| 1. |
- Lindström, Sofie, et al.
(författare)
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Intraspecific variation of taeniate bisaccate pollen within permian glossopterid sporangia, from the Prince Charles Mountains, Antarctica
- 1997
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Ingår i: International Journal of Plant Sciences. - 1058-5893. ; 158:5, s. 673-684
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Tidskriftsartikel (refereegranskat)abstract
- Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf A. africana Pant ana Nautiyal. These sporangia contain between 2000 and 3000 taeniate, saccate pollen grains that are predominantly haploxylonoid bisaccate and referable to the palynotaxon Protohaploxypinus limpidus (Balme and Hennelly) Balme and Flayford. However, the sporangia also contain greater than 4% of diploxylonoid bisaccate forms comparable to Striatopodocarpidites cancellatus (Balme and Hennelly) Hart 1963, together with sporadic monosaccate and trisaccate grains that, if found dispersed, would be assigned to several different pollen form genera. Morphometric analysis of in situ bisaccate pollen grains and taeniate bisaccate pollen in the dispersed palynoflora indicates that in situ grains occupy only the smaller end of the total size range. The tendency for in situ grains to cluster into two different size groups may reflect differential predispersal expansion of the corpus. The in situ pollen grains are variable in most qualitative and quantitative features used for taxonomic discrimination of dispersed taeniate bisaccate pollen, and this may lead to unreliable estimates of Late Permian floristic diversity if an overly restrictive species delimitation scheme is used.
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| 2. |
- McLoughlin, Stephen, et al.
(författare)
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Gondwanan floristic and sedimentological trends during the Permian-Triassic transition: new evidence from the Amery Group, northern Prince Charles Mountains, East Antarctica
- 1997
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Ingår i: Antarctic Science. - 1365-2079. ; 9:3, s. 281-298
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Tidskriftsartikel (refereegranskat)abstract
- The Permian-Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the Bainmedart Coal Measures and overlying Flagstone Bench Formation, based on the first regular occurrence of Lunatisporites pellucidus and the first appearance of Aratrisporites and Lepidopteris species. The Permian-Triassic boundary is marked by the extinction of glossopterid and cordaitalean gymnosperms, and by the disappearance or extreme decline of a range of gymnospermous and pteridophytic palynomorph groups. Earliest Triassic macrofloras and palynofloras of the Flagstone Bench Formation are dominated by peltasperms and lycophytes; corystosperms, conifers, and ferns become increasingly common elements of assemblages through the Lower Triassic part of the formation and dominate floras of the Upper Triassic strata. The sedimentary transition across this boundary is conformable but marked by a termination of coal deposits; overlying lowermost Triassic sediments contain only carbonaceous siltstones. Typical red-bed facies are not developed until at least 100 m above the base of the Flagstone Bench Formation, in strata containing ?Middle Triassic palynofloras. Across Gondwana the diachronous disappearance of coal deposits and appearance of red-beds is suggestive of a response to shifting climatic belts, resulting in progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic. The abrupt and approximately synchronous replacement of plant groups at the Permian-Triassic boundary suggests that factors independent of, or additional to, climate change were responsible for the turnover in terrestrial floras.
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| 3. |
- McLoughlin, Stephen, 1964-, et al.
(författare)
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Pachytestopsis tayloriorum gen. et sp. nov., an anatomically preserved glossopterid seed from the Lopingian of Queensland, Australia
- 2018
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Ingår i: <em>Transformative Paleobotany: Papers to Commemorate the Life and Legacy of Thomas N. Taylor</em>. - Amsterdam : Elsevier. - 9780128130124 ; , s. 155-178
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Bokkapitel (refereegranskat)abstract
- A permineralized seed, Pachytestopsistayloriorum gen. et sp. nov., is described from the Changhsingian (upper Permian) Fort Cooper Coal Measures at the Homevale locality in the northern Bowen Basin, Queensland,Australia. This largest permineralized seed species yet recorded from Permian deposits of Gondwana conforms to a size accommodated by either Rigbyaceae or Lidgettoniaceae (glossopterid) fructifications recorded elsewhere in the Sydney-Bowen basin complex. The seeds are characterized by a thin endotesta of longitudinally orientated cells, thick mesotesta incorporating an inner band of very thick walled sclereids and an outer layer of thin-walled parenchymatous cells, and an exotesta that comprises a well-developed epidermis and several layers of thick-walled hypodermal cells. Vascular supply to the base of the seed passes through the integument and bifurcates into the nucellar pad. Taeniate bisaccate pollen of Protohaploxypinus-type occurs in the pollen chamber of the seed. A comparison of the characters of P. tayloriorum with other permineralized seeds from the Permian of Gondwana indicates that several of the characters used in previous phylogenetic analyses incorporating glossopterids are wrongly scored or ambiguous in their definition.
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