THE OTIC NOTCH/ QUADRATE BONE/ FOSSAE
AND THERE RELATIONSHIPS:

The Quadrate bone can be placed in two ways, caused by the otic notch mechanical weakness:

Picture B: either the upper end of the quadrate forms the pivot (figure 1.5 B) and the lower end swings forward.

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Picture C: Or the lower end forms the pivot and the upper end swings backward. Which is found in all Theropsida or are clearly derived from it.

.....These two different motions of this bone caused different ways in which the jaw muscles closed the mouth. This led to other changes to the skull structure.

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