What is an Alioramus?
Alioramus became known from parts of a skull and three foot bones, which were found in the sediments of humid floodplains near Bayankhongor in Mongolia. These belonged to the Upper Cretaceous.
Russian paleontologist Sergei Kurzanov named and described this new species of dinosaur in 1976.. It was also determined that it is a sub-branch of the Tyranosauridae, which is within the Tyranosaurinae. This would be closely related to the Tarborsaurus bataar.
This relationship is due to the fact that it has a longer snout and more teeth than the Tyrannosauridae. Furthermore, the holotype specimen could be a juvenile specimen.
A second species, the Alioramus altai offered a more complete skeleton. It was described by Stephen L. Brusatte and a team in 2009. It had a row of five bony protuberances on the upper edge of its snout.
This established a characteristic that differentiated it from other specimens of its species.
It was also smaller than other tyrannosaurs. The skull of Alioramus remotus It measured about 45 cm in length.
On the back it had a small crest, which projected forward and was formed by the fused parietal bones. This was a common feature in tyrannosaurs.
The crest of Alioramus was very thick, similar to that of Tarbosaurus and Tyrannosaurus. Its lower jaw was long and narrow, which could also be indicative that it was a specimen that had not yet reached the adult stage.
Paleontologists long placed Alioramus within the tyrannosaurs, as there was not enough fossil evidence to give it a more accurate classification.
Before he found it Alioramus altaia publication on a cladistic analysis from 2003 placed the Alioramus in the family Tyrannosauridae and in the subfamily Tyrannosaurinae. In this way it was classified alongside Tyrannosaurus, Tarbosaurus and Daspletosaurus.
Another 2004 study supporting this finding suggested that it was equally likely to be part of the family Tyrannosauridae, in a more basal position within the Tyrannosauroidea.
Further research was unable to classify it due to a lack of fossil material. Despite the discovery of Alioramus altai In 2009 he confirmed for sure that it was part of the Tyrannosaurinae.
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Finding of the Alioramus
The discovery of Remote Alioramus It was the merit of an expedition that was carried out in Mongolia with a contingent of Russian and local specialists who investigated the Gobi Desert in the early 1970s. They found a partial skull and three metatarsal bones in what is known as Nogon-Tsav in Aimag in Bayankhongor.
The Russian paleontologist Sergei Kurzanov described and named them in 1976. Among their characteristics he indicated the humps and a flat skull that would differentiate them from other tyrannosaurs. This motivated the name that refers to its specific characteristics.
On the other hand the Alioramus altai was described by Brusatte, Carr, Erickson, Bever and Norell. This one had an almost complete skull, and in a good state of preservation.
What does Alioramus mean?
The name Alioramus comes from Latin alius What does it mean different and of ramus what does it mean branch. In this way it clearly establishes that it is a different branch.
The epithet remutus in latin it means remove. In the case of Altai This refers to the Altai mountains, which was where the second specimen was found.
The Tyrannosaurinae family
Alioramus was part of the family Tyrannosaurinae whose name means shaped like a tyrant lizard. It is a subfamily of the Tyrannosauridae, which were part of the coelurosaur theropod dinosaurs.
This consisted of at least three tribes, which included several genera. All fossils of these genera have been discovered in deposits corresponding to the Upper Cretaceous, in what is Western North America and Eastern Asia.
When compared to the subfamily Albertosaurinae with which it is related, tyrannosurines mostly have a more robust and larger structure. The exception would be presented by Alioramus which was more agile in comparison.
This subfamily also includes the oldest genus of tyrannosaurids called Lythronaxand also the youngest and possibly one of the last known as Tyrannosaurus.
In the same way as the Albertosaurus, the tyrannosaurus had a set of teeth. heterodont. That is to say, it had more than one type of tooth, since they adapted to different functions.
Their large heads were designed to catch and kill their prey. They also had short teaching arms. Based on the growth stages of Tyrannosaurus, and probably also those of Tarbosaurus, the Tyrannosaurinae underwent ontogenetic changes in which they gained height, agility, and size.
In this way they covered different ecological niches as they developed. While there is evidence that earlier tyrannosauroids possessed feathers, there is no agreement on this topic in the Tyrannosaurinae.
In a study that Bell and his collaborators carried out in 2017, they could not demonstrate that the specimens of this group had a feathered integument. They used small skin impressions, which are scattered along the postcranium in different parts of the body. It turned out that they had a pattern similar to that of crocodiles.
