Vertebrates Jaw Formation

420 million years
or 102 meters before today

Geolo­gical era: Paleo­zoic / Silurian

At the begin­ning of the Silurian, verteb­rates develop movable jaws that allow them to grasp, hold and chop food. This opens up completely new feed­ing possib­il­it­ies for the jawed anim­als. Bone scales form teeth that can sit on the edges of the jaws, in the oral cavity or in the gullet. This devel­op­ment is so success­ful that today there are only two jawless verteb­rate groups (lampreys and hagfish).

After the end of the Ice Age at the begin­ning of the Silurian, a warm temper­ate climate prevails with a global aver­age temper­at­ure of about 17 °C. For the first time, the oxygen concen­tra­tion rises to 14 %, while the carbon diox­ide concen­tra­tion drops below 0.4 %. The contin­ent Euramer­ica (Laur­us­sia) is formed from the land masses Lauren­tia and Baltica.

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