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What Is the Cranium?

The Cranium is a group of bones that can generally and simply be defined as the skull or the bones on a human head, simple enough but still not too vague for everyday consumption. If you look for a more detailed meaning you’ll see that it’s actually a fair definition. On a side note “craniates” is a term used to refer to animals in possession of a skull.

When examined in more detail it’ll be discovered that the Cranium is actually a 2 groups of bone having a total of 21 different pieces. The first group being the splanchnocranium, this supports portions of the face, and second is the neurocranium, apply refered to as “brain case”, this is responsible for protecting the Brain.

Animals can be classified by the kind of skull they have, some of the reptiles, birds and mammals are classed this way under the classification Aminotes. Aminotes can have a temporal fenestrae, bilaterally symmetrical holes that are found in the cranium’s temporal bone.

Animals with small openings on the each side of their head can be classified into one of three groups Synapsids, Diapsids, or Euryapsids. Synapsids only have openings behind their ears, a small and low one at that. Diapsids have four openings, you for each side. Euryapsids, dispite their having evolved from Diapsids, are now extinct had high openings behind each eye.

Consisting mostly of cartilage most fish craniums are much less developed then most Aminotes. This is not true for the actinopterygii or Ray-finned fish that have a much harder cranium as compared to other fish.

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