Was Spinosaurus a deep diver or more like a 'heron from hell'?

In the latest issue of ScienceAdviser's Deep Dive, the question is raised: Was Spinosaurus a deep diver or simply a "heron from hell"? The debate around Spinosaurus, a massive sail-backed predator that lived near water during the Cretaceous era, revolves around how it hunted for its meals. While most researchers agree that Spinosaurus primarily fed on fish and other aquatic creatures, there is disagreement on whether it hunted near the water's edge or was a proficient underwater predator.

The controversy stems from a scarcity of fossils and differing interpretations of existing evidence. Some scientists argue that Spinosaurus likely stalked shorelines or caught prey in shallow waters, while others propose that it was an adept aquatic predator that dove deep to capture its food. Recent research published in PloS ONE has reignited the discussion, highlighting the ongoing uncertainty surrounding Spinosaurus's hunting behavior.

In a 2014 Science paper, a team of researchers presented the first nearly complete Spinosaurus specimen, suggesting that the dinosaur hunted on land or swam close to the water's surface. However, in a subsequent Nature paper six years later, another group, including some of the original authors, put forth evidence that Spinosaurus propelled itself through water using a flipper-like tail. Utilizing a statistical method called phylogenetically flexible discriminant analysis (pFDA), they analyzed bone density and proportions to support their hypothesis that Spinosaurus had adaptations for underwater hunting.

On the other hand, skeptics, including scientists Sereno and Myhrvold, created digital reconstructions of Spinosaurus and a related dinosaur, concluding that both creatures were likely unstable swimmers due to their top-heavy nature and the presence of a large sail on Spinosaurus's back. They argued that these features would have hindered the dinosaur's ability to fully submerge in water.

Sereno and Myhrvold have critiqued the methodology of the Nature study, citing flaws such as small sample sizes, data biases, and misapplications of statistical techniques. They question whether Spinosaurus was a fast predator chasing fish like a sea lion or an ambush predator at the water's edge. The debate continues, with no definitive resolution in sight.

Despite the scientific disagreements, researchers like Nizar Ibrahim remain committed to advancing our understanding of Spinosaurus. While the debate rages on, it has not caused any rifts in professional relationships, with researchers like Fabbri continuing their postdoctoral work alongside colleagues who hold differing views on Spinosaurus's aquatic abilities.

The ongoing debate over Spinosaurus underscores the complexities of paleontological research and the challenges of interpreting limited fossil evidence to reconstruct the behavior of long-extinct creatures.

(Source: https://www.science.org/content/article/scienceadviser-was-spinosaurus-deep-diver-or-heron-hell)