Theropod Diversity Study (Upper Cretaceous South Pyrenees Basin of Spain)

Large dinosaur bones might make the headlines and attract the most media attention, but an analysis of shed theropod teeth, some of them tiny, indicate that there were potentially many more different types of theropod dinosaur roaming around Spain in the Late Cretaceous.   Dinosaurs were able to replace teeth that they shed.

A meat-eating dinosaur for example, could lose hundreds of teeth over its lifetime and although no other part of it might be preserved as a fossil, these teeth could potentially provide an insight for palaeontologists as to the diversity of theropod dinosaurs in a given area.  That’s exactly what has happened as researchers from Spain and Canada have identified a further six non-avian dinosaurs in Upper Cretaceous strata from the South Pyrenees Basin (Spain).  Only two theropod dinosaurs had been known from this region prior to this new study.

Isolated Teeth Fossils Hint at Theropod Diversity on the Iberian Peninsula

scale bar = 5mm

scale bar = 5mm

Picture credit: Acta Palaeontologica Polonica

Theropod Teeth Hint at Diversity in Ecosystem

Publishing their work in the academic journal Acta Palaeontologica Polonica, the research team, which included lead author Angelica Torices, (University of Alberta) and famous Canadian palaeontologist Professor Phil Currie, have quadrupled the theropod dinosaur diversity in the areas studied.  At least one of the new types of theropod would have been “large”, although it is difficult to classify down to little more than taxonomic family level.

It has been speculated that the teeth indicating a large predator could represent either an abelisaurid like Tarascosaurus, (it has been proposed that the fragmentary fossil material assigned to this genus shows affinities to the Abelisauridae), known from Upper Cretaceous strata of France or a possible tyrannosaurid.

The Study Area

The area of study consists of eight localities from Treviño County, Huesca and Lerida, including the exceptional site of Laño, an abandoned sand quarry, strata of which represents Upper Cretaceous and Early Palaeogene deposits.  The study of 142 isolated teeth suggests that theropod numbers may have been underestimated elsewhere in the world.

Commenting on the research, Angelica Torices, (University of Alberta), explained:

“Studying these small parts helps us to reconstruct the ancient world where dinosaurs lived and to understand how their extinction happened.”

The post-doctoral fellow in biological sciences added:

“Teeth are especially important in the study of Upper Cretaceous creatures in Spain and the rest of Europe because we don’t have complete skeletons of theropods from that time in those locations.  We have to rely on these small elements to reconstruct the evolution of these dinosaurs, particularly the theropods.”

Reconstructing the Fauna

This study shows the value of isolated and fragmentary teeth fossils in helping to reconstruct the fauna in an ancient environment, when more other, more complete material, such as skeletal material is not present.

Locations of the Fossil Sites in the Study and Their Stratigraphical Sequence

The fossil study localities.

The fossil study localities.

Picture credit: Acta Palaeontologica Polonica

Theropod Teeth

A spokesperson from Everything Dinosaur commented:

“We have long suspected that the dinosaurs were more diverse than previously thought at the end of the Mesozoic.  However, the lack of fossilised bones that can provide an identification down to genus level has hampered scientists in the study of European dinosaurs.  It is this “under storey” of prehistoric life that can provide palaeontologists with a more complete understanding of the palaeofauna.  Tiny teeth can be just as important as the largest dinosaur bones.”

The research will have implications for the way in which the extinction of the dinosaurs at the end of the Cretaceous is viewed.  If this study is typical, then theropod diversity in the north of Spain does not experience a significant decline over the Campanian to Maastrichtian faunal stages.

Small Dinosaurs such as Dromaeosaurids were Present

A typical "raptor".

A typical “raptor”.

Picture credit: Everything Dinosaur

Lead author Angelica Torices stated:

“It completely changes the vision of the ecosystem.  We now understand that these dinosaurs disappeared very quickly in geological time, probably in a catastrophic event.  Climatic models show that we may reach Cretaceous temperatures within the next century, the only way we can study biodiversity under such conditions is through the fossil record.”

The study of 142 Late Cretaceous theropod teeth reveals that theropods were much more diverse in northern Spain towards the end of the “Age of Dinosaurs” than previously thought.