The ocean's first large swimming apex predators had exceptionally rapid growth, fossil study finds

The rapid diversification of animals over 500 million years ago—often referred to as the Cambrian Explosion—saw the appearance of the first large swimming predators in our oceans. Amplectobelua symbrachiata, a member of the group Radiodonta, which are relatives of modern arthropods, was the largest of these, reaching nearly one meter in length, and can be easily recognized by their fearsome spiny feeding appendages.