Historically, Poland has been part of the barrier against the steppe invassions, first the Mongols, then the Russians themselves. From that point of view, it would be central Europe, as the steppe peoples would be eastern Europe. Poles often lived within the HRE, which would place them squarely in the Mittel-europa.
The Cambrian Explosion refers to the metaphorical explosion of life that began 542 million years ago and lasted for roughly 40 million years. This lesson will cover the events that occurred during this time period.
the Cambrian. 45 Indeed, for 525 million years after the Cambrian explo-sion and for 3 billion years before it, the fossil record does not show any-thing like a steadily increasing number of new phyla. Nor does the sudden The Cambrian Explosion: Biologyâs Big Bang 351 # --)#B'5%)#  FIGURE 19A. Animal phyla and subphyla ï¬rst appearances: based on fossil dataalone (see appendix D) # --)#B'5%)# 8 FIGURE 19B.