Synopses of Previous Seminars
Evidence for early life in the Eo- and Paleo-archean
Dr Dominic Papineau (London Centre for Nanotechnology and Department of Earth Sciences, University College London)
The investigation of the earliest life and carbon cycle is extremely challenging as biosignatures are inevitably degraded during geological history. Additional difficulties include abiotic pathways, contamination during sample preparation, and fluid alterations and remobilisation during metamorphic history. This presentation will review recent controversies over Eo- and Paleoarchean samples. The goal is to emphasize the critical role that new micro-analytical approaches have in complementing and challenging previous observations. Controversies to be addressed will include contaminant diamonds and graphite inclusions in >4.0 Ga zircons from Western Australia, possible evidence of life in ca. 3.83 Ga (billion years old) iron formations from Akilia in Greenland, evidence for late fluid-deposition of graphitic carbon coatings on apatite grains from the ca. 3.75 Ga Nuvvuagittuq Supracrustal Belt in Canada, and likely biosignatures in ca. 3.5-3.4 Ga chemical sedimentary rocks from Western Australia. Altogether, these controversies demonstrate that careful sample preparation protocols, an unbiased consideration of the data, and the use of novel micro-analytical techniques are all necessary in the search for the earliest traces of life on Earth.
Animals and the invention of the Phanerozoic Earth system
Professor N. J. Butterfield (Department of Earth Sciences, University of Cambridge)
Animals pervade the modern biosphere and control how it works. Their unique combination of organ-grade multicellularity, motility and heterotrophic habit makes them powerful geobiological agents, imposing myriad feedbacks on nutrient cycling, productivity and environment. Most significantly, animals have ‘engineered’ the biosphere over evolutionary time, forcing the diversification of, for example, phytoplankton, land plants, trophic structure, large body size, bioturbation, biomineralization and indeed the evolutionary process itself. This metazoan-based expression is readily recognized through the Phanerozoic fossil record, with earlier (and much more tenuous) evidence of animals extending back no further than the middle Neoproterozoic. The relatively belated appearance of animals is the topic of much speculation, with the effects of permissive physical environments – particularly oxygen availability – currently in vogue. I will argue here that such extrinsic hypotheses fail to recognize the uniquely disruptive effects of even the simplest animals on environment; as such, the conspicuous biogeochemical and climatic perturbations of the late Neoproterozoic are more likely to be the consequences than the cause of early animal evolution. The delayed appearance of animals is better understood in terms of intrinsic constraints – in particular, the uniquely complex nature of the gene regulatory networks necessary to build even the simplest animals.
The origin of vertebrates and your fishy ancestors
Dr Robert Sansom (Faculty of Life Sciences, University of Manchester)
The origin and early radiation of vertebrates is one of the most important episodes in the history of life as well as our own evolutionary history as humans. During this period there were massive leaps in anatomical complexity, associated with overhauls of the genome and the way our bodies develop. Much of the architecture of being human was put in place from our paired eyes and nostrils to our brains, arms, legs, bone teeth and immune systems. Fossil evidence has been invaluable in reconstructing these events from the earliest chordates appearing the Cambrian explosion to the radiation of jawed vertebrates in the Devonian ‘age of fishes’. Here we explore this fossil evidence and the light it sheds on our fishy origins.
New tetrapods from Romer’s Gap: unrecorded diversity that laid the foundations of the modern fauna
Dr Tim Smithson. (University Museum of Zoology, University of Cambridge)
The end-Devonian extinction event marked a change in fortune for tetrapods. No longer confined to an aquatic habit, they developed the attributes for sustained life on land. These changes are thought to have started in the Early Carboniferous, during Romer’s Gap, but the evidence for it has been poor. Tournaisian tetrapod fossils are rare and, until recently, they were only known from a few isolated limb and girdle bones collected from the Horton Bluff Formation at Blue Beach, Nova Scotia, in the 1960s and 70s, and a single articulated skeleton found in the Ballagan Formation near Dumbarton in Scotland in 1971. Over the past 15 years regular walking of the shore at Blue Beach has uncovered a wealth of new material in the talus from the eroding cliffs. New material has also been collected from sites in northern Britain. Together, these new discoveries are providing evidence of a rich and diverse tetrapod fauna and include tantalising glimpses of the changes required for terrestrial life. In this talk I will introduce the new sites and describe the tetrapod fossils that have been found there. I will discuss the new techniques being used to study these fossils and describe the associated fauna and flora and the environment in which they lived. I will describe the changes that we observe in the limbs of Early Carboniferous tetrapods and consider the significance of small size in the acquisition of terrestrial characteristics. Finally, I will review the palaeogeography of Tournaisian tetrapods and discuss how this is helping to identify potential new Early Carboniferous tetrapod fossil sites across the world.
