Placodermo - Cosmocaixa

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The lower jaw is born. This is one of the first fortunate ones to have it. The first fish with jaws evolved at the beginning of Silurian, about 80 million years after the appearance of jawless fish (agnates). Jaws likely evolved from the first gill arch that folded back and articulated. The gill arches are skeletal rods that support the gills. With jaws, they significantly increased their ability to feed themselves. The fossil we show here belongs to placoderms, a group of primitive jawed fish that protected themselves from predators with rugged osseous frontal armor. To open their mouths, they raised their heads instead of lowering their lower mandible.