While Splitting Rocks in Wyoming, a High School Student Discovered a Giant Complete Prehistoric Fish Skull Buried for 52 Million Years

A California high‑school student working in a summer paleontology program has uncovered a remarkably intact skull of a giant gar that lived 52 million years ago. The fossil, recovered from Wyoming’s Green River Formation, is being hailed as one of the most important fish discoveries in the program’s 16‑year history.

The find came during fieldwork for the Stones and Bones program, which the University of Chicago runs each summer. After weeks of classroom training, participants travel to one of North America’s most productive fossil sites to hunt for ancient remains.

The Green River Formation is renowned for preserving a wide array of Early Eocene organisms in extraordinary detail. While previous student teams have brought back turtles, stingrays and other specimens, the size and completeness of this gar skull immediately set it apart.

Student Unearths 52‑Million‑Year‑Old Giant Gar Skull in Wyoming

High‑schooler Gabe Robinson was chipping away at a rock layer when teaching assistant Patrick Riordan spotted irregular protrusions. The seemingly minor features soon attracted the attention of the entire dig crew.

According to a release from the university, Lance Grande, the program director and Negaunee Distinguished Service Curator at Chicago’s Field Museum, was summoned to assess the find. Robinson later described the buzz that followed.

“Lance came over, and he said, ‘I think there is something very interesting here. Everyone rushed over and crowded around. We kept going back to it, and finally the verdict was ‘It’s a giant gar skull.’”

As more of the surrounding matrix was cleared, the team realized they had uncovered an unusually complete predatory‑fish skull. Grande noted that the program routinely yields discoveries that reshape scientific understanding.

“Every year we find many truly remarkable fossils, including species new to science or specimens like this indicating new information about the ancient ecosystem. All of what we find has not seen the light of day for 52 million years,” he said.

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The Predator That Dominated an Ancient Lake

Gar fishes are characterized by elongated jaws and formidable teeth. The skull recovered from the Green River Formation bears a striking resemblance to a crocodile’s, with a long snout packed with hundreds of tiny teeth and rows of larger fangs. Researchers estimate the animal would have measured at least eight feet, placing it among the largest gar specimens known from the site.

To confirm the identification, the fossil was sent to a nearby hospital for X‑ray imaging. The scans verified that the bone belonged to a gar, and Grande emphasized that the degree of preservation is exceptional.

“If fossilization does happen, it’s often kind of fragmentary. The completeness of this skull is amazing.”

Most fossils survive as isolated fragments or partial skeletons; this skull remained largely intact after spending millions of years buried in sediment.

A Window Into Early Eocene Life

The Green River Formation captures a detailed snapshot of life from the Early Eocene, when a subtropical lake system supported fish, reptiles, plants and countless other organisms. Today the fossil beds sit in a high‑altitude desert about 7,200 feet above sea level, where temperature swings can be extreme.

Grande described the site as a complete ecological record frozen in stone.

“It’s a whole Early Eocene community locked in stone.”

The skull will now be cataloged in the Field Museum’s collections, joining roughly 30 million specimens that support ongoing research. For Robinson, the experience turned a classroom lesson into a hands‑on encounter with deep time.