About Opisthias rarus:
Opisthias rarus is a lizard-like reptile that reached a length of a foot or more. It is not a true lizard but a sphenodont. The last living sphenodont is the tuatara of New Zealand, which helps us understand how Jurassic sphenodonts might have lived. The living tuatara eats insects, worms, snails, slugs, spiders, lizards, young birds, and eggs.
Why is Opisthias rarus a superstar?
Sphenodonts, like other microvertebrates, have extremely fragile and delicate bones. In spite of this, several extremely well preserved skulls have been preserved at the Monument. Scientists are now using CT scans to study these specimens. The resulting high resolution images make it possible to research the bones in great detail with less risk of damaging them. It also allows them to see bones that are still buried in the rock.
Jurassic Fact: Sphenodonts are common reptile fossils in terrestrial Mesozoic rock (Age of Dinosaurs). After this time they disappeared from the fossil record everywhere but New Zealand.
For more information: Visit the Quarry Exhibit Hall where a cast is on display.
Did You Know?
Split Mountain, the name John Wesley Powell gave to one of the Dinosaur’s most recognizable features, is aptly named: over millions of years, the Green River has carved a canyon into the center of the mountain, splitting it in two.