Fossil Expert Interviewed

Insight from Jonathan Geisler, Ph.D., interim dean of research at the College of Osteopathic Medicine, is featured in a Smithsonian magazine article about a mystery surrounding the origins of the giant extinct mammal Andrewsarchus. The skull of the creature, which appeared much like a wolf with hoof-like feet, is on display at New York City’s American Museum of Natural History. However, the limited and worn condition of the fossil complicates comparisons with other animals, as Geisler, an expert on the evolutionary history of mammals, notes. He shares that the skull’s damaged and altered features—including worn teeth and missing inner ear bones—make it hard to match anatomical traits with known relatives, leaving its evolutionary placement uncertain. He also suggests that similarities between Andrewsarchus and other hoofed mammals might reflect convergent evolution rather than close ancestry, highlighting how challenging it is to interpret the beast’s true nature with so little material.