A new Late Campanian/Early Maastrichtian Forest Flora From Patagonia

A new Late Cretaceous (late Campanian to early Maastrichtian) wood flora from southern Patagonia

Authors:

Egerton et al

Abstract:

The Cerro Fortaleza Formation, in southernmost Patagonia (Argentina), contains a unique Late Cretaceous (Campanian) flora and fauna. This formation is characterized by lithified fluvial sands, overbank mud deposits, and paleosols deposited in fluvial, fluvial–palustrine, and coastal plain environments from the northeastern margin of the Austral (Magellanes) Basin. The overlying and underlying formations have been dated as Campanian and Maastrichtian, respectively. Therefore, the Cerro Fortaleza Formation putatively falls within the late Campanian–Maastrichtian. This formation is known for its diverse fauna including dinosaurs, fishes, and turtles. Furthermore, poorly preserved leaf impressions from indeterminate conifers and cycads have also been discovered but not yet described.

Fossil wood taxa from the Cerro Fortaleza Formation yields a diverse flora of gymnosperm wood but only two genera of angiosperm wood. Gymnosperm genera identified in this study include Agathoxylon, Planoxylon, Taxodioxylon, Cupressinoxylon, and Podocarpoxylon; and angiosperm genera identified include Hedycaryoxylon and Nothofagoxylon. This is the first record of Planoxylon, Taxodioxylon, Cupressinoxylon, and Hedycaryoxylon from Argentina. Additionally, this is the oldest occurrence of Nothofagoxylon in Argentina. Both the angiosperm and gymnosperm wood samples possess distinct growth rings, providing strong evidence for seasonal growth regimes in the region. All of the wood genera from the Cerro Fortaleza Formation, except Planoxylon, have also been described from Late Cretaceous sediments of the Antarctic Peninsula. Thus, the presence of these taxa in both regions supports Late Cretaceous plant dispersal between them. Despite sharing the same taxa, the floras from the Cerro Fortaleza Formation and the Antarctic Peninsula exhibit strikingly different relative abundances. The ratio of gymnosperm to angiosperm wood in the Cerro Fortaleza Formation is 75:25; whereas coeval floras from the Antarctic Peninsula are ~ 25:75. The floral differences between these locations may be a relict from a widespread older flora that included Antarctica, regional floristic variations or a result of different depositional and/or taphonomic controls in discrete paleoenvironments.

Cenomanian Cretaceous Paleobotany Fossils From Italy

Cretaceous conifers and angiosperms from the Bonarelli Level; Reassessment of Massalongo's plant fossil collections of “Monte Colle”, Lessini Mountains, northern Italy

Authors:

Gomez et al

Abstract:

The lost plant fossil and fish locality of “Monte Colle”, near the village of Bolca, Verona province, northern Italy has been considered to be of Eocene age since the middle of the nineteenth century. However, upon re-examination of the plant fossils, especially the specimens of Aularthrophyton Massalongo, which closely resemble the fossil conifer Frenelopsis Schenk, led us to suspect that a Cretaceous age was more probable. Fieldwork to re-evaluate the local stratigraphy, and the identification of the radiolarians Crucella cachensis Pessagno and Patellula helios (Squinabol) within the matrix of surviving hand specimens, all definitively show that the fossil bed actually belongs to the uppermost Cenomanian Bonarelli Level. With this revised age, we properly describe the gross morphology of the surviving plant specimens and reinterpret their identifications and affinities. Frenelopsis petraepurae comb. nov., Geinitzia sp., and a single angiosperm leaf type are described and the consequences for nomenclature outlined. Comparisons with coeval Cretaceous plant taxa are also discussed.

Using Neutron Tomography to Examine Eocene Paleogene Araucarian Conifer Fossil From Antarctica

New views of plant fossils from Antarctica: a comparison of X-ray and neutron imaging techniques

Authors:

Dawson et al

Abstract:

A fossil plant of Eocene age from Antarctica was studied using X-ray and neutron tomography to reveal the three-dimensional plant structures encased within carbonate nodules. The fossil was identified as a branch and leaves of an araucarian conifer, which grew on the volcanic highlands of the Antarctic Peninsula region approximately 50 million yr ago. Both X-ray and neutron imaging techniques successfully exposed the full three-dimensional structure of the fossil without destroying the original specimen, revealing that most of the fossil was present as voids in the concretion and little organic matter was present. However, neutron tomography was found to produce images with superior quality and detail.

