Until Now
Biology

Plesiosaurs and the underwater fliers

Long-necked reptiles row through the sea with four wings, a method of swimming nothing else has used.

When
Known to
± 8 million years
Era
Jurassic, Mesozoic

Plesiosaurs radiate through the Early Jurassic, propelling themselves with four large flippers in a motion closer to underwater flight than rowing — computer simulations indicate the forelimbs did most of the work. Alongside them ichthyosaurs continue and marine crocodiles appear. The Jurassic sea has more independently evolved reptilian swimmers than any period before or since.

Just before

Just after