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Simon
SFN Regular
USA
1992 Posts |
 Posted - 07/04/2009 : 20:53:51 [Permalink]
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Originally posted by Landrew
Originally posted by Simon
Originally posted by Landrew
Large arrays of genes can be lost in one fell swoop sometimes, usually however this results in a fatality in the womb. It seems a stretch for a mammal to suddenly revert to egg-laying. I'm more in favor of the theory that either the echidna is a holdover from a time when all mammals laid eggs, or it evolved slowly back to egg-laying slowly over time.
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It is a holdover and well recognized as such.
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That's the consensus? Is it based on conjecture or is there evidence in the fossil record to support that theory?
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Yeah, it is fairly well established.
Monotreme diverged from the rest of the mammals relatively early in the Evolutionary history while many of the traits that we now associate with mammals were just emerging.
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Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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Argumentum ad ignorantum -- the willful sort.