Northern Hemisphere Conifers Are Evolving Faster

Hemisphere-scale differences in conifer evolutionary dynamics

Authors:

1. Andrew B. Leslie (a,*)
2. Jeremy M. Beaulieu (b)
3. Hardeep S. Rai (c)
4. Peter R. Crane (a)
5. Michael J. Donoghue (b,*)
6. Sarah Mathews (d)

Affiliations:

a. School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511;

b. Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520;

c. Wildland Resources Department, Utah State University, Logan, UT 84322; and

d. Arnold Arboretum of Harvard University, Boston, MA 02131

*. To whom correspondence may be addressed. E-mail: andrew.leslie@yale.edu or michael.donoghue@yale.edu.

Abstract:

Fundamental differences in the distribution of oceans and landmasses in the Northern and Southern Hemispheres potentially impact patterns of biological diversity in the two areas. The evolutionary history of conifers provides an opportunity to explore these dynamics, because the majority of extant conifer species belong to lineages that have been broadly confined to the Northern or Southern Hemisphere during the Cenozoic. Incorporating genetic information with a critical review of fossil evidence, we developed an age-calibrated phylogeny sampling ∼80% of living conifer species. Most extant conifer species diverged recently during the Neogene within clades that generally were established during the later Mesozoic, but lineages that diversified mainly in the Southern Hemisphere show a significantly older distribution of divergence ages than their counterparts in the Northern Hemisphere. Our tree topology and divergence times also are best fit by diversification models in which Northern Hemisphere conifer lineages have higher rates of species turnover than Southern Hemisphere lineages. The abundance of recent divergences in northern clades may reflect complex patterns of migration and range shifts during climatic cycles over the later Neogene leading to elevated rates of speciation and extinction, whereas the scattered persistence of mild, wetter habitats in the Southern Hemisphere may have favored the survival of older lineages.

A pop sci write up of the same.

Will This Hold True For All Gymnosperms?

Pine trees grown for 12 years in air one-and-a-half times richer in carbon dioxide than today's levels produced twice as many seeds of at least as good a quality as those growing under normal conditions, a Duke University-led research team reported Monday (Aug. 3) at a national ecology conference.

Carbon dioxide readings that high are expected everywhere by mid-century. The findings suggest some woody tree species could, in the future, out-compete grasses and other herbaceous plants that scientists had previously found can also produce more seeds under high-CO2, but of inferior quality.

"Even if both groups were producing twice as many seeds, if the trees are producing high-quality seeds and the herbaceous species aren't, then competitively you can get a shift," said Danielle Way, a Duke post-doctoral researcher.

Way is scheduled to present the results at a poster session 5 p.m. Aug. 3 during the Ecological Society of America's 2009 annual meeting in Albuquerque, N.M. She is also first author of a report on the study scheduled for publication in the research journal Global Change Biology.

Way and her co-researchers collected, counted and analyzed seeds produced at the Duke Free Air CO2 Enrichment (FACE) site in Duke Forest, near the university's campus. There, growing parcels of loblolly pine trees have been receiving elevated amounts of CO2 around the clock since 1997 in a Department of Energy-funded project designed to simulate natural growing conditions.

Their analysis found the high-CO2 loblolly seeds were similar in nutrient content, germination and growth potential to seeds from trees growing under present-day CO2 concentrations. "If anything, they actually seem to be slightly better seeds rather than more seeds of poorer quality," Way said.

"The notion here is that if the trees are producing more high-quality seeds at high CO2 compared to grasses and herbs, then the trees may be at an advantage," added study participant Robert Jackson. Jackson is Way's advisor at Duke, where he is a biology professor, as well as professor of global environmental change at the university's Nicholas School of the Environment.

Could we have another CO2 content proxy here?