When paleontologists studying Ice Age fossils in Wyoming’s Natural Trap Cave stumbled upon a recently deceased pack rat, they saw a unique research opportunity, Cowboy State Daily reports.
Instead of discarding the modern remains, they named the rat “Packy Le Pew” and observed its decomposition over several years, leading to new insights about the conditions within the cave and how they impact fossil preservation.
Natural Trap Cave, located in the Bighorn Mountains, is a significant paleontological site. This 85-foot-deep sinkhole has preserved bones of Ice Age animals like mammoths, American lions, and short-faced bears for over 30,000 years due to its cool, humid environment. It also contains remains of ancient ancestors of modern species such as rabbits, bighorn sheep, and bison.
During a 2014 excavation, Julie Meachen, a biologist from Des Moines University, and her team found the freshly dead pack rat at the bottom of the cave. Instead of moving it, they decided to monitor its decomposition to better understand the taphonomy—the processes that occur to an organism after death—under the unique conditions of the cave.
“We wanted to know what kind of processes bodies go through in decomposition when they’re down in the cave,” Meachen explained.
To protect Packy from scavengers, the team placed a small cage over its body but left it exposed to insects and the cave’s environment.
Over three summers, the researchers tracked the rodent’s decomposition. Unlike the Pleistocene fossils in the cave, which were exposed to rain and snow, Packy was kept dry. As a result, the body dried out and mummified, providing valuable data on how moisture influences decomposition.
“He still has skin, fur, and bones,” Meachen noted,
Meachen added that the modern pack rat’s mummification helped reveal why no Ice Age animals in the cave underwent the same process—precipitation likely accelerated their decomposition.
The experiment shed light on the preservation conditions at the site, but the researchers’ attachment to Packy didn’t end there. When the cave closed after the team’s last excavation in 2017, they took the mummified rat with them to Des Moines University, where it remains frozen. Meachen joked that while Packy may not contribute further to scientific studies, they keep him around as a reminder of the unexpected experiment.
Meachen has since returned to Natural Trap Cave, continuing to uncover rare fossils, including bones from mammoths and American lions. Her ongoing research now focuses on how changing climate conditions impacted the large mammals of the Late Pleistocene.
