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Jan 07 2012
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Therizinosaurus

Filed under: Time Period » Cretaceous,

Incredibly Large Teropod Dinosaur

TherizinosaurusIf every the Cretaceous period produced a strange dinosaur that piques the interest of every dinosaur lover, the Therizinosaurus would most certainly be it. Roaming the Earth during the late Cretaceous period the Therizinosaurus is known for being an incredibly large Theropod and one of the last Therizinosauria dinosaurs to make its appearance before the Cretaceous-Tertiary extinction. It is not just the size of the Therizinosaurus nor its existence as one of the last of its family that make this humongous herbivorous so wondrous but also its incredibly unique physical appearance.

Therizinosaurus Roaming Location and Size

Therizinosaurus roamed the area of the Gobi desert some 72 to 68 million years ago and is one of the most peculiar looking dinosaurs of all time. The Therizinosaurus measured approximately 23 feet long and 10 feet tall at the hips and is believed to have weighed in at around 3 tons. This large plant eater is believed, like other Therizinosauria to be bipedal, and questions have arisen as to whether this bipedal beast actually was strictly vegetarian or whether it also feasted on insects. Either way it is known that the Therizinosaurus would not have fed on other dinosaurs and were it to be considered “omnivorous” this would only incorporate vegetation and insect life. The wide majority of paleontologists; however, believe that the Therizinosaurus was an herbivore based on its leaf shaped teeth similar in shape to the teeth of the much larger Sauropods.

The Therizinosaurus leaf shaped teeth were contained in a long and slender skull which some paleontologists believe ended with a beak like structure. The Therizinosaurus would have utilized its beak for stripping vegetation from branches or possibly snapping off twigs and branches. The Therizinosaurus had a particularly unique feature which it would have utilized to bring down branches to its mouth, or, in fact simply brought them closer. The Therizinosaurus is known to have had three incredibly large claws on each of its hands. These claws are thought to have measured somewhere around 3.3 feet long and tipped their already 8 foot long forelimbs. Some biologists and paleontologists liken these incredibly long claws to the hands of the giant sloth although it is unlikely that these claws were ever utilized for climbing as the Therizinosaurus was certainly too large to ever consider climbing, at least to any great heights. The claws of the Therizinosaurus are a particularly unique feature to this dinosaur and make it look something akin to a prehistoric Edward Scissorhands. Paleontologists believe that the Therizinosaurus would have not only utilized these large and long claws for pulling food closer but they also would have used them as a means of defense both against predators and against other individuals in the species.

Non-Aggressive Herbivores

While the Therizinosaurus were most likely non-aggressive and docile creatures despite their size they would have likely utilized their large claws to defend against each other during mating season. For many docile herbivores mating season became a time when the males would have had to display their strength and dominance over other males in order to win a mate. For all dinosaurs winning a mate was a matter of continuing a genetic line and while all males would have desired to continue their genetic line, females would only pick the largest and best males of the species to ensure their young a better chance at survival. In addition to fighting other males the Therizinosaurus would also have had to fight off the large carnivorous dinosaurs that roamed the Earth during the late Cretaceous period. Paleontologists remain split over the actual usage of the large claws for defense against carnivores; however, due to the relative bluntness of the large claws although for many dinosaurs the size of the claws alone may have served as enough of a deterrent. Just one of the many carnivores that lived alongside the Therizinosaurus during the late Cretaceous period in Mongolia is the Velociraptor, also known for its incredibly long and sharp scythe shaped claws.

The Therizinosaurus did not feature large claws on its hind feet which, had they resembled the claws on the forelimbs is a fortunate occurrence as it would be impossible for the Therizinosaurus to walk with 3.3 feet long claws on its toes! The Therizinosaurus did have four toes on its almost bird like structured feet, the appearance of four toes in the Therizinosaurus is unique for Theropod dinosaurs as most of them had three weight bearing toes and one dewclaw where the first toe generally grew. The Therizinosaurus does not feature this first toe dewclaw and instead had the four large weight bearing toes which supported this large dinosaur’s weight. From its assumed appearance one may be tempted to believe that the Therizinosaurus would have moved from bipedal to quadrupedal motion; however, its large claws on its forelimbs make this an impossibility.

Physical Features

One of the physical features of the Therizinosaurus that would tempt dinosaur fanatics in to thinking that the Therizinosaurus was an herbivore that switched between bipedal and quadrupedal locomotion is the strange shape of its large body. The Therizinosaurus stood on two hind legs like Theropods like Tyrannosaurus Rex; however, it featured an incredibly large pot belly. Due to the fact that this large herbivore would have had to eat quite a lot of vegetation in order to sustain its large frame it would have utilized this large stomach to break down vegetation, yet this feature is generally more common in giant quadrupedal Sauropods. The large belly of the Therizinosaurus is not the only unusual feature of this large dinosaur that set it apart from other Theropods. Theropods in general are always carnivores, with the exception of the Ornithomimids, Oviraptors and Therizinosaurus which are not considered as carnivores. No one is truly sure why these large Theropods stick out from the pack and feature characteristics typical of quadrupedal Sauropods. The Therizinosaurus not only had these peculiar features that set it apart from other Theropods but it also featured a much longer neck than many other Theropods which it would have utilized to reach for leaves and branches on nearby trees. The theory exists that the Therizinosaurus evolved in to such a peculiar creature in order to be able to reach higher growing vegetation in order to feed itself; however, like most things about this giant herbivore, this remains just a theory.

