Not much is known about the skeletal structure of the big cats outside of what scientists can infer based off of what we know from the domestic cat. The cat family is remarkable and unique because despite populating all over the world, their skeletal system, among other systems, are extremely similar. In fact, when comparing the skeletal structures, the skeletons of the Pantherinae subfamily are just a larger-scaled version of the Felinae subfamily with a few minor adaptations.
However, we can compare the skulls of the big cats. The skull’s function is to protect the eyes and the brain. But for cats, it is also built to allow the feline to have maximum strength in its jaw, which is essential considering its hunting methods and carnivorous diet. Short and rounded, majority of the support and power in the skull are in the teeth and jaws. In addition, a tiger’s septum is made up of hard, compared to human’s which are made out of membrane, that separates the cerebrum and cerebellum, protecting the brain more effectively.
The two biggest and well known out of the large cat species are the lion and tiger.
The most notable differences between the two skulls is the relative skull profile and how the snout is positioned. As you can tell by the lateral view of the two skulls, the lion’s skull profile is relatively flatter whereas the tiger’s skull profile is much more rounder. Overall, the lion has a broader forehead than the tiger. In the front view, the lion’s snout is also much more upturned; the tiger’s snout is more downturned.
Back to the lateral view, notice the differences between the two mandibles. The ventral margin of the lion’s mandible is much more rounded, causing the skull to rock back and forth despite being on a flat, even surface. On the other hand, the ventral margin of the tiger’s mandible is relatively straight.
In the dorsal (from the top) view, the positioning of the maxillo-frontal and nasofrontal sutures. The apex of the nasals of the lion are either in line or anterior to the maxilla (the eye opening); the apex of the nasals of the tiger are farther posteriorly to the maxilla.
Further down the skull, the lion has a flatter dorsal surface (bridge) of the nasal and broader nose openings that are lower down on the skull than that of the tiger’s. The tiger’s nasal opening is constricted ventrally and the strongly convex dorsal surface of the nasals forms a prominent bride along the lateral margin of the nasals.
Next is the jaguar, leopard, and snow leopard.
By size alone, the jaguar has a much larger skull than the leopard or snow leopard. The jaguar is a much more stockier and bigger animal and is shown through skull comparison. The greatest recorded skull length is 204 to 302 mm for the jaguar, the leopard’s is 170 to 200 mm, and snow leopard’s is 165 to 200 mm . On the other hand, the leopard has a slimmer and narrower features than the jaguar. A distinct feature that of the snow leopard is that it has a broad frontal that also has a dip.
There is a difference when observing the nasal and teeth profile. The jaguar’s and snow leopard’s concave nasal profiles mean that from the forehead to the nose, it curves inward whereas for the leopard, it has a convex nasal profile. Therefore, it curves outward. The nasal cavity for the snow leopard is a special adaption to suit their cold environment. Its wide and short nasal cavity can heat up the chilled outside air before it reaches the lungs.
When comparing teeth, the jaguar has large, robust, conical (cone-shaped) upper and lower canines, but the leopard and snow leopard has elongate saber-like upper and lower canines. Furthermore, there is a difference in canine grooves which are typically on the inner and outer surface of the tooth. With jaguars, the canine grooves are absent or faint, barely noticeable. However, leopard and snow leopard’s canine grooves are prominent.
Last but not least, the clouded leopard.
The clouded leopard has the smallest skull out of all the other members of the Pantherinae subfamily. This, among other factors, set the clouded leopard and its relative, the sundra clouded leopard, to be categorized into its own separate genus. Like the leopard’s skull, the clouded leopard’s skull is narrow and skinny.
Its most distinctive feature is its long canine teeth. The clouded leopard has the longest upper canine teeth relative to skull size of any living carnivore. This feature caused some people to compare the cat with the saber-toothed cat. Studies by Dr. Per Christiansen of the Copenhagen’s Zoological Museum revealed connections between the two species to bear distinctive resemblance to primitive saber-toothed cats and the clouded leopard. Only the clouded leopard has the same enormous gape, around 100 degrees, with the various adaptations to support such a gape. In contrast, a modern lion can only open its mouth about 65 degrees.
Now we’ve gone over the skull comparisons, but what about the differences between the Pantherinae and Felinae subfamilies? There are two main differences: the sagittal crest and the larynx.
Short and rounded, majority of the support and power in the skull are in the teeth and jaws. All the large cat species and males in medium-sized species have bony ridges called sagittal crests along the top of the skull. This provides the necessary surface area to attach and create even greater jaw strength. The smaller cat species lack this adaptation as they hunt small prey.
The larynx isn’t located in the skull. It is the voice box, the hollow muscular organ that forms an air passage to the lungs and holds the vocal chords. When air passes through the larynx on the way from the lungs, the cartilage walls of the larynx vibrate, producing sound. The skeletal differences is also the reason why some cats can purr but others roar.
Only four species can actually roar: the lion, tiger, leopard, and jaguar. This is due to a bone situated near the larynx called the hyoid and an elongated and specially adapted larynx. In all roaring cats, the hyoid bone is not completely ossified. The larynx is attached to the skull by cartilage, allowing for flexibility. So when the larynx stretches, coupled with the flexible bone, these large cats are able to make a deep, roaring sound.
The only exception to this rule is the snow leopard. Though it has a flexible hyoid, it can’t purr or roar the same way like the other feline species. Instead, it makes a semi-roaring sound that is sometimes referred to as chuffing.
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