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Baryonyx

Baryonyx ("heavy claw") is a large, carnivorous dinosaur exposed in clay pits just south of Dorking, England. It is known from a single, young specimen, and apparently ate fish because remains of its last meal were discovered fossilized in its ribcage. It has been dated to the Barremian period of Early Cretaceous, approximately 125 million years ago.

Description Baryonyx was about 8 to 10 m long (26 to 33 ft), and around 5 m (16 ft) tall. It almost certainly weighed in the region of 2,000 kg, but psychoanalysis of the bones suggests that the one only known specimen was not yet fully grown. Baryonyx is a very strange tetanuran. The design of its hips and pelvis suggests that it was bipedal for the purposes of on foot from place to place. However, its forelimbs were absurdly large for a theropod, telling that it also spent much of its time on all fours.

Like the dromaeosaurids, the person had a long curved claw on the thumb of each hand, which deliberates at about 31 cm (12 in). However, instead of having them on the rear foot, it is supposed that Baryonyx had them on the frontage feet.

The skeleton was not accepted 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 huge 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 rigid, and was not S-shaped as in many other theropods. The skull was set at an sharp angle, not the 90° angle common in similar dinosaurs. The long jaw was distinctly crocodilian, and had 96 teeth, twice as many as its relations. Sixty-four of the teeth were located in the lower jaw (mandible), and 32 large ones in the upper (maxilla). The snout almost certainly bore a small crest.

Fish-eater

The crocodile-like jaws and huge number of finely serrated teeth suggested to scientists that Baryonyx was a fish-eater. As verification, a number of scales and bones from the fish Lepidotes were also discovered in the body cavity.

It is speculated that Baryonyx would sit on a riverbank, sleeping 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 posture and angled head support this theory.

Until the discovery of the closely-related Suchomimus, Baryonyx was the only known piscivorous (fish-eating) dinosaur. On the other hand, bones of an Iguanodon were also found in organization with the Baryonyx skeleton. Although not definitive proof, it seems possible that Baryonyx scavenged any extra meat it could find.

Discovery

During the early Cretaceous, Wealden Lake covered the bulk of what is now northern Europe. Alluvial plains and deltas stretch from the uplands surrounding the area where London now stands and eventually ran into this great lake.

Baryonyx was exposed in these former deltas. In 1983, an amateur fossil hunter named William Walker came across an huge claw sticking out the side of a clay pit in Surrey. He received some help in retrieving the specimen, which was astonishingly intact.

The skeleton was agreed to Alan J. Charig and Angela C. Milner, Ph.D.s, of Natural History Museum in London. They available their description of the type species, B. walkeri, in 1986, and named it after Walker.

About 70 percent of the skeleton was improved, including the skull. Therefore paleontologists can make many useful deductions about Baryonyx from just a particular find.

It was the first carnivorous dinosaur exposed in England. The skeleton can be seen at the Natural History Museum in London.

Classification

There is only one specimen of Baryonyx, so there is small debate about classification. There is a resemblance to the tetanuran Becklespinax, but there is no evidence that Baryonyx had similar elongated spines on the back of its neck.

Another crocodile-like fish-eater, Suchomimus, was described in 1998, and located in the same subfamily (Baryonyichae). It has recently been suggested that (Hutt, 2004) that Suchomimus tenerensis should be redefined as Baryonyx tenerensis due to similarities in their spine.