Baryonyx

*Baryonyx walkeri*

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***Baryonyx*** (meaning "heavy claw") is a species of large, carnivorous spinosaurid dinosaur discovered in clay pits just south of Dorking, England.

The species only known from a single; subadult; specimen, and because remains of its last meal were discovered fossilized in its ribcage; both remains of fish and a juvenile Iguanodon; it gave true clear indication that spinosaurids wouldn't have only ate fish. It lived in the Barremian period of Early Cretaceous, around 125 million years ago.

## Description

*Baryonyx* estimated about 7.6 to 9 meters long (25 to 29 feet) and around 2.3 meters (7.5 feet) tall at the hip. It probably weighed in the region of 1-2 tons, but analysis of the bones suggests that the only known specimen was not even fully grown. The fact that the skull and vertebra of *B. walkeri* holotype specimen (NHM R9951) do not appear to have fused suggests that the individual was not even fully grown, and the mature animal may have been much larger; as is the case for some other species of spinosaurids.

On the other hand, the specimen's fused sternum indicates that it may have been mature. *Baryonyx* is a very unusual tetanuran. The design of its hips and pelvis suggests that it was bipedal for the purposes of walking from place to place. However, its forelimbs were large for a theropod, this has been speculated by some, that it being an indicator of the theropod spent at least some of its time on all fours. Unlike dromaeosaurids, the creature had a long curved claw on the thumb of each hand, rather than on its hind legs. This claw measured at about 30.4 centimeters (12 inches).

### Anatomy

The skeleton was not arranged exactly as it would have been in life (articulated), so the paleontologists reconstructing it placed them on the front feet because these legs were so powerful. The bone structure suggests a massive bulk of muscle ran down the sides of these front legs, and it therefore seems probable that the claws were placed here.

The long neck was fairly inflexible, and was not S-shaped as in many other theropods. The skull was set at an acute angle, not the 90° angle common in similar dinosaurs. The long jaw was distinctly crocodilian, and had 96 teeth, twice as many as its relatives. Sixty-four of the teeth were placed in the lower jaw (mandible), and 32 large ones in the upper (maxilla). The snout probably bore a small crest.

According to a scientific study officially published in 2023; Spinosauridae families; in particular specimens taken as exemplary samples and clade representatives from Baryonychidae; shows their brain anatomy and skull cavity structure shows no identifiable differentiation or any significant deviation from other common Theropod clades; particularly megalosauridae . The results interpreted as these theropods; presumably, showing similar behavior and traits with other general theropods in terms of brain structure and behavior.

## Classification

Baryonyx was a basal member of the Spinosauridae family within the Megalosauroidea. It was a member of the sub-family Baryonychinae.

## Paleobiology

Until the discovery of the closely-related *Suchomimus*, *Baryonyx* was the only known piscivorous (fish-eating) dinosaur; the crocodile-like jaws and large number of finely serated teeth suggested to scientists that *Baryonyx* was a fish-eater.

As confirmation, a number of scales and bones from the fish *Lepidotes* were also discovered in the body cavity; However bones of an immature *Iguanodon* were also found in direct association with the *Baryonyx* skeleton. A definitive proof, that *Baryonyx* wouldn't have only gone after fish. Even more fossil evidence shows the Portuguese/Iberian Baryonyx fossils are, also, found directly associated with Iguanodon teeth, and listed with other such associations as support for opportunistic feeding behaviour in spinosaurs

It was one of the biggest carnivores of its habitat; its only competitor was the *Neovenator*; a relative of the *Allosaurus*.

Thought not depicted as a truly semiaquatic theropod, a 2022 study presented that it had the physical features fit for such an animal.

## Paleoenvironment

It is speculated that *Baryonyx* would sit on a riverbank, resting on its powerful front legs, and then sweep fish from the river with its powerful striking claw. This is similar to the modern grizzly bear. The long but low stance and angled head support this theory.

