Genetic Study Reveals American Cheetah Was Actually a Puma Relative

Scientists at the University of California, Santa Cruz have published new research in the journal *Current Biology* that challenges long-held beliefs about the extinct "American cheetah," scientifically known as Miracinonyx trumani. The study overturns previous assumptions and clarifies that this species was not a true cheetah but rather an evolutionary offshoot of the puma, adapted to various ecological niches across North America.

The research team analyzed fossils dating back 23,000 to 31,000 years ago, focusing on nuclear paleogenomes and stable isotopes. This genetic analysis revealed that M. trumani diverged from the puma lineage approximately 2.6 million years ago but developed similar physical characteristics independently due to convergent evolution. This evolutionary path led to a creature with long front legs and a slender body, enabling it to achieve speeds comparable to modern cheetahs.

Molly Cassatt-Johnstone, a Ph.D. candidate at UC Santa Cruz's Paleogenomics Lab, highlighted the adaptability of M. trumani, noting its ability to occupy different ecological niches based on geographic location. In temperate grasslands like Florida and Wyoming, it functioned as a generalist predator. However, in the Arctic Yukon, where fossils were also found, it adapted to a diet primarily consisting of fish such as salmon.

The study also uncovered genetic adaptations that allowed M. trumani to cope with extreme light cycles typical of northern latitudes. Loss-of-function mutations in circadian rhythm-regulating genes suggest these cats had unique biological clocks suited for the Arctic environment. Additionally, researchers found that this species lacked a sour taste receptor, which is typically used by animals to identify safe foods.

Beth Shapiro, professor of ecology and evolutionary biology at UC Santa Cruz and co-director of the Paleogenomics Lab, noted that M. trumani exhibited low genetic diversity over its long existence, without signs of inbreeding as it declined gradually during the Pleistocene epoch. This pattern suggests that environmental changes rather than genetic factors were responsible for its eventual extinction.

The findings underscore the importance of thorough scientific investigation and highlight how superficial similarities can lead to incorrect classifications. The research also provides insights into evolutionary processes and adaptation strategies, contributing valuable knowledge about biodiversity in prehistoric North America.

This study not only corrects a significant misunderstanding in paleontology but also offers a cautionary tale about the limitations of visual comparisons in species classification, emphasizing the need for rigorous genetic analysis in future studies.