Many groups of animals have been proposed as the closest relatives of, or ancestral to, the vertebrates. Some hypotheses make strange reading today, but one should remember that this strangeness could, in part, be a reflection of our familiarity with ideas of a different kind, rather than any inherent crankiness or error in these others29.
KeywordsNeural Crest Nerve Cord Hermit Crab Planktonic Larva Gill Slit
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