New research from Museum researchers suggests that cheetahs’ high-speed hunts are helped by a unique inner ear that allows these powerful predators to maintain their balance during a 65-mile-an-hour chase.
“If you watch a cheetah run in slow motion, you’ll see incredible feats of movement: its legs, its back, its muscles all move with such coordinated power. But its head hardly moves at all,” says Camille Grohé, who conducted this work during a National Science Foundation and Frick Postdoctoral Fellowship in the Museum's Division of Paleontology, and is the lead author of a study out today in the journalScientific Reports. “Until now, no one has investigated the inner ear’s role in this incredible hunting specialization.”
In most vertebrates, the inner ear is essential for maintaining balance and head posture during movements. The “balance system” includes three semicircular canals that contain fluid and sensory hair cells that detect the head’s movement. As the fluid shifts, the semicircular canals send signals to the brain about whether the head is moving up and down, side to side, or tilting.
For this study, Grohé and colleagues created detailed 3D virtual images of inner ear shapes and dimensions of several different felid species using skulls of 21 cat specimens, including modern cheetahs (Acinonyx jubatus), a closely related extinct cheetah (Acinonyx pardinensis) that lived in the Pleistocene between about 2.6 million and 126,000 years ago, and more than a dozen other living species.
They found that compared to the extinct cheetah species or its felid contemporaries, the modern cheetah has a unique inner ear, with a greater overall volume and longer semicircular canals.
“This distinctive inner ear anatomy reflects enhanced sensitivity and more rapid responses to head motions,” said co-author John Flynn, the Frick Curator of Fossil Mammals in the Museum’s Division of Paleontology.
These give the swift sprinters an edge during a high-speed hunt—and likely helped their ancestors compete for prey with other powerful predators, such as panthers and sabertooth cats.
