Definition of synapomorphy in US English:



  • 1A characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants.

    ‘the study of skulls of this primitive reptile has led to the discovery of numerous synapomorphies with turtles’
    • ‘The only known synapomorphy of this group is the presence of a sesamoid bone in the heel region.’
    • ‘Those specimens include conclusive evidence of the strongest possible bird-theropod synapomorphy - completely modern feathers and the oldest, most birdlike dromaeosaurs.’
    • ‘This observation hints at one putative morphological synapomorphy of a Petopentia / Periploca clade.’
    • ‘These four genera form a monophyletic group defined by one synapomorphy (loss of one anterior left marginal).’
    • ‘But this is not very convincing, as it reveals only one valid synapomorphy.’
    1. 1.1 Possession by two or more organisms of a characteristic inherited exclusively from their common ancestor.
      ‘synapomorphy delineates the relative status of particular features with respect to a specific evolutionary problem’
      • ‘Based on cell lineages, the blastomere-by-blastomere derivation of most major larval organs, there is good reason to infer synapomorphy across the larvae of most lophotrochozoan phyla, if not the lophophorates.’
      • ‘Thus, when a SINE sequence is found at an orthologous locus in two or more lineages, it can be regarded as evidence for synapomorphy.’
      • ‘This conflict can be resolved as either parallelism, reversal, or synapomorphy.’
      • ‘The diagnosis of Glades through synapomorphy becomes the starting point for the investigation of functional, temporal, adaptive and biogeographic questions.’
      • ‘It is through cladistic analysis that we are able to tell homoplasy from synapomorphy.’


1960s: from syn- ‘together’ + apo- ‘away from’ + Greek morphē ‘form’.