SKULL FACT
Instead of being fused to the skull, some bird beaks are connected to the skull with ligaments, so both the top and bottom portions can move. This adaptation helps predatory birds avoid beak breakage while holding wriggling prey in their mouths. It also allows macaws to crack open nuts without transferring that pressure to the skull.

SKULL FACT
The elongated structure on top of the cassowary’s skull, called a casque, is filled with a network of very thin bone. The reason that cassowaries evolved casques is still debated, but the protruding structures may help them poke through the dense vegetation of their rainforest habitat without hurting their heads.

Q: Is convergent evolution common?
PR: Although species normally diverge from their ancestors over time, many distantly related animals develop similar adaptations. This convergence can complicate the process of reconstructing evolutionary paths, since shared traits are often used to determine relatedness.

Dr. Peter D. Roopnarine
Assistant Curator and Department Chair
Department of Invertebrate Zoology & Geology

SKULL FACT
In high-impact sports like football, players wear helmets to protect their heads. Nature designed the first helmet nearly 500 million years ago, when vertebrate fish developed skulls to protect their brains. Over time, these early skulls have been modified to match a variety of high and low impact lifestyles.

Q: Why do some animals have a large sagittal crest?
NJ: Predators that tackle large prey often develop a sagittal crest, since it provides attachment space for the temporalis muscle, which is used to snap the jaws shut. Sagittal crests are often larger in males than in females, because they are associated with larger body size.

Dr. Nina Jablonski
Curator and Department Chair
Department of Anthropology

Q: Why is there a large hole at the base of each skull?
NJ: This hole, called the foramen magnum, allows the spinal cord and nerves to pass from the base of the brain through to the rest of the body. Because it connects the skull to the spine, its placement can be used to determine an animal’s typical posture.

Dr. Nina Jablonski
Curator and Department Chair
Department of Anthropology

Q: How do skulls protect horned animals during head butting matches?
DL: A special honeycombed bone structure around the base of the horns absorbs the shock of impact during repeated head-on collisions, allowing the muskox and many other horned animals to survive dominance competitions without damaging the skull or brain.

Dr. Douglas J. Long
Collections Manager and Acting Department Chairman
Department of Ornithology & Mammalogy

Q: Are skulls specialized to help an animal chew?
NJ: The skull provides a framework for the face and neck muscles – animals that need stronger chewing muscles will develop larger bony attachment ridges for these muscles, such as the sagittal crest along the top of the skull and the zygomatic arches on the sides.

Q: Why do humans have such large brains?
NJ: A large brain gives humans the ability to process, integrate and compare a tremendous amount of sensory stimuli. It also allows a great degree of behavioral flexibility and provides an immensely increased capacity for memory.

Dr. Nina Jablonski
Curator and Department Chair
Department of Anthropology

Q: Why does the owl monkey have such enormous eye sockets?
RB: The owl monkey is the only nocturnal anthropoid, or higher primate. In order to avoid predators that prowl during the day, it feeds on fruits and insects in the dark of night. Its large eyes allow it to collect more available light, giving it sharper night vision.

SKULL FACT
Due to their environments and lifestyles, many animals require particularly acute senses. These adaptations are sometimes recorded in an animal’s skull, where bone has grown to accommodate larger sense organs or a larger brain – the center where all sensory intake is processed.

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© 2002 California Academy of Sciences