The Mycenaeans were the Greek-speaking coat of paint as it were over a number of other related peoples in (mostly western) Anatolia, Greece, and tghe Aegean. As everywhere else in those areas where the Minoans had been found either as residents or as maritime traders, the Mycenaeans took over.
And before anyone brings it up, no, it had nothing to do with Thera.
Nevertheless there were many therapods in ancient Greece (and there are many still today). I remember seeing some when I was in Greece many years ago. They were turkeys (no doubt a legacy of the Ottoman period).