Caught between two mass extinctions: The rise and fall of Dicroidium

Chris Mays and Stephen McLoughlin (Sweden) In the aftermath of Earth’s greatest biotic crisis 251.9 million years ago – the end-Permian mass extinction – a group of plants arose that would come to dominate the flora of the Southern Hemisphere. Recovery of the vegetation from the end-Permian crisis was slow; but steadily, one group of seed plants, typified by the leaf fossil Dicroidium, began to diversify and fill the dominant canopy-plant niches left vacant by the demise of the Permian glossopterid forests (Fielding et al., 2019). Eventually, Dicroidium re-established a rich peat-forming vegetation across Gondwana through the Late Triassic, dominating the flora between 30°S and the South Pole (Kustatscher et al., 2018). Indeed, few fossil plant assemblages of this age can be found in Gondwana that do not contain this plant. The importance of Dicroidium is not just its role in showing biogeographic and tectonic linkages between southern lands or its value in determining the age of continental strata. Dicroidium and its associated plant groups were so successful that they were major contributors to the development of thick coal seams in the Late Triassic that are now mined to produce electricity. Although Dicroidium is generally envisaged as a plant of cool temperate climates, the very first fossils that might belong to this group are from the Permian-Triassic transition of Jordan, located near the palaeoequator (Blomenkemper et al., 2018). Nevertheless, the distribution of Dicroidium soon shifted to high southern latitudes in the Early Triassic and they overwhelmingly dominated the southern vegetation … Read More

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Headbanging, rocking and moonwalking fossils

Mats E Eriksson (Sweden) One can never be too careful when given the opportunity to name a fossil organism that has proved to be new to science. In addition to a meticulous description and accompanying images showing the characteristic traits of the fossil, a unique and formal, Latinized scientific name must be attached to the creature. Many people, who get the chance honour an older colleague or famous palaeontologist, use the name of the discovery site or region to indicate the provenance of the fossil or, of course, christen the fossil after its characteristic looks (for example, Eriksson, 2017a). But you can also glance towards completely different areas, such as the art and music scenes. As a lifelong music fan and hobby musician (who, just like many of my peers, had aspiring yet quite ludicrous ‘rock star dreams’ in my teens) and a palaeontologist by profession, I cannot help myself but feeling blissful and delighted about the possibility of joining my two passions – ‘heavy’ music and palaeontology – in ‘unholy matrimony’. This has, among other things, led me to name some extinct polychaete annelid worms (bristle worms – the marine ‘cousins’ of earth worms and leeches) from the Silurian and Devonian periods after some of my favourite ‘metal’ musicians. These largely soft-bodied animals generally have poor preservation potential, although full body fossils are known from the fossil record. However, some representatives are equipped with resistant jaws (when preserved as microfossils they are known as scolecodonts) that, by contrast to … Read More

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Finders, keepers: The lost world of some Isle of Wight geological heroes

Martin Simpson (UK) There is a growing misconception that most of the earliest important fossil discoveries were made by a select few famous geologists – established names, who were supposed to have ‘found’ everything in their collections. In reality, however, the true ‘discoverers’ of the original specimens were an often unknown or forgotten assortment of amateurs, labourers, beach-combers, longshoremen or quarrymen: opportunists, who were finding ‘new’ material with surprising regularity. These people not only had local knowledge, but also had the distinct advantage of being in the right place at the right time, thanks to the hours they devoted to searching. On the other hand, the early geological pioneers were fervently adding to their private museum cabinets by whatever means possible. As news of major finds of unusual fossils came to their attention, perhaps by way of the reports in some of the provincial broadsheets mentioned later, the more diligent and successful collectors (the acquirers) put their money where their mouths were and purchased directly from the sources (the finders). Eventually some of this material found its way to the academics and their institutional museums (the keepers). In the case of the Isle of Wight – that classic locality for Cretaceous and Palaeogene fossils – the earliest and most important historical discoveries have been attributed to a small group of generalised geologists. These include William Buckland, Adam Sedgwick, William Fitton, Edward Forbes and the surgeon, Gideon Mantell between the 1820s and the 1850s; and later to a whole host of … Read More

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Jurassic Coast (or is it?) with the Geologists’ Association

