The cheetah, renowned globally as the fastest land mammal, is commonly perceived as a “big cat” due to its size and predatory nature. Scientifically, however, the cheetah is taxonomically considered part of the “small cat” lineage. This classification relies not on the animal’s impressive mass or stature, but on specific anatomical characteristics that determine its place within the larger cat family, Felidae.
The Scientific Definition of Cat Groups
The entire cat family, Felidae, is broadly divided into two primary subfamilies: Pantherinae and Felinae. This division is not based on the cat’s physical size, which is a common misconception, but on a subtle difference in its vocal apparatus. The ability to produce a true roar is the defining characteristic that separates the big cats of the Pantherinae subfamily from all other felines. This group includes the lion, tiger, leopard, and jaguar, all members of the genus Panthera.
The physical mechanism for roaring is tied to the hyoid bone, a structure in the throat that supports the tongue and larynx. In roaring cats, the hyoid bone is only partially ossified, or hardened, containing an elastic ligament that allows the larynx a greater range of movement necessary for a deep, resonant roar. Conversely, Felinae, or the small cats, possess a fully ossified, rigid hyoid bone. This rigid structure prevents them from roaring, but it allows them to produce a continuous purr on both the inhale and the exhale.
The Cheetah’s Unique Place in the Cat Family
The cheetah, Acinonyx jubatus, is firmly placed within the Felinae subfamily because its hyoid structure is fully ossified, like that of a domestic house cat. This anatomical trait means the cheetah cannot roar, but it can purr, chirp, and make a variety of other small cat vocalizations. Its membership in the small cat group is a consequence of its internal anatomy, not its external appearance or weight, which can reach up to 140 pounds.
The cheetah is the sole living member of its own genus, Acinonyx. While it is grouped with other small cats like the cougar and the jaguarundi in the Puma lineage, it represents an early, highly specialized branch of this evolutionary path. Genetic studies place the Puma lineage as one of the eight major evolutionary groups within the cat family, diverging relatively early in felid history.
Physical Adaptations Beyond Classification
The cheetah’s classification as a small cat belies its extreme physical specialization, which makes it an outlier in the entire Felidae family. The most obvious difference is the cheetah’s claws, which are semi-retractable (or non-retractable), unlike the fully sheathed claws of most other cat species. These blunt, exposed claws function like the cleats on a running shoe, providing the necessary traction for rapid acceleration and sharp turns during a high-speed chase.
Its body is an aerodynamic masterpiece built for speed, featuring a deep chest, long, slender limbs, and an extremely flexible spine. This skeletal and muscular structure allows the cheetah to achieve speeds of up to 75 miles per hour in short bursts. The long tail, which can be two-thirds the length of its body, acts as a sophisticated rudder, helping the cat maintain balance and change direction instantly while sprinting.
The distinctive black “tear tracks” running from the corner of the eye down to the mouth serve a functional purpose. These markings absorb sunlight and reduce glare, similar to the black grease applied under the eyes of human athletes, enhancing the cheetah’s long-distance vision for hunting in bright savanna environments.