Search

Premise of research. Cyclocarya Iljinskaya (Juglandaceae) is a genus with a single living species that is endemic to central and south China. The genus has an abundant North American and Eurasian fossil record from the Paleocene to the Pliocene, documenting its spread across Europe to western Siberia during the Oligocene and its arrival in Japan by the Miocene. However, there have been no fossil occurrences of Cyclocarya near its modern distribution. In this study, we describe a new species of Cyclocarya from the upper Miocene Nanlin Formation in Lianghe County, western Yunnan Province, southwest China, and discuss its biogeographic implications. Methodology. We examined the fossil fruit usingLMand SEM, and we compared its morphology with fruits of fossil Cyclocarya and extant Cyclocarya paliurus (Batalin) Iljinsk. Pivotal results. The fossil fruit of Cyclocarya simipaliurus sp. nov. consists of a small nutlet that is surrounded by a circular and flange-likewing. The nutlet is circular in plan viewand oblate in longitudinal view. Nutlet structure and the epidermal characteristics of the wing indicate that this fossil fruit is almost identical to that of the extant species, C. paliurus. Conclusions. The specimen reported here is the only reliable fossil of Cyclocarya known from China. The new fossil species helps to fill a significant gap in the fossil record of Cyclocarya, indicating that the genus had reached the westernmost boundary of its modern distribution by the late Miocene. Western Yunnan had a warm and humid climate during the late Neogene, and the rapid uplift of the Yunnan Plateau began in the Pliocene. Pleistocene glaciations may have forced Cyclocarya to retreat from western Yunnan, and the uplifted mountains and deep river valleys might have posed barriers for reconnection during the interglacials. [ABSTRACT FROM AUTHOR]

Leaf teeth are conspicuous and often diagnostic features of many plant species. In mesic environments with sufficient nutrient resources, the percentage of toothed species in extant floras generally correlates negatively with temperature; consequently, fossil leaf teeth are widely used to estimate continental paleotemperatures. However, the function of leaf teeth with respect to climate is poorly understood. Here, we test the hypothesis that teeth enhance rates of carbon uptake at the beginning of the growing season when temperatures are limiting. We measure the seasonal patterns of leaf-margin photosynthesis and transpiration for 60 woody species from two temperate regions with differing climates (Pennsylvania and North Carolina). Three significant results are, first, physiological activity at leaf margins is greatest early in the growing season (first 30 d); second, toothed margins are more active with respect to photosynthesis and transpiration than untoothed margins; finally, leaf margins are more active in species native to colder Pennsylvania. The toothed species increase transpiration and photosynthate production early in the growing season relative to untoothed species and do so more in the Pennsylvania sample, maximizing carbon gain when temperature is limiting but moisture and nutrient availability are not. This mechanism may provide a proportionally increasing selective advantage to toothed species with decreasing temperature that is reflected in empirical correlations used for paleotemperature estimation. [ABSTRACT FROM AUTHOR]

Premise of research. Winteraceae, a family within the Canellales, is composed of tropical trees and shrubs broadly distributed in the Southern Hemisphere. The family is found today in eastern Australia, New Zealand, Malesia, Oceania, Madagascar, and the Neotropics across a range of dry to wet tropical to temperate climate regions. The fossil record of woods related to the Winteraceae in the Southern Hemisphere is limited to the Late Cretaceous of the Antarctic Peninsula. Here, we present a detailed anatomical description of the secondary xylem of a well-preserved trunk from the early Eocene Laguna del Hunco site, Huitrera Formation, Patagonia (Chubut Province, Argentina), that is referable to a new species of the genus Winteroxylon (Gottwald) Poole and Francis. Methodology. The wood is preserved as a siliceous permineralization; it was sectioned using standard petrographic techniques and observed under both light and scanning electron microscopy. The anatomy was compared with that of extant and fossil species of Winteraceae. Pivotal results. The diagnostic anatomical features of Winteraceae preserved in the fossil include an absence of growth rings, a lack of vessels, tracheids that are rectangular in cross section with circular bordered pits, diffuse axial parenchyma, rays showing two distinct size ranges (uniseriate-biseriate or multiseriate, 3–15 cells wide), and the presence of heterocellular rays containing sclerotic nests, cells with dark contents, and oil cells. The new fossil species most resembles extant genera within the Zygogynum s.l. clade from Australasian and Malesian rain forests; its anatomy is very similar to that of the extant genus Bubbia. The new Patagonian Winteraceae fossil wood is characterized by the presence of sclerotic nests and oil cells in the rays, which differ from those of previously described species of Winteroxylon. Conclusions. On the basis of the distinctive characters preserved, we erect Winteroxylon oleiferum sp. nov. The new fossil is the first reliable macrofossil record of Winteraceae from South America, supporting the abundant palynological record of the family from the continent, and it is the oldest record of the Zygogynum s.l. clade, adding to the long list of southern biogeographic connections between South America and Australasia via Antarctica during the warm early Cenozoic. [ABSTRACT FROM AUTHOR]