Mervyn Jones (UK) Since 2012, the Geologists’ Association (GA) has put on annual field trips to the Dorset coast led by Prof John CW Cope (of the National Museum Wales), who is author of the definitive Field Guide No 22. The second edition was published in April 2016 (Geology of the Dorset Coast (2nd ed)). In fact, the trips were started to celebrate the publication of the first edition of the guide. The Dorset Coast is often equated with the ‘Jurassic Coast’ when, in fact, the geology stretches from the topmost Triassic, near the Devon border, through Jurassic and Cretaceous successions, to Eocene deposits at Studland. For this and other reasons, it attracts amateur geologists in large numbers. John’s guide provides essential information including descriptions of the succession and practical guidance about access. What’s missing are the entertaining stories that John Cope can provide and the context provided by exploring inland a bit. Day 1 – Saturday (1 October) For our fifth field meeting, we met up in Lyme Regis (in the car park next to the newly-restored house originally owned by John Fowles – see below) – a town to stir the heart of any geologist. Our mission for the weekend was to look at the unconformity below the Cretaceous, as it oversteps the older Jurassic and Triassic strata progressively in a westerly direction. En route, we observed the instability of the cliffs and suffered the same ourselves, as we scrambled over the boulders and shingle. On this occasion, … Read More

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Fossil folklore: Fish

Paul D Taylor and Mike Smith (UK) Fish are the most diverse animals with backbones – that is, vertebrates – living today. Bone and teeth of fishes abound in the fossil record, from the armour-plated, primitive fishes of the Devonian, through the cartilaginous sharks with their shiny dagger-like teeth, to the bones of advanced ray-finned teleosts related to modern carp and cod. Along with other marine fossils, fossil fishes were once used as ‘proof’ of the biblical deluge, for example, the fabulous Cretaceous fossil fish deposits of Lebanon. Gayet et al. (2012) recorded that, in the third century, the Bishop of Palestine wrote: “That Noah’s Flood covered the highest mountains is for me the truth, and I say that the witness of my eyes confirms it: for I have seen certain fishes, which were found in my lifetime on the highest peaks in Lebanon. They took stones from there for construction, and discovered many kinds of sea fishes which were held together in the quarry with mud, and as if pickled in brine were preserved until our times, so that the mere sight of them should testify to the truth of Noah’s Flood”. Petrified nails Hugh Miller, in his book Foot-prints of the Creator (Miller, 1849), mentioned that amateur geologists of Caithness and Orkney would refer to one particular fossil in the Old Red Sandstone, presumably relatively common, as ‘petrified nails’ (Fig. 1). Fig. 1. A so-called ‘petrified nail’, about 150mm long, as depicted by Hugh Miller. These fossils represent … Read More

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Australia’s Polar Cretaceous mammals

Dr Thomas H Rich (Australia) The Cenozoic Era is commonly referred to as the ‘Age of Mammals’. That is certainly the time in the history of life when their fossils are most abundant and diverse. However, two-thirds of mammalian history was during the Mesozoic Era – and they appeared about the same time as the dinosaurs. All continents except Antarctica have some record of the early, Mesozoic mammals. Of those that do, Australia has the most meagre record of all. Despite this, with this landmass that today has the most distinctive terrestrial mammals on the planet, their Mesozoic origins are so enigmatic that it has motivated a major effort since 1984 to search for fossils of those mammals that lived alongside the dinosaurs on this now isolated continent. Fig. 1. A map of Australia showing the location of the four sites where Cretaceous mammals have been found on the continent. During the Cretaceous, Australia was much further south than at present. Shown here are the lines of latitude at that time on the continent: 50o south, 60o south and 70o south. The famous Lightning Ridge opal field has provided some of the answers – two different early Late Cretaceous egg-laying mammals (the monotremes), as well as a third mammal that may be a monotreme, have been discovered there. One thousand, three hundred kilometres to the south-southwest along shore platforms pounded by the waves of the Southern Ocean, which expose those rocks on south coast of the continent, are three sites … Read More

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Jamaica’s geodiversity (Part 1): Introduction and some older highlights (Cretaceous to Miocene)

