About a quarter of all known animal species are beetles and the scarab beetles are one of the most diverse families of beetles. During the Jurassic period 200 million years ago, flowering plants evolved and beetle species branched off to specialise in feeding on them. Scarab beetles emerged around 145 million years ago, at the start of the Cretaceous period. This was when New Zealand split from Australia and South America drifted away from Antarctica. Scarabs found themselves on all the main continents and the isolated populations continued to diversify to fill different niches.
Answered by Luis Villazon.