User:PaleoGeekSquared/sandbox
From Wikipedia, the free encyclopedia
Spinosauridae (or spinosaurids, meaning "spined reptiles") is a family of theropod dinosaurs comprising up to thirteen genera. They came into prominence during the Cretaceous period, with possible origins in the Middle or Late Jurassic. Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America, Asia, and possibly Australia. Their remains have generally been attributed to the Early to Mid Cretaceous, with the exception of the earliest named genus, Ostafrikasaurus from the Late Jurassic.
Spinosaurids | |
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Skeletal reconstruction of Spinosaurus aegyptiacus, National Geographic Museum, Washington, D.C. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | Avetheropoda |
Clade: | †Carnosauria (?) |
Family: | †Spinosauridae Stromer, 1915 |
Type species | |
†Spinosaurus aegyptiacus Stromer, 1915 | |
Subgroups | |
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Synonyms | |
Spinosaurids were large bipedal carnivores. Their crocodilian-like skulls were long, low and shallow, bearing conical teeth with reduced or absent serrations. The tips of their upper and lower jaws fanned out into a spoon-shaped structure similar to a rosette, behind which there was a notch in the upper jaw that the expanded tip of the lower jaw fit into. Spinosaurids' nostrils were retracted to a position further back on the head than in most other theropods, and they had bony crests on their heads along the midline of their skulls. Their robust shoulders wielded stocky forelimbs, with three-fingered hands bearing an enlarged claw on the first digit. In many species, the upwards-projecting neural spines of the vertebrae (backbones) were significantly elongated and formed a sail on the animal's back (hence the family's namesake), which supported either a layer of skin or a fatty hump.
The genus Spinosaurus, from which the family, subfamily (Spinosaurinae), and tribe (Spinosaurini) borrow their names, is the largest known terrestrial predator from the fossil record, with an estimated length of up to 15 meters (49 ft). The closely related genus Sigilmassasaurus may have reached a similar or greater size, though its taxonomy is disputed. Direct fossil evidence and anatomical adaptations indicate that spinosaurids were at least partly piscivorous (fish-eating), with additional fossil finds indicating they also fed on other dinosaurs and pterosaurs. The osteology of spinosaurid teeth and bones has suggested a semiaquatic lifestyle for some members of this clade. This is further indicated by various anatomical adaptations, such as retracted eyes and nostrils; and the deepening of the tail in derived members of the Spinosaurinae, which has been suggested to have aided in underwater propulsion akin to that of modern crocodilians.