Coming out from the shadow of the dinosaurs; a new look at the first mammals
Dr Pamela G. Gill. (School of Earth Sciences, University of Bristol)
The origin of mammals is a key event in vertebrate history and a classic example of an evolutionary transition. Mammals are warm-blooded, large brained, agile organisms. They lactate, have complex teeth with precise occlusion, and possess a unique middle and inner ear, capable of high frequency sound detection. The sequence of transformations leading up to the mammalian condition is remarkably well-documented in the fossil record, and so our story starts before the first tiny mammals appeared 200 million years ago. However, what was historically less well known was what happened after this. Mammals evolved in the Late Triassic and for the first two thirds of their history lived alongside the dinosaurs, so were they just skulking in the undergrowth all this time? Recent finds of exceptionally preserved fossils, and new techniques available to researchers, reveal a far more interesting and diverse history. I shall cover some of the highlights to explain why we have had to rethink the early history of the mammals.
Dr Fiona Coward (Department of Archaeology, Anthropology and Forensic Science, Bournemouth University)
What does it mean to 'be human'? What makes us unique as a species? We now know that many other animals demonstrate some of the skills we once thought were distinctively 'human', for example making and using tools, living together co-operatively in large groups, communicating in highly complex ways and even using and understanding symbols. What are the implications of these findings for how we think about what it means to be human? This talk will discuss when and how some of the most obvious characteristics that distinguish us as a species evolved, and ask: what makes us unique, and why?
The Anthropocene: geology and the human process
Dr Michael Ellis (British Geological Survey, Keyworth)
The Anthropocene is a newly proposed geological epoch, marking the all-but permanent role of humans and the human process in the geological evolution of our home planet. We have known for a long time that humans have an impact on our living environment, but the scale of the impact is now dominant enough that it stands a good chance of being ossified in the geological record; a marker for all time. But of course, the Anthropocene goes beyond geology. It is an idea that speaks to the meaning of being human, to the way we regard nature, to the role of law as a natural process, and to the state of the future Earth. Some have suggested that the Anthropocene portends the end of us, and it’s bad news. I suggest that it opens up a new and untrampled path into a future that we make for ourselves. This lecture will touch on all of these things.
Swamps, rivers, lagoons and shallow seas - shifting shorelines in Rutland's Mid Jurassic
A. J. Mark Barron (Honorary Research Associate, British Geological Survey
The Jurassic strata of England clearly display the signs of continually fluctuating sea levels, in varied sedimentary rock types and their fossils. Britain lay about 20° latitude further south than now in an archipelago surrounded by shallow seas. Relief of these islands varied from very low-lying to mountainous, with coastal zones ranging from gentle slopes to steep and rugged. The climate was warm with high rainfall, leading to intense weathering, erosion and runoff, and we can make direct comparisons with a modern setting. In the region around Rutland, low-lying terrain on the London Platform grades north-west into the shallow marine East Midlands Shelf. The topography’s interaction with the oscillating sea level gives rise to the complex mosaics of depositional environments and lithofacies that are now preserved in the successions, which are related to the mapped stratigraphy. Rarely found dinosaur trackways in the wider region provide further intriguing evidence of the local conditions.
Prof John D. Hudson (University of Leicester)
In the nineteenth century, several Middle Jurassic formations including the strata that yielded the Rutland dinosaur were called “estuarine”. The term was then used in a very wide sense: some of the units so-named would now be regarded as deltaic or fluvial, such as much of the Middle Jurassic in Yorkshire. These are rich in plant fossils but have a sparse fauna. Other units are abundantly fossiliferous, especially in bivalves and gastropods. Although fossils are numerous, their diversity is low, a well-known characteristic of brackish water estuaries today. However, we now interpret the deposits as having been formed in wide, shallow lagoons, close to the sea and variably connected to it, rather than in tidal estuaries like those of the Thames or Severn.
