Lepidopteran leaf mine from the early eocene wind river formation of northwestern wyoming.

A lepidopteran mine, probably of Phyllocnistis, on a leaflet impression of Cedrela (Meliaceae) discovered in late early Eocene strata near Dubois, Wyoming, is the earliest record of leaf mining and of the Phyllocnistidae. Considerable prior evolution of the mining habit, antiquity of the Cedrela-Phyllocnistis relationship, and subtropical climatic conditions are indicated.

An aptian plant with attached leaves and flowers: implications for angiosperm origin.

Recent phylogenetic studies and fossil finds support a new view of the ancestral angiosperm. A diminutive fossil angiosperm from the Aptian of Australia has attached leaves, with intermediate pinnate-palmate, low-rank venation, and lateral axes bearing pistillate organs subtended by bracts and bracteoles that are the oldest direct evidence of flowers. A variety of data suggests a similar morphology for the ancestral angiosperm. This hypothesis explains similarities between rhizomatous to herbaceous Magnoliidae and basal monocots, scarcity of early agniosperm wood, and lack of recognition of earlier remains.

Arctic terrestrial biota: paleomagnetic evidence of age disparity with mid-northern latitudes during the late cretaceous and early tertiary.

Magnetostratigraphic correlation of the Eureka Sound Formation in the Canadian high Arctic reveals profound difference between the time of appearance of fossil land plants and vertebrates in the Arctic and in mid-northern latitudes. Latest Cretaceous plant fossils in the Arctic predate mid-latitude occurrences by as much as 18 million years, while typical Eocene vertebrate fossils appear some 2 to 4 million years early.

Fission-track dating of haughton astrobleme and included biota, devon island, Canada.

Haughton Astrobleme is a major extraterrestrial impact structure located on Devon Island in the Canadian Arctic Archipelago, Northwest Territories. Apatite grains separated from shocked Precambrian gneiss contained in a polymict breccia from the center of the astrobleme yielded a fission-track date of 22.4 million +/- 1.4 million years before the present or early Miocene (Aquitanian). This provides a date for the impact event and an upper limit on the age of crater-filling lake sediments and a flora and vertebrate fauna occurring in them. A geologically precise date for these fossils provides an important biostratigraphic reference point for interpreting the biotic evolution of the Arctic.

The molecular fossil record of oleanane and its relation to angiosperms.

Oleanane has been reported in Upper Cretaceous and Tertiary source rocks and their related oils and has been suggested as a marker for flowering plants. Correspondence of oleanane concentrations relative to the ubiquitous microbial marker 17alpha-hopane with angiosperm diversification (Neocomian to Miocene) suggests that oleanane concentrations in migrated petroleum can be used to identify the maximum age of unknown or unavailable source rock. Rare occurrences of pre-Cretaceous oleanane suggest either that a separate lineage leads to the angiosperms well before the Early Cretaceous or that other plant groups have the rarely expressed ability to synthesize oleanane precursors.

Paleobotanical evidence for near present-day levels of atmospheric Co2 during part of the tertiary.

Understanding the link between the greenhouse gas carbon dioxide (CO(2)) and Earth's temperature underpins much of paleoclimatology and our predictions of future global warming. Here, we use the inverse relationship between leaf stomatal indices and the partial pressure of CO(2) in modern Ginkgo biloba and Metasequoia glyptostroboides to develop a CO(2) reconstruction based on fossil Ginkgo and Metasequoia cuticles for the middle Paleocene to early Eocene and middle Miocene. Our reconstruction indicates that CO(2) remained between 300 and 450 parts per million by volume for these intervals with the exception of a single high estimate near the Paleocene/Eocene boundary. These results suggest that factors in addition to CO(2) are required to explain these past intervals of global warmth.