Sagittal crest

Paranthropus aethiopicus

File:CanineSkull.jpg

CanineSkull

Sagittal crest

A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (cranium) 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 mastication (chewing). The presence and prominence of a sagittal crest can vary significantly among different species and even among individuals within a species.

Anatomy and Function

The sagittal crest is typically found in species that have strong jaw muscles and require significant force for chewing. It provides additional surface area for the attachment of the temporalis muscle, which extends from the crest down to the mandible (lower jaw). This muscle is crucial for the elevation and retraction of the mandible, enabling the animal to bite and chew effectively.

Occurrence in Mammals

In mammals, the sagittal crest is most commonly observed in species with a diet that requires heavy chewing, such as carnivores and some herbivores. For example, it is prominent in large canids like wolves and hyenas, as well as in some primates like gorillas and orangutans. In these animals, the sagittal crest supports the powerful jaw muscles needed to process tough food items.

Occurrence in Reptiles

Among reptiles, the sagittal crest can be found in some species of dinosaurs and modern crocodilians. In these animals, the crest serves a similar function, providing an attachment site for strong jaw muscles.

Evolutionary Significance

The development of a sagittal crest is often associated with dietary adaptations. Species that consume hard or fibrous food items tend to develop more pronounced crests to accommodate the larger temporalis muscles needed for processing such foods. The presence of a sagittal crest can thus provide insights into the dietary habits and ecological niches of extinct species based on fossil evidence.

Related Anatomical Features

The sagittal crest is one of several cranial features that can indicate muscle attachment and dietary habits. Other related features include the zygomatic arch, which also serves as an attachment site for jaw muscles, and the nuchal crest, which provides attachment for neck muscles.

See Also

• Cranium
• Temporalis muscle
• Mandible
• Zygomatic arch
• Nuchal crest
• Mastication
• Carnivores
• Herbivores
• Primates
• Dinosaurs
• Crocodilians