## JPInstitute.com Description

Baryonyx was first discovered in a clay pit in England in 1983 by an amateur fossil collector named William Walker. He found its one-foot-long hand claw and took it to the British Museum in London for help in finding out just what he had discovered. Like its relative, Spinosaurus, this dinosaur seems to have eaten mainly fish. It is thought that the huge claw on its hand would have been used to reach into the water and hook the fish.

The body and back legs of Baryonyx are similar to other theropod dinosaurs, but from there it gets a little peculiar. The arms were long and powerfully built. They had three fingers, one with an enormous claw. The skull was long and low with twice as many teeth - 128 - as most other theropods. Even more strangely, the nasal openings were located on top of its head, just in front of the eyes. It had teeth similar to Spinosaurus, long and conical with small serrations, which was also very unlike most theropods. Baryonyx's neck was long and relatively slender. It is no accident that its skull and teeth are very similar to those of a crocodile as they probably both had a diet consisting primarily of fish. Imagine them as huge reptilian grizzly bears, fishing with those terrible foot long claws.

Scientists are still studying the curiosities this dinosaur presents. It seems to combine some very primitive characteristics with more advanced dinosaurian design. As the only known specimen seems to have been a sub-adult, the upper limits of its size are still theoretical.

## Dinosaur Field Guide Description

Baryonyx ("heavy claw") was discovered by an amateur fossil hunter, William J. Walker, who came across its enormous thumb claw in a clay pit in Surrey, England. Further digging by paleontologists revealed one of the largest meat-eating dinosaurs ever found in Great Britain. Baryonyx is a spinosaur; a member of the same group as the northern African dinosaurs Spinosaurus and Suchomimus. Baryonyx was smaller than these relatives but was still a big predator. It had a long, narrow snout filled with teeth that were cone-shaped-a real difference from the blade-shaped teeth of typical meat-eating dinosaurs. Because of the shape of its snout and teeth (both of which are similar to those of modern crocodiles and alligators), some paleontologists think that Baryonyx ate lots of fish. Others, however, think that it ate other dinosaurs, In fact, both ideas are supported by the original Baryonyx specimen from Surrey. In the guts of this dinosaur, paleontologists found the partially digested scales of large fish as well as the partially digested bones of a young Iguanodon. This strongly supports the idea that Baryonyx ate both fish and dinosaurs!

### Fun Facts

Baryonyx was given the nickname "Claws because of its giant thumb claw.

### Trivia

Baryonyx is the only definite spinosaur known from a northern continent.

## Links

http://web.archive.org/web/20040113115813fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_baryo.html

## References

1. ↑ https://pubmed.ncbi.nlm.nih.gov/36781174/
2. ↑ https://blog.everythingdinosaur.com/blog/\_archives/2023/02/14/spinosaurs-modified-skulls-but-conservative-brains.html
3. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703214/
4. ↑ https://www.nationalgeographic.com/science/article/spinosaurus-had-penguin-like-bones-a-sign-of-hunting-underwater

* https://www.nhm.ac.uk/discover/dino-directory/baryonyx.html
* https://kids.britannica.com/students/article/Baryonyx/310096
* https://pubmed.ncbi.nlm.nih.gov/3785404/
* https://www.smithsonianmag.com/science-nature/how-baryonyx-caused-the-great-spinosaur-makeover-113934266/
* https://www.deviantart.com/britishpalaeontology/art/Baryonyx-walkeri-skeletal-809007250https://www.researchgate.net/publication/285762094\_A\_new\_specimen\_of\_the\_theropod\_dinosaur\_Baryonyx\_from\_the\_early\_Cretaceous\_of\_Portugal\_and\_taxonomic\_validity\_of\_Suchosaurus
* https://www.nature.com/articles/324359a0
* https://www.nhm.ac.uk/discover/how-did-baryonyx-change-what-we-knew-about-spinosaurs.html