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Reflectance Transforming Imaging (RTI) produces photographs in which the angle of the light can be changed at will, allowing to investigate remotely minute details of the 3D structure of sub-planar objects. Here we apply this technique to the type specimen of Gingkophyllum grassetii , a vegetative shoot with putative ginkgophyte affinities from the early Permian of Lodève (France). Gingkophyllum grassetii , the type species of the genus, was originally described by Saporta in 1875 and has never been illustrated other than by drawings representing only portions of the shoot. Using RTI, we describe and illustrate the specimen and discuss some key features, such as the arrangement of the leaves on the shoot or the presence of abundant secretory structures. Through an historical account, we show how the lack of illustration led to confusion about the morphology of Ginkgophyllum and we discuss the importance of reinvestigating type specimens of Paleozoic ginkgophyte taxa in order to clarify their taxonomy and better understand their evolutionary history. The sharing of RTI files is one example of approaches that can be further developed to improve remote access to specimens. • Ginkgophyllum grassetii , the type species of the genus, is a putative Permian ginkgophyte. • Lack of published photos led to confusions about Ginkgophyllum morphology and taxonomy. • We re-investigate the type specimen using Reflectance Transforming Imaging. • We provide new information on the morpho-anatomy of the specimen. • RTI files could be further used to improve remote access to collection specimens. [ABSTRACT FROM AUTHOR]

Abstract: We describe a distinct type of heteromorphic basal frond element in four species of the seed-fern foliage Dicroidium, based principally on a survey of plant-fossil collections from the Triassic of Antarctica. The modified foliar elements are conspicuously enlarged, and arise at wide angles and obliquely to the frond plane. Those of D. elongatum and D. crassinerve arise more or less directly from the petiole base; they are overall wedge- to fan-shaped with variably dissected margins and fan-shaped venation. Those of D. odontopteroides and D. dubium are (sub)circular, reniform, or obcordate, also with fan-shaped venation, or divided into narrow tongue-shaped segments with alethopteroid venation. The basal elements of some species commonly occur isolated. By analogy with comparable structures among other plant groups, we conclude that the basal elements represent a distinct, early leaf-ontogenetic architectural unit in the frond bauplan of Dicroidium, which provides an important additional character for a more accurate delimitation and systematic classification. Similar structures also occur on the corystosperm reproductive organs Umkomasia and Pteruchus. It appears that the basal elements were particularly common among high-latitude Dicroidium trees that flourished in a strongly seasonal light regime. We hypothesize that the modified elements may represent the initial foliar outgrowths during spring flush, ensuring a rapid re-initiation of sap flow and metabolic activity after the extended period of winter dormancy. [Copyright &y& Elsevier]

Abstract: The transfer technique is a method for exposing compression fossils that entails embedding the specimen in an adhesive material and dissolving the matrix in appropriate acids. This technique has been used for many years, and played an important role in several classic paleobotanical studies. However, in recent years it appears to have fallen into relative disuse and is not discussed at all in recent compilations of paleobotanical techniques. This is unfortunate, as the method is often extremely effective, especially for revealing the detailed structure of complex plant organs. In this paper, case studies using fossil conifer ovulate cones are presented. The first entails a modification of the classic transfer technique using a polyester resin as the embedding medium on an unnamed cone from the Triassic of Pennsylvania. The second study entails producing serial sections through a polyester resin embedded cone of Telemachus from the Triassic of Antarctica in a manner analogous to the classic cellulose acetate peel method. This modification is most useful when the organic material is too fragile for the more classic method. The results of these case studies are presented in the hope of re-stimulating use of the transfer technique in paleobotany. [Copyright &y& Elsevier]

A Middle-Late Jurassic fossil plant assemblage is described from the Bahía Laura Complex at the Laguna Flecha Negra locality, Santa Cruz Province. The fossil assemblage is autochthonous, preserved in volcaniclastic sediments in the fringes of a geothermal landscape. Taxonomic study of the palaeoflora revealed 17 taxa. The recognized species have been previously described in Jurassic localities of Gondwana and illustrate the diversity of plant communities that lived in a volcanic setting. The dominant elements of this flora are microphyllous conifers of the families Araucariaceae and Cheirolepidiaceae. Fossil leaves of Cycadeoidales co-dominate the community. There is a low diversity and abundance of ferns. Composition of the plant community is compared to coetaneous floras of the Bahía Laura Complex to analyse geographical variations in the diversity of Middle-Late Jurassic assemblages of Santa Cruz Province, and a relative uniformity is recognized. Forest landscapes were dominated by conifer trees, with cycadeoids as small trees or shrubs. The herbaceous understory was dominated by fern communities with low species diversity; Equisetales and Isoetales appeared as subordinated elements. Microphyllous conifers and cycadophytes, as well as a low diversity of ferns, are indicative of relatively dry weather. • New Middle-Late Jurassic megaflora is described for Patagonia Argentina. • Forest landscapes appear to be dominated by conifer trees and small cycads. • Megafloras of the Bahía Laura Complex are analysed and compared. • Climatic signature of megafloras indicate dryer weather than the Late Triassic. [ABSTRACT FROM AUTHOR]