New spinosaurid dinosaur species found in Spain sheds light on group’s evolution

A new proposed species of dinosaur from Castellón, Spain has been added to the illustrious, yet misunderstood, group of spinosaurid dinosaurs.

The group famously includes Spinosaurus aegyptiacus – a huge semi-aquatic dinosaur. Spinosaurus was first discovered in 1915 and has become a classic case study of how dinosaur reconstructions change as we learn more about the long-extinct creatures. Many palaeontologists now believe the massive carnivore would have spent much, if not most, of its time in water, like a crocodile.

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Some estimates suggest that Spinosaurus may have been up to 18 metres long and had a mass of up to 20 tonnes, making it longer and heavier than Tyrannosaurus rex. It may have been the largest terrestrial carnivore of all time.

All spinosaurids have long, narrow skulls resembling that of a crocodile. Nostrils and eyes situated high up on the skull suggest at least a semi-aquatic lifestyle. Long, straight conical teeth indicate that spinosaurids had a largely piscivore (fish-based) diet.

But other spinosaurids like Baryonyx from England, Irritator from Brazil, and Suchomimus from Niger are much smaller than Spinosaurus. It is thought that spinosaurids first emerged in Europe before migrating to Africa and Asia.

The discovery of the new spinosaurid, named Protathlitis cinctorrensis, suggests that the Iberian Peninsula may have seen a diverse range of medium and large spinosaurids in the early Cretaceous period. The discovery follows the announcement last year of a new nine-metre spinosaurid species, Iberospinus natarioi, found in Portugal, that lived 125 million years ago.

Protathlitis lived in a sub-period of the early Cretaceous called the Barremian between 126 and 127 million years ago. Comparing the fossil fragments of the specimen (a right jaw bone, one tooth and five vertebrae), it is believed to have been 10–11 metres long.

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The researchers believe that it indicates spinosaurids appeared during the early Cretaceous in Laurasia – a supercontinent consisting of the modern day continents North America, Europe and Asia – as two sub-groups found in western Europe.

Spinosaurids then migrated to Africa and Asia where they diversified further. In Europe, so-called baryonychines like Protathlitis were dominant, while Africa saw the proliferation of spinosaurines like Spinosaurus.