Technical Description: The Cenozoic rock record contains a rich and critically important history of varied climates and biotic communities, and these serve as aids to understanding current and future climatic and biotic change. While the scales are different, the deep geologic past provides test cases against which climate models can be compared or from which they can be created. However, spatial coverage by paleoclimate proxies is best for middle latitudes, and quite limited for the tropics and subtropics, especially in the terrestrial realm. This project will investigate a new extraordinary Early Miocene (22 Ma) site where carbonaceous shales and tuffaceous sediments preserve lagerstätten-quality fossils including abundant compressed leaves, fruits and seeds with exquisite cuticular features, complete frogs with both skeletal and soft body parts, fish and large mammal bones. These enable reconstruction of paleoclimate, pCO2, paleoecology, and significant biogeographic data for African flora, and perhaps fauna. The objectives of this project are to: 1. compare Early Miocene and Late Oligocene paleoclimate, paleoecology, and biogeography using multiple independent proxies. 2. provide pCO2 estimates from pedogenic goethite and stomatal indices. 3. provide Early Miocene paleoecological and paleoclimatological context for faunal evolution during an otherwise poorly known, but significant time interval for Africa. 4. address plant biogeographic questions, e.g. a decline in palm richness and importance 5. test methods by (a) comparing δD isotopes from aquatic and terrestrial lipids to test for enrichment of D due to evapotranspiration, (b) comparing goethite and stomatal index pCO2 data (c) evaluating the consistency of paleotemperature and precipitation reconstructions using methods based upon leaf physiognomy, overlapping ranges of plant taxa, qualitative and quantitative paleosol analyses, and multiple isotope geochemical proxies. Non-technical Description and Broader Significance: This grant funds a multidisciplinary team of scientists who will sample rocks and fossils from the Ethiopian Plateau northeast of Addis Ababa to reconstruct past climate, vegetation, atmospheric CO2 concentration (pCO2), and the physical landscape 22 million years ago in an integrated and collaborative way. Team members, who have collaborated before on rocks from the Plateau that are 27 million years old, have expertise in the study of plant fossil identification, insect damage to fossil leaves, the reconstruction of past climate and ecology, the geochemistry of ancient soils and organic plant compounds, and geology. The locality preserves extraordinary plant fossils having cellular detail, smaller vertebrates including frogs with soft tissue preservation, and large mammal bones. The scientific significance of our work is that it will resolve currently conflicting data regarding global temperature and pCO2 between 27 million and 22 million years ago. Marine records show a significant rise in global temperature between these times, but some records of pCO2 show a decline and others a rise. Resolution of this conflict by acquisition of temperature and pCO2 data from one region using multiple independent sources will tell us if our understanding of CO2, in relation to global temperature is correct. Furthermore, the modern land connection between Africa and Eurasia was established about 24 million years ago, so we will be able to compare the younger plant and animal fossils with those from a time prior to contact with Eurasia. Africa?s flora and fauna was in a period of transition at this time, and its documentation is important for understanding the origins of modern biomes. Educational outreach includes distance learning for thousands of K-12 students. This team has a history of blogs, currently hosted by the SMU Public Affairs office on the main website, and recently through the NY Times Scientist at Work pages. Students will be an integral part of this project ? this team has regularly taken students into the field and will continue to do so. We also plan to host an Ethiopian graduate student for training in the U.S.
was focused on understanding the fossil flora, paleoenvironment, and paleoclimate for a nearly 22 million year old fossil site from northwestern Ethiopia known as Mush. The goals of this project were to (1) identify and describe fossil plant material from Mush, (2) determine the past vegetation based on this material, and (3) compare the fossil assemblage with other African fossil floras, particularly a 28 – 27 million year old site, also from Ethiopia, known as Chilga. A fossil species was identified and described from the nearly 22 million year old Mush flora (during the funding period of EAR 1339228), Tacca umerii. The fossils of Tacca umerii are large (mesophyllous and macrophyllous) palmately-lobed leaf compressions. Tacca is a genus of large herbaceous monocot flower plants (commonly known as bat-flowers) that have a distribution throughout the tropics. Today, Africa is represented by only one widespread species, Tacca leontopetaloides, which is also found in Madagascar, southern and Southeast Asia, and the western Pacific. The early Miocene African Tacca, represents a different group of species of Tacca (than Tacca leontopetaloides) which is restricted to southeast Asia (4 species) and Madagascar (1 species). All of these species possess large leaves that are palmately-lobed. The prehistoric species, Tacca umerii, is abundant in the Mush Deposits and likely was represented an important member of the forest understorey. The species above was published in a distinguished botanical science journal, the Botanical Journal of the Linnean Society: Pan AD, Jacobs BF, Currano ED. 2014. Dioscoreaceae fossils from the late Oligocene and early Miocene of Ethiopia. Botanical Journal of the Linnean Society 175: 17 – 28. Study of the early Miocene (21.73 million year old) Mush Deposits flora indicate that tropical moist forest continued to be prevalent in northwestern Ethiopia after collision of Africa and the Arabian Peninsula with Eurasia. The early Miocene Ethiopian forest plant composition was similar to that of the late Oligocene (28 – 27 million year old) Chilga assemblages near Gonder, Ethiopia, although no palm material (which is prevalent and diverse at Chilga) has been found at Mush. Most of the material that has been identified to the generic taxonomic level is still common in Africa forests today, although the species complex that the fossil Tacca has affinity with does not occur in Africa today. The identification of palmately-leaved Tacca from the Mush Deposits represents one of the only known fossil records of the genus (an fossil seed of Tacca is also known from the Oligocene of central Europe) and provides an important calibration for molecular clock studies for the species group. In addition, the presence of an extinct species of palmately-lobed Tacca may indicate that Tacca ankaranensis, from Madagascar, may be a relictual species and could be a candidate for increased conservation. Based on the sediments, morphology and size of the leaf morphotypes, and the taxonomic make up of the flora and fauna, the Mush Deposits likely represent a tropical moist forest fringing a (likely) crater lake. EAR 153315 funded herbarium travel and research to the Missouri Botanical Gardens from August 15 - August 19, 2011, field and museum research in Ethiopia from December 31, 2011 - January 17, 2012, and laboratory and research work of the PI at the Fort Worth Museum of Science and History, Botanical Research Institute of Texas and the Southern Methodist University. The grant EAR 1053315 was transferred from the Fort Worth Museum of Science and History to the Don Harrington Discovery Center as EAR 1339228 when the PI took over the directorship of the second institution. Other activities included the continued description and identification of fossil plant material from the early Miocene Mush deposits and preparation of manuscripts. In addition, distribution maps of modern plant taxa (lower than the familial taxonomic level and above the species taxonomic level) were created for fossil groups represented in the Mush deposits for use later in overlapping distribution analyses (ODA) which can be used to derive qualitative paleoclimate information. This study also produced another paper, Pan et al. (2012).
