Ichthyosaurs

Ichthyosaurs

Ichthyosaur means “fish-lizard”. These large animals lived a long time ago and are now known by their fossil remains—but they are not dinosaurs.

Dinosaurs were specialized reptiles whose limbs were held directly beneath their bodies. Typical reptiles have limbs that stick out to the sides and cannot be drawn under the torso. Ichthyosaurs were a separate group of marine reptiles.

Both groups lived during the Mesozoic Era (ca. 252 to 66 million years ago). Dinosaurs moved on land and ichthyosaurs swam in the oceans.

Ichthyosaurs had long, fish-like bodies. Some reached body lengths of over 50 feet, with chest depths up to eight feet. They lacked gills and had to breathe surface air. Several anatomical features indicate most ichthyosaurs filled an ecological niche similar to modern-day dolphins and killer whales.

Cymbospondylus piscosus

The ichthyosaur replica on the wall before you is based on fossil material found near Lovelock in northwestern Nevada. This species swam in the warm ocean waters that covered part of what is now Nevada’s west Humboldt Mountain Range.

This 27-foot-long individual represents a young adult, not fully grown, that weighed an estimated eight tons.

Cymbospondylus piscosus appears adapted to life as a predator. Its body was streamlined with flipper-shaped limbs and it probably moved speedily through the water. The forward-facing eyes suggest it hunted mobile food. Sharp conical teeth set in a long narrow jaw are adaptations to catching and killing squid-like creatures such as the belemnites represented by their cone shaped fossil body parts on the left wall.

This species died out at least nine million years before another, much larger, Nevada ichthyosaur, Shonisaurus popularis, depicted and discussed to your left.

Shonisaurus popularis: Nevada State Fossil

At approximately 50 feet in length and weighing an estimated 35 tons, Shonisaurus popularis is one of the largest known ichthyosaurs. All examples of this animal are from the Shoshone Mountains near the site of the mining town of Berlin in central Nevada. Berlin-Ichthyosaur State Park was established to protect and display these remains. The 1977 Nevada Legislature designated the official State Fossil to be an ichthyosaur. In 1989 this statute was amended to specify this state symbol as Shonisaurus popularis.