Stephen K Donovan (The Netherlands) and Trevor A Jackson (Trinidad) With a length of only about 240km, Jamaica cannot be considered a large island. It is also relatively ‘young’ geologically, the oldest rocks being only about 140myrs old. This might sound old enough, but contrast it with, for example, rocks in the islands of the Scottish Outer Hebrides, which are about 2,000myrs old. But Jamaica is nevertheless noteworthy in having a rich diversity of rock types and geological features, and it is rightly known for its high biodiversity, both on land and in the surrounding seas. To give one example, the 500 or more species of extant land snails make Jamaica a biodiversity ‘hot spot’ for these familiar molluscs. However, Jamaica should similarly be recognised as a geodiversity hot spot, with a range of geological and physiographic features, strata and fossils that make it an unusually fruitful focus for earth sciences research. We could support our bold assertion by a detailed exposition with tabulation of principal features and comparison with similar-sized islands elsewhere, although such an approach would perhaps be better suited to a dry research journal. The potential for producing such a long, boring discursion is large and we intend to avoid the temptation to do so. Rather, we want to illustrate Jamaica’s geodiversity by reference to a dozen key features. These are available for inspection to anyone who is interested and which we will describe in two articles in Deposits. The choice of these features is personal – … Read More

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Other mass extinctions

Neal Monks (UK) The extinctions at the Cretaceous-Tertiary (K/T) boundary make up what is probably the most famous geological event in popular culture. This is the point when the great reptiles that characterise the Mesozoic went extinct. Alongside the dinosaurs, the giant marine reptiles died out too, as did the pterosaurs, and a whole host of marine invertebrates, including the ammonites and belemnites. What happened? Some geologists argue the climate changed over a period of a million years or more, thanks to the massive volcanism that created the Deccan Traps in India. Others maintain that the K/T extinctions happened suddenly, pointing to evidence of a collision between the Earth and an asteroid. Perhaps there wasn’t a single cause, but rather a variety of factors: volcanism, climate change, asteroid impact, underlying changes in flora and fauna, and perhaps even variation in the output of the Sun and resulting weather patterns. That life on Earth can be wiped out this way is the stuff of disaster movies as much as TV documentaries. However, what comes as a surprise to many people is that there wasn’t just one mass extinction at the K/T boundary, but a whole series of them that can be observed throughout the fossil record. One of them, the Permo-Triassic extinctions, appear to have been even more catastrophic than the K/T extinctions, and at least three other extinction events are comparable in scale. In between these five big extinctions were lots of smaller extinctions that aren’t well studied, but had … Read More

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Geology and fossil fauna of the South Ferriby foreshore

John P Green (UK) The large working quarry at South Ferriby, North Lincolnshire (SE991204) is a well known and productive source of Late Jurassic and Cretaceous fossils, exposing beds from the Upper Oxfordian stage, Upper Jurassic (Ampthill clay, Ringsteadia psuedocordata zone) to the Terebratulina lata zone of the Turonian stage (Welton Chalk Formation, Upper Cretaceous). Research on the stratigraphy and palaeontology of the site has been carried out by many authors, and a generalised section detailing the overall stratigraphy and macrofossil occurrences was published by the local amateur geologist, Dr Felix Whitham (1992). However, in recent years, access to the quarry for geologists has been relatively curtailed due to health and safety concerns. In light of this, my research at South Ferriby has shifted to the nearby geological exposures on the easily accessible foreshore, on the southern banks of the Humber Estuary. Fig. 1. South Ferriby foreshore, looking east. In general terms, the beds exposed on the South Ferriby foreshore tilt eastward, exposing the older (Jurassic) rocks to the west and the younger (Cretaceous) rocks to the east. The exposures are largely wave-cut platforms, accessible only at low tide, and are often covered with sand and estuarine sediments, as well as a large variety of erratic rocks and fossils. Especially prominent among the latter are carboniferous corals and limestones, Cretaceous flints, the Jurassic oyster, Gryphaea, and specimens of the Cretaceous (Late Campanian) belemnite, Belemnitella mucronata, most likely derived from chalk of this age that floors the North Sea. The low … Read More

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Histology of a sauropod rib bone from the Wessex Formation, Hanover point, Isle of Wight

