Scientists, not content to let a not-so-living legend lie, have determined that the viral Chicago "rat hole" was probably actually made by a different kind of rodent.

Researchers published an article in the Oct. 2025 issue of the journal Biology Letters, using methods from paleontology to analyze the "remarkable full body impression" that attracted hundreds of people to Roscoe Village neighborhood last year.

The scientists noted that when comparing the impression to measurements from eight species of rodents, the one that most closely matched that of a tree squirrel. Based on those measurements, scientists said the most likely rodent to leave the impression was either an eastern grey squirrel or a fox squirrel, with the scientists giving a slight statistical edge to the eastern grey squirrel.

While the "rat hole" had been in front of a three-flat on West Roscoe Street for years, it became a viral sensation in the early months of 2024. City crews removed and paved over the slab of concrete the "rat hole" previously occupied last April.