What We Do
Paleobotany is the study of all aspects of ancient plants, including their anatomy, morphology, evolution, and ecological relationships. Most paleobotanical research involves the study of variously-preserved larger plant fossils, including wood, leaves, cones, flowers, seeds, etc.
Palynology is a specialized field within paleobotany, dedicated to the study of microscopic plant remains, including spores and pollen grains. Palynology is an important tool in oil exploration, where both the age of specific rock layers and the environment of deposition can be determined using the palynomorphs preserved in the rocks. Palynology is also valuable for the reconstruction of ancient ecosystems.
Paleoecology involves the reconstruction of various aspects of ancient ecosystems. Since plants are the defining elements in most terrestrial communities, paleobotanical and palynological research provides a means to reconstruct the major components of terrestrial ecosystems. Such studies can include the composition and distribution of various community elements; the prevailing climate with respect to temperature and rainfall; and patterns of vegetation dynamics (succession) in response to factors such as climatic change, volcanism, fire, and hydrologic disturbance. Reconstruction of the plant components of ancient ecosystems provides a basis for defining the nature of the interactions between plants and the animals present in ancient communities.
What follows is a very brief description, often with a listing of Selected Recent Publications:, of a range of current and past research initiatives.
It is expected that more papers will be available for downloading in the near future. Please be aware that most of these papers had to be scanned from their original form and thus the files may be very large! This should not be a problem if you have high-speed Internet access, typical of most college and university terminals, but could result in very long download times when using typical dial-up Internet providers (AOL, MSN, etc.).
There are extensive exposures of Lower Paleozoic rocks in northern Michigan, but most represent ancient reef deposits and thus typically do not have good plant fossils. One interesting exception are some reef deposits exposed along the northern shore of Lake Michigan, which contain good compression fossils of a unique form of marine alga, most likely related to the Phaeophyta or "brown algae". This particular deposit was brought to our attention by a student who had been enrolled in BOT/GLG335, our undergraduate fossil plants course.
Although Michigan has extensive "coal age" deposits, most are buried by much younger glacial sediments and are thus not accessible for study. Occasionally material is uncovered by excavation and we have extensive collections from Grand Ledge, Michigan, not far from the campus. Much of the material in our collections has been derived from elsewhere in the mid-continent region, including sites in Pennsylvania, West Virginia, Ohio, Kentucky, and Indiana, and Illinois. One of us (Cross) has been engaged in a long-term study of Megalopteris, an enigmatic seed fern (Pteridosperm). Past graduate research projects have included analysis of coal ball and compression floras.
The deposits from the Hamilton Quarry in Kansas are particularly significant because they contain structurally-preserved remains of early conifers. This material has been extensively studied by Gene Mapes and Gar Rothwell at Ohio University in Athens, OH. Because the fossil conifers in this deposit are so well-preserved, the age of the material is of more than passing interest. The fossils occur in a channel-fill deposit in a Virgilian limestone, so the deposit is typically considered to be Upper Pennsylvanian. However, our study of the palynology of the deposit indicate a late Lower Permian age.
It has been known for some time that some problematic "red beds" could be found in the sub-surface of south-central Michigan, overlying beds of Carboniferous age. It had been generally assumed that these deposits were Permian in age. One of us (Cross) has now shown that these beds are Middle Jurassic - the only strata of the "Age of Dinosaurs" known to occur in Michigan. These "Michigan Redbeds" have small outcrops in old quarries near Ionia, Michigan and we continue to explore such sites, looking for larger plant and animal fossils.
Our laboratory has a long track record of student theses dealing with the palynology and paleobotany of the Cretaceous deposits of the Western Interior. Listed below are a few ongoing research initiatives:
Dinosaur Herbivory. For most of their history, herbivorous dinosaurs must have consumed ferns and a variety of gymnosperms, including conifers. During the Cretaceous, there was a rapid change in the Earth's vegetation with the rise and adaptive radiation of the angiosperms (flowering plants). Our research suggests that the dinosaurs generally failed to make the transition to these "new" food plants and that their populations may have been critically stressed at the time of the K/T boundary asteroid/comet impact, making them particularly vulnerable to extinction.
Ecological Consequences of the K/T Boundary Impact Event. It is now generally accepted that the Earth was struck by a relatively large extraterrestrial object (asteroid or comet) at the time of the K/T boundary. It has generally been argued that this impact had catastrophic consequences on a planetary scale. Our analysis of the degree of ecological disturbance, as indicated by palynology, suggests that the most significant effects were regional in scope, limited to a radius of perhaps 3600 km from the impact site.
Missouri Ozark Dinosaur Project. The Chronister local fauna site (Bollinger County, MO) is unique in that in represents the only known occurrence of dinosaur remains in the state of Missouri. Animal fossils from the site include at least one hadrosaur, a tooth of a small tyranosaurid, remains of two species of turtle, one or two species of crocodile, and bowfin fish. We have just begun a program, in association with the Missouri Ozark Dinosaur Project, to date this site using stratigraphic palynology and to attempt to reconstruct the ecological setting. Quite apart from the inherent interest in the site, if we are successful, we have the opportunity to learn more about the paleoecology of North America east of the Cretaceous Interior Seaway.
Much of the work of the laboratory in recent years has been directed toward understanding the paleoecology of a range of Tertiary and Quaternary assemblages:
Origin of Pinaceous Conifer Forests. Because conifers (sensu latu) are an ancient group of plants, it is generally assumed that conifer dominated biomes, such as the boreal forest and western cordilleran conifer forests, must be relict assemblages. Recent work in the Eocene Thunder Mountain (Idaho) and Bull Run (Nevada) floras suggest that the boreal forest may be one of the youngest forested biomes, derived from western cordilleran forests in as a consequence of Late Eocene-Early Oligocene global cooling.
Taggart, R.E. and A.T. Cross. 2000. Paleogene upland vegetation - unique North American paleoecological perspectives. Acta Universitatis Carolineae - Geologica 44:87-99.
Systematics of the Miocene Succor Creek Flora. One of us (Fields) is involved in an ongoing revision of the megafossils of the Succor Creek assemblage known from the Oregon-Idaho border region. As a result of this work, the Succor Creek assemblage appears to be the most diverse Neogene fossil assemblage of North America.
Neogene Vegetation Dynamics of the Northern Intermountain Region. Many years of ongoing study of fossil assemblages such as Succor Creek (eastern Oregon and western Idaho), Trapper Creek (southern Idaho) and Stinking Water (eastern Oregon) suggest that much of the fossil record does not record vegetation in dynamic equilibrium with climate. Instead, these floras, which are preserved in volcaniclastic sediments, largely represent seral vegetation in varying stages of recovery from volcanism, fire, and hydrologic disturbance.
Quaternary Projects. Several new projects are on-going, including pollen analysis of the Beale Mastodon site in Athens County, Ohio, several sites in Ingham County near the M.S.U. campus, and the study of a 10,000-12,000 year-old seed and leaf assemblage from the Coldwater Creek drainage in Missouri.
Ralph E. Taggart, Professor, Department of Botany and Plant Pathology, Department of Geological Sciences, Curator of Fossil Plants. Paleoecological reconstruction and vegetation dynamics of late Mesozoic, Tertiary, and Quaternary assemblages.
Aureal T. Cross, Professor Emeritus, Department of Geological Sciences. Coal geology, stratigraphic palynology, paleobotany and palynology of Upper Paleozoic, Mesozoic, and Cenozoic assemblages.
Patrick F. Fields, Research Associate, Department of Botany and Plant Pathology. Evolution, systematics, and paleoecology of Neogene megafossil assemblages.