Ancient DNA shows the 'American cheetah' was a fish-eating cousin of the puma
A study of ancient DNA from Yukon and Wyoming fossils finds that Miracinonyx trumani, nicknamed the 'American cheetah' for its long-limbed build, is genetically closer to today's puma than to any cheetah, the two lineages having split about 2.6 million years ago. Chemical signatures in the northern fossils show those populations lived mostly on fish rather than chasing fast prey like pronghorn, pointing to a more flexible predator than the nickname suggests.
Science··Night
Ancient DNA ties Miracinonyx trumani to the puma, not the cheetah
A new genetic analysis of Miracinonyx trumani, the extinct predator nicknamed the 'American cheetah' for its long-limbed, high-speed build, finds its closest living relative is the puma rather than any cheetah species. Researchers recovered ancient DNA from fossils in Canada's Yukon Territory and at Natural Trap Cave in Wyoming and reported in Current Biology on 4 September that the puma and Miracinonyx lineages split from a common ancestor about 2.6 million years ago, while the split from true cheetahs came roughly 4.7 million years ago. The team had not set out to rewrite the animal's family tree: the Yukon fossils were first logged tentatively as pumas because of their far-northern location, and only ancient DNA revealed they belonged to Miracinonyx instead.[1], [2]
Yukon fossils push the cat's range north and reveal a fish-heavy diet
The Yukon specimens extend Miracinonyx trumani's documented range far north of its previously known territory, which had stretched from Florida to the northern plains. Nitrogen-isotope analysis of those northern fossils found the animals ate mostly fish rather than chasing fast-moving prey such as pronghorn, which can run at nearly 90 kilometres per hour; predators higher in the food chain carry more of the heavy nitrogen isotope than plant-eating prey does, and the Yukon specimens' signatures matched a fish-heavy diet. That is a marked contrast with the pursuit-predator image the 'American cheetah' nickname implies.[2]
The genomes also show low diversity and genes tied to circadian rhythm
The recovered genomes carry loss-of-function changes in genes that govern circadian rhythm, and show low genetic diversity overall. Researchers found no clear signature of inbreeding in that low diversity; the study reads this pattern as consistent with a slow, long-term population decline before the species went extinct rather than a sudden collapse. Southern Miracinonyx populations lived as generalist hunters much as pumas do today, while the northern, fish-eating populations described in the Yukon fossils show how flexible the species could be across its range.[1]
