Ankylosaurus‭ (‬Fused lizard‭)

Short Info

Ankylosaurus‭ (‬Fused lizard‭)

Phonetic : An-kie-lo-sore-us.

Named By : Barnum Brown‭ ‬-‭ ‬1908

Diet : Herbivore

Size : Estimated 6 – 7 meters long

Type of Dinosaur : Armoured Dinosaur

Type Species : A.‭ ‬magniventris (type)

Found in : Alberta – Horseshoe Canyon Formation, Scollard Formation. USA, Montana – Hell Creek Formation, New Mexico – Kirtland Formation, Wyoming – Ferris Formation, Lance Formation.

When it Lived : Late Cretaceous, 74-67 million years ago

Ankylosaurus is one of the genus that includes armored dinosaurs. The fossils are found in fossilized geological structures dating back to the end in the Cretaceous Period, about 68-66 million years ago in the western part of North America, making it one of the last non-avian dinosaurs. The name was coined after Barnum Brown, who was born in 1908, and the only species of the Genus was A. magniventris. The genus’ name is “fused lizard”, and the particular name translates to “great belly”. A few specimens have been discovered until now, however an entire skeleton hasn’t been found. While other members of the Ankylosauria group are represented with more extensive fossil material Ankylosaurus is generally thought of as the archetypal member in the group, despite possessing unique characteristics.

Perhaps the most well-known ankylosaurid, Ankylosaurus is estimated to have measured between 6 to 8 metres (20 and 26 feet) in length and to weigh approximately 4.8 to 8 tonnes (5.3 to 8.8 shorter tons). It was quadrupedal with large, sturdy bodies. It was a large low skull with two horns that pointed backwards from the rear of the head. It also had two horns beneath them which pointed downwards and backwards. Contrary to other ankylosaurs’, its nostrils were oriented sideways, instead of facing towards the front. The front of its jaws were covered by beaks, and rows of leaf-like, small teeth that were further back. The jaws were covered with armor plates or osteoderms. They had bone-like half-rings that covered the neck, and an enormous club at the tail end. Bones of the skull as well as other body parts were joined, increasing their strength. This aspect is the basis for the name genus.

Ankylosaur head - cast - Custer County Montana - Museum of the Rockies - 2013-07-08
Tim Evanson, CC BY-SA 2.0, via Wikimedia Commons

Ankylosaurus is part of the family Ankylosauridae which is the closest relatives seem to be Anodontosaurus and Euoplocephalus. Ankylosaurus is believed to be an animal that was slow moving, but capable of swift movements when required. Its wide muzzle suggests that it was a non-selective hunter. The nasal chambers and sinuses on the snout could be used for heat or balance of water or contributed to vocalization. It is believed to have served as a defense against predators as well as in intraspecific combat. Ankylosaurus is discovered within areas such as the Hell Creek, Lance, Scollard, Frenchman, and Ferris formations, however it appears to be rare in the environment it was found. While it was the nodosaurid ankylosaur areas of operation and niches in ecology don’t appear to have been overlapping, and Ankylosaurus could have been found in areas of upland. Ankylosaurus was also associated with dinosaurs like Tyrannosaurus, Triceratops, and Edmontosaurus.

In the year 1906 in 1906, in 1906, an American Museum of Natural History group under the direction of American paleontologist Barnum Brown, discovered the original sample from Ankylosaurus magniventris (AMNH 5895) within the Hell Creek Formation, near Gilbert Creek, Montana. Its object (found through the efforts of the collector Peter Kaisen) consisted of the upper portion of the skull with two teeth, the upper part of the shoulder’s shoulder girdle cervical, dorsal, as well as caudal vertebrae, ribs and more than 30 osteoderms (armor plates). Brown published a scientific description of the creature in 1908, and the name of the genus originates of the Greek words agkulos ankulos (‘bent or crooked’), referring to the medical term ankylosis which describes the stiffness caused by an fusion between bones inside the body and skull as well as sauros sauros (‘lizard’). The name could mean “fused lizard”, “stiff lizard” and “curved lizard”. Magniventris, the name for the type species, is derived from Latin magnus (‘great’) and Latin venter (‘belly’), referring to the large size in the size of the animals body.

Skull of Ankylosaurus
Barnum Brown, Public domain, via Wikimedia Commons

The skeletal reconstruction that was included with the 1908 report repaired the missing pieces in a way like Stegosaurus and Brown said that the result was similar with the armored mammal that died out Glyptodon. Contrary to the modern portrayals of stegosaurs, Brown’s reconstruction had strong forelimbs, a well-arched rear, and a pelvis that had prongs that protruded forwards from the pubis and ilium and the tail being droopy and short with no tail club that was not known in the early days. Brown also rebuilt the armor plates as parallel rows running along the back, although this design was only a speculative idea. Brown’s reconstruction gained a lot of attention and restorations of the animal that were based on his diagrams were published in the 1980s. In a 1908 critique on Brown’s Ankylosaurus description The American paleontologist Samuel Wendell Williston criticised the reconstruction of the skeleton built on a limited number of fossils and claimed that Ankylosaurus was just an alias for the genus Stegopelta that Williston had declared in 1905. Williston added that a reconstruction of the skeleton of Polacanthus from the Hungarian paleontologist Franz Nopcsa was a better illustration of how ankylosaurs could appear in the real world. The notion of synonymy was rejected in other studies, which is why both genera have been deemed to be distinct.

