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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Seeing into the ‘Stone Age’: The stone tools of early man

Bob Markham (UK) In the early part of his evolution, man made great use of rock and stone to assist him in his activities. The term ‘Stone Age’ has been given to the period of time during which stone was the main material used for the manufacture of functional tools for daily life. It is generally thought to have commenced about 3.3Ma and was the time when man firmly established his position on earth as a ‘tool-using’ mammal. However, it should be remembered that stone was not the only material used for this purpose. More perishable materials, such as wood, reeds, bone and antler, were also used, but very few of these materials have survived to be found today (but see the box: Non-stone tools). Non-stone toolsA notable exception to the general rule that non-stone tools have not been preserved is the Palaeolithic wooden spear shaft that was recovered in 1911 from a site in Clacton in Essex. At 400,000 years old, the yew-wood spear is the oldest, wooden artefact that is known to have been found in the UK (see http://piclib.nhm.ac.uk/results.asp?image=001066).A number of wooden spears dating from 380,000 to 400,000 years ago were also recovered between 1994 and 1998 from an open-cast coal mine in Germany (see https://en.wikipedia.org/wiki/Schoningen_Spears). Other items are found from time to time from peat-bog conditions, which offer the most favourable medium for the preservation of such material.The stones used to make tools Being a non-perishable material, stone has survived the ravages of time and is … Read More

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Geoscience highlights from the Harvard Museum of Natural History

Ruel A Macaraeg (USA) Harvard University in Cambridge, Massachusetts, is among the world’s leading academic institutions and natural science is one of its most celebrated programs. Since its founding in the seventeenth century, the university has been a repository for specimens of scientific curiosity. Over time, these grew into three comprehensive reference collections – the Museum of Comparative Zoology, the Harvard University Herbaria and the Harvard Mineralogical Museum. Selections from these were eventually gathered into the Harvard Museum of Natural History, which, in 1998, opened to the public alongside the Peabody Museum of Archaeology and Ethnology with which it shares a building. Though retaining separate names and administration, the HMNH and PMAE are physically connected, and visitors to either gain entry to both with a single ticket. As one of these more recent visitors, I will share some brief impressions of the major palaeo and geoscience exhibits below. Mineralogical and geological gallery Geology displays worldwide tend to look the same – rows of labelled rocks grouped into categories in ascending shelves. Harvard’s geological gallery follows this pattern, but is distinguished by the inclusion of several large and notable mounts. Chief among these are two very large rocks, a gypsum crystal (Fig. 1) and an amethyst (Fig. 2). Fig. 1. Gypsum. Fig. 2. Amethyst. There are also several, well-preserved meteorites from locations across North America, some of which are shown in Fig. 3. Fig. 3. Meteorites. Fossil mammals A narrow, winding hallway somehow manages to display quite a few large Cainozoic … Read More

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Pico Partido: Volcanic perfection in the Canaries

Dr Trevor Watts (UK) Lanzarote is the easternmost island of the Canaries, less than 100 miles (about 150km) off the coast of Morocco. It is part of Spain, but not officially in the European Union and Pico Partido is a sharp, prominent peak near the centre of the island, between the small town of Mancha Blanca and the volcano of Timanfaya. The name means “divided mountain”, so called because the high peak is split by a deep fissure that seems to chop it in two. And it is enthralling. It is a basket of volcanic jewels to be treasured, particularly after the disappointment of the lack of access to Timanfaya itself (of which, more later). And Pico Partido is accessible, unlike much of the island where too many roads have no lay-bys or even a patch of cinder where you can pull in and explore. The geology of Lanzarote Lanzarote, with its volcanoes, is sitting on the tectonic plate that forms most of Africa. It is not near the edge, so it is not formed by one plate sinking under the other. Nor is it above a rising mass of magma, a hot spot. A little surprisingly, it is on a line of fractured rocks that stretches to the Atlas Mountains in North Africa, and further over to the European Alps. Fig. 1. The “Devil” sign that marks the start of the National Park, and the site of a parking space. The fractures formed, and are still moving, as a … Read More

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I, a Geologist (Part 1): The geology of Charles Darwin

Stephen K Donovan and Cor F Winkler Prins (The Netherlands) Darwin … devoted 1383 pages of notes to geological topics, compared with only 368 pages to biological topics.” – (Rhodes 1991, pp. 194-195) Like the writer, Johann Goethe, who inscribed himself in the guest book of Karlsbad – present day Karlovy Vary, in the Czech Republic – as “J.W. Goethe, Geognost”, Charles Darwin considered himself a geologist (“I, a geologist” citation from his notebooks in Herbert 2005, p. 2), and rightfully so. He was a true savant and an amateur in the positive sense of the word, as commonly used in the seventeenth and eighteenth centuries (see Rudwick 2004, p. 23), This is despite the fact that he belonged, for some time after his return with HMS Beagle, to the geological elite (Rudwick 1982). This may be deduced, for example, from the fact that he was asked to write the part on geology of a naval manual (Darwin 1849). Early geological influences: Edinburgh, Cambridge and Lyell’s Principles Henslow then persuaded me to begin the study of geology [in 1831] … [T]he sagacious Henslow ¼ advised me to get and study the first volume of the Principles, which had just then been published, but on no account to accept the views therein advocated.”  (Darwin 1983, pp. 39, 59) Darwin’s geological education took a new direction as he read volume one of Lyell’s Principles of Geology (Fig. 1) on-board HMS Beagle. However, his instruction in the new science actually began when he attended formal … Read More

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Book review: A History of Life in 100 Fossils, by Paul D Taylor and Aaron O’Dea

I wouldn’t say I know Paul Taylor, but I did once go on a fieldtrip with him, organised by the Natural History Museum (NHM) in London, more years ago than I care to remember. It was to the Coralline Crag of Suffolk, which was chock full of bryozoans – Paul’s favourite niche fossil. And very interesting it was too – as was Paul. Therefore, I am not surprised how fascinating this book turns out to be.