North America's fossil record has long housed a "cheetah": *Miracinonyx trumani*, tall, slender, with long limbs—a New World mirror of the African cheetah. Textbooks cast it as the ecological equivalent of the savanna sprint specialist. But a paper published September 4 in *Current Biology* has uprooted that name entirely: it is not a close relative of the cheetah. Its genes say its closest living relative is the puma.
The study comes from the UC Santa Cruz ancient DNA laboratory, with corresponding author Beth Shapiro and first author Molly Cassatt-Johnstone, among nine authors—including Yukon paleontology veteran Grant Zazula.
A Two-City Archive From Over 20,000 Years Ago
The team obtained two nuclear genomes: a Wyoming individual dating to roughly 23,000 years ago, from a radius bone found in Natural Trap Cave, and a Yukon individual dating to about 31,000 years ago—separated by eight thousand years and more than twenty degrees of latitude.
The phylogenetic conclusion is unambiguous: *M. trumani* is the sister species of the puma (*Puma concolor*), with the two lineages splitting about 2.6 million years ago, amid the severe climate upheavals of the late Pliocene and early Pleistocene. The cheetah-like build has a different origin—convergent evolution. Long legs and narrow shoulders are a general-purpose solution for runners, not evidence of family ties.
What Surprised Us: The Diet
The truly striking finding concerns diet. The evidence isn't DNA but stable isotopes—the carbon and nitrogen ratios preserved in bone, a running tally of an animal's menu over the final decades of its life. The Yukon population's trophic level is markedly higher, consistent with a diet dominated by anadromous (migratory) fish; the Wyoming population was a generalist terrestrial predator. One cat. Two diets.
The abstract also contains a sentence easy to skim past: the Yukon sample extends the species' known range northward by more than 20 degrees of latitude—into the Arctic Circle. At 111 km per degree, that's roughly 2,200 km. The species' actual territory was nearly half the diagonal of China larger than the textbook maps showed.
The Fine Print in the Genome
The genomes also revealed two inactivated genes. A set of circadian rhythm genes lost function—in the Arctic summer there is no night, in winter no day, and a biological clock loses its warranty in the far north; the abstract calls it "relaxed constraint." The other, according to the phys.org release, is the first documented loss of a sour-taste perception gene in cats. Both are examples of evolution "coming clean": what isn't used, breaks and stays broken.
The extinction story gains new texture as well. As Shapiro put it: "The decline was slow, not sudden, and that may be what left it unable to adapt when the climate shifted."
A side note on an old case: the popular explanation for the pronghorn's speed—that it evolved to outrun the American cheetah in a predator-prey arms race—loses another piece of its foundation given this paper's range and diet data. As Cassatt-Johnstone summarized: "These cats were remarkably flexible, much like pumas are today."
Why This Matters
1. Convergent evolution's textbook case gets new evidence—morphology can lie, genes cannot. Names like "American cheetah" based on shape alone deserve extra scrutiny. 2. The Pleistocene megafauna extinction ledger continues to fill in: the slow-decline hypothesis gains testimony from one more species. 3. The workflow itself: samples came from the traditional territories of the Tr'ondëk Hwëch'in and Vuntut Gwitchin, with community collaboration reflected in authorship and acknowledgments—the ethical foundation of ancient DNA is being built alongside its technical one.
The last American "cheetah" left the stage more than ten thousand years ago. The exculpatory document it awaited took twenty thousand years to write—and was filed this September weekend.
References: Paper DOI · UCSC press release · phys.org coverage