I➤ Amphicoelias – Resumenea

What is an Amphicoelias?

He Amphicoelias altus It was a diplodocid dinosaur, named in 1877 by Edward Drinker Cope. He did so from the study of an incomplete skeleton that only had two vertebrae, a pubis or hip bone and a femur or thigh bone.

A year later Cope found parts of another species in Colorado, which was very large but very deteriorated. She called Amphicoelias fragillimus. The discovery was packaged and shipped to New York, but never reached its destination.

The only thing that remained of this discovery was a sketch and a description, so this specimen retains the status of a doubtful species. Some time later in 2018 there was a new description from Kenneth Carpenter, who appointed A. fragillimus as a new genus which he called Maapunisaurus fragilis.

Previously in 2015, Emanuel Tschopp and a group of collaborators classified Amphicoelias in the family Diplodocidae, as a result of a comprehensive phylogenetic study.

Finding of Amphicoelias

The first discovery of Amphicoelias fossils was in 1877 by Oramel William Lucas, who found them on rock outcroppings in Colorado, near Canyon City. Then Edward Drinker Cope assigned its origin to the Cretaceous Dakota Formation in the same way as other specimens such as Camarasaurus supremus, Caulodon and Laelaps trihedrodon.

These remains were sent to Cope, who studied them and determined that they corresponded to the Sauropoda taxon. He named it as Amphicoelias altus. He also specified that it was related to the Camarasaurus, which had also been found in the area. This was because both specimens had solid limbs and light vertebrae.

The collection was sold by Cope to the American Museum of Natural History shortly before his death. He had previously worked with the artist Charles Knight to represent various species of dinosaurs, including the Amphicoelias altus.

Cope considered Amphicoelias and to Brontosaurus as minor synonyms of Camarasaurus supremus.

Based on the collection data, it was indicated that the specimen originated in the Morrison Formation of the Late Jurassic, within the most recent layers, which were apart from the fossils of the Camarasaurus.

Then a third species entered the scene, which was named Amphicoelias fragillimus. It was a very deteriorated fossil that contained an incomplete neural arch of 1.5 meters, which would have originally measured 2.7 meters.

In 2018 it was assigned as a primitive rebbachisaurid and named Maraapunisaurus fragilis.

In an informal publication in 2010 Raimundo Albersdorfer and Henry Galiano described the species A. brontodiplodocus. It was made from complete specimens found at Dana Quarry in Wyoming, which are part of a private collection.

The idea was based on a kind of sexual dimorphism or growth stages that would represent the majority of specimens of Amphicoelias. However, the hypothesis was viewed with skepticism by the scientific community. Some time later the same author rejected the article.

In 1921, A. altus and A. fragillimus They were considered synonymous by Osborn and Monk. In fact they suggested that the A. fragillimus It was actually a larger version of A. altus. This was accepted by many specialists, except for Carpenter who rejected this classification in 2006.

Citing differences in the structure of their vertebrae, which Cope himself pointed out at the time, he proposed that they were sufficient to establish a new species, or a genus separate from A. fragillimus.

Although he also recognized that the validity of the proposal was not possible to determine without the original fossil.

What does Amphicoelias mean?

The name Amphicoelias comes from the Greek amphi what does it mean on both sides and koilos what is gap either concave. Therefore his name is translated as hollow on both sides either biconcave.

The epithet altus It was possibly chosen to reference his height. In the same way fragillimus describes the state of deterioration of the skeleton found.

The Diplodocidae family

The Amphicoelias belonged to the Diplodocidae family. This was a group of sauropod dinosaurs, including some of the longest creatures to ever walk the planet. Two famous representatives are the Diplodocus and the Supersaurus, which are thought to have reached up to 42 meters in length..

While they were massive compared to titanosaurs and brachiosaurs they were actually thin. Although that didn’t take away from the fact that they were very long. Their tails were short, and their hind legs were longer than their front legs.

They also did not have the longest necks. Computer reconstructions indicated that they were unlikely to elevate as most sauropods did. In any case, these studies have been reconsidered because they did not consider the role of vertebral cartilage, which would possibly improve their ability to move.

Consequently, it is estimated that they probably used their necks to graze over a wide area. They could have been used to reach plant matter in dense coniferous forests, or through swampy areas.

