Richard Buchmann
Universidade Federal do Espírito Santo, Brazil
March 07, 2023
From fossils to pterosaur neck
Pterosaurs have necks of varying lengths, adapted to different life habits. Soft tissue inference according to the osteological correlates recognized in the cervical vertebrae indicate that pterosaurs could have a slightly sinuous neck. In addition, the likely robustness of muscles responsible for dorsoventral movements indicates wide cervical range. The presence of articular and segmented ligaments and specialized muscles may have contributed to the stabilization of the neck.
Nichola Strandberg
University of Southampton, UK
March 28, 2023
Biotic homogenisation of South Pacific Island vegetation through the Holocene
The increasing similarity of plant species composition between distinct areas is leading to the biotic homogenisation of global ecosystems. Human actions such as ecosystem modification, the introduction of non-native plant species, and the extinction or extirpation of endemic and native plant species drive this trend. However, little is known about when this process of homogenisation began or pre-human patterns of biotic similarity. Here we investigate vegetation trends across the South Pacific islands during the Holocene using fossil pollen records from 20 sites on 15 islands. The site comparisons show increasing similarity between pollen records throughout the Holocene which began to accelerate between 3400–2900 cal. years BP, synchronous with the timing of human colonisation of the Southwestern Pacific islands. More recent pollen records appear to be more biotically homogenised as people were present on the islands for the majority of the periods studied. While biotic homogenisation is often referred to as a contemporary issue, we have identified earlier homogenisation patterns across the Pacific islands.
Allison Stegner
Stanford University, USA
April 4, 2023
Biotic and abiotic signals of the Anthropocene in the geologic records
Humans have been altering our planet throughout the Holocene, but the scale of impacts increased dramatically in the mid-20th century, representing the start of the proposed Anthropocene Epoch. These pervasive anthropogenic impacts are comparable in magnitude, uniqueness, and geologic perseverance to the global changes that mark previous major geologic time intervals. To identify the geologic signals that characterize the Anthropocene, we studied sediment cores from Searsville Reservoir, a ~130 year old reservoir located at Jasper Ridge Biological Preserve in the eastern foothills of the San Francisco Peninsula, California. One of these cores is being considered as the “golden spike” for the Anthropocene.
Shinya Iwasaki
Hokkaido University, Japan
April 11, 2023
The Search for the glacial deep ocean carbon reservoir -Development of paleo-proxy for deep water carbonate chemistry
Southern Ocean deep-water circulation plays a vital role in the global carbon cycle. On geological time scales, upwelling along the Chilean margin likely contributed to the deglacial atmospheric carbon dioxide rise, but little quantitative evidence exists of carbon storage. Here, we develop an X-ray Micro-Computer-Tomography method to assess planktonic foraminiferal shell dissolution as a proxy for paleo-carbonate ion concentrations. Our subantarctic Southeast Pacific sediment core depth transect highlights the importance of a dynamic Pacific-Southern Ocean deep-water reconfiguration for shaping late-glacial oceanic carbon storage and subsequent deglacial oceanic-atmospheric CO2 transfer.
Zoe Roseby
University of Exeter
April 18, 2023
Sea level change in Ireland: Reconstructions and outreach
Spatial patterns of relative sea level (RSL) provide critical insights into the drivers of sea level change. The development of techniques to extract RSL data from saltmarsh sediments, has produced a suite of near continuous reconstructions spanning several centuries to millennia, supplementing and extending the records provided by instrumental tide gauges. Ireland’s location on the Atlantic edge of Europe means it is ideally placed to refine our understanding of sea level variability in the North Atlantic region. This talk will present the results of a study, that tests the application of the saltmarsh-based geological tide gauge (GTG) approach in Ireland, by reconstructing two centuries of RSL change in Dublin from duplicate sediment cores recovered from neighbouring sites. I will discuss the implication of our results for the production of longer GTG records from Ireland and similar European contexts. Such reconstructions are the basis of my current work under the A4: Aigéin, Aeráid, agus athrú Atlantaigh, project. Finally, I will present outcomes of an art-science outreach project ‘Línte na Farraige’ that aimed to raise awareness of the impacts of future sea level change in Ireland.
