This huge bone comes from a giant fish-catching machine known as a short-necked plesiosaur. Although it is not a dinosaur, it lived in a Jurassic sea during the Age of Dinosaurs. This seaway covered southern Alaska and extended southward to Wyoming. Although other plesiosaurs are well known from Europe, this particular type is very rare. It is only the second pliosauroid found in the Arctic region and the only the third Jurassic bone ever found in Alaska!

How large was Mr. Mega-Bite? By comparing the size of this bone to those in more complete skeletons, scientists think Megalneusaurus was about 15 feet long! His large head, large mouth, barrel-shaped body, powerful paddles, and large eyes were his trademarks. This bone (a humerus) is very robust suggesting that very powerful muscles were attached to it. It was connected to many smaller bones that gave the limb a paddle-like shape. With these limbs, Megalneusaurus was propelled through the water like a submarine rowboat with four oars powered by two strong oarsmen.

Two geologists from the U.S. Geological Survey rediscovered this fossil in 1994. They found it in the Smithsonian Museum where it had lain unnoticed since 1922! They volunteered to make this cast and donated it to our museum so that others may see and appreciate it.

What did Mr. Mega-Bite eat? Short-necked plesiosaurs had very long jaws that were lined with conical teeth. It must have been a very efficient fish-catching machine! It is thought to have chased prey and swallowed it whole. It may have dined on squid, turtles, and small ichthyosaurs as well as fish.

The bone you see here is a plaster cast made from the original bones which are in the National Museum of Natural History in Washington,. D.C. (the Smithsonian). Two pieces were found, but their proportions suggest they were once part of the same bone. The dark brown "center" is a restoration showing that the size of the original bone must have been. It is 19 inches long with a small diameter of 9 inches. With muscles and skin attached it may have been nearly 18 inches in diameter. How does this compare with the size of your upper arm?

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