The structure of umkomasiacean fructifications from the Triassic of Queensland
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School of Earth Sciences, The University of Queensland, St. Lucia Campus, Brisbane, Queensland 4072, Australia
Online publication date: 2016-06-22
Publication date: 2016-06-22
Acta Palaeobotanica 2016; 56(1): 17–40
The plant fossil genera Umkomasia Thomas 1933 and Pteruchus Thomas 1933 emend. Townrow 1962 are known chiefly from the Middle and Upper Triassic of Gondwana. The structure of these fructifications has been conjectural, some being identified as pinnate, others as helically arranged. Specimens from the Ladinian–lower Norian of Queensland (northeastern Australia) show that the female and male fructifications – U. geminata (Shirley 1898) Rigby in Playford et al. 1982 emend. nov. and P. dubius Thomas 1933 emend. Townrow 1962, respectively – have a bipinnate structure. Those fructifications and the bipinnate leaf, Dicroidium feistmantelii (Johnston 1894) Gothan 1912, probably all belonged to the same parent plant. It was first suggested by John Townrow in 1962 that the sporangial heads of P. dubius have a pinnate structure; this character is confirmed herein. Pteruchus is recorded for the first time from the Carnian Tarong Basin, Queensland. The holotype of Stachyopitys simmondsii Shirley 1898 is shown to be ovuliferous. The species is recombined as Umkomasia simmondsii (Shirley 1898) comb. et emend. nov. Genuine male fructifications, previously identified as S. simmondsii, and later as Pteruchus simmondsii (Shirley 1898) Jones and de Jersey 1947, are assigned to P. minor Thomas 1933. That species comprises the smallest fructifications of the genus. Townrovia polaris Bomfleur et al. 2011 and Stachyopitys lacrisporangia Anderson & Anderson 2003 are identified as junior synonyms to P. minor. The diagnosis of Townrovia Retallack 1981 is inaccurate and the genus is insufficiently distinguished from Pteruchus.