Bongekile Zwane
Nelson Mandela University, South Africa
April 25, 2023
The ecological implication of the presence of some woody plants in Sibudu and
Border Caves, at the time of the youngest Toba super-eruption
The debate about the impact of the youngest Toba volcano super-eruption on global climate has not received much attention from southern Africa; however, this has changed following the discovery of volcanic ash from this eruption in Lake Malawi and Pinnacle Point cave 5-6, South Africa. Since it was established that this is the only super-eruption to occur during the Quaternary period and human history, there have been debates about the possible impact that the release of more than 3,000 km 3 of volcanic debris from this single event had on global ecosystem. For example, it has been suggested through the Toba Catastrophe Theory that there was a 6–10-year long period of inhospitable climate called the “volcanic winter” which was followed by decades of reduced global temperatures. These conditions, some researchers argue, resulted in the die-out of plant and animal biomass and sent Late Pleistocene human populations to near-extinction. We, therefore, investigated if a ‘volcanic winter,’ that is commonly associated with this event, was present in south-east Africa between 74 and 72 ka. We sought to understand if extreme stressful conditions affected the
growth of woody vegetation, based on a sub-set of archaeological wood charcoal. We
analysed wood charcoal from Sibudu and Border Caves, two important archaeological sites
that have evidence for the continuity of life across the estimated time of the eruption. We identified different types of vegetation communities around the two caves, all of which
require plenty of moisture to thrive. Our results suggest no evidence for an extended and
catastrophic ‘volcanic winter’ in the south-east parts of the subcontinent. This may be due
to the influence of local climate drivers, which prevented the full impact of the Toba super eruption from overwhelming the southern African ecosystem. This, in turn, ensured the continued supply of woody plant resources for people who frequented the landscape
including at Sibudu and Border Cave localities.
Pierre Gueriau
University of Lausanne, Switzerland
May 2, 2023
Enhancing the description of flat fossils using ‘superhero laser vision’ imaging methods
Fossils play a pivotal role in our understanding of the origin and evolutionary history of life by providing unique insights into organism relationships and ancestral states. Nonetheless, most fossils can only be interpreted based on their preserved anatomy, often incomplete or hardly accessible. By revealing the internal (hidden) morphology of fossils preserved in 3D, or inside rocks or amber, X-ray micro-computed tomography (μCT) has clearly revolutionized the field, allowing paleontologists to describe fossil anatomy better than ever before. But other new imaging techniques can also unveil previously inaccessible anatomical information, sometimes even when µCT cannot, notably in the case of flat fossils. During this seminar, I will illustrate the potential of these methods by the study of a variety of flat fossils, including vertebrate, invertebrate and plant specimens, ranging in age from the Paleozoic to the Cenozoic.
Sara ElShafie
Weber Shandwick, United States
May 9, 2023
A tale of two reptiles: Climate change effects on giant lizards and crocs over millions of years + Skills & careers in science communication
We need to understand how current climate change will affect existing biodiversity, but we cannot do that using only data from the last few decades because the rate of current climate change is unprecedented in recent history. We need a frame of reference that spans a much longer time interval. Dr. Sara ElShafie addresses this need by investigating climate change effects on past communities of reptiles, which are especially sensitive to changing climates. Her research indicates that warming leads to large body size in some groups of lizards, whereas large body size in crocodylians and their extinct relatives correlates with high precipitation, over spans of millions of years. ElShafie will share the story of her work, including her journey as a science storytelling consultant and entrepreneur, and discuss useful skills and career paths in science communication.
Roger Creel
Columbia University, United States
May 16, 2023
Glacial Isostatic Adjustment reduces past and future subsea permafrost
Sea-level rise submerges terrestrial permafrost in the Arctic, turning it into subsea permafrost. Subsea permafrost underlies ~1.8 million km^2 of Arctic continental shelf, with thicknesses in places exceeding 700 meters. Sea-level variations over glacial-interglacial cycles control subsea permafrost distribution and thickness, yet no permafrost model has accounted for glacial isostatic adjustment (GIA), which deviates local sea level from the global mean due to changes in ice and ocean loading. We incorporate GIA into a pan-Arctic model of subsea permafrost over the last 400,000 years. Including GIA significantly reduces present-day subsea permafrost thickness, chiefly because of hydro-isostatic effects as well as deformation related to Northern Hemisphere ice sheets. Additionally, we extend the simulation 1000 years into the future for emissions scenarios outlined in the International Panel on Climate Change’s sixth assessment report. We find that subsea permafrost is preserved under a low emissions scenario but mostly disappears under a high emissions scenario.
Pal(a)eoPERCS 