This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study led by researchers at the University of California, Santa Cruz, has overturned decades of assumptions about Miracinonyx trumani, the extinct predator popularly known as the American cheetah. By analyzing nuclear paleogenomes and stable isotopes from fossils found as far north as the Yukon, scientists have discovered that this iconic cat was not a true cheetah but a highly adaptable relative of the puma that specialized in eating fish to survive in the Arctic.
The findings, published Sept. 4 in Current Biology, reveal that the species' range extended 20 degrees of latitude farther north than previously recognized. While southern populations in regions like Wyoming and Florida lived as generalist predators in temperate grasslands, their northern counterparts in the Arctic Yukon carved out a unique niche as tertiary consumers, likely specializing in anadromous fish such as salmon. With slender bodies and long front legs that may have helped them move efficiently across the open landscapes of Pleistocene North America, an adult Miracinonyx trumani was thought to weigh around 150 pounds (68 kilograms) on average, stand about 3 feet (0.9 meters) tall and measure about 8 feet (2.4 meters) long to the tip of its tail.
Despite its cheetah-like appearance, this and other recent research suggest it was a versatile predator, capable of both terrestrial pursuit and grasping prey with powerful forelimbs. "These cats were remarkably flexible, much like pumas are across their range today," said Molly Cassatt-Johnstone, a Ph.D. candidate in the Paleogenomics Lab at UC Santa Cruz and lead author of the study. "We found loss-of-function mutations in certain genes that regulate circadian rhythms, suggesting they may have adapted to the extreme light cycles of summers and winters in northern latitudes." For decades, M. trumani has been a staple of North American paleoecology, often cited as the evolutionary reason why the American pronghorn is so fast.
This "ghosts of predators past" hypothesis suggested that the pronghorn's extreme speed was a coevolved defense against the high-speed pursuit of a cheetah-like hunter. However, the new genomic data confirm that M. trumani was actually a sister species to the modern puma, having diverged from that lineage roughly 2.6 million years ago. Its slender, "cheetah-like" body is now understood as a striking example of evolutionary convergence, in which two unrelated species evolve similar traits to survive in similar environments.
By sequencing high-coverage genomes from fossils dating back 23,000 to 31,000 years, the team identified specific genetic blueprints that allowed these cats to thrive in the extreme environments of the Late Pleistocene. Fossil specimens analyzed in this study from Yukon Territory were recovered from the Tr'ondëk Hwëch'in and Vuntut Gwitchin Traditional Territories, with respect for their deep-rooted relationship to and stewardship of these lands. The study also revealed a unique sensory loss: M. trumani and all lineages of felids sampled in this study lacked a functional gene that encodes a receptor for sour taste.
While all cats are known to lack a "sweet tooth," this is the first recorded instance in felids of inactivation of genes involved in the perception of sour flavors, a trait sometimes associated with highly specialized diets. "This species of carnivore has this massive range, all the way from the Arctic to the Lower 48," said co-author Matthew Wooller, a professor in the College of Fisheries and Ocean Sciences at the University of Alaska Fairbanks (UAF). "They're demonstrating uber-specialization at two ends of their range, while also feeding on two completely different food sources." Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly.
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