistoric animals could eat while sitting!
They would collect the plant matter using their hands and necks, thus facilitating the process.
If standing, they could reach almost any type of vegetation they wanted thanks to their enormous size and strong feet that supported their weight.
However, Therizinosaurus wasn’t always considered a herbivore.
At first, scientists thought it was a carnivore because it evolved from a carnivorous lineage.
It’s a theropod, and the theropod group is believed to have had a strict carnivory ancestral diet.
Despite that, many theropod species evolved to become omnivores and herbivores, which further supported scientists’ thoughts that the Therizinosaurus was, in fact, a herbivore.
Another significant debate in terms of the Therizinosaurus diet was in regard to its claw usage.
Some scientists believed that the claws were used to collect seaweed – that is when the creature was thought to be a turtle-like animal – and other plant matter.
Others suggested that they specialized in opening termite mounds, which gave birth to the assumption that these animals ate termites.
Scientists aren’t 100% sure what the answer to this question is, and we can only hope that further paleontological discoveries will reveal the truth!
Their unguals tell a lot about the species’ behavior as well.
They were considered useful as defense mechanisms, arboreal locomotion in the case of juveniles, stabilization by grasping tree trunks while browsing, and holding mates while mating.
But how much of this is actually true? Did they indeed use their claws to defend themselves?
Many sources show that the claws served as long swords against predators.
Recent discoveries demonstrated that Therizinosaurus claws could not bear any stress. As such, they were likely never used as defense “tools.”
Other studies confirm that the unguals of Therizinosaurus creatures were purely decorative, featured no mechanical function, and weren’t even too useful in pulling down branches!
On the other hand, the claws might’ve served as elements in “courtship rituals,” during which males showed off their long unguals to conquer females.
Some scientists believe that the claws might have been used for grooming! After all, they were feathered, weren’t they?
Little to no scientific confirmation is available regarding the Therizinosaurus life cycle.
However, we could guide ourselves by discussing the theropod reproductive system.
This could give us a broad perspective on how therizinosaurs might have reproduced.
Studies show that male theropods had internal testes and retractable penises, while females featured paired ovaries, oviducts, and an egg-storing system similar to that of crocodilians.
As such, theropod eggs were fertilized and then laid in clutches.
Some species incubated the eggs, while others didn’t.
As such, we can assume that therizinosaurs followed the same reproductive “pattern.”
The available information about all types of therizinosaurs (Therizinosauria) shows that, upon laying the eggs, the adults parted ways with their babies, as no adults could be associated with nests.
This indicates that the hatchlings were precocial, meaning that they were relatively mature right after birth and were able to live independently.
Apart from this, there’s no information about the reproduction of Therizinosaurus.
We could, of course, resort to general details about dinosaur reproductive biology, but it would be impossible to mention what specifically can be attributed to the species in question.
We do know, though, that the claws were of major importance during courtship!
Evolution and History
As we’ve already mentioned, the first remains of a Therizinosaurus were discovered in the Nemegt Formation.
The paleontological expedition was organized by the USSR Academy of Sciences, and its participants recovered multiple turtles and dinosaur fossils.
The ones belonging to the species we’re discussing today were by far the most significant discoveries!
Paleontologists uncovered three partial manual unguals in a locality called Quarry V. They were found near a theropod skeleton and other fossils like rib and metacarpal fragments.
Later on, Evgeny Maleev described the fossils and named the Therizinosaurus cheloniformis species, which was, back then, considered a turtle-like creature resembling Protostega and Archelon sea turtles, which measured around 2.5 meters long and 2 meters wide.
Maleev states that the scientific name, Therizinosaurus cheloniformis, translates as “the mowing lizard” (Therizinosaurus) and “turtle-like” (cheloniformis).
In 1968, paleontologists found another fossil that was thought to belong to the same animal – an upper portion of a manual claw.
Following this discovery, Anatoly K Rozhdestvensky, a Soviet paleontologist who focused on naming dinosaurs, suggested that the fossils were most likely closer to theropods than turtles.
This suggestion was backed up by comparing the discovered unguals to those of Chilantaisaurus.
His thoughts were supported by a Polish paleontologist named Halszka Osmólska.
In 1972, scientists recovered another fossil – the lower portion of an ungual.
A year later, a significant discovery impacted the research – paleontologists found some ribs, a right hindlimb, as well as a left and a right arm, which were much larger and more complete.
This served as a turning point in classifying this species and outlining its evolution and history, supporting the belief that the prehistoric animal was a theropod.
The discovery of the Segnosaurus and Erlikosaurus was significant in understanding the history of the Therizinosaurus.
Paleontologists concluded that the morphology of the latter was very similar to that of the former dinosaur types, which is why all three are now part of the same superfamily.
The description of Beipiaosaurus was also of essential help in confirming that therizinosaurs were theropods.
Besides the information that fossil discoveries provide, little is known about how Therizinosaurus cheloniformis evolved, changed, and behaved.
Interactions with other Species
Therizinosaurus was thought to inhabit the same habitats as the following creatures:
- Alvarezsaurs (Nemegtonykus, Mononykus)
- Pachycephalosaurids (Prenocephale, Homolocephale)
- Ankylosaurids (Tarchia, Saichania)
- Tyrannosaurids (Alioramus, Bagaraata, Tarbosaurus)
- Ornithomimosaurs (Anserimimus, Gallimimus, and Deinocherius)
- Deinonychosaurs (Adasaurus, Zanabazar)
- Hadrosaurids (Surolophus, Barsboldia)
- Titanosaurs (Opisthocoelicaudia, Nemegtosaurus)
- Paralligator crocodylomorph
- Aquatic turtles (Nemegtemys, Mongolochelys)
- Freshwater ostracods
- Birds (Teviornis and Judinornis, to name a few)
Considering that the Therizinosaurus was a giant herbivore, it likely had few enemies in the wild.
But confrontations with other large dinosaurs like the Tarbosaurus were likely.
The latter, which translates as “alarming lizard,” was an apex predator in its habitat and measured around 10 meters (33 feet) long and weighed 4.5-5 metric tons (5-5.5 short tons), meaning it was about the same size as our herbivore dinosaur.
Considering the fact that the Tarbosaurus is believed to have had a bite force of around 8,000-10,000 pounds per force, crushing the bones of other large dinosaurs was likely not a problem.
We’ll never know how often these creatures crossed paths, but we can assume that some confrontations occurred occasionally!
If you’re reading about the Therizinosaurus, you probably already know that it appears in Jurassic World: Dominion.
However, the movie doesn’t depict the dinosaur just as fossil records describe it.
The most misleading difference is that the movie shows that the Therizinosaurus can use its claws to fight off other dinosaurs, which was highly likely untrue.
Other movies, animations, and games the Therizinosaurus is portrayed in include Tarbosaurus: The Mightiest Ever, The Dino King, Dinosaur King, Dino Dan: Trek’s Adventures, The Isle, Walking With Dinosaurs, Dino Crisis, Jurassic World: The Game, and the PC and console game ARK: Survival Evolved.
While the species is popular in the movie and game industries and has helped people broaden their knowledge about its characteristics and evolution, many of these portrayals are inaccurate and misleading.
However, there’s always room for improvement as long as paleontologists and researchers continue looking for clues that would reveal more about Therizinosaurus cheloniformis!
The Therizinosaurus fossils are undoubtedly remarkable paleontological discoveries!
Pointing to a huge bipedal dinosaur with unique long claws, the recovered fossils helped researchers put another essential piece of the world’s evolution and history in place.
Needless to say, Therizinosaurus is also important in outlining the development of herbivorous species.
To wrap it up, here’s a short recap of what we’ve learned today about the Therizinosaurus.
The first Therizinosaurus fossils were discovered in Mongolia in 1948, and paleontologists first believed it was a turtle-like species.
Only later did scientists conclude it was a herbivorous theropod, almost as large as a T-Rex, with remarkably long claws, a long neck, a large belly, a beak, and a sparsely feathered body.
The creature roamed the Earth during the Late Cretaceous period, around 70 million years ago.
Although many details have already been confirmed about the species, much more is yet to be discovered!
Was Therizinosaurus a predator?
The Therizinosaurus was not a predator, as it was a herbivorous species.
Although it was once believed that the dinosaur was carnivorous, recent discoveries confirmed that, although it evolved from a carnivorous lineage, the Therizinosaurus was a herbivore and, as such, was not a predator.
Was Therizinozaurus aggressive?
There’s no scientific confirmation that the Therizinosaurus was aggressive.
However, some cultural portrayals (movies, anime, and games) show that the species was aggressive.
We can assume they did defend themselves if predators were around, but there’s no certainty as to whether they attacked other creatures out of aggression.
Was Therizinosaurus blind?
It is not known whether Therizinosaurus was blind or had fully functional eyes.
The concept that these creatures couldn’t see well comes from the Jurassic World Dominion universe, where the Therizinosaurus was portrayed as being blind and relying on echolocation, hearing, and smell to move around.
This, however, has no scientific or paleontological backup.
Is Therizinosaurus related to Tyrannosaurus?
The Therizinosaurus is only distantly related to the Tyrannosaurus, as they’re part of the same clade, the Theropoda.
Going further, these two theropods part ways, as the latter is in the Tyrannosauroidea superfamily, while the former is a species in the Therizinosauroidea superfamily.
Who would win in a fight between a Therizinosaurus and a T-Rex?
Because these two dinosaurs are almost equally large, both the Therizinosaurus and the T-Rex have a chance of winning in a confrontation.
However, since the Tyrannosaurus rex is a predator (most likely an apex predator), we can assume that his fighting skills are much more developed than those of a Therizinosaurus, which indicates that its chances of survival are much higher.