The reclassification rests on four individuals: three specimens from Bluefish Caves and Upper Quartz Creek in the Yukon, plus one from Natural Trap Cave in Wyoming [8]. Four genomes carry the revision [2]. The Yukon bones were recovered in the Tr'ondek Hwech'in and Vuntut Gwitchin Traditional Territories [23].
The team did not set out to redraw the cat family tree. It wanted to confirm what three roughly 31,000-year-old Yukon fossils were, and those had been tentatively logged as pumas precisely because they turned up so far north; the sequences came back as Miracinonyx trumani, and Molly Cassatt-Johnstone told Science News that everything else followed from there [9]. The prior that failed was geographic as much as anatomical.
Divergence dates put the split from pumas near 2.6 million years ago [2] and the split from cheetahs near 4.7 million [3], leaving about 2.1 million years between the two branch points [1]. The slender frame is read as convergent evolution [15]. The pronghorn argument deserves more care than the nickname invites: its "ghosts of predators past" version holds that the pronghorn's sprint, close to 90 kilometers per hour [14], evolved against a cheetah-like pursuer [13]. Removing the cheetah relationship does not remove the running, and the same work describes an animal capable of terrestrial pursuit as well as grasping prey with powerful forelimbs [16]. What the genome withdraws is permission to read the animal's ecology off its name, which is close to how Cassatt-Johnstone frames it [25].
Nitrogen isotopes answer a narrow question: how many steps up a food chain an animal sat, not what was on the plate or how it got there [6]. Salmon in particular is an inference from anadromy [5] and from the many Pleistocene fish fossils in one of the same Yukon caves [26]. Larisa DeSantis of Vanderbilt, who was not part of the study, notes the payoff of exploiting an abundant prey resource that does not injure the hunter [21].
That leaves the two-ended ecology, which co-author Matthew Wooller of the University of Alaska Fairbanks describes as uber-specialization at opposite ends of a huge range [19], resting on one Wyoming genome against three from the Yukon [8]. More specimens across the range, including south of Wyoming, are what the researchers say would show how adaptable the species really was [24], and that is the number that decides whether this is a species-wide flexibility or three animals near a good fishing spot.
