Gas-guzzling clams 1 April 2008 The new species and Genus Spinaxinus sentosus, collected from the organic cargo of the sunken ship Francois Vieljeux. The genus bears little resemblance to other known thyasirids and remains the only record of this species. Thyasira methanophila, a clam new to science from a methane seepage area off Concepción, Chile. Its name suggests its dependence on methane. An extreme magnification of the exterior shell covering of Spinaxinus sentosus, recovered from the organic cargo of the sunken ship Francois Vieljeux. The spines witnessed at this magnification lead scientists at the Museum to name the new genus 'Spinaxinus'. Deep beneath the sea floor there are large reservoirs of oil and natural gas, but it is only relatively recently that methane has been discovered to seep from the surface of the sea bed. These areas are known as 'gas seeps' and certain animals have evolved specifically to take advantage of this unique environment. A diet of methane and sulphur Found alongside these methane gas seeps are communities of clams that use the gas as a source of food. They don't actually eat the gas but they have evolved to harbour bacteria in their tissues that do the job for them. These organisms are known as 'chemosymbiotic' and a few groups of clams have been very successful in adapting to this environment. The same group of clams can also exploit sulphur and these are found living in areas where there are layers of rotting vegetation, around decaying whale carcasses, at hot vents and even on mud contaminated with diesel oil. Because these clams come from unusual environments and often from deep water, many have yet to be studied in detail. A number of these gas guzzling clams were sent to Amgueddfa Cymru - National Museum Wales for identification and description. Several scientific papers have now been written on these species new to science Clams from Chile Clam shells and whole specimens were sent to the Museum following the discovery of a methane seep off the coast of Chile at a depth of 700-900m. One of these species, belonging go the genus Thyasira, was new to science and has been described in a scientific paper. The bacteria in the gill tissue of the clam were studied using a scanning electron microscope. This confirmed the symbiosis (reliance) between the bacteria and the clam. A species of the genus Lucinoma was also discovered to be new to science but only shells have been found so far. It is likely that the majority of species living at this site are endemic (restricted to this location) and found nowhere else in the world. The Pakistan Margin From the other side of the world, we were sent a small species from the same group as the Chilean bivalve - Thyasira - but from the Indus Fan, off the coast of Pakistan, collected while investigating the unusual fauna that live in the very low oxygen waters of this region. The Museum worked with the Natural History Museum, London to investigate the DNA alongside describing the anatomy and shell of this bivalve. A clam with a taste for shipwrecks Man-made sources of methane and sulphur are also exploited and one of the strangest was the cargo of the sunken container ship Francois Vieljeux. This ship sank off the north coast of Spain in 1,160m of waters, taking with it its cargo of castor beans and sunflower seeds. During attempts to salvage the vessel it was noted that clams had settled and grown on the cargo. All the clams belonged to chemosymbiotic groups and were exploiting the sulphur released by the rotting cargo. One clam was a Thyasira, similar to the specimen from Chile. Cascadia Basin, off Washington State The Baby Bare Seamount in the north-east Pacific Ocean is a hot spring and home to a new species of Axinus (similar to Thyasira). This site is unusual in that no other species of bivalve typically found at other methane seeps and hot vent sites are found here. Methane and Hydrogen sulphide levels are low, so initially it was a mystery as to what these animals were using as nutrition. Cadiz Mud Volcanos Off the Southern coast of Portugal there are numerous marine mud volcanoes created by stresses on the African and Eurasian tectonic plates. These stresses cause hot, methane and sulphur rich fluids to eject from deep within the volcanoes out into the sea bed above. By the time the fluids reach the sediment surface they are cold, so the mud volcanoes are classed as cold-seeps. Many species of Thyasira clams are found at some of these sites, but only a few are known to harbour the chemosymbiotic bacteria that help them to extract nutrition from sulphur and methane. A collaboration between the Museum and Cadiz University, Spain has resulted in the newly described species Thyasira vulcolutre , meaning 'belonging to mud volcano'. Finally, in conjunction with Bangor University, the Museum is carrying out the taxonomic work on a Thyasira collected from a mud volcano in the Arctic and a mussel of the genus Idas which was collected from diesel contaminated mud beneath an oil rig in the North Sea. This work by Amgueddfa Cymru - National Museum Wales is helping research the possibility of using these clams to clean up contaminated areas of the sea bed.