I shall concentrate on the Great Estuarine Series of the Inner Hebrides, Scotland, so named by Judd in the 1870s (who also named the Rutland strata), and especially on its more argillaceous and fossiliferous parts (it also contains deltaic units). Because the shells are so well preserved, we can use geochemical and isotopic analyses to supplement taxonomic comparison, along with the abundant microfauna and palynomorphs. It appears that much of the water in the lagoons came from rainfall on land, via rivers. Seawater-freshwater mixing was limited to certain horizons.
Environments like this were important in the colonising of marginal marine waters, for instance by oysters. Dinosaurs also strode across the shallow waters, leaving footprints and trackways. The Rutland dinosaur’s environment has intriguing similarities and differences.
Scotland’s Jurassic mammals: from the English Midlands to the Hebridean Everglades
Elsa Panciroli (National Museums Scotland and the University of Edinburgh)
Until recently, Middle Jurassic fossils in the UK came almost exclusively from deposits in England, such as those of the Midlands, Oxfordshire, and the Dorset coast. Discoveries of Middle Jurassic (Bathonian) fossils on the Isle of Skye forty-five years ago were the first of their kind in Scotland. In the last ten years, fieldwork by a multi-institutional team led by researchers from National Museums Scotland and the University of Oxford has led to new and significant Middle Jurassic fossil discoveries. This work suggests parts of Skye are of international significance for small vertebrate skeletal remains, particularly mammals, basal squamates, and salamanders.
To date, the Kilmaluag Formation on the Isle of Skye has yielded skeletons and fragmentary material from early mammals such as Borealestes and Palaeoxonodon, the tritylodontid Stereognathus, lissamphibians like Marmorerpeton, basal squamates including Marmoretta, and the basal turtle Eileanchelys. Fragmentary fossils including those of crocodiles, dinosaurs and pterosaurs have also been recovered, although not all have been described. In the last few years in other parts of Skye, a second team led by researchers from the University of Edinburgh have recovered extensive dinosaur footprint sites, and the isolated bones of dinosaurs, marine reptiles and pterosaurs, from older Bathonian deposits.
Many of the Bathonian rocks on Skye represent shallow to brackish coastal lagoon and shallow water environments, containing comparable fauna and habitats to those represented in England, including the Ravenscar Group in Yorkshire. The Kilmaluag Formation however, reveals a more freshwater-lagoon environment, not unlike the Florida Everglades today. This unusual depositional setting has preserved some of the most complete Jurassic mammal skeletons outside China. Their unique three-dimensional preservation is providing new insights to early mammal anatomy and taxonomy. Research currently underway on this internationally significant fossil material will provide new insights into these ancient animals, and add colour to our vivid picture of the rich ecosystems of the British Isles in the Middle Jurassic.
Phylogenetic relationships of the Rutland Cetiosaurus in the Middle Jurassic (aka: ‘Rut’ and his Jurassic pals)
Femke Holwerda1,2,3 1Bavarian State Collections for Palaeontology and Geology, Ludwig-Maximilians University, Munich, Germany
2Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
3Naturalis Biodiversity Centre, Leiden, The Netherlands
Sauropods, the ‘quintessential dinosaur’ for the general public (Upchurch et al., 2004; Wilson, 2005) have slightly obscure historical beginnings: the first sauropod described, was, due to superficial morphological similarities with cetaceans, named ‘Cetiosaurus’ (‘whale lizard’, Owen, 1841; Taylor, 2010). It was not until a year later that the Dinosauria were classified (R. Owen, 1842). Although recognized as a dinosaur later (Richard Owen, 1842; Phillips, 1871) the name ‘whale lizard’ prevailed. Cetiosaurus as a taxon is still valid currently, and is the most common dinosaur in the UK (Upchurch & Martin, 2003).
Remains attributed to Cetiosaurus have been found in Oxfordshire, Buckinghamshire, Northamptonshire, Rutland, Leicestershire, Gloucestershire, Sussex, Yorkshire, the Isle of Wight, and Skye. This stratigraphic and biogeographic range are probably not realistic, however, and indeed, Cetiosaurus is a ‘wastebasket’ taxon (Upchurch and Martin, 2003), with most early Middle Jurassic sauropod material being assigned to it. The type material, Cetiosaurus oxoniensis, from the Bathonian Forest Marble of Bletchingdon Station, Oxfordshire, is housed in the Oxford Natural History Museum, and has recently received an extensive revision by Paul Upchurch and John Martin (Upchurch and Martin, 2002). The second-most numerous collection is housed in the New Walk Museum in Leicester, and comes from the Bajocian of Rutland, Leicestershire.
