synapomorphy


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Related to synapomorphy: Symplesiomorphy

synapomorphy

[si′nap·ə‚mȯr·fē]
(systematics)
A derived trait shared by two or more taxa that is believed to reflect their shared ancestry.
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chryses within this group, is supported by molecular synapomorphies, no concordant morphological synapomorphy is presently known.
If not, the neural arch should present an anterior position, a synapomorphy of Titanosauriformes (e.
Subsequently, with the discovery of the dinosauriform Silesaurus from the Late Triassic of Poland (Dzik 2003), it became apparent that at least North American examples of Atreipus also share a potential synapomorphy with Silesaurus to the exclusion of Dinosauria and non-dinosauriform dinosauromorphs.
An apparent synapomorphy for subfamily Persoonioideae is the presence of very large stomata, sometimes with guard cell lengths as much as 100 [micro]m (typical lengths elsewhere in the family and in angiosperms generally are less than half this).
Moreover, these specimens belong to the genus Gigantobatrachus because of its gigantic size (the largest known taxon within the family), external ornamentation composed by very deep and wide pits separated by strong osseous ridges (see CASAMIQUELA, 1958), proximal articular end of urostyle strongly dorsoventrally compressed and transversally expanded (unambiguous synapomorphy of Gigantobatrachus; Appendix 3), and very small and deeply concave orbital margins of the maxilla (unambiguous synapomorphy of Gigantobatrachus; Appendix 3).
The presence of a Mullerian duct (character 4, state 1) appears to be a synapomorphy for all salamanders excluding the Sirenidae, which does not possess a Mullerian duct (character 4, state 0); however, the fact that this trait is polymorphic in the ancestor to salamanders results in the pleisiomorphic condition of this character for salamanders recovered as equivocal.
Nuclear content estimates suggest a synapomorphy between Dictyota and six other genera of the Dictyotales (Phaeophyceae).
The sister group relationship between this clade and the Rhagadotarsinae + Trepobatinae clade were diagnosed by the presence of four pairs of cephalic trichobothriae, possibly a strong synapomorphy for a more narrowly defined Gerridae, but this would leave Halobatinae + Ptilomerinae without a family assignment.
Indeed, the absence of a mitochondrion is considered a synapomorphy for the Eucestoda (Ehlers, 1985).
Cigliano (2007), after a review ofthe genus Eurotettix taking into consideration the results of a phylogenetic analysis performed on a matrix comprising 29 adult morphological and one karyotypic character, the sex-determining mechanism, and twenty taxa--considered that the synapomorphy 'tegmina narrow at base' was inadequate justification for a group at the genus level.
Absence of a bulge-stem-loop in stem G16 (domain V) is a synapomorphy for all Heterobranchia, with a reduced stem size of 20 to 30 bases, while stem size for the rest of mollusks is 41 to 43 bases.
The third synapomorphy uniting the clade is a long, straight intestine (43:0-1), although only in a few species can probable gut endocasts be seen.