Evolutionary History
The first spinosaurids appeared during the Late Jurassic and became abundant in the Early Cretaceous. So far, the Late Jurassic record of spinosaurids consists only of referred teeth, dating to 155 million years ago. They seem to have declined sharply in the Cenomanian, and while teeth from the Turonian of Argentina have been attributed to spinosaurid dinosaurs, but they recently turned out to be crurotarsan teeth. Some are known to have persisted into the mid-Santonian, represented by a single baryonychine tooth found in the Majiacun Formation of Henan, China.
Read more about this topic: Spinosaurids
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