Acrocanthosaurus‭ (‬High spined lizard‭)

Short Info

Acrocanthosaurus‭ (‬High spined lizard‭)

Phonetic : Ak-row-can-fo-sore-us

Named By : John Willis Stovall‭ & ‬Wann Langston,‭ ‬Jr.‭ ‬-‭ ‬1950

Diet : Carnivore

Size : Up to 11.5 meters long

Type of Dinosaur : Large Theropod

Type Species : A.‭ ‬atokensis‭ (‬type‭)‬

Found in : USA,‭ ‬Oklahoma,‭ ‬Antlers Formation,‭ ‬and the Texas,‭ ‬Twin Mountains Formation.‭ ‬Some specimens from other parts of the US

When it Lived : Early Cretaceous, 115-105 million years ago

Acrocanthosaurus (/,aekroU,kaenth@’so:r@s/ ak-ro-KAN-th@-SAWR-@s; meaning “high-spined lizard”) is a genus of carcharodontosaurid dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. As with most dinosaur genera, Acrocanthosaurus is the only kind of species: A. atokensis. The fossil remains are discovered mostly throughout three U.S. states of Oklahoma, Texas, and Wyoming teeth, however teeth believed to belong to Acrocanthosaurus have been discovered in the east of Maryland which suggests that the continent has a that spans a large area.

Acrocanthosaurus was an animal that was a bipedal predator. The name implies that it is most well-known for the large neural spines found on several vertebrae that most likely provided a muscle ridge across the animal’s neck, back and hips. 1 Acrocanthosaurus was among the largest theropods. It was 11.5 meters (38 feet) in length and weighing in excess of 6.2 meters (6.8 shorter tons). Theropod footprints that are large found in Texas could have been created by Acrocanthosaurus however there is no evidence of a direct link with skeletal remains.

Acrocanthosaurus skeleton (1)
Famille Wielosz-Caron, CC BY 2.0, via Wikimedia Commons

Recent discoveries have clarified numerous details about its anatomy and allowed for the development of specialized research focused on its brain structure and the function of its forelimbs. Acrocanthosaurus was one of the most massive theropod of its environment and was likely to be an apex predator that was a prey for sauropods, ornithopods, as well as ankylosaurs.

Acrocanthosaurus is named for its large neural spines taken from the Greek Akra/Akra (‘high’), akantha/akantha (‘thorn or’spine’) and saUros/sauros (‘lizard’). There is a single species named (A. atokensis) and it is named for Atoka County in Oklahoma, which is where the original specimens were discovered. This name was invented in the year 1950 by American paleontologists J. Willis Stovall and Wann Langston Jr. Langston had suggested his name “Acracanthus atokaensis” for the species and genus in his unpublished master’s thesis. However, the term was later changed Acrocanthosaurus atokensis to make it official.

The holotype and the paratype (OMNH 10146 as well as OMNH 10147) were discovered in the early 1940s , and published in 1950, are comprised of two skeletons that are partially complete and an ossified piece of skull material found in the Antlers Formation in Oklahoma. Two more complete specimens were discovered in the late 1990s. One (SMU 74646) is a fragmented skeletonthat is missing the majority of the skull. It was recovered out of the Twin Mountains Formation of Texas and is now in the Fort Worth Museum of Science and History collection. Another skeleton that is more complete (NCSM 14345, also known as “Fran”) was recovered from the Antlers Formation of Oklahoma by Cephis Hall and Sid Love, prepared by the Black Hills Institute in South Dakota which is currently in the North Carolina Museum of Natural Sciences in Raleigh. This is the largest specimen and contains the only fully-constructed skull as well as forelimb. The skull bones from OMNH 10147 are nearly identical to comparable bones found in NCSM 14345 which suggests an animal that is roughly the same size, whereas the Holotype along with SMU 74646 are much smaller.

Acrocanthosaurus Hendrickx
Christophe Hendrickx, CC BY-SA 3.0, via Wikimedia Commons

The existence of Acrocanthosaurus in the Cloverly Formation was established in 2012 by the description of another partial skeleton UM 0797. The specimen, comprised of pieces of two vertebrae pubic bones that are partially buried as well as a femur, partial fibula, as well as fragments, indicates an animal that was a young one. It was found in a bone bed located in the Bighorn Basin of north-central Wyoming It was discovered close to the shoulders of the Sauroposeidon. A variety of other fragmentary remains from the formation might be related to Acrocanthosaurus that could be the only significant theropod found in the Cloverly Formation.

