New Fossils Re-Write The History Of Dinosaurs And The ‘River Monster’ Spinosaurus

Don Wood – MessageToEagle.com – Scientists have long opposed the idea that dinosaurs lived in aquatic habitats.

However, an international team of researchers has discovered unambiguous evidence that Spinosaurus aegyptiacus, the longest predatory dinosaur known to science, was aquatic and used tail-propelled swimming locomotion to hunt for prey in a massive river system.

It is the first time that such an adaptation has been reported in a dinosaur. The study is based on the investigation of the world’s only existing Spinosaurus skeleton, found in the Kem Kem region of the Moroccan Sahara. The skeleton is now also the most complete one to date for a Cretaceous predatory dinosaur from mainland Africa.

Two Spinosaurus hunt Onchopristis, a prehistoric sawfish, in the waters of the Kem Kem river system in what is now Morocco. Credit: Jason Treat, NG Staff, and Mesa SchumacherArt: Davide Bonadonna Dr. Nizar Ibrahim, University of Detroit Mercy

In a previous study, Spinosaurus had been identified as a fish-eating dinosaur with adaptations for an amphibious lifestyle, supported by its relatively short hindlimbs, wide feet, dense bones and elongated jaws studded with conical teeth.

However, suggestions that it may have been a truly water-dwelling dinosaur were met with considerable opposition, in large part because the partial skeleton provided little to no evidence of the propulsive structure needed to move such a giant dinosaur through water.

Scientists recovered many more fossils of the skeleton, including a remarkably complete, fin-like tail capable of extensive lateral movement and characterized by extremely long spines.

After preparing all of the fossils, the researchers used photogrammetry to digitally capture the anatomy of the tail.

To quantitatively assess the performance of the tail, a team of Harvard researchers made a flexible model and attached it to a robotic system that mimics swimming movements. They then compared the swimming performance of the model Spinosaurus tail to model tails from other animals, including crocodiles, newts and other dinosaurs. The results were fully consistent with the idea of a truly water-dwelling, tail-propelled, “river monster.”

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“This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm,” Dr. Nizar Ibrahim, paleontologist at the University of Detroit Mercy said.

“This dinosaur was actively pursuing prey in the water column, not just standing in shallow waters waiting for fish to swim by. It probably spent most of its life in the water.” The discovery also points to the possibility of a persistent and widespread invasion of aquatic habitats by relatives of Spinosaurus.

Written by Don Wood – MessageToEagle.com Staff