Question 1

How do you say Cranial?

Accepted Answer

Cranial is pronounced KRAY-nee-ul. The stress falls on the first syllable, so you say KRAY loud and clear, then drop your voice for nee and ul. It rhymes roughly with the word 'brainy-ul' if that helps you remember it. Once you hear it a couple of times it sticks really fast.

Question 2

What does Cranial mean?

Accepted Answer

Cranial means relating to the skull or cranium. Scientists use it as an adjective to describe anything connected to the head bones, like cranial crest, cranial dome, or cranial nerves. It comes from the Latin word cranium, which itself came from the Greek word kranion meaning skull. So when a paleontologist says a dinosaur had impressive cranial features, they mean the dinosaur had something cool going on with its skull.

Question 3

What dinosaur had the biggest cranial crest?

Accepted Answer

Parasaurolophus walkeri had one of the longest cranial crests ever found, with some specimens measuring around 1.8 meters from the tip of the snout to the end of the crest. That is longer than most adult humans are tall. The crest was hollow and connected to the nasal passages, working almost like a musical instrument to produce deep resonating calls. Different species of Parasaurolophus had differently shaped crests that probably produced different sounds.

Question 4

Why did some dinosaurs have crests on their heads?

Accepted Answer

Cranial crests likely served multiple purposes depending on the species. In hadrosaurs like Parasaurolophus, the hollow crest was almost certainly used to make sounds for communication with the herd. In other dinosaurs, crests may have been used for visual display to attract mates or intimidate rivals, similar to the way peacocks use their feathers. Some crests may also have helped with species recognition, since each species had a uniquely shaped crest that made it look and sound different from closely related species.

Question 5

How thick was Pachycephalosaurus's cranial dome?

Accepted Answer

The cranial dome of Pachycephalosaurus was up to 25 centimeters thick, which is roughly the same as the thickness of a bowling ball. It was made of solid, dense bone rather than hollow or spongy bone, which strongly suggests it was built to absorb impact. Scientists confirmed through microscopic bone analysis that the dome grew and thickened as the animal aged, with juveniles having much flatter skulls. This growth pattern mirrors what you see in modern animals that use their heads for fighting.

Question 6

What is an endocranial cast and how do scientists use it?

Accepted Answer

An endocranial cast, or endocast, is a three-dimensional model of the inside of a dinosaur's skull cavity, the space where the brain sat. Scientists make them by filling the skull cavity with material or, more commonly today, by using CT scanning to digitally map the space. The resulting shape gives scientists a rough idea of how big the brain was and which parts were most developed. A 2005 study used this technique on T. rex and found it had unusually large olfactory bulbs, suggesting a powerful sense of smell.

Question 7

Did T. rex have a flexible skull?

Accepted Answer

Yes, surprisingly, T. rex did not have a fully rigid skull the way humans do. The cranial bones of T. rex were connected at joints that allowed very slight movement between the plates, a feature called cranial kinesis. Scientists believe this flexibility helped absorb and distribute the enormous forces generated when T. rex bit down hard on prey or bone. Without some degree of cranial flexibility, the stress of those bone-crushing bites might have fractured the skull itself.

Question 8

How do scientists figure out what a dinosaur's cranial crest was for?

Accepted Answer

Scientists use a combination of methods to figure out the function of cranial crests. They study the internal structure of the crest to see if it is hollow, which suggests a role in sound production, or solid, which suggests a role in combat or display. They also look at airflow modeling, comparing the crest's internal chambers to known sound-producing structures in living animals. Additionally, they study which individuals within a species had larger crests, since if only adults or only one sex had big crests, that strongly points to a role in mating display or competition.

Question 9

Are cranial horns and cranial crests the same thing?

Accepted Answer

No, they are different types of cranial structures even though they are both found on the skull. Cranial horns like those of Triceratops are solid or semi-solid bony projections used for defense and combat. Cranial crests like those of Parasaurolophus or Dilophosaurus are typically more elaborate, flattened or hollow structures primarily associated with display or sound production. Both are examples of cranial ornamentation, but they differ in shape, internal structure, and likely function. Some dinosaurs, like Styracosaurus, had both horns and elaborate frill ornamentation on the same skull.

Question 10

What can a dinosaur's skull tell us about what it ate?

Accepted Answer

An enormous amount actually. The shape and size of the teeth, the angle of the jaw joint, the strength of the jaw muscles indicated by ridges on the cranial bones, and the size of the temporal fenestrae, the openings on the sides of the skull where jaw muscles attached, all reveal dietary habits. Carnivores tend to have deep, narrow skulls with serrated teeth and strong jaw muscle attachments. Herbivores often have broader, flatter snouts with teeth designed for grinding or cropping plants. Paleontologists can reconstruct jaw muscle size from the markings left on cranial bones, giving a good estimate of bite force.

Question 11

What is cranial kinesis in dinosaurs?

Accepted Answer

Cranial kinesis refers to the ability of different bones in the skull to move relative to each other, rather than being locked in a completely rigid unit. In some dinosaurs and many modern reptiles and birds, the upper jaw can flex or the skull bones can shift slightly during biting or feeding. This is actually inherited by birds from their dinosaur ancestors, and modern parrots are famous for having highly mobile upper beaks as a result of cranial kinesis. In theropod dinosaurs, some degree of cranial kinesis likely helped manage the stresses of powerful biting.

Question 12

Why do paleontologists get so excited about finding a complete dinosaur skull?

Accepted Answer

A complete cranial skeleton is incredibly rare and incredibly informative. Most dinosaur fossils are fragmentary, just a few bones scattered by time and geological processes. A complete skull tells scientists the species identity, the age of the individual through bone texture and growth plates, the diet through tooth shape and jaw structure, the sensory abilities through the size of brain regions preserved in the endocast, and even social behavior through the presence or absence of display structures. Finding a complete skull is often described by paleontologists as the single most valuable discovery you can make at a dig site.

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