Acrocanthosaurus could be identified from the less complete remains the boundaries of Oklahoma, Texas, and Wyoming. A tooth found in southern Arizona is referred to as the genus and similar teeth marks were discovered in sauropod bone from the same region. A number of teeth found in The Arundel Formation from Maryland are described as nearly identical to those found in Acrocanthosaurus and could represent one of the eastern representatives in the Genus. A variety of other bone and teeth from different geologic formations across Western United States have also been called Acrocanthosaurus however, the majority of them are misidentified although there is there is some doubt about the assessment of fossils from the Cloverly Formation.

Acrocanthosaurus was one of the largest theropods to exist. The largest fossil (NCSM 4345) is thought to be 11.5 millimeters (38 feet) from the snout to the tip of its tail and measured 5.7 to 6.2 tonnes (6.3 to 6.8 short tons) and a maximal weight at 7.25 tonnes (7.99 shorter tonnes) within the range of possibility for the specimen. The skull itself was almost 1.3 meters (4.3 feet) long.

Acrocanthosaurus skeletons
Carpenter, Kenneth, CC BY-SA 4.0, via Wikimedia Commons

The skull of Acrocanthosaurus as with other allosauroids, was large and narrow, as well as low. The opening that reduced weight just in the front of the socket for the eye (antorbital the fenestra) was quite big over half all the width of the skull, and about the equivalent of two-thirds height. The exterior of the maxilla (upper jaw bone) as well as the upper portion of the bone on the top of the snout were much rougher than those that were found in Giganotosaurus as well as Carcharodontosaurus. The ridges were long and low. They arose from the nasal bones which ran along the entire length of the snout and from the nostril and back towards the eye, and they continued to the lacrimal bone. This is a common aspect of all the of the allosauroids. As opposed to Allosaurus There was no obvious lacrimal bone with a crest just in front of the eyes. The postorbital and the lacrimal bone came together to form a strong eyebrow over the eye, as observed in carcharodontosaurids, as well as the unrelated abelisaurids. Nineteen serrated, curved teeth lined both sides of the jaw’s upper part. However, the number of teeth in the lower jaw hasn’t been released. Acrocanthosaurus teeth were wider than those of Carcharodontosaurus and did not have the wrinkled texture that characterized the carcharodontosaurids. Dentary (tooth-bearing lower jawbone) was rounded off on the front like in Giganotosaurus and was also was a little slender and the rest of the jaw that was behind was extremely deep. Acrocanthosaurus and Giganotosaurus were both surrounded by a massive horizontal ridge along the exterior face of the supragnaular bone that forms the lower jaw, beneath the articulation of the skull.

The most prominent feature in Acrocanthosaurus was its large neural spines. They were situated in the vertebrae on the back, hips, neck and the upper tail. They can be as high as 2.5 times the size of the vertebrae to which they extended. Some dinosaurs had tall spines on their backs which were often higher than the ones of Acrocanthosaurus. For example the African Genus Spinosaurus had spines up to 2 meters (6.6 feet) tall, which is about 11-times taller than vertebrae of its bodies. In the lower part of its spines, Acrocanthosaurus were attached to powerful muscles similar to those found in modern bison, likely making a long, strong ridge that ran down the back of its. The purpose of the spines is still unclear however they could be involved in communication, fat storage muscles, or temperature control. The cervical (neck) and dorsal (back) vertebrae showed distinct depressions (pleurocoels) along the sides as well as their cervical (tail) vertebrae had smaller ones. This is more like carcharodontosaurids rather than Allosaurus.

Apart from vertebrae, Acrocanthosaurus was a typical allosauroid skeleton. Acrocanthosaurus was bipedal, having the long, massive tail that balanced the body and head while keeping it’s center of gravity above its hips. The forelimbs of Acrocanthosaurus were smaller and stronger than the forelimbs of Allosaurus however, they were remarkably similar and each had three clawed fingers. In contrast to other dinosaurs that were smaller and faster-running the femur of Acrocanthosaurus was larger than its metatarsals and tibia and metatarsals, indicating that Acrocanthosaurus wasn’t a quick runner. Not surprisingly, its hind leg bone of Acrocanthosaurus were more robust than the smaller Allosaurus. Its feet were four digits, but like theropods the first one was smaller than the rest , and did not touch the ground.

Source: Wikipedia