Learn more about a time period marked by an intense burst of evolution. 3 min read The Cambrian period, part of the Paleozoic era, produced the most intense burst of evolution ever known.

By the start of the Cambrian period 541 million years ago ... triggered the Cambrian explosion—there also were changes in ocean chemistry that allowed animals to acquire hard parts (calcium ...

Among the many fossilized stars is a 26-meter-long Mamenchisaurus jingyanensis, a gigantic herbivore that lived around 150 million years ago and had one of the longest necks of its species. It is ...

Internal, genetic factors were also crucial. Recent research suggests that the period prior to the Cambrian explosion saw the gradual evolution of a "genetic tool kit" of genes that govern ...