Name Meaning: Phosphate Reptile
Geologic Era: Eocene
Location Found: Mali, Africa
Estimated Range: Modern Africa
Size: Up to 5 meters long
Extinction Date: 49 million years ago
This is a caudal vertebra from the dyrosaurid crocodilomorph Phosphatosaurus. Phosphatosaurus is the only crocodilian that I could find evidence for in Mali, so that was the genus that I assigned it. It was sold to me as a “crocodile vertebra.” Overall, it is in a decent state of preservation, just missing the vertebral processes. This bone would probably have been from the base to middle of tail.
Dyrosaurs were an extinct lineage of crocodilians that are known worldwide. They were one of the few crocodile groups to escape the extinction that killed the dinosaurs and a great deal of other life on Earth. A strange thing about this particular species is that, though clearly related to the Cretaceous dyrosaurs of the area, such as Sokotosuchus, there is no fossil evidence to directly support a relationship.
There is a several million year gap from the Cretaceous dyrosaurs to species like Phosphatosaurus. This is called a “ghost lineage.” This lineage extends the better part of 20 million years. A very similar situation arose with the modern coelocanth, which has a ghost lineage extending 80 million years. Like with the coelocanth, it is possible that Phosphatosaurus and its relatives tended to die in places that did not favor preservation, leading to the seeming gaps in the fossil record.
Being a marine crocodile, Phosphatosaurus probably fed mostly on fish and other smaller vertebrates. In terms of its snout, Phosphatosaurus looks somewhat similar to the modern gharial, a fish-eating crocodilian. They may have shared similar habitats and habits, sacrificing raw strength for a more refined approach to catching fish. If they follow the pattern of the modern gharial, this would have involved swinging their heads from side to side to snare fish. The sharp, evenly spaced teeth would have been well suited for this task.
Life Restoration: By Nobu Tamura (http://spinops.blogspot.com) – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=19459924
Skeleton: By incidencematrix – DSC_0056, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=34562858