Bennettitalean foliage in the Rhaetian–Bajocian (latest Triassic–Middle Jurassic) floras of Scania, southern Sweden

Burgh²,

Cittert

2016

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Editor: Patrick S. Herendeen Premise of research. During the ongoing investigation of Upper Triassic-Lower Cretaceous plant macrofossils from Svalbard, Norway, some ginkgoalean leaf fossils were found from Carnian and Aptian deposits of Spitsbergen and Edgeøya that represent new ginkgophyte species. One new species is described as Baiera aquilonia sp. nov., and one ginkgophyte leaf is assigned to Ginkgoites sp. Along with the description of the new material, an overview of the presence and distribution of ginkgophytes in the high-latitude ecosystems of Svalbard through time is provided.Methodology. The plant macrofossils have been analyzed with transmitted-light and epifluorescence microscopy. Attempts to isolate cuticles were made.Pivotal results. The investigation resulted in the description of one species new to science, Baiera aquilonia sp. nov., and one specimen assigned to Ginkgoites sp. The presence of ginkgophytes on Svalbard changed significantly through time: periods of dominance and wide distribution interchanged with periods of very low diversity and abundance.Conclusions. Ginkgophytes were thriving in Svalbard, which was already located above 607N by the Carnian, from the Late Triassic to the Cenozoic in varying abundance and were finally extirpated, probably as a result of dramatic climatic changes at the end of the Paleogene.

Section: Material Methods and Geologymentioning

confidence: 99%

New Ginkgophytes from the Upper Triassic–Lower Cretaceous of Spitsbergen and Edgeøya (Svalbard, Arctic Norway): The History of Ginkgoales on Svalbard

Burgh²,

Cittert

2016

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“…It was first examined under an Olympus BX51 light microscope, which was modified for epifluorescence microscopy. Subsequently, a sample of the organic remains was treated according to standard maceration procedures (e.g., Pott and Kerp 2008;Pott and McLoughlin 2009) to obtain cuticle fragments for light microscopy. To remove sediment remains, the organic material was treated with 40% hydrofluoric acid for 1-5 d and then bathed in Schulze's reagent (30% HNO 3 with a few crystals of KClO 4 ) for up to 2 wk for maceration.…”

Section: Methodsmentioning

confidence: 99%

“…Even the type of Williamsonia (viz., Williamsonia gigas [Lindley and Hutton] Carruthers) was originally described as a whole plant (Carruthers 1870). The Jurassic Williamsoniella Thomas is the only williamsoniaceous reproductive structure confidently confirmed as bisporangiate (Harris 1969;Crane and Herendeen 2009;Zavialova et al 2009;Pott and McLoughlin 2014): a central ovulate organ similar in structure to Williamsonia is surrounded by a whorl of complex microsporangiate organs-a structure similar to the elaborate forms of Cycadeoidaceae (Wieland 1906(Wieland , 1916Watson and Sincock 1992). The reproductive structures of the latter, however, seem to have never fully opened and were probably self-pollinated (Delevoryas 1968).…”

Section: Introductionmentioning

confidence: 99%

Williamsonia carolinensis sp. nov. and Associated Eoginkgoites Foliage from the Upper Triassic Pekin Formation, North Carolina: Implications for Early Evolution in the Williamsoniaceae (Bennettitales)

Axsmith

2015

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Editor: Patrick S. Herendeen Premise of research. Few reproductive organs unequivocally attributable to the important but enigmatic Mesozoic seed plant order Bennettitales have been described from the Triassic of all of North America outside of Greenland. Here, the first ovulate reproductive organs (gynoecia) of the group from the Upper Triassic of eastern North America are described and assigned to a proposed new species, Williamsonia carolinensis, of the family Williamsoniaceae.Methodology. The excellently preserved plant fossils were investigated using cuticular analysis and light, fluorescence, and scanning electron microscopy.Pivotal results. The description is based on 10 specimens from the Late Triassic (Carnian) Pekin Formation of North Carolina. They are interpreted as representing progressive developmental stages. Williamsonia carolinensis lacks a corona (sterile apical projection of the receptacle) and bracts subtending the receptacle. The lack of bracts is particularly unusual and appears to be the original condition and not a preservation artifact based on their absence even on immature specimens. The two largest specimens, interpreted as mature gynoecia, occur together on the same slab in exclusive association with the unusual bennettitalean leaf Eoginkgoites, suggesting that these organs were produced by the same parent plant species.Conclusions. The unique features of W. carolinensis, along with the probable affinity with Eoginkgoites foliage, expands the known diversity of the Williamsoniaceae and supports previous suggestions of remarkably high levels of morphological disparity in the earliest history of the Bennettitales.

“…INTERNATIONAL JOURNAL OF PLANT SCIENCES the past century (Seward 1917;Harris 1969;Watson and Sincock 1992;Rees and Cleal 2004;Wang et al 2008;Pott and McLoughlin 2009). Most bennettitalean leaves can be readily assigned to one of several morphogenera on the basis of the shape of the leaflet base, the gross proportions of the leaflets, and the venation pattern (Watson and Sincock 1992).…”

mentioning

confidence: 99%

“…However, there are some cases of ambiguity, in which pinnules within a single leaf may bear the characters of different morphogenera. For example, Pott and McLoughlin (2009) outlined the difficulties in consistently differentiating leaves attributed to Pterophyllum, Anomozamites, and Nilssoniopteris on the basis of traditional criteria, and they documented several cases of erroneous identification. Where fragmentary material is available, and where a single population of leaves shows a range of variation, the typical pattern of leaf characters should be used for generic assignment rather than that of individual atypical leaflets.…”

mentioning

confidence: 99%

Ptilophyllum muelleri(Ettingsh.) comb. nov. from the Oligocene of Australia: Last of the Bennettitales?

McLoughlin

Carpenter

2011

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Several small pinnate leaves of early Oligocene age from Cethana, Tasmania, are newly described and found to be conspecific with Anomozamites muelleri Ettingsh. recorded from coeval strata at Emmaville, northern New South Wales. These fossils are most probably referable to the Bennettitales on the basis of leaf size, leaflet shape, and venation patterns, in the absence of diagnostic cuticular details. They are transferred to Ptilophyllum on the basis of leaflet morphology and represent the youngest putative bennettitalean remains yet documented. Their occurrence reinforces previous arguments that the highest-paleolatitude fragments of southeastern Gondwana provided moist temperate refugia for the survival of Mesozoic gymnosperm taxa well into the Cenozoic.