• Acrocanthosaurus

Acrocanthosaurus atokensis was a theropod dinosaur, part of the Carnosauria family. The remains of this specimen include several partial skeletons, and a practically complete skeleton, which were found in the United States.

It was a large bipedal carnivore that was originally known as Achocantus, when the first fossil was found in 1947. It later obtained the designation Acrocanthosaurus.

The skeleton, nicknamed Fran, had a length of 11.5 meters. Its skull measured 129 cm, making it slightly longer than Allosaurus. It is estimated that it could weigh up to 6 tons. It is one of the best-known theropods, and was a little smaller than its relative the Giganotosaurus that could measure up to 13 meters in length.

It had two additional small cranial openings in the maxilla, in addition to the usual five. It also had an antorbital window, which was an opening in the skull that was in front of the eye opening. Unlike many relatives, Acrocanthosaurus did not possess cranial horns.

The cervical, caudal, and anterior dorsal vertebrae had processes elongated about 2.5 times longer than the respective vertebrae. These vertebral spines have also been found in other dinosaurs such as the Spinosaurus Egyptianon, which holds the record with a length of 1.5 m.

It is possible that the vertebral spines in Acrocanthosaurus formed a low sail. It is also likely that like modern bison, they were surrounded by muscle that formed a high hump on their back.

Finding of the Acrocanthosaurus

The description of Acrocanthosaurus was made in 1950 by paleontologists Willis Stoval and Wann Langston. It was based on 2 partial skeletons that included part of the skull, which were found in the Antlers formation in Oklahoma.

Two additional skeletons have also been described. One comes from the Twin Mountain Formation in Texas, which is 70% preserved.

The other is the one nicknamed Fran and was also found in the same place. It is the most complete Acrocanthosaurus fossil to date. Even his skull is complete. Numerous individual bones and bone fragments were also recovered in Texas, Oklahoma, and Utah. In the latter case in the Cedar Mountain Formation.

These discoveries date back to the Aptian and middle Albian, which place Acrocanthosaurus between 126 and 108 million years ago. Deinonychus, Sauroposeidon and Tenontosaurus lived at that time and in the same territory.

That is why they constitute one of the richest dinosaur faunas of the Cretaceous, in which Acrocanthosaurus was the main predator.

A discovery of three dorsal bones in England, which possessed even taller spines, were initially named Acrocanthosaurus altispinax. But it was later assigned separately to the genus Becklespinax.

There were many fossil footprints in the United States that have been attributed to Acrocanthosaurus. The most famous are the Glen Rose footprints at Dinosaur Valley State Park in North Texas.

It is not possible to say if it is really a footprint of this dinosaur. But they are known to be approximately the same age, according to fossils. They also have the appropriate size, which increases the possibility that it does belong to you.

Some of these marks were found near those left by a herd of sauropods, as they pointed in the same direction as those of these herbivores. This suggests that they followed these groups of dinosaurs on their migrations and preyed on those who were vulnerable, either because they were weak or sick.

What does Acrocanthosaurus mean?

Acrocanthosaurus was named after its vertebral spines. Comes from Akro either highof akantha or spike and also saurus What does lizard mean? The epithet albertensis was added in honor of the site of its discovery in Atoka Country, which was where the holotype material was found.

The Carnosauria group

It is a superfamily of giant theropod dinosaurs that existed during the Jurassic and Cretaceous periods. It covers a large majority of the largest land carnivores of all time, such as Carcharadontosaurus, Giganotosaurus, and Allosarus. However, the one that is left out is the Tyrannosaurus rex.

They had a large size, large eyes, an imposing skull and short front legs., along with powerful hind limbs, particularly adapted for running. They were capable of taking imposing prey.

They originated among the primitive tetanurans that were part of the megalosaurids, such as Megalosaurus or Magnosaurus from the Middle Jurassic. The first carnosaurs must have developed at the end of this era, but very few are known, such as the Metriacanthosaurus from England.

This group is made up of two families. We are talking about allosaurids and synraptorids. The first are typical of the United States and the second were lighter and have been found in Asia.

They constituted the highest links in the food chain of their habitat. But at the beginning of the Cretaceous, they became extinct, leaving in their place the carcharodontosaurids that were characteristic of Africa and South America.

Acrocanthosaurus atokensis vs Spinosaurus aegyptiacus

Dinosaurs were characterized by having unique characteristics with their advantages and disadvantages. To understand them better, it is useful to compare them with those of another specimen with similar characteristics. Let’s see below.