Brown had found 77 bone fragments during the excavation of the Tyrannosaurus specimen from the Lance Formation of Wyoming in 1900. Brown mentioned the osteoderms (specimen AMNH 5866) in his description of Ankylosaurus but believed that they were from the Tyrannosaurus rather than the Tyrannosaurus. The paleontologist Henry Fairfield Osborn also expressed this opinion in his description of his Tyrannosaurus specimen as being part of the identical Genus Dynamosaurus during 1905. Recent examinations have revealed they are like those found in Ankylosaurus It is believed that Brown had compared them to the Euoplocephalus osteoderms that were incorrectly classified by the name of Ankylosaurus in the AMNH.

In 1910 , another AMNH expedition under the direction of Brown located the remains of an Ankylosaurus species (AMNH 5214) within the Scollard Formation by the Red Deer River in Alberta, Canada. The specimen comprised the complete mandible, skull, the first and only tailclub known in this genus and vertebrae, ribs and the limb bones and armor. In 1947, American fossil hunters Charles M. Sternberg and T. Potter Chamney collected the skull and mandible (specimen CMN 8880, previously NMC 8880) 1 kilometers (5/8 mile) north of the site where that specimen from 1910 was located. It is the most well-known Ankylosaurus skull, however it is damaged in a few places. A caudal vertebrae section (specimen CCM V03) was discovered in the 1960s in the Powder River drainage, Montana which is part of the Hell Creek Formation. In addition to the five specimens that were not fully complete, numerous additional isolated osteoderms as well as teeth have been discovered.

In the year 1990, American paleontologist Walter P. Coombs pointed that two of the skulls’ teeth that were assigned to A. magniventris varied from the holotype specimen in a few particulars. Although Coombs offered the “considerate temptation” to name the different species in the family of Ankylosaurus for theseteeth, he resisted the idea due to the wide range of species-specific variation was not fully documented. Coombs also suggested that the teeth found in the sample of the holocene weren’t part of the species because they were discovered in a matrix inside these nasal chambers. A. magniventris American paleontologist Kenneth Carpenter accepted the teeth as belonging to A. magniventris back in 2004 and concluded that all specimens were of the same species. Carpenter also pointed out that the dental teeth found in different ankylosaurs vary greatly.

The majority of known Ankylosaurus specimens were not described in detail, even though some paleontologists had plans to do so up until Carpenter described the genus again in 2004. Carpenter pointed out that Ankylosaurus had been regarded as the archetypal animal of the group, and is the most well-known of all ankylosaurs within popular media, possibly because of a large-scale reconstruction of the animal which was displayed during the 1964 World’s Fair in New York City. The sculpture, in addition to its counterpart, the American painter Rudolph Zallinger’s 1948 painting The Age of Reptiles and others later popular representations included an image of Ankylosaurus sporting tail clubs, which was its first encounter with the feature in the year 1910. Despite its popularity however, it has less remains than its nearest cousins. In 2017 , Canadian paleontologists Victoria M. Arbour and Jordan Mallon redescribed the genus in light of recent ankylosaur finds, which included parts of the holotype not previously been mentioned within the scientific literature (such as the parts of the skull and neck half-rings). They concluded that even though Ankylosaurus is famous and the most well-known of the group, it was atypical in comparison to the related ankylosaurs and was therefore is not representative for the entire group.

A lot of popularly depicted images illustrate Ankylosaurus in a squatting position and with a massive tail club being pulled over the ground. Modern reconstructions show the creature with a more upright position, and with its tail slung above the ground. Also, the large and imposing spines that extend outwards off the back (similar to those found in ankylosaurs from the nodosaurid genus) appear in a variety of traditional representations, but they aren’t found in Ankylosaurus in itself. The armor of the Ankylosaurus has frequently been confused with the armor of Edmontonia (earlier known as Palaeoscincus) and, in addition to depicting Ankylosaurus sporting spikes Edmontonia was also shown sporting an Ankylosaurus-like tail club (a characteristic that nodosaurids do not have) as well as in a painting by American painter Charles R. Knight from 1930.

Ankylosaurus is the most famous ankylosaurine dinosaur. It was also possibly the biggest ankylosaurid. In 2004, Carpenter determined that the dinosaur with the biggest-known skull (specimen CMN 88880) that measured 64.5 centimeters (2 1+1/2 inches) in length and 74.5 centimeters (2 5 1/4 in) wide, measured 6.25 meters (20 6 inches) in length and was hip-high at around 1.7 1 m (5 7 feet). The skull with the smallest amount of information (specimen AMNH 5214) is 55.5 centimeters (1 9+3/4 in) in length and 64.5 centimeters (2 1 1/2 inches) wide. Carpenter estimates that it was around 5.4 millimeters (17 9 inches) long and 1.4 1 m (4 7 inches) taller on the hips. A study by American paleontologist Roger B. J. Benson and colleagues put the weight of AMNH 5214 as 4.78 millimetric tonnes (5.27 shorter tons) in 2014.

In 2017 Based on comparisons with more complete ankylosaurines Arbour as well as Mallon estimated an approximate length of 7.56 to 9.99 meters (24 9′ 9+1/2” to 32 ft 9+1/2 inches) for CMN 080 in addition to 6.02 and 7.95 m (19 9 ft to 26 feet 1 inch) to AMNH 5214. Although the latter is the tiniest specimen of Ankylosaurus however, its skull is larger than the skulls of other ankylosaurins. Some other ankylosaurs measured around 6 meters (20 feet) of length. Because the vertebrae in AMNH 5214 do not appear to be much larger than other ankylosaurines Arbour and Mallon thought their upper range estimate of about 10 meters (33 feet) for the Ankylosaurus that was large to be too long and suggested an 8-meter length (26 feet) instead. Arbour and Mallon estimated a weight of 4.78 t (5.27 short tons) for AMNH 5214. They also approximated an approximate weight for CMN 080 as 7.95 7 t (8.76 small tons).

Source: Wikipedia