The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution
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more closely related. Whether or not Halkieria fits the bill, it would be worrying if there were not an ancient animal that united annelids, brachiopods and molluscs. Note the shells, one at each end, in the illustrations above. As we saw at Rendezvous 22, Chengjiang has fossils that appear to be true vertebrates, pre-dating the amphioxus-like Pikaia of the Burgess Shale and other Cambrian chordates. Traditional zoological wisdom never had vertebrates arising so early. Yet Myllokunmingia, of
pecially given that nobody had looked at the animal itself for more than half a century? It languished as an alleged cnidarian larva until the molecular revolution opened up the possibility of discovering its real affinities. Whatever else it is, it is definitely not a cnidarian. Preliminary indica- tions from rRNA studies (see Taq's Tale) suggest that Tricho- plax is more distant from the rest of the animal kingdom than any other group except the sponges, and it may be that even the
multicellular bacteria, multicellular ciliates, multicellular flagellates and multicellular amoebas, including his beloved slime moulds. These creatures might represent instructive re-enactments (or pre-enactments) of our kind of metazoan multicellularity. But I suspect that they are all completely different, and the more fascinating because of it. RENDEZVOUS 36 PLANTS Rendezvous 36 is where we meet the true lords of life, the plants. Life could get along without animals and without fungi.
ancestor, even if the anatomical evidence suggests that they were. Geographical parsimony is being subconsciously allowed to pull rank over anatomical parsimony. Anatomical parsimony suggests that Ouranopithecus is a closer cousin to us than Kenyapithecus is. But, without being explicitly so called, geographical parsimony is assumed to trump anatomical parsimony. Stewart and Disotell argue that, when you take into account the geography of all the fossils, anatomical and geographical parsimony
dinosaurs is not the biggest — that honour falls to the mass extinction that ' It is tempting to see the marks the end of the Permian, about a quarter of a billion years ago, in which catastrophe as strangely selective. The deep sea some 95 per cent of all species went extinct. Recent evidence suggests that an Foraminifera (protozoa even larger comet or meteorite was responsible for that mother of all extinc-in tiny shells which fossilise in enormous tions. We are uneasily aware that a