Ancient 'American Cheetah' Evolved From Puma Relative, DNA Reveals
New DNA evidence shows the extinct 'American cheetah' was not closely related to modern cheetahs but was a relative of the puma. The study also reveals a surprising northward expansion of its range, with some populations specializing in eating fish.
New genetic analysis has overturned long-held scientific assumptions about the extinct big cat known as the Miracinonyx trumani, or the "American cheetah." Far from being a close cousin to Africa's speedy feline, this ancient North American predator was actually a highly adaptable relative of the modern puma. The findings, published in the journal Current Biology, also reveal that these cats inhabited a much wider territory than previously understood, with some populations thriving in the frigid Arctic Yukon by specializing in a diet of fish.
First described in 1979, Miracinonyx trumani earned its nickname due to striking physical similarities with modern cheetahs, including elongated limbs and large sinuses—traits typically associated with high-speed pursuit predators. This initial interpretation led paleontologists to believe it was an American counterpart to the Old World cheetah. "That was kind of the first understanding of this species," Molly Cassatt-Johnstone, lead author and a Ph.D. candidate at the University of California, Santa Cruz, explained to Gizmodo. "We’ve got an American cat that seems adapted for high-speed pursuit, so we have an American cheetah."
However, subsequent research, including a 2005 mitochondrial DNA sequencing of a fossil from Wyoming, began to challenge this notion. Those results indicated a closer evolutionary relationship to pumas, a genus native to the Americas, rather than cheetahs, which are found in Africa and Asia. "Which evolutionarily makes sense," Cassatt-Johnstone noted. "Pumas are a new world lineage; they are found in the Americas. Cheetahs are old world, so in Asia and Africa, and so there would have had to have been a migration event if they were most closely related to cheetahs." This new study solidifies that understanding, confirming that the cheetah-like characteristics were a remarkable instance of convergent evolution—where unrelated species independently develop similar traits in response to similar environmental pressures.
An Arctic Fish-Eating Predator Emerges
The latest research, spearheaded by Cassatt-Johnstone and her colleagues, involved analyzing ancient DNA and stable isotopes from fossils discovered as far north as the Yukon. These specimens, dating between 23,000 and 31,000 years old, were initially mistaken for pumas by the research team. "Our job was to figure out what [species] they belonged to, and we were super surprised when we found out they weren’t pumas, they were American cheetahs," Cassatt-Johnstone said. The discovery of Miracinonyx trumani in this frigid region, especially as it approached the Last Glacial Maximum, was highly unexpected. Previously, scientists had no indication that this species ventured so far north.
The genetic analysis confirmed that Miracinonyx trumani was indeed a sister species to the modern puma, diverging approximately 2.6 million years ago. Stable isotope analysis of the fossils provided an even more astonishing insight: the Arctic populations of this cat primarily consumed fish. This dietary specialization suggests these cats, while living in a harsh and vastly different ecosystem than their southern counterparts, were incredibly flexible survivors. "The Pleistocene Beringia is a really well-studied paleontological ecosystem, so it’s very cool to be able to add a new carnivore into a really well-studied ecosystem," Cassatt-Johnstone added. This adaptation for fishing, likely using powerful forelimbs, highlights the species' capacity to exploit available resources in extreme environments.
The ability of Miracinonyx trumani to adapt and diversify its diet and habitat underscores a broader theme in evolutionary biology: the remarkable plasticity of life. "They’re able to predate and exist and engage with their ecosystem in very different ways, depending on where they live and what resources are around them," Cassatt-Johnstone observed. While the evolutionary lineage of the "American cheetah" is now clearer, further research aims to explore the coexistence of these cats with other large predators like pumas and to understand the competitive dynamics they may have faced across North America.