Paleo-ecology, ethology, & physiology


Two Spinosaurus mirabilis fight over a coelacanth fish (Art & 3D sculpture by Dani Navarro; storyboard by Jonathan Metzger; animation by Davide la Torre)

New Spinosaurus species

We describe a new carnivorous dinosaur species, Spinosaurus mirabilis, from the Cretaceous of Niger. It had a well-developed casque on its head, showing similar variations in shape and symmetry to those seen in the casques of modern birds, such as cassowary. The midline structures on these Spinosaurus, including its broad sail down its spine, were likely used for displaying to other members of its species, as they fished from the shores and shallow waters.

Study: Sereno et al. 2026, (Cover Story)

Press Release: University of Chicago

Media: Reuters (twice), UChicago News, Natural History Museum(London), National Geographic, BBC Science Focus, Scientific American, Popular Science, BBC Discover Wildlife, Discover Magazine, IFL Science, Live Science, New Scientist, Interesting Engineering, UF Health, Fox 32 Chicago, WTTW Chicago’s PBS, The Independent, Geo (German), New York Post, NBC News, ABC News, Newsweek, Smithsonian Magazine, NPR, CBS News, Nautilus, Folha de S.Paulo (Portuguese), Earth.com (twice), El País (Spanish), My Modern Met, Houston Museum of Natural Science, Know Idea (Australia), Focus (Italian)

Art: Dani Navarro

Coauthor Youtube Documentary: Pakozoico (Spanish)

The mystery of stegosaur ‘armor’

A hypothetical model for the evolution and function of stegosaur plates, spikes, and ossicles is proposed, involving calcium storage, defense, thermoregulation, and sexual display and combat.

Preprint: Saitta et al. 2025, bioRxiv


Spinosaurus might not have dove underwater

Did Spinosaurus dive underwater to chase fish? Bone density as a proxy for ballast possibly lacks the statistical predictive power to make such an inference. Instead, its sail was likely under sexual selection for display rather than a propulsive fin.

Study: 2024, PLoS One

Press Release: University of Chicago

Media: New York Times, Newsweek, Discover Magazine, Science


Independent replication of Longrich & Saitta (2024):

The ceratobranchial histology of the N. lancensis holotype indicates that it was nearing or had reached skeletal maturity, suggesting that it is taxonomically distinct from the coeval Tyrannosaurus rex” – Griffin et al. (2025)

Art: Raul Martin

Tiny tyrants alongside T. rex

Decelerating growth rates measured from bone tissue, along with other lines of evidence, suggest that the latest Cretaceous of western North America probably had a much smaller species of tyrannosaur alongside the giant Tyrannosaurus rex.

Study: Longrich & Saitta 2024, Fossil Studies

Press Release: University of Bath

Media: New York Times, Smithsonian, New Scientist, Cosmos, Live Science, IFLScience, USA Today, Sky News, Discover Magazine, Cowboy State Daily, I Know Dino, briefly discussed by Joël Ignasse (2025) Sur les traces du nouveau T. rex Eyrolles (French)

Coauthor video summary

Spinosaurus fishing (Art: Dani Navarro)