Acrocanthosaurus atokensis

It was a theropod dinosaur that lived during the Cretaceous period in North America. It only has the species A. atokensis, which lived in Oklahoma, Texas and Arkansas. It was a bipedal predator, with tall neural spines on many of its vertebrae.

They probably supported a muscular crest over the animal’s neck, back, and hips. It was 12 meters long and could weigh between 6 and 7 tons. It was the largest theropod in its ecosystem. It is estimated that it was a predator of sauropods and ontitopes.

Spinosaurus aegyptiacus

The spinosaurus was a theropod that lived in North Africa, in the Cretaceous period between 112 to 97 million years ago. It was the largest of the known carnivores. It was about 18 meters long and weighed up to 20.9 tons.

Its skull was long and narrow, and it was known that it ate fish. The growth of its vertebrae was at least 1.65m in length and it is thought that they were covered by a skin that connected them.

In this way it formed a structure composed of a sail, possibly covered in fat, that formed a hump. It has been proposed that its function was thermoregulation and visualization.

Who would win?

Although they did not coexist at the same time, everything seems to indicate that in a fight between these specimens the Spinosaurus would have emerged victorious. It had a larger size, more strength and an attack capacity that Acrocanthosaurus atokensis could not have surpassed.

Characteristics of Acrocanthosaurus atokensis

Since it is a species with a good variety of fossils available, it has been possible to study it and understand it better. The following are its characteristics.

Classification

There is no definitive agreement on the place that Acrocanthosaurus atokensis should occupy within the Allosauroidea. This group consists of the families Allosauridae, Carcharodontosauridae and Sinraptoridae.

Initially it was placed within the Allosaurids. But many specialists today consider it more of a carcharodontosaurid, although this has also been reconsidered in recent studies.

Some research seems to reflect that its skull does not have any typical characteristics of carcarondontosauruses, so it could not be part of this group. However, a 2002 study detected clear similarities between the skulls of Acrocanthosaurus, Allosaurus and Carcharadontosaurus.

In 2001 it was proposed to form the family Acrodontosaridae, in which Acrocanthosaurus should be classified together with Carcharodontosaurus. But this is also rejected by most researchers today.

brain structure

In 2005, a study was carried out using computed tomography through which the material from the holotype skull of Acrocantosaurus was digitized. This is how his brain and neural pathways were rebuilt.

It could be observed that the olfactory bulbs were large and thick, which indicated that they had a great sense of smell. Reconstruction of the semicircular canals of the ear showed that his head maintained an angle of 25 degrees below the horizontal.

Its brain was S-shaped, similar to that of a crocodile.. It was most similar to that of Carcharodontosaurus and Gigantonosaurus. This reinforces the idea that it belongs to the carcharandontosaurids.

The use of computed tomography was a relatively new method in paleontology, which has also been used to reconstruct brain casts of large theropods such as Tyrannosaurus, Ceratuosaurus, Allosaurus and Carcharodontosaurus.

Habitat

The site where Acrocanthosaurus inhabited was a swampy area with an exit to the sea. Changes that would happen over the next few million years would include a maritime invasion that would create the Niobrara Sea, which would divide North America in two until the end of the Cretaceous.

This coastal environment was what allowed this dinosaur to leave its footprints in the marshes or swamps. It was the largest predator in its environment and lived in vast territories that it needed to hunt.

Some of their prey were species such as Paluxysaurus, Sauroposeidon, Denonicchus and Tenontosaurus.

Feeding

Acrocanthosaurus was a ferocious carnivore and a fearsome hunter. It had strong jaws and three-clawed limbs with which it easily tore apart its prey. It could take down ornithopods and sauropods.

It is possible that Deinonychus was also its rival, and that it lived alongside Utahraptor, although there is no fossil evidence of this.

Speed

The hind legs of the Acrocanthosaurus were very firm and strong. It is possible that they allowed him to display maximum speed and attack power. It is thought that a fully developed adult specimen could reach 32 kilometers per hour.

Behavior

The Acrocanthosaurus was a vicious and very aggressive predator. It displayed its ferocity at levels similar to the Spinosaurus or the T-rex. This was stimulated by search and competition for food, territory and possibly by claiming mating rights. It is to be expected that it would threaten by showing its sharp teeth and crouching to attack.

Life expectancy

Although theropods could live around 40 years, it is thought that the lifespan of Acrocanthosaurus was approximately 70 years.

Why did Acrocanthosaurus become extinct?

There is no concrete evidence to explain why Acrocanthosaurus became extinct. But there are some theories about it.

Acrocanthosaurus atokensis exhibited traits ideal for hunting giant prey, particularly…