Biology subjects

Fish, F. E.

Publications and source records attributed to Fish, F. E..

3 recordsLinked to original sources

bioRxiv2023

Diving dinosaurs? Caveats on the use of bone compactness and pFDA for inferring lifestyle

Measures of bone compactness in amniote tetrapods of varying lifestyle were used to infer that two spinosaurid dinosaurs (Spinosaurus aegyptiacus, Baryonyx walkeri) were diving "subaqueous foragers," whereas a third spinosaurid (Suchomimus tenerensis) and other sampled nonavian dinosaurs were non-diving terrestrial feeders entering water only as waders. We outline shortcomings in this analysis that involve bone compactness sampling and measurement, lifestyle categorization, the inclusion and exclusion of taxa in the dataset, and flawed statistical methods and inferences. These many shortcomings undermine the evidence used to conclude that two spinosaurid taxa were avid divers. Bone compactness indices remain a valuable tool for interpretation of lifestyle in extinct species when based on sound dataset composition, robust statistical analysis, and consilience with evidence from functional, biomechanical, or paleoenvironmental considerations.

paleontology↗

bioRxiv2022

Spinosaurus is not an aquatic dinosaur

A predominantly fish-eating diet was envisioned for the sail-backed theropod dinosaur, Spinosaurus aegyptiacus, when its elongate jaws with subconical teeth were unearthed a century ago in Egypt. Recent discovery of the high-spined tail of that skeleton, however, led to a bolder conjecture, that S. aegyptiacus was the first fully aquatic dinosaur. The aquatic hypothesis posits that S. aegyptiacus was a slow quadruped on land but a capable pursuit predator in coastal waters, powered by an expanded tail. We test these functional claims with skeletal and flesh models of S. aegyptiacus. We assembled a CT-based skeletal reconstruction based on the fossils, to which we added internal air and muscle to create a posable flesh model. That model shows that on land S. aegyptiacus was bipedal and in deep water was an unstable, slow surface swimmer (<1m/s) too buoyant to dive. Living reptiles with similar spine-supported sails over trunk and tail in living reptiles are used for display rather than aquatic propulsion, and nearly all extant secondary swimmers have reduced limbs and fleshy tail flukes. New fossils also show that Spinosaurus ranged far inland. Two stages are clarified in the evolution of Spinosaurus, which is best understood as a semiaquatic bipedal ambush piscivore that frequented the margins of coastal and inland waterways.

paleontology↗

bioRxiv2022

Spinosaurids as 'subaqueous foragers' undermined by selective sampling and problematic statistical inference

Fabbri et al.1 claim that the huge sail-backed dinosaur Spinosaurus aegyptiacus and the spinosaurid Baryonyx were "subaqueous foragers," diving underwater in pursuit of prey, based on their measure of bone "compactness." Using thin-sections and computed tomographic (CT) scans of thigh bone (femur) and trunk rib from various living and extinct vertebrates, they claim to be able to distinguish taxa with "aquatic habits" from others. Their conclusions are undermined by selective bone sampling, inaccuracies concerning spinosaurid bone structure, faulty statistical inferences, and novel redefinition of the term "aquatic."

paleontology↗