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Why are the bones in a caecilian’s skull fused together?

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Zoom in on the serpentine locomotion of the limbless, amphibious caecilian over soil — Gymnophiona Caecilian moving over soil.

The bones in a caecilian’s skull are fused together to create a strong, spadelike braincase. This compact, bony structure is a specialized adaptation that aids the animal in tunneling through the soil during its subterranean existence. By reducing the number of independent cranial bones through the fusion of ossification centers, caecilians achieve the structural integrity necessary for their fossorial lifestyle.12