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Abstract A new genus and species, Austrocupressinoxylon barcinense , based on remains of cupressaceous wood is described for the Lower Cretaceous of central Patagonia, Argentina. The studied specimens are silicified fragments of picnoxylic and homoxylic wood that exhibit a combination of characters not previously reported, therefore a new genus is erected. The characters are: 1- growth ring boundaries distinct, 2- transition from earlywood to latewood gradual, 3- axial parenchyma diffuse,4- radial tracheid pitting predominantly abietinean,5- cross-field pitting cupressoid, arranged in both cupressoid and araucarioid patterns, 6- rays uniseriate heterocellular, 7- end and horizontal walls of ray parenchyma cells smooth or slightly nodular, and 8- ray tracheids with smooth walls. The cross-field pitting patterns and the presence of ray tracheids are two traits of particular interest in the context of systematic affinities. The fragments were collected from two stumps found in life position attached to each other by a main root, consequently, the disposition of the stumps suggests a case of clonal growth by root suckering. This is the second report of such mechanisms in the fossil records worldwide and the first one for South America. [ABSTRACT FROM AUTHOR]

Today, the ginkgophytes are represented by the single species Ginkgo biloba , naturally distributed in China and cultivated worldwide. However, the ginkgophyte lineage shows an extensive fossil record going back to the Paleozoic of both hemispheres. In South America, its record began in the upper Paleozoic and reached the middle Eocene, and it includes both vegetative and reproductive remains. The Cretaceous macrofossil record of this group in South America is restricted to Lower Cretaceous deposits, where it is relatively abundant, whereas there is a gap in its Upper Cretaceous to lower Paleogene record. We present the new species Ginkgoites villardeseoanii collected from Maastrichtian (uppermost Cretaceous) deposits of the Lefipán Formation (Patagonia, Argentina). The studied material consists of three specimens preserved as adpressions of isolated, flabellate, and petiolate (Ginkgo -like) leaves, with few epidermal characters preserved. One of the studied specimens shows evidence of insect damage consistent with hole feeding, constituting the first Cretaceous record of interaction between ginkgophytes and insects in the Southern Hemisphere. We infer that this damage was produced when the leaf was still attached to the plant, as the specimen shows evidence of a physiological reaction of the plant in the form of a border of necrotic tissue around the wound. Ginkgoites leaves are common among different lineages within the Ginkgoales, having been associated to three families (Ginkgoaceae, Karkeniaceae, and Yimaiaceae). Therefore, G. villardeseoanii was assigned to an incertae sedis family. [Display omitted] • We describe leaf remains and erect the new species Ginkgoites villardeseoanii. • G. villardeseoanii would belong either to Karkeniaceae or Ginkgoaceae. • We describe the first ginkgophyte-insect interaction Cretaceous record worldwide. • The fossil record of insect damage on Ginkgophyta is scarce. • Insect-repellent properties could be a cause of the lineage success and longevity. [ABSTRACT FROM AUTHOR]

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]