The mystery of stegosaur ‘armor’
A 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)
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)
Evan T. Saitta, Ph.D. 