Thomas Carr and his team in 2017, when studying the snout of Daspletosaurus, suggested that they had large scales with connections to sensory neurons under the skin.
Tyrannosaurus lived from 80.6 million to 66 million years ago, during the Late Cretaceous. Different fossils have been discovered in various formations in North America and Asia.
Although the alioramis from Asia are the most basal group of Tyrannosaurus, the geographical location and other eutyranosaur tyrannosaurs in North America would suggest that the group largely has its origin in the United States.
Until 2010, the relationships of tyrannosaurines were simpler since Tyrannosaurus had a taxonomic relationship with Tarbosaurus. These in turn were considered twinned with Daspletosaurus, which was more related to Tarbosaurus and Alioramus than to Tyrannosaurus.
Gregory Paul in 1988 considered that all tyrannosaurs so far, except for Aliramus, were a species of Tyrannosaurus. In the second edition of the publication The Princeton Guide To Dinosaurs In 2016, Paul also included Bistahierversor, Teratophoneus, Lythronax, and Nanuqsaurus.
Characteristics of Alioramus
Although the fossil material of Alioramus could be scarce, scientists have managed to identify its peculiarities. Keep reading below to find out about them.
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Classification
Initially paleontologists placed Alioramus within the Tyrannosauroidea. But they soon reconsidered this due to the scarcity of fossil remains. The 2003 cladistic analysis placed it as a member of the Tyrannosauridae and within the Tyrannosaurinae subfamily. It was later assigned a possible basal position within the Tyrannosauridae.
Hunting specialization
The legs of Alioramus were characterized by having lower limb segments that were proportionally longer. This is a peculiarity similar to that of Gallimimus. Such longer legs fit the tyrannosauroid body morphs in younger individuals.
Even consistent evidence has been observed in Albertosaurus that tyrannosauroids had proportionally longer legs when they were young. These became shorter as they reached adulthood.
This was an adaptation that allowed small tyrannosaurs to hunt small, fast prey until they grew up. They would then eat slower and larger prey, for proper food management.
In any case, as long as there are no more fossils of juvenile or adult specimens, it is not possible to determine the characteristics of their legs with certainty. However, the fact that its legs still maintained these proportions was ideal for a fast race, at a stage when its overall growth would be slowing.
With this particularity it can be seen that he was relatively agile and fast compared to others in his class.
In fact, it stood out for its graceful shape, which may be indicative that it was a niche specialist that hunted dinosaurs, too fast for the Tarbosaurus. This would give him a concrete advantage in his survival.
Its numerous teeth were of moderate size. They were spaced and arranged with relative uniformity. So his ideal prey were fast ones without armor or shield. This also gave it a larger area to capture its food.
The fact that they had a narrow skull also meant biting muscles that were narrower and weaker, confirming the requirement that their prey be soft and unarmored (carapace).
Specimens such as Daspletosaurus and Tyrannosaurus had large teeth and deep snouts to house powerful biting muscles that could reach the bone of their prey. This is also proven by fossil evidence.
Something more curious is that the coexistence of Alioramus with Tarbosaurus in the same site seems to be indicative of a robust and graceful morphological disposition in the dinosaur family, which could be observed on more than one occasion.
This seems to have been repeated in North America with the Daspletosaurus which was robust and the Gorgosaurus which was more graceful. Another example is the Tyrannosaurus which had an iron build with the Albertosaurus which was more agile. In all cases they were present in the same areas.
Morphology of your body
The shape of its head was similar to that of the basal members of the Tyrannosauroidea, whose shape was that of small theropods. The fact that it retained this morphology suggests that it was undergoing a different evolutionary path that allowed the retention of this more basal trait.
It had five centimeter-high ridges that extended along the top of its snout. Such ornamentation is unknown in later tyrannosauroids, which were also larger.
The fact that earlier specimens such as the Guanlong possessed them could be an indication that the Alioramus was experiencing a regression to its previous forms. They had a sexual function, since the largest ones were the most attractive to the opposite sex.
In the same way, these would have served to differentiate between members of its own genus and juvenile Tarbosaurus that could have been similar.
On the other hand, its dimensions have been a matter of controversy. When the specimen was studied remotus Its estimated size turned out to be 5 or 6 meters long…