Temporal Bone
Irregular bone; part of the axial skeleton (the central core of the body)
Also known as: Temple bone, side of the skull, ear-housing bone
Classification
Irregular bone; part of the axial skeleton (the central core of the body)
Dimensions
In mammals, this is a relatively flat but complex piece forming the lower side and base of the skull. It is roughly the size of a person's palm and features several deep stony ridges and thin plates.
Key Features
The blue arrows point to the Mandibular Fossa—a smooth, shallow, oval-shaped scoop that acts as a socket for the lower jaw. Other landmarks include a long, slender 'zygomatic process' that reaches forward like a handle to form the cheekbone, and a rough, downward-pointing bump behind the ear area. The underside is often very rugged and contains various sized holes for nerves and vessels.
Similar Bones
It can be confused with the Sphenoid bone, which sits just in front of it. However, the temporal bone is easily distinguished by the presence of the external ear opening and the very specific socket for the jawbone. The Sphenoid is more butterfly-shaped and lacks these ear-related features.
Across Species
The temporal bone is a marvel of evolutionary engineering. In many mammals, a portion of it swells into a rounded 'auditory bulla' to enhance hearing—think of the large, thin-walled bony bubbles on the bottom of a desert fox skull. In aquatic mammals like whales, these bones are incredibly dense and often detached from the rest of the skull to allow for better underwater sound localization. In birds, the equivalent structures are much lighter and highly fused to the neighboring braincase bones to save weight for flight.
Evolutionary History
This bone is actually a composite of several smaller bones found in our ancient reptilian and early mammalian ancestors, such as the squamosal and the petrosal. Over millions of years, these separate pieces fused together into a single, sturdy unit that fulfills three roles: anchoring jaw muscles, protecting the brain, and housing the delicate internal structures used for hearing and balance.
Photography Tips
To identify this bone, take a photo from the side to show the cheekbone connection and ear opening. A second photo from the bottom looking up is essential to see the jaw sockets (where the blue arrows are) and the complex ridges that house the inner ear.
Notes
What are the blue arrows pointing to