| 单词 | crown group |
| 释义 | > as lemmascrown group crown group n. Biology the group consisting of all the living species of a clade together with their latest common ancestor and any of its extinct descendants; contrasted with stem group. ΚΠ 1979 R. P. S. Jefferies in M. R. House Orig. Major Invertebr. Groups xvii. 443 The term ‘crown group’ (as opposed to ‘stem group’) is proposed for the latest common ancestor of the living members of a monophyletic group, plus all descendants of that ancestor. 1991 Systematic Zool. 40 298/2 It has not been established that this fossil lies within the Ambystoma crown group. 2004 Nature 29 July 506/2 A distinction can then be made between the crown group (the descendants of the last common ancestor of all the living members of the phylum, including this ancestor) and the stem group (everything else). < as lemmas |
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