Megan Jacobs (Isle of Wight) In September 2015, I went to Compton Bay on the Isle of Wight to hunt for dinosaur bones. It was equinox tides all week, so an ideal time to get out on the furthest rocks of the Wessex formation, dating from the Barremian stage of the early Cretaceous (about 130Ma) also famous for the bone debris beds, which are highly fossiliferous. Time passed and I hadn’t had a great amount of luck. So, deciding today was not my day, I decided to head home. As I turned, I glanced down to see a beautiful piece of rib bone with the most amazing internal structure I’ve ever seen (Fig. 1). But also nothing like I’ve ever seen before. Fig. 1. The bone when found at Hanover Point, Isle of Wight, September 2015. I took it show my tutor, David Martill, at the University of Portsmouth. He was quick to identify it as being from a sauropod, due to the large air cavities now filled in with a clear mineral banded by pyrite. He then followed the identification by: “how’d you fancy cutting it in half for a thin section?” I was dubious about the idea at first: I’d never looked at a bone and thought ‘you know what, that would be better cut in half’. But I went along with it and handed over my prize. What is a thin section? A thin section is an approximately 30µm thick slice of rock, or in this case, … Read More

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Who did it? Bite marks in Jurassic and Cretaceous ammonites

Adiël A Klompmaker (USA) Ammonites are among some of the best fossils to collect. They are relatively easy to find, for example, in the Lower Jurassic Posidonia Shale in Germany and the Jurassic sediments of Dorset in the south of England. The larger, well-preserved ones will always be sought after and, if of sufficiently high quality, may even be displayed in museum exhibitions. However, while these nicely-preserved, complete ammonites are ideal for identifying species, they often do not say much about the life history and, more specifically, the death of the ammonite itself. On the other hand, studying the sub-lethal or lethal damage to the fossil shell certainly does. This article is about a relatively newly discovered type of bite mark. It is found on Jurassic and Cretaceous ammonites, might have occurred worldwide, is easy to recognise and is also fairly common. Ventral damage When I was browsing through the ammonite collections of several Dutch museums (including, Naturalis and Oertijdmuseum De Groene Poort) and the Geologisch-Paläontologisch Institut der Universität Münster in Germany, it became apparent to me that there were many specimens with damage to the outer whorl, on the back side of an ammonite (the ventral side) in its living position. This damage was not only visible on the ventral side, but could also be seen on both lateral sides, if preservation permitted. Fig. 1. Measurements relative to the aperture (A) and relative to the last septum (B). After Klompmaker et al. (2009). When viewed from the lateral side, … Read More

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Jamaican fossil crabs

Stephen K Donovan (The Netherlands) and Joe SH Collins (UK) Decapod crustaceans (crabs) are among the most attractive of fossils. Yet, the beautifully preserved specimens seen in museum displays and dealers’ catalogues are in stark contrast with the usual haul of the collector, that is, scraps, commonly claws or (more rarely) bits of carapace, which we all find in (mainly) Cretaceous and Cenozoic sedimentary rocks. However, these bits and pieces represent most of the fossil record of crabs and, as such, are of importance to the systematist and anyone with an interest in aspects such as taphonomy and palaeoecology. Just as it is possible to identify a shark from a tooth or a cidaroid echinoid from a spine, so a crab claw can commonly provide data that permits its identification to the level of genus or species (Collins, 1999). The present authors, in collaboration with Roger Portell of the Florida Museum of Natural History at the University of Florida in Gainesville, have been collecting and studying the fossil crabs of Jamaica (and the wider Antilles) for over 20 years. Until the 1990s, reports of fossil crabs from the island were limited to a few fragmented specimens and rare, well-preserved carapaces (some retaining claws) or the isolated claws of mud shrimps (=Callianassa sensu lato), which were collected mainly from the Upper Cretaceous and Eocene by visiting geologists as an aside to their own research. They were sent to the British Museum (Natural History) for description. These early records were reviewed and … Read More

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Artistic reconstructions of palaeoenvironments: A unique fusion of science and art

