Baryonychine
| Spinosaurids Temporal range: Late Jurassic–Late Cretaceous, 148–93.5 Ma Possible Late Maastrichtian record |
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| Skeletal reconstruction of Spinosaurus aegyptiacus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| Clade: | †Megalosauria |
| Family: |
†Spinosauridae Stromer, 1915 |
| Type species | |
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Spinosaurus aegyptiacus Stromer, 1915 |
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| Subgroups | |
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| Synonyms | |
Spinosauridae is a family of Cretaceous theropod dinosaurs within the clade Megalosauroidea, which contains Spinosauridae (spinosaurids) as well as Megalosauridae. Baryonyx, Suchomimus, Irritator, and Spinosaurus are all spinosaurids. Spinosaurids are large predators with elongated, crocodile-like skulls, sporting conical teeth with no or only very tiny serrations. The teeth in the front end of the lower jaw fan out into a structure called a rosette, which gives the animal a characteristic look. They hunted mostly fish, and fed opportunistically on other animals, and recent evidence suggests a semiaquatic existence for members of this clade. Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America, and Asia.
Spinosaurids have relatively large forearms and an enlarged claw on the first digit of the hand. Spinosaurids have a hook shaped coracoid, external nares which are at least behind the teeth of the pre-maxilla or even further posterior on the skull, a long secondary palate, a terminal rosette of enlarged teeth at the front of both the upper and lower jaws, and subconical teeth with small denticles or no denticles.
Spinosauridae is traditionally divided into the subfamilies Spinosurinae and Baryonychinae. Spinosaurinae, which contains the genera Irritator and Spinosaurus, is marked by unserrated, straight teeth, external nares which are further back on the skull than in Baryonychinae.Spinosaurus aegypticus, the type species for the family and subfamily, is known for the vertebrae with elongated neural spines which have been reconstructed as a sail running down its back. Baryonychinae, which contains the genera Baryonyx and Suchomimus, is marked by serrated, slightly curved teeth, smaller size than spinosaurines, and more teeth in the lower jaw behind the terminal rosette than in spinosaurines.Suchomimus is thought to have had a half-meter sail over its hips, smaller than that of Spinosaurus.Irritator also had extended neural spines, though again, to a smaller degree than the previously mentioned genera. Other spinosaurids, such as Siamosaurus, may belong to either Suchomimus or Spinosaurus, but are too incompletely known to be assigned with confidence.
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