Spinosaurids were an unusual family of megalosauroid tetanuran theropods (partly because they didn't strongly resemble their close cousins). They had large claws on the first finger of their hands, tall spines on their backs (some taller than others) and long, crocodile-like jaws with a notch in the upper jaw just before the tip (similar to the unrelated coelophysoids and dilophosaurids), fitting into a bulge on the tip of the lower jaw. Some scientists have speculated that spinosaurids fed at least in part on fish, as their teeth were straight and unserrated, although there is evidence of a Baryonyx having fed on an Iguanodon, and a spinosaur tooth embedded inside a pterosaur. A study of oxygen isotope levels proved that spinosaurids spent far more of their time in water than most other theropods (the smaller members more than the larger ones). Many species are named only from teeth, so their validity is questionable.
All spinosaurids are Water Dinosaurs, and are the only theropods to be so.
- Angaturama limai (considered a synonym of Irritator)
- Cristatusaurus lapparenti (possibly Baryonyx or Suchomimus)