Mind-Blown Science: Dr. Luis Chiappe and NHM's Extraordinary Plesiosaur

Plesiosaurs were a diverse family of giant marine reptiles (not dinosaurs) that lived during the Mesozoic Era. They typically had broad bodies, short tails, and large flippers. They were among the top predators in the Western Interior Seaway, the large inland sea that existed during the Cretaceous period stretching from the Gulf of Mexico to the Arctic Ocean. 

This extraordinary mounted Plesiosaur skeleton in the Dinosaur Hall shows us a rare surprise. A closer look shows a baby’s skeleton inside her, showing scientists that Plesiosaurs had live births during the age of dinosaurs.