Proatlas


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Proatlas

 

a small, paired bony element (more rarely, having fused parts) located between the skull and the atlas in tuataras, crocodiles, chameleons, and many fossil reptiles; it is uncommon in turtles and mammals (hedgehog). The proatlas apparently develops from the ossified neural part of the sclerotome. Externally it resembles the neural arch of the vertebra, since it articulates anteriorly with the lateral occipital bone and posteriorly with the anterior articular process of the atlas.

References in periodicals archive ?
reptiles) the cranial half of the first cervical sclerotome remains as a separate bone, 'the proatlas', between the occiput and atlas vertebra.
The caudal portion of the fourth occipital somite fuses with the cranial portion of the first cervical somite to form the proatlas. The proatlas gives rise to the exoccipital bone and participates in the formation of the occipital condyle and the tip of the odontoid process).
It has come to be known as the proatlas and constitutes the main portion of the odontoid process.