Spinosaurids were massive, sail-backed predators that evolved to hunt like modern crocodilians.

Nature · Published 3 October 2026 Swipe more like this →

In short: Spinosaurids were not typical theropods. With long, narrow skulls, conical teeth, and retracted nostrils, these dinosaurs abandoned the land to dominate aquatic environments. From the sail-backed Spinosaurus to the fish-eating Baryonyx, these creatures represent a unique evolutionary experiment in becoming the apex predators of the Cretaceous waterways.

Spinosauridae, a family of theropod dinosaurs, thrived from the Early to Late Cretaceous, roughly 130 to 95 million years ago. While most theropods possessed blade-like, serrated teeth for tearing flesh, spinosaurids evolved specialized, conical teeth with reduced serrations. These teeth, combined with a spoon-shaped snout tip known as a terminal rosette, allowed them to grip slippery, struggling prey. This anatomy, alongside retracted nostrils and secondary palates, shows a remarkable convergence with modern crocodilians, suggesting a semiaquatic lifestyle focused on piscivory.

The family is traditionally split into two subfamilies: the Spinosaurinae and the Baryonychinae. Spinosaurines, including the massive Spinosaurus, generally featured unserrated, straight teeth and were among the largest terrestrial predators, with Spinosaurus reaching lengths of 14 meters and weights of 7.4 metric tons. Baryonychines, such as Baryonyx, were typically smaller and possessed slightly curved, serrated teeth. The iconic sails found on their backs—formed by elongated neural spines—varied significantly between genera, ranging from the tall, comb-like structure of Spinosaurus to the lower, ridge-like sails of Suchomimus.

The biogeography of these dinosaurs remains a subject of intense debate. Early theories suggested a split between northern Laurasian baryonychines and southern Gondwanan spinosaurines. However, the discovery of diverse remains across Europe, Africa, Asia, and South America has complicated this narrative. Some researchers propose that spinosaurids originated in Laurasia and dispersed into Gondwana via an Iberian land bridge, while others argue for a Gondwanan origin. Regardless of their exact path, their disappearance after the Cenomanian stage is thought to be linked to environmental shifts, such as rising sea levels, which likely displaced them in favor of other predators like abelisauroids.

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