A5032058269- Geology and Paleoclimatology Research
- Evolution and Paleontology Studies
- Silicon Effects in Agriculture
- Plant Diversity and Evolution
- Ecology and Vegetation Dynamics Studies
- Pleistocene-Era Hominins and Archaeology
- Botany, Ecology, and Taxonomy Studies
- Plant Taxonomy and Phylogenetics
- Paleontology and Stratigraphy of Fossils
- Species Distribution and Climate Change
- Botany and Geology in Latin America and Caribbean
- Botany and Plant Ecology Studies
- Geochemistry and Elemental Analysis
- Archaeology and ancient environmental studies
- Marine and environmental studies
- Soil and Environmental Studies
- Geological and Geochemical Analysis
- Plant and animal studies
- Social and Educational Sciences
- Ethics in medical practice
- Plant Ecology and Soil Science
- Isotope Analysis in Ecology
- Education and Critical Thinking Development
- Horticultural and Viticultural Research
- Education, Healthcare and Sociology Research
University of Washington
2016-2025
Burke Museum of Natural History and Culture
2016-2025
University of Massachusetts Amherst
2021
Luleå University of Technology
2016-2019
Boise State University
2017
American Museum of Natural History
2010-2014
University of Sheffield
2013
SIB Swiss Institute of Bioinformatics
2013
Brown University
2013
University of Lausanne
2013
The evolution and subsequent ecological expansion of grasses (Poaceae) since the Late Cretaceous have resulted in establishment one Earth's dominant biomes, temperate tropical grasslands, at expense forests. In past decades, several new approaches been applied to fossil record elucidate patterns processes this ecosystem transformation. data indicate that development grassland ecosystems on most continents was a multistage process involving Paleogene appearance (C 3 C 4 ) open-habitat...
Opal phytoliths (microscopic silica bodies produced in and between the cells of many plants) are a very resilient, often preserved type plant microfossil. With exponentially growing number phytolith studies, standardization morphotype names description is essential. As first effort standardization, International Code for Phytolith Nomenclature 1.0 was published by ICPN Working Group Annals Botany 2005. A decade use code has prompted need to revise, update, expand improve it.
Silicified plant tissues (phytoliths) preserved in Late Cretaceous coprolites from India show that at least five taxa extant grass (Poaceae) subclades were present on the Indian subcontinent during latest Cretaceous. This taxonomic diversity suggests crown-group Poaceae had diversified and spread Gondwana before became geographically isolated. Other phytoliths extracted (from dicotyledons, conifers, palms) suggest suspected dung producers (titanosaur sauropods) fed indiscriminately a wide...
Abstract The Miocene epoch (23.03–5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned toward modern conditions, many flora fauna evolved into the same taxa that exist climate dynamic: long periods early late glaciation bracketed ∼2 Myr greenhouse interval—the Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, p CO 2 , ocean atmospheric circulation mostly (but not ubiquitously) covaried with these...
Because of a dearth Cenozoic grass fossils, the timing taxonomic diversification modern subclades within family (Poaceae) and rise to ecological dominance open-habitat grasses remain obscure. Here, I present data from 99 Eocene Miocene phytolith assemblages North American continental interior (Colorado, Nebraska, Wyoming, Montana/Idaho), constituting only high-resolution mid-Cenozoic record grasses. Analyses these show that had undergone considerable by earliest Oligocene (34 million years...
Vegetation structure is a key determinant of ecosystems and ecosystem function, but paleoecological techniques to quantify it are lacking. We present method for reconstructing leaf area index (LAI) based on light-dependent morphology epidermal cells phytoliths derived from them. Using this proxy, we reconstruct LAI the Cenozoic (49 million 11 years ago) middle-latitude Patagonia. Our record shows that dense forests opened up by late Eocene; open shrubland habitats then fluctuated, with brief...
Many questions in evolutionary biology require an estimate of divergence times but, for groups with a sparse fossil record, such estimates rely heavily on molecular dating methods. The accuracy these methods depends both adequate underlying model and the appropriate implementation evidence as calibration points. We explore effect Poaceae (grasses), diverse plant lineage very limited focusing particularly early divergences group. show that based data set plastid markers is strongly dependent...
Research Article| March 01, 2013 A new chronology for middle Eocene–early Miocene South American Land Mammal Ages Regan E. Dunn; Dunn † 1Department of Biology, University Washington, Box 351800, 24 Kincaid Hall, Seattle, Washington 98195, USA †E-mail: dunnr@uw.edu Search other works by this author on: GSW Google Scholar Richard H. Madden; Madden 2Department Organismal Biology & Anatomy, Chicago, Illinois 60637, Matthew J. Kohn; Kohn 3Department Geosciences, Boise State University, 1910...
The rapid ecological expansion of grasses with C 4 photosynthesis at the end Neogene (8–2 Ma) is well documented in fossil record stable carbon isotopes. As one most profound vegetation changes to occur recent geologic time, it paved way for modern tropical grassland ecosystems. Changes CO 2 levels, seasonality, aridity, herbivory, and fire regime have all been suggested as potential triggers this broadly synchronous change, long after evolutionary origin pathway grasses. To date, these...
Summary Solid biosilica (phytoliths) deposited in plant tissues is thought to function as structural support, a cost‐effective alternative lignin, and herbivore defence, by limiting nutrient access/extraction abrading mouthparts. It has been assumed that active phytolith accumulation evolved for these purposes, but hypotheses remain untested. For example, an influential idea holds grasses became so silica‐rich through antagonistic co‐evolution with mammalian grazers during the Cenozoic. We...
Grassy biomes are >20 million years old but undervalued and under threat today.
The assembly of Africa's iconic C4 grassland ecosystems is central to evolutionary interpretations many mammal lineages, including hominins. grasses are thought have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than Ma sparse, limiting assessment the timing and nature biomass expansion. This study uses a multiproxy design document vegetation structure from nine Early Miocene site complexes across eastern Africa. Results...
The independent acquisition of high-crowned cheek teeth (hypsodonty) in several un- gulate lineages (e.g., camels, equids, rhinoceroses) the early to middle Miocene North America has classically been used as an indication that savanna vegetation spread during this time. Implicit interpretation is untested assumption hypsodonty was evolutionary response feeding open habitats, either due a change food source (from browse graze) or in- creased incorporation airborne grit diet. I examined...
Abstract Accurate age-depth models for proxy records are crucial inferring changes to the environment through space and time, yet traditional methods of constructing these assume unrealistically small age uncertainties do not account many geologic complexities. Here we modify an existing Bayesian model foster its application deep time U-Pb 40Ar/39Ar geochronology. More flexible input likelihood functions use adaptive proposal algorithm in Markov Chain Monte Carlo engine better variability...