Explanation

• Trilobites evolved in the Cambrian period, approximately 521 million years ago.
• Trilobites are a group of extinct marine arthropods that flourished throughout the lower Paleozoic era before declining during the Devonian period.

Explanation

The answer is H.J. Muller.

In his experiments, Muller exposed fruit flies (Drosophila) to X-rays, mated the flies, and observed the number of mutations in the offspring.

In 1927, Muller described the results of his experiments in "Artificial Transmutation of the Gene" and "The Problem of Genic Modification".