Smithsonian on Instagram: "With a scientific name meaning “thick-headed lizard” and a domed head often compared to a bowling ball, Pachycephalosaurus lived alongside species like Tyrannosaurus rex and Triceratops 67 million years ago. Today, our @SmithsonianNMNH has acquired a remarkably complete skull of Pachycephalosaurus. The rare fossil was donated to the museum by Eric and Wendy Schmidt. Visitors will have a chance to see the new Pachycephalosaurus skull up close starting Dec. 22, when the