Richard Bizley (UK) Life on Earth has been affected and shaped by geological and astronomical events during the 4.5 billion years since it was formed. Scientists study geological and palaeontological processes to answer some rather fundamental questions. What did the animals and plants look like and how did they interact? What were the environment and ecology like? What about the climate? Was it dry, wet, cold or humid? Scientific descriptions of fossil species and published descriptions of fossil assemblages are the first steps in recreating theoretical reconstructions of the palaeoenvironments of the past. These normally take the form of descriptive prose in academic papers, only occasionally accompanied by an interpretative sketch. My interest lies in bringing the palaeoenvironments to life much more vividly. Fig. 1. Devonian of Scotland. One of the earliest known terrestrial ecosystems is from Scotland near Rhynie, where beautifully preserved fossils have been found in Rhynie Cherts. This palaeoenvironmental reconstruction is approx 400myrs ago. There were geysers, with water runoffs. Along the fringes of the runoffs and ponds, there were bacterial mats (which I have painted in reddish/pinkish colours). First terrestrial plants were small and here I’ve shown Horneophyton lignieri (Horneophytopsida), these grew approx 20cm high. Occasionally, hot silicated water from the geysers would flood the area, coating, killing and preserving the life forms. They would be covered with whitish silicated material (sinter). In the extreme foreground is a pair of springtail (Collembola: Ryniella praecursor). These were only between 1 and 2mm in length. Behind this an … Read More

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Collecting fossils in Florida

Niels Laurids Viby (Denmark) I didn’t go to Florida especially to look for fossils, but I am always looking for opportunities when I am abroad. Being an architect, I actually went there to study houses, in particular, the Art Deco district at Ocean Drive in Miami. However, it seems that every museum in the State (other than art museums) has a fossil exhibition: the Science museum in Miami was showing Chinese dinosaurs, the Orlando Science Centre had displays of Upper Cretaceous dinosaurs and the Natural History Museum in Gainesville had the very best – complete skeletons of mammals from Florida. Fig. 1. Fossil exhibition with complete skeletons of mammals from Florida, at the Natural History Museum in Gainesville. The result was that I spent a lot of time looking at things (including buildings) rather than finding fossils. In fact, out of thirteen days in Florida, I spent three in or waiting for planes, four driving long distances (but with some stops checking out potential fossil sites), four looking at houses, one on paperwork for a report on buildings and only one full day looking for fossils. The time spent driving was a big surprise. Florida looks small on a map of USA, but all of Denmark (my home country) could fit into the area south of Gainesville and the Danish population is probably equal in number to half of the people living in Greater Miami. However, I saw this trip as an expedition into unknown territory – a future trip … Read More

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Ashdown maniraptor: The world’s smallest dinosaur?

Dr Steven C Sweetman (UK) Most palaeontologists now accept that birds are descended from non-avian dinosaurs and are therefore the only living representatives of otherwise terrestrial animals that ruled the world during the Mesozoic. That being the case, the Cuban bee hummingbird, which measures just 5cm in length and weighs about 1.8g, is arguably the world’s smallest dinosaur. However, if birds are excluded and looking only at the non-avian dinosaurs, all of which became extinct in the often-discussed mass extinction event at the end of the Cretaceous, what is the world’s smallest dinosaur? Until very recently and considering only animals that are thought to be fully grown, the answer is Anchiornis huxleyi (Hu et al., 2009; and Fig. 1) from the earliest Late Jurassic of China. This tiny, feathered troodontid has been estimated to be between 34 to 40cm long (excluding the tail feathers). In the ever-changing environment of what represents the world’s largest and what the smallest, Anchiornis’ position as the world’s smallest dinosaur has now been threatened and quite possibly overturned. The fossil concerned is not another wonderful specimen from the Late Jurassic or Early Cretaceous of China, but a single, tiny cervical (neck) vertebra (Fig. 2) discovered at a brickworks near Bexhill, in East Sussex. Fig. 1. Anchiornis – an artist’s impression by Matthew Martyniuk. Fig. 2. The maniraptoran cervical vertebra discovered at Ashdown Brickworks by Dave Brockhurst in: A: left lateral; B: right lateral; C: anterior; D: posterior; E: dorsal; and F: ventral views. For more … Read More

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Book review: Geology and Fossils of the Hastings Area (2nd ed), by Ken Brooks

I remember buying the first edition of Ken Brook’s fascinating little guide on Hastings a long time ago, and bumbling off to Hastings in the hope of finding Lower Cretaceous dinosaurs and tree ferns. Sadly, I was disappointed, as the area is not as productive as, say, the Dorset or North Yorkshire coastlines. Having said that, I have been back a few times armed with that first edition and have enjoyed the visits every time.