stem-group
|stem-group|
/ˈstɛm.ɡruːp/
ancestral lineage outside crown group
Etymology
'stem' originates from Old English, specifically the words 'stemn' / 'stefn', where it meant 'trunk' or 'stem'; 'group' originates from Old French, specifically the word 'groupe' (from Italian 'groppo'), where it meant 'knot' or 'cluster'. The compound 'stem-group' was formed in modern scientific English to denote lineages related to but outside a crown group.
'stem' changed from Old English 'stemn'/'stefn' (meaning 'trunk, stem') into Middle and Modern English forms 'stem'; 'group' evolved from Old French 'groupe' (from Italian 'groppo') into Middle English 'grop'/'groupe' and then 'group'. The combined scientific term 'stem-group' arose in 20th-century evolutionary biology literature to contrast with 'crown group'.
Initially, 'stem' meant 'trunk' or 'stalk' in a physical sense; in biological and phylogenetic usage it was extended metaphorically to mean an ancestral or basal lineage, and 'stem-group' came to mean the extinct lineages outside and leading up to a crown group.
Meanings by Part of Speech
Noun 1
in phylogenetics, a paraphyletic assemblage of extinct taxa (or lineages) that are more closely related to a particular crown group than to any other, but lie outside the crown group; collectively, the ancestral or side-branch lineages leading up to the crown group.
Fossils assigned to the stem-group of mammals show a mixture of primitive and derived features.
Synonyms
Antonyms
Last updated: 2026/01/06 10:49