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BaryonyxBaryonyx ("heavy claw") is a large, carnivorous dinosaur discovered in clay pits just south of Dorking, England. It is known from a single, juvenile specimen, and apparently ate fish because remains of its last meal were discovered fossilised in its ribcage. It lived in the Barremian period of Early Cretaceous, around 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 probably weighed in the region of 2,000 kg, but analysis of the bones suggests that the one only known specimen was not yet fully grown. 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 absurdly large for a theropod, suggesting that it also spent much of its time on all fours. Like the dromaeosaurids, the creature had a long curved claw on the thumb of each hand, which measured at about 31 cm (12 in). However, instead of having them on the rear foot, it is believed that Baryonyx had them on the front feet. 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. Fish-eater 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. 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. 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 association 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 majority of what is now northern Europe. Alluvial plains and deltas spread from the uplands surrounding the area where London now stands and eventually ran into this great lake. Baryonyx was discovered in these former deltas. In 1983, an amateur fossil hunter named William Walker came across an enormous claw sticking out the side of a clay pit in Surrey. He received some help in retrieving the specimen, which was surprisingly intact. The skeleton was passed to Alan J. Charig and Angela C. Milner, Ph.D.s, of Natural History Museum in London. They published their description of the type species, B. walkeri, in 1986, and named it after Walker. About 70 percent of the skeleton was recovered, including the skull. Therefore paleontologists can make many useful deductions about Baryonyx from just a single find. It was the first carnivorous dinosaur discovered 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 little debate about classification. There is a similarity 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-eather, Suchomimus, was described in 1998, and placed in the same subfamily (Baryonyichae). It has recently been suggested that (Hutt, 2004) that Suchomimus tenerensis should be redefined as Baryonyx tenerensis due to similiarities in their vertebrae. References - Steve Hutt and Penny Newbery. "A new look at Baryonyx walkeri (Charig and Milner, 1986) based upon a recent fossil find from the Wealden" (2004), from the Symposium of Vertebrate Palaeontology and Comparative Anatomy. (abstract)
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