Premise of research. Cenozoic macrofloras from South America are fundamental for understanding extant Southern Hemisphere biotas. The Paleogene Ligorio Márquez Formation (LMF) straddles the Chile-Argentina border; leaf fossils from its Chilean outcrops were previously assigned to 150 morphotypes and interpreted as primarily representative of tropical-subtropical lineages, with dominance by diverse Lauraceae of extant Neotropical affinities. Here, we present new collections of Argentine LMF mudstones that are thus far unique in the Patagonian region in containing organically preserved plant fossils, including leaves with cuticular preservation. Methodology. Leaf fossils were exposed by splitting blocks of mudstone or collected by flotation from disaggregated samples. Smaller fossils, including reproductive parts, conifer needles, and isolated cuticles, were recovered from sieved slurry. Fossils were examined under light microscopy, epifluorescence, and SEM. Pivotal results. Twenty taxa were recognized from cuticle-bearing leaf fossils or dispersed cuticles. The most abundant leaf species is a morphologically variable form that is like Lauraceae in architecture but with clearly nonlauraceous cuticular details. Four-parted flower fossils are attributable to the same species, and its eudicot affinities are indicated by adherent triaperturate pollen. Lauraceae were present but much less diverse than reported from the LMF in Chile and arguably with Gondwanan (not Neotropical) affinities. Other taxa include the conifers Dacrycarpus chilensis and Coronelia molinae and possibly Cunoniaceae and a new Ginkgoites. A wet mesotherm paleoclimate is inferred. Conclusions. The new fossils complement and improve our understanding of the LMF and contribute to a greater understanding of high southern latitudes at a time when overland dispersal was possible between South America andAustralasia. The fossils provide further evidence forwarmand humid climates in Patagonia during the early Paleogene and for a stronglyGondwanic flora, with little conclusive evidence of taxa belonging toNeotropical and megatherm lineages. [ABSTRACT FROM AUTHOR]

Premise of research. The early Eocene Laguna del Hunco (LH) fossil site, northwestern Chubut Province, Argentina, holds one of the best-preserved and most diverse paleofloras worldwide. The paleoflora comprises ferns, gymnosperms, and flowering plants. Despite the rapidly growing knowledge of its macrofossil record, little is known about the site's palynological content. Herein, we present the first dispersed spore-pollen assemblages recovered from LH. Methodology. Palynological samples were collected from seven stratigraphic levels of the Tufolitas de LH (Huitrera Formation), of which six yielded palynomorphs. We determine the botanical affinities of fossil morphotypes and provide systematic descriptions of some taxa. In addition, we establish similarities between LH and other Patagonian Eocene localities, and we compare palynological and prior megafloral records from LH. Pivotal results. We identify 56 spore and pollen species and 28 plant families, of which eight (Cyatheaceae, Schizaeaceae, Polypodiaceae, Asteraceae, Chloranthaceae, Nothofagaceae, Rubiaceae, and Ulmaceae) are reliably reported from the site for the first time. Among other Eocene Patagonian palynofloras, the LH assemblage is similar to Pampa de Jones/Nahuel Huapi Este and Confluencia. Conclusions. The LH spore-pollen assemblages augment the plant fossil record for this significant Eocene locality by incorporating new taxa (e.g., Asteraceae, with one morphotype that represents the oldest record of the family in Patagonia). The new data also reinforce the presence of plant families previously reported from macrofossils, such as Juglandaceae, with pollen grains similar to those of the Engelhardia-Alfaroa group, and Fagaceae (Castaneoideae), complementing the macrofossil record of leaves and reproductive structures. [ABSTRACT FROM AUTHOR]

Premise of research. The ginkgophytes are an ancient group of gymnosperms with a long history starting during the late Paleozoic and reaching the present with the unique species Ginkgo biloba L. In order to better characterize the early and middle Eocene (ca. 52.2 and 47.7 Ma) leaf species Ginkgo patagonica Berry from northwest Patagonia, Argentina, new specimens were studied, focusing on their morphological and anatomical characters. Methodology. The specimens were studied with LM, epifluorescence, SEM, and TEM. Pivotal results. The diagnosis of the species Ginkgoites patagonica comb. nov. is enlarged to include anatomical and ultrastructural epidermal characters. Herein, the species Ginkgo patagonica is shown to have characteristics that clearly separate it from the genus Ginkgo L., and it is therefore recombined to the genus Ginkgoites Seward. Conclusions. Eocene Ginkgoites patagonica was present in plant communities, and it is the last representative of a still poorly understood southern ginkgophyte lineage that was distinct from the ancestors of G. biloba of the Northern Hemisphere. [ABSTRACT FROM AUTHOR]