These New Fossil Discoveries Show Why Evolution is the Coolest

Iguana-sized Antarctanax lived in a temperate Antarctic forest. Illustration by Adrienne Stroup.

Winter in Chicago is frigid (even more than usual—we see you, polar vortex), but our science keeps heating up. Field Museum scientists published some fascinating research on their latest fossil finds from Antarctica, China, and the same spot where SUE the T. rex was found in South Dakota.

“Antarctic king” gave rise to the dinosaurs

It may sound like a lofty name for an iguana-sized reptile—Antarctanax means “Antarctic king”—but this creature has an important spot in evolution. Field Museum researcher Brandon Peecook and a team of paleontologists unearthed this new member of the archosaur group, the early relatives of crocodiles and dinosaurs.

Antarctanaxshackletoni lived in Antarctica 250 million years ago, when the continent was practically balmy—covered in forests and rivers rather than ice and snow.

About two million years before Antarctanax lived, Earth experienced its biggest-ever mass extinction. Climate change, caused by volcanic eruptions, killed 90 percent of all animal life. In the aftermath, new groups of animals started evolving like crazy—including archosaurs, the early dinosaur relatives. Finding Antarctanax supports the picture of Antarctica as a place of rapid evolution with an array of unique wildlife.

A weird ancient platypus lookalike

This marine reptile is something of an evolutionary smorgasbord: small head, tiny eyes, and a big platypus-like bill, plus a long tail. Top it off with bony stegosaurus-style plates along the back and you’ve got Eretmorhipis carrolldongi.

Olivier Rieppel, an evolutionary biology curator at the Field, was part of the team studying this unusual animal found in China. Living about 250 million years ago—the same period as Antarctanax and other early dinosaur relatives—this reptile bears unmistakable similarities to the platypus, a mammal that’s alive today.

With large duckbills and very small eyes—meaning, probably not great vision—this prehistoric reptile and the platypus might’ve shared a strategy for finding food. Scientists think that, like platypuses, the extinct reptile relied on its sense of touch and used its duckbill to poke around for food underwater. The shared duckbill is an example of convergent evolution: when organisms that aren’t closely related evolve similar traits because their environments are similar.

Read the scientific paper in Nature.

Fossil shark with spaceship-shaped teeth

Another species odd couple? SUE the T. rex and a shark were probably next-door neighbors 67 million years ago, in what is now South Dakota.

Reaching a foot to 18 inches in length, this small shark swam in a prehistoric river where SUE might’ve taken a drink. This also changes how we think about SUE’s landscape, showing a connection to a marine environment—the shark had to come from a sea and then swim up the river.

The shark’s rad name, Galagadon nordquistae, helps tell the story of how we made this discovery. For many years, museum volunteer Karen Nordquist has meticulously sorted through the matrix—the rock, dirt, and small particles—that surrounded SUE’s bones.

Because shark’s bodies are soft cartilage, they don’t usually last in the fossil record. But with a microscope and a sharp eye, Nordquist caught sight of the shark’s teeny tiny teeth. They’re about as big as the head of a pin, and remarkably similar in shape to the spaceships in the classic arcade game Galaga. Field paleontologists Pete Makovicky and Eric Gorscak helped describe the new species in Journal of Paleontology.

Now that deserves some serious bonus points.