Birds are the most diverse and widely distributed groups of tetrapod animals. They inhabit a myriad of different environments, and exhibit incredible disparity in their forms and lifestyles. Unravelling how, when, and why modern bird diversity has arisen demands an appeal to the fossil record of modern birds, as fossils provide us with the only direct evidence of the history of life on Earth. Additionally, understanding the origins of the features that make birds unique - such as feather-assisted flight - forces us to look beyond the fossil record of modern birds themselves. For these answers, we must turn to the Mesozoic record, more than 66 million years ago, to study the early antecedents of modern birds: non-avian dinosaurs.
I will discuss my research related to modern birds and their dinosaurian relatives, covering questions like "how did the ancestors of modern birds survive the end-Cretaceous mass extinction?"; "how have the geographic distributions of modern bird groups changed over the last 66 million years?"; and "how and when did modern avian flight arise?".
Due to their widespread and abundant fossil record, pollen and spores have become a mainstay of research into past vegetation change and floral evolution, and are widely used to infer past climates and date sedimentary sequences. However, palynology as a discipline has remained largely unchanged in its approach for the last 100 years. In this talk I’ll describe how a whole new field of research is opening up, based on using the chemical signature of pollen and spores to extract previously inaccessible information on past climate and vegetation change.
One key insight has been that pollen and spores contain a direct chemical record of past ultraviolet irradiance via concentrations of ‘sunscreen’ compounds, offering the potential to quantify the role of solar irradiance in climate change, identify episodes of past ozone collapse, and determine the timing and rate of mountain uplift. Another has been the discovery of a taxonomic signature in pollen and spore chemistry, greatly increasing the amount of information on plant composition and diversity that can be recovered from palynological samples. I’ll talk about recent developments in both of these areas, and offer some thoughts on the future direction of chemical palynology.
The necks of sauropod dinosaurs were by far the longest of any animals, exceeding 15m. Four clades with very different cervical morphologies (mamenchisaurids, diplodocids, brachiosaurids, and titanosaurians) evolved ten-meter necks. By contrast, the neck of the giraffe, the longest of any extant animal, reaches only 2.4m. Those of theropods and pterosaurs attained at most 3m (Even among aquatic animals, the record is only 7m for elasmosaurs).
Four factors contributed to sauropod neck length: the sheer size of the animals, their distinctive vertebral architecture, air-sacs, and heads that merely gathered food without processing it. Cervical vertebral innovations included: extreme pneumatisation, which lightened the neck and increased bending resistance; elongate cervical ribs, which allowed hypaxial muscles to shift posteriorly; and, in several clades, bifid neural spines, which aided stability by shifting epaxial tension elements laterally. Bifid cervical neural spines evolved at least four times among sauropods and were never secondarily lost; they are otherwise found only in Rhea.
However, other aspects of sauropod cervical anatomy remain puzzling: low neural spines reduced the moment arm of epaxial tension members; ventrally displaced cervical ribs increased bulk; and epipophyses were not posteriorly elongated. These apparent flaws suggest our understanding of sauropod neck mechanics remains incomplete.
The Antarctic Peninsula is a mountain glacier system comprised of over 400 glaciers, and is an important contributor to historical and future sea level rise. Assessment and monitoring of Antarctic Peninsula glaciers is crucial for understanding sensitivity to climate change. Changes to glacier fronts and ice shelves and glacier acceleration are well documented, but there are almost no data on mass changes on the Antarctic Peninsula. Satellite data have been used to calculate change over the last 3 decades, but methods to quantify this over longer timescales have eluded researchers. However, there is an archive of aerial photography dating back to the 1940s, this has been largely ignored due to the range of technical problems associated with deriving quantitative data from historic imagery and the lack of ground control data. This talk will introduce some of the early expeditions that collected aerial photography of the Antarctic Peninsula and then demonstrate how advances in image processing and capture of modern aerial photography has allowed this archive to be ’unlocked’. The spatial and temporal changes that have occurred on the glaciers over the period of record will then be explored.
Natural hazards such as earthquakes, volcanic eruptions, floods, droughts, wildfires, landslides, storms and tsunamis have happened throughout geological time. The difference now is that as the population of the world increases some people are living in areas that maybe are not particularly sensible from a hazard perspective, but they have little choice. For others, the complexity of modern society means that a major event such as Hurricane Harvey can inflict catastrophic economic and social consequences on even the most sophisticated cities in the western world. This talk will examine the causes of consequences of a variety of hazards and show how, looking ahead, the impact of some such events is likely to increase as climate, population and land use combine to amplify what are in reality entirely natural phenomena.