Meet 'Jim' - the Field Museum's sea monster

January 8, 2013

Greta Johnsen and Andrew Gill

Chicago's Field Museum has unveiled a new fossil: it's called an ichthyosaur, but for short, Field Museum scientists call it "Jim."

The 244 million year-old fossil is named after Jim Holstein, who first saw Jim’s four-foot long skull poking out of a rock in Nevada in 1998.

The fossil just sat there for about 10 years before it was excavated and brought to the Field Museum.

Now, the skull and vertebrae sit on a table next to Holstein, who said Jim would have been about 28 feet long.  

"It's a monster!"

So what, aside from its age and size, makes Jim so unique?

The truth is in the tooth.

Most sea predators from the Triassic period have pointy, conical teeth-- perfect for puncturing food and swallowing it whole.

But Jim’s teeth look more like an arrowhead, which means they could bite chunks out of animals their same size. So I had to ask Jim the scientist one last question: in a theoretical fight, who would win between the ichthyosaur and the Field Museum’s famous T-Rex, Sue?

The short answer is, no one wins. Sue lives on land, and Jim in the sea. Not to mention they loved about 50 million years apart.

No word yet on when the Field Museum opens its Jim vs. Sue cage match.