MEANING: Heavy claw
PERIOD: Early Cretaceous
CONTINENT: Europe
Baryonyx is a spinosaurid theropod from the Early Cretaceous of what is now England. The name, meaning "heavy claw," references the animal's large claw on the first finger, which measures about 30 cm along its curve. Baryonyx was the first theropod dinosaur demonstrated to have been piscivorous (fish-eating), as evidenced by fish scales in the stomach region of the holotype specimen. It is estimated to have been between 7.5 and 10 m long and 2.5 m in hip height.
Baryonyx is from the Cretaceous. The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.
The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct flora and fauna, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.
Baryonyx is a spinosaurid. Spinosaurids are a group of large theropod dinosaurs, mainly from the Early Cretaceous. They are known for their crocodilian-like skulls with long narrow snouts. The tips of their upper and lower jaws fanned out into a spoon-shaped structure, with a notch in the upper jaw that the tip of the lower jaw fit into. The nostrils of spinosaurids were further back on the snout than in most other theropods. Adaptations such as these suggest that they were at least partially piscivorous, and likely led a semi-aquatic lifestyle.
Spinosaurids had bony crests on their heads along the midline of their skulls, and large arms, with three-fingered hands. In many species, the neural spines of the vertebrae were elongated and formed a sail-like structure on the animal's back, giving the group their name. The genus Spinosaurus, from which the clade gets its name, is the longest known terrestrial predator from the fossil record, with an estimated length of up to 14 m and body mass of up to 8 t.