The term “big cat” is commonly used to describe any large, powerful feline predator. This general perception does not align with the precise system scientists use to classify animals. Biological taxonomy places a much stricter boundary on which species earn the title of “true big cat” by belonging to a specific genus. This distinction excludes certain impressive felines often mistaken for big cats.
Defining the True Big Cats
The true big cats are grouped together in the genus Panthera, which includes five extant species. This genus is home to the Lion (P. leo), the Tiger (P. tigris), the Jaguar (P. onca), and the Leopard (P. pardus). A fifth member, the Snow Leopard (P. uncia), is also included based on genetic evidence, despite possessing a unique vocal limitation.
For the first four species, the unifying characteristic that historically defined their membership in Panthera was the ability to produce a full, resonant roar. This powerful vocalization is possible because of a specialized anatomical structure. The hyoid apparatus, a set of bones supporting the tongue and larynx, is not completely hardened or ossified in these cats.
Instead of a solid bone, the epihyal element of the hyoid is replaced by a long, elastic ligament. This flexible structure works in conjunction with a specially adapted larynx that features large, muscular vocal folds. The combination allows air to pass over the folds, creating the low-frequency vibrations necessary to generate the signature sound of the roar.
The Excluded Giant
The large feline that is frequently misidentified as a member of Panthera is the Cougar, known by many regional names including Puma and Mountain Lion. This species, scientifically named Puma concolor, belongs to the genus Puma, firmly placing it outside the true big cat lineage. It holds the distinction of being the fourth-largest cat species in the world.
The Cougar possesses the widest geographical distribution of any terrestrial mammal in the Western Hemisphere, ranging from Canada’s Yukon territory down to the southern Andes in Patagonia. Its impressive size, with adult males reaching over 200 pounds and nearly eight feet in length from nose to tail, contributes significantly to its mistaken identity as a Panthera species.
Despite its formidable size, the Cougar is classified within the subfamily Felinae, which contains all the smaller cat species, including the domestic house cat. The Puma genus currently contains only this single extant species. The Cougar’s exclusion from the Panthera genus is a prime example of how scientific classification relies on internal biology rather than outward appearance alone.
How Scientists Classify Feline Genera
The exclusion of Puma concolor from the Panthera genus is mandated by distinct differences in both anatomy and evolutionary history. While the roaring cats have an incompletely ossified hyoid, the Cougar possesses a fully hardened, bony hyoid apparatus. This complete ossification prevents the Cougar from achieving the necessary vocal resonance to produce a true roar.
This anatomical structure, common to the Felinae subfamily, enables the Cougar to purr continuously, a vocalization the roaring Panthera species cannot achieve. The ability to purr is linked to simpler vocal folds that allow for vibration during both inhalation and exhalation. In contrast, the large, fibro-elastic vocal folds of the lion and tiger are better suited for low-frequency sound production.
Modern taxonomy relies heavily on genetic analysis to map the evolutionary divergence of species, a method that often supersedes older classifications based solely on morphology. Genetic studies confirm that the Puma genus diverged from the Panthera lineage millions of years ago, placing it on a different branch of the cat family tree.
This genetic evidence also helps to explain the classification of other large, non-roaring felines, like the Cheetah (Acinonyx jubatus), which is also in the Felinae subfamily. The Cheetah is another large cat excluded from Panthera, distinguished by its semi-retractable claws, specialized for high-speed traction. The classification of the Cougar and other large cats is a testament to the fact that shared evolutionary lineage and specific internal anatomical features, not just body size, dictate a species’ place in the biological hierarchy.