Reading Assignment 41.a.“Minor phyla” are the many different phyla with small numbers of species being alive today. They are also not typical when one thinks of “animals”—so they are unloved and often forgot. b.According to Gould, they are not minor because they embody some interesting problems of natural history, some dominated the early fossil record of multi-cellular animal life, and they are all completely distinct from one another. The minor phyla “soften” the extraordinary nature of the Cambrian Explosion by showing that it was merely an intensification of ordinary possibilities. 2.a.Since pentastomes are parasites that live almost exclusively on terrestrial vertebrates that did not evolve until after the Cambrian Explosion, this makes them seem as if they are a relatively recently evolved phylum. b.Onychophorans, tardigates, and pentastomes all go back to the initial diversification of multi-cellular life in the Cambrian Explosion.
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