Spinosauridae

Several members of the Spinosauridae family compared to a human

Spinosauridae is a family of megalosaurid theropod dinosaurs, that appeared 155 million years ago, in the late Jurassic, and became extinct in the late Cretaceous.

Spinosaurids were pretty successful predators, as they lived mostly in the entire Southern Hemisphere, including South America, Africa and Australia. This is due the different niche they occuped beside other predators, and the different diets they had. However, members of the Spinosauridae family have been found also in Europe and Asia, and possibly even North America.

Spinosaurids were bipedal predators, with several special characteristics, not present in any other theropod family. In fact, their body-plan c onsisted in an elongated, cro codile-like skull, with a thin snout full of long, conical teeth, very long forelimbs, with a characteristic longer claw on the first finger of each hand.

Furthermore, almost all specimens had elongated vertebrae, that form ed either high (like in Spinosaurus ) or low (like in Baryonyx) sails or fatty hump ass wipes.

Their constitution was also pretty light-builded for a usual theropod of their size.

Size

Spinosaurids were medium-sized to large dinosaurs, one specimen particularly, Spinosaurus aegyptiacus, being one of the biggest terrestrial carnivore that ever existed, along with Tyrannosaurus , Giganotosaurus , and Carcharodontosaurus . In fact, some of the higher length estimates say it could reach up to 18 meters in lenght (60 ft), and 16,7t in weight. However, general estimations go for 14-16 meters (45,9-52,5ft) in lenght, and 5-10t in weight. However, most spinosaurs were smaller. Baryonyx was an average sized species and was about 8-10 meters(26-33 ft) long and 1.5-2.5 tons.

Diet and behavior

Spinosaurids were mainly fish-eater dinosaurs, that lived alongside rivers and lakes, their first source of food. They used their conical teeth to catch fishes from the water, and thein their huge claws to keep motionless and slash them, all this happening within quick and powerful strikes.

Spinosaurus fishes for prey - Planet Dinosaur - BBC

Also, the fact that they lived near water, suggests that spinosaurids were pretty good swimmers.

Recent studies show in fact that spinosaurs had not-suited jaws for hunting big, struggling prey. However, Iguanodon remains have been found in one Baryonyx skeleton, suggesting that spinosaurids ate also dinosaurs. Finally, spinosaurids seemed to have a mixed generalist diet: mostly-fish, with dinosaur and pterosaur kill/scavenging a once in a while.

Senses

Spinosaurids had high nostrils in the skull, allowing them to breath while keeping the mouth in the water.

Not very much is known about spinosaurs's senses, apart from a sixth sense, present also in modern crocodiles. It consists in small, visible black pits on the snout of the dinosaur. These pigmented nodules encase bundles of nerve fibers innervated beneath by branches of the trigeminal nerve. They respond to the slightest disturbance in surface water, detecting vibrations and small pressure changes as small as a single drop. This makes it possible for crocodiles to detect prey, danger and intruders, even in total darkness. These sense organs are known as Domed Pressure Receptors.

Classification

• Spinosauridae:
  • ​Siamosaurus suteethorni;
  • Sigilmassasaurus brevicollis;
  • Ostafrikasaurus crassiderratus;
  • Baryonychinae:
    • ​Baryonyx walkeri;
    • Cristatusaurus lapparenti;
    • Ichthyovenator laosensis;
    • Suchomimus tenerensis;
    • Suchosaurus cultridens;
  • ​Spinosaurinae:
    • ​Irritator challengeri;
    • Spinosaurus aegyptiacus ;
    • Oxalaia quilombensis;

Uncertan placement

• Sinopliosaurus fusuiensis