Sagittal crest

File:CanineSkull.jpg

Sagittal Crest

The sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) in many mammals and some reptiles. This bony ridge is an attachment site for the temporalis muscle, which is one of the main muscles involved in chewing.

Anatomy and Function

The sagittal crest is most commonly found in animals that have exceptionally strong jaw muscles, such as carnivores and some primates. The presence of a sagittal crest indicates that the animal has a powerful bite force, as the temporalis muscle is responsible for closing the jaws. In humans, the sagittal crest is typically absent or very small, as our jaw muscles are not as developed as those of some other mammals.

Evolutionary Significance

The development of a sagittal crest is often associated with dietary habits. For example, in gorillas, the sagittal crest is more pronounced in males than in females, reflecting the greater muscle mass required for their diet, which includes tough vegetation. In contrast, chimpanzees and bonobos, which have a more varied diet, have less pronounced sagittal crests.

Examples in Animals

• Gorillas: Male gorillas have a prominent sagittal crest due to their large temporalis muscles.
• Big cats: Species such as lions and tigers have sagittal crests to support their powerful jaw muscles.
• Canids: Some members of the Canidae family, like wolves, also exhibit sagittal crests.

Human Evolution

In the context of human evolution, the sagittal crest is more commonly found in early hominins. For instance, the species Paranthropus boisei had a well-developed sagittal crest, which suggests that they had a diet requiring significant chewing power.

Related Anatomical Features

• Nuchal crest: Another bony ridge found at the back of the skull, serving as an attachment for neck muscles.
• Zygomatic arch: The bony arch on the side of the skull that also serves as an attachment for the temporalis muscle.

See Also

• Skull
• Temporalis muscle
• Human evolution
• Gorilla
• Carnivora

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