They had tiny heads compared to their bodies, and had nostrils on the top of their heads. In life they would have been located near the tip of the snout.

They are often represented with upward-facing nostrils, due to their position on the skull. This has generated hypotheses regarding whether such orientation could be indicative that they had a proboscis.

In 2006 a study stated that there was no evidence that they had it. If so, they would have a facial nerve that is evident and large in animals such as elephants. This was very small in the diplodocids.

On the other hand, they had whip-shaped tails, which were thick at the base, which tapered towards the end, giving them a thin shape. Simulations made from a computer have shown that they could hit with it very firmly to defend themselves.

It would also produce a sonic boom that would be around 200 decibels and that may have served to scare away predators or rivals in the mating era.

Characteristics of Amphicoelias

Amphicoelias was one of the largest and tallest dinosaurs that lived during prehistory. Below you will learn about its most important characteristics.

Classification

In the description made in 1878 in the publication American Naturalist, Edward Drinker Cope assigned the new genus to the family Amphicoeliidae. It is currently considered a nomen oblitumthat is, as a forgotten name.

Today it has been assigned to the Diplodocidae family. However, modern studies have found it to be a diplodocid. incertae sedismeaning it has an uncertain location.

The first species to be named, the Amphicoelias altus It was found in 1877. But although it was a partial skeleton, it had enough unique characteristics to give it an initial description.

Feeding

Amphicoelias fed exclusively on plants, which was the rule with sauropods. It processed it with a long and slow digestive system. This slow digestion allowed it to thrive on foods with fewer calories and a lower level of nutrients than an animal of its size would require.

It is something that can still be observed in large animals today such as giraffes and elephants.

Considering that they lived in what is now the United States, it can be inferred that they fed on plants such as ferns. Added to this were ginkgos, cycads, horsetails, fern seeds and mosses.

Where and when did he live

It lived in the final phase of the Jurassic, between 160 and 145 million years ago.. Its ecosystem likely consisted of a lush tropical savannah and was covered with vegetation on which it could feed. It would be the ideal scenario for the survival and life of sauropods.

Cope’s specimen was found in Garden Park in Colorado. This would be the only confirmed location of the species, although it could possibly have also lived in other nearby places.

Threats and predators

As is often assumed about massive sauropods, the enormous size of this dinosaur would act as a deterrent against possible predators. It was not aggressive, but if it had to defend itself it was capable of delivering blows with its large tail.

The only threat to its existence was possibly climate change and other sauropods with which it would compete for space, food or the right to mate.

Size

The Amphicoelias was a huge specimen, with a long neck, short legs and an extended tail. He weighed less than one might think due to his thin, hollow bones.

It is believed to have had scaly brown skin and a small head compared to the rest of its body.

Estimated measurements often vary. But in general terms It could measure between 40 and 60 meters in length and up to 2.5 meters in height. Instead, Its body volume ranged between 88 and 130 tons..

Biology and habitat

In a 2006 study, paleontologist Ken Carpenter examined why sauropods like Amphicoelias They had reached an enormous size. He indicated that any pressure in the evolutionary process that favored increasing size was already present at the origin of sauropods.

He made comparisons with studies on elephants and rhinos, which showed that their larger size offered them better management of their feeding efficiency. Large animals have longer digestive systems, which helps them survive on lower nutrient food sources.

This is confirmed when observing animals that have fermentation chambers along the intestine, thus encouraging the microbiota to accumulate and deeply ferment the plant matter.

Sauropods typically lived in semiarid environments, which were also seasonally dry. They therefore faced a periodic drop in food availability during droughts.

The habitat of Amphicoelias was mostly a savanna, which had characteristics similar to those of arid environments. This shows that a desert environment favored the evolution of herbivores towards gigantic size.

Such enormous size would also have other benefits, such as relative immunity from predators, lower energy expenditure and a longer life.

The savannah in which Amphicoelias would have lived lacked pastures, something that did not yet exist in the Cretaceous. So it most likely lived on ferns, something that its digestive system could have processed perfectly.

The presence of trunks with a length of 20 to 30 meters would put trees in the scene, something that contradicts the idea of the savanna. However they were rare, their presence was actually limited. More were present…