Terror of the Silurian Seas 26 July 2007 The eurypterid from Radnor Forest (x1.5) The reconstruction of the eurypterid from Radnor Forest The small specimen from the Woolhope district (x3.5). Note that the headshield is displaced to the left. Numerous specimens are brought in to the Department of Geology every year by the general public for identification. In most cases, these are common fossils or minerals, but from time to time something more unusual turns up, as happened in December 1989 when Mr Stephen Jenkins of Brecon produced a strange-looking fossil that he had found on the side of a forestry road in Radnor Forest. A large scorpion-like animal Although it superficially resembled a fish jaw with a series of pointed teeth of different sizes, careful examination led us to dismiss this possibility, and we eventually succeeded in tracking down what it was - half a pincer of an extinct, aquatic, scorpion-like animal called a eurypterid. A remarkable aspect of this specimen is its size - 64mm (2.5 inches) long, which indicates that it belonged to an individual that must have been around 70cm (27 inches) long. The rocks in which it was found in Radnor belong to the Ludlow Series of the Silurian System - about 420 million years old. Despite their superficial resemblance to scorpions, eurypterids are not closely related to them, although they belong to the same general division of the arthropods - invertebrate animals with jointed legs that include spiders, crabs, lobsters and insects. Flourishing from about 480 million years ago until their extinction 250 million years ago, most eurypterids are found in rocks that were deposited in fresh or brackish (mix of salt and fresh) water; only a few, including the Radnor Forest specimen, are from rocks of truly marine origin. It is possible, however that the specimen was washed out to sea from shallower waters that lay to the east of Radnor Forest. Gigantic carnivores of the sea The pincer belongs to a eurypterid genus named Pterygotus, which was an active swimmer. We can only speculate what might have been its prey, but it probably included primitive fish. The largest known specimens from other parts of the world are almost 3m (10 feet) long, and are the largest arthropods known. The specimen in Amgueddfa Cymru is not quite of those gigantic dimensions! The majority of eurypterids did not reach such a large size. By coincidence, a short while after the pincer was brought into the Museum, another eurypterid was presented, this time with the 'body' section preserved. It was collected from slightly younger (400 million years old) Silurian rocks exposed near Woolhope (Herefordshire) by Dr. Paul Selden, formerly of Manchester University, and measuring only 0.9cm (0.3 inches) long, it is at the other end of the size scale. This is probably an immature specimen, and the full-grown animal might have been in the region of 10cm (4 inches) long. Both specimens are now in the Museum collections, thanks to the generosity of their finders. Over the years the general public and academic colleagues have constantly enriched our collections, and donations of this kind remain an important source of material. You never can tell what might be brought in tomorrow...
A duckbilled dinosaur named Ruth 26 July 2007 Few visitors to National Museum Cardiff, and indeed few staff outside the Department of Geology, are aware that the spectacular duckbilled dinosaur Edmontosaurus, is known affectionately as 'Ruth'. The logo for the Black Hills institute of Geological Research featuring Ruth the duck billed dinosaur from Amgueddfa Cymru This name would seem to suggest that we know the sex of the 8-metre long specimen, although in fact there is no evidence to determine whether it is a male or female. Such evidence is not often available in fossils of this kind. So why 'Ruth'? The answer is quite simple and without any hidden scientific mysteries. It's because the specimen was found in a quarry in the Black Hills of South Dakota, USA, belonging to Mrs Ruth Mason. The pet name was first used by the staff of the Black Hills Institute of Geological Research when they were excavating the dinosaur in 1986-7, in recognition of the many kindnesses shown to them by Mrs Mason. Following our purchase of the specimen, we learned very quickly of the name from the people who came over to reconstruct the skeleton for us, and we have continued to use this affectionate name in informal reference to the specimen. The Black Hills Institute, based in Hill City, South Dakota is one of the leading companies in the world engaged in the collection, preparation and supply of fine quality mineral and fossil specimens, which are particularly attractive to museums for display purposes. The Edmontosaurus on display in Cardiff is one of the finest examples of a 'duckbilled' dinosaur ever excavated, and was mounted by the Black Hills Institute in a wonderfully life-like pose based on our own particular design requirements. Such is the aesthetic beauty and dynamic realism of the specimen that the Black Hills Institute has incorporated the skeletal drawing into its logo: it forms both a striking image and a fine testament to the skill of the preparators. From humble beginnings over 65 million years ago, Ruth has now achieved world-wide recognition in promoting the availability of geological display specimens, while also providing a unique experience for all those who visit her at National Museum Cardiff.
International fame for Wales's 'National Fossil' 26 July 2007 A specimen of Paradoxides davidis from Porth-y-rhaw, x 0.75. Amgueddfa Cymru collection Stage one in the evolution of the north Atlantic area. Triangles indicate areas yielding 'Welsh' trilobites, with dots showing 'North American' forms. Stage two in the evolution of the north Atlantic area. Triangles indicate areas yielding 'Welsh' trilobites, with dots showing 'North American' forms. Stage three in the evolution of the north Atlantic area. Triangles indicate areas yielding 'Welsh' trilobites, with dots showing 'North American' forms. Fossil collecting around the St. David's Peninsula, Pembrokeshire In 1862 the well-known palaeontologist J W. Salter was collecting fossils in south-west Wales as part of his duties for the British Geological Survey. While examining coastal exposures by boat around the rocky St David's peninsula, Salter one day landed in a small inlet called Porth-y-rhaw, in the mistaken belief that it was Solva Harbour, only a short distance to the east. His mistake turned out to be extremely lucky, because in the rocks of Porth-y-rhaw, he discovered the remains of one of the largest trilobites ever found (over 50 cm long), and this discovery ensured that the locality became established as a classic and well-known source of fossils. Life in the sea hundreds of millions of years ago The dark mudstones exposed there were deposited in an ancient sea some 