However, in the last decade, several authors and visitors to both collections have remarked on differences between the Cetiosaurus oxoniensis type material, and the Leicester ‘Rutland’ Cetiosaurus (Läng, 2008; Läng & Mahammed, 2010, Pedro Mocho pers. comm.). Currently, the ‘Rutland’ Cetiosaurus is being coded for a new phylogenetic analysis (Upchurch, Holwerda & Evans, ongoing research), as a recent analysis placed it outside of Cetiosaurus oxoniensis, and as sister taxon to the Aalenian-Bajocian Patagonian taxon Patagosaurus (Holwerda, Pol & Rauhut, ongoing research).
We will explore the relationships between the ‘Rutland’ Cetiosaurus (‘Rut’) and Patagosaurus (‘Pat’) and other Middle Jurassic sauropods; e.g. Volkheimeria from Patagonia, Barapasaurus from India, Lapparentosaurus from Madagascar. Is the ‘Rutland’ Cetiosaurus a different taxon from Cetiosaurus oxoniensis? How diverse was the Middle Jurassic in terms of sauropod taxa? And how did these sauropods get to be related? And how many cetiosaurs were there, really?
Placing the Rutland Cetiosaurus in the wider context – an over view of sauropod dinosaur evolution
Prof Paul Upchurch (Dept. Earth Sciences, University College London)
Sauropodomorph dinosaurs originated in the Late Triassic (c. 230 Million years ago [Mya.]) and died out in the mass extinction at the end of the Cretaceous (66 Mya.). Early forms were small (c. 1-2 m) and bipedal, but as these dinosaurs started to specialise towards herbivorous diets and browsing from the tops of trees, they evolved into the gigantic quadrupedal sauropods (body masses of up to 70 tonnes [Fig. 1A]). As a result, sauropods represent the largest land animals ever known. The demands of herbivory, high browsing and gigantic body size imposed numerous evolutionary pressures on the skulls and skeletons of sauropods. In particular, they were forced to evolve novel ways of lightening their skeletons via a complex system of air sacs (Fig. 1B) which probably also helped them to radiate excess body heat. Their limbs became straighter and column-like, with simplified joints, in order to support large body masses. Sauropod necks were often extremely long (up to c. 10 m) in order that they could position their heads within tree canopies during feeding.
Figure 1. A Reconstruction of the skeleton of the sauropod dinosaur Giraffatitan (estimated body mass = 32 tonnes), with an average adult human being for scale (drawing by Michael Taylor). B, Cross-section through part of a neck vertebra of the English sauropod “Chondrosteosaurus gigas”. Dark areas are fossilised bone; light areas are matrix infilling what would have been air spaces in the living animal. Sauropod vertebrae were often invaded by parts of their air sac system, lightening the skeleton and also providing a means for expelling excess heat through exhalation of air.
Within a few million years of their origin, sauropods had achieved a virtually global distribution, which they maintained throughout most of their evolution until their final extinction. As a result, the geographic ranges of sauropods were controlled by both intrinsic factors (such as their physiologies) and extrinsic factors (such as sea level, the break-up and Collision of continents, and climatic zones). Sauropods experienced a crisis at around 145 Mya., during which they lost 60-80% of their diversity. This extinction event resulted in the disappearance of many familiar forms such as Diplodocus and Brontosaurus, and a marked reduction in the geographic range of groups such as brachiosaurids. However, new groups of sauropods (in particular the peculiar titanosaurs) diversified in the Early Cretaceous (c. 125 Mya.), and went on to dominate many terrestrial ecosystems during the final 30 million years of the Cretaceous.
Cetiosaurus lived during an important time in sauropod evolution. New evidence from China indicates that the late Early and early Middle Jurassic (c. 180-160 Mya.), was a critical phase in sauropod evolution. In particular, many of the groups that dominated the Late Jurassic and Cretaceous, probably originated at this time, somewhat earlier than previously realised. Indeed, there is growing evidence that the poorly known Early Jurassic and early Middle Jurassic was a key phase in dinosaur evolution as a whole, being the period of rapid diversification and innovation that enabled dinosaurs to dominate the following 130 million years of life on land.