Unfortunately not too much is actually known about the physical appearance of the Therizinosaurus and most assumptions about this giant herbivore are centered around conjecture based on various other dinosaurs similar to the Therizinosaurus in habitat. As far as discovery of the Therizinosaurus, so far only claws and limbs of the Therizinosaurus have been discovered. While the main body of the Therizinosaurus and the skull has not yet been discovered paleontologists believe that the Therizinosaurus has a close relationship to Segnosaurs, other Theropods with similar skeletal features to the Therizinosaurus. Utilizing these other dinosaurs as well as the pieces of the discovered Therizinosaurus specimens has assisted paleontologists in putting together a rough sketch of what this large herbivorous Theropod actually looked like.

The first Therizinosaurus specimen to be unearthed was found in the Nemegt Formation in southwestern Mongolia by a Soviet-Mongolian fossil expedition in the 1940s. This expedition discovered the claws of the Therizinosaurus which measured 3.3 feet in length. This discovery would later be examined by Russian paleontologist Evgeny Maleev in 1954. Maleev thought the giant claws of the Therizinosaurus to be fossilized remains of a giant turtle which led to his titling the species “Therizinosaurus cheloniformis” which translates to mean “scythe lizard” “turtle formed”. These large appendages were believed to be those of a turtle until later in the 1950’s when further discovery of Therizinosaurus specimens revealed that the bones belonged to a dinosaur. It was during the later 1950’s that further sets of Therizinosaurus claws along with fore and hind limbs were discovered enabling paleontologists to determine that this creature was not a turtle.

A Complete Therizinosaurus Skeleton Does Not Exist

While limbs and claw sets of the Therizinosaurus have been unearthed in Mongolia, no further discovery of Therizinosaurus specimens has led to any concrete information on the body of this giant Theropod. While paleontologists are able to assume the physiological appearance of the Therizinosaurus by utilizing similar types of dinosaurs these ideas behind the Therizinosaurus are only conjectures. Until further discovery of more complete Therizinosaurus specimens no one can know for sure what this peculiar beast actually looked like but if mock ups from paleontologists are anything to go by the Therizinosaurus was a strange beast indeed. From its mix of Sauropod and Theropod characteristics to its extremely large and peculiar claws on its forelimbs the Therizinosaurus seems to be something of an oddity.

What is it about this large creature that makes it so unique? Aside from its physiological appearance the Therizinosaurus simply does not seem to fit its appearance. One glance at its large claws and Theropodal body and one would assume that this pot bellied beast was a carnivore and a vicious one at that. With large and muscular hind legs it could be assumed that this was a beast bred for hunting and possibly even running…although this last fact is unlikely due to the fact that running with a pair of claws like the Therizinosaurus possessed would be much like running with a pair of gardening sheers and one trip could result in a fatal accident. Still the mish mash of features of the Therizinosaurus combined with the appearance of many of these features in contrasting dinosaurs leaves the casual observer with absolutely no idea what the Therizinosaurus actually was or its function within the dinosaur society.

The Late Cretaceous period was not unknown for producing some particularly strange looking dinosaurs though and were it not for the Cretaceous Tertiary extinction event it is possible that these huge beasts could have continued to develop even more peculiar features. The Therizinosaurus certainly wins the prize for being one of the most unique looking beasts of the prehistoric ages; however, it is certainly not alone in that feat. As time progressed dinosaurs began to evolve and from smaller lizards they grew to mammoth proportions during the Jurassic period and specialized during the Cretaceous period. In an ever changing environment dinosaurs like the Therizinosaurus may have been considered “strange” but they also may have been one of the more successful genera due to their unique peculiarities.

There is certainly no evidence to suggest that the development of such unique features in the Therizinosaurus contributed to any type of success within the species due to the fact that no dinosaur species made it out of the Cretaceous Tertiary extinction alive. It is, however, believed that the dinosaurs that featured much more specialized physiological features did so for a reason and that reason was most likely survival. Much like the Tyrannosaurus evolved in to such an incredible killing machine with a bite that could crush a modern day car in order to feed its incredibly large hunger, the Therizinosaurus likely evolved to such a peculiar looking creature in order to survive. With such unique features it is unlikely that the Therizinosaurus would have evolved as a result of a series of fluke genetic occurrences. It takes a lot of specialization within a species to develop features such as the incredibly large claws of the Therizinosaurus and so it is likely that these claws were developed as a result of a need for them, perhaps a need for better feeding techniques or simply the appearance of defensive weapons in a creature that otherwise had very few methods of defending itself.

Until More Discoveries Are Made, We Must Rely on Estimations and Assumptions

Regardless of all of the speculation on the Therizinosaurus and the questions that arise in regard to its strange and unusual features this herbivore of the late Cretaceous period remains elusive. Until further discovery reveals the skeleton of a more complete Therizinosaurus specimen paleontologists can only guess what this incredible beast would have looked like. It is possible that all of the current beliefs about the Therizinosaurus are complete fantasy but for now they are all that can be determined about the physical appearance of this unusual beast by utilizing common families of similar dinosaurs. It is the hope of dinosaur lovers everywhere that Mongolia will soon reveal future Therizinosaurus discoveries but until then we are left to rely upon estimations and assumptions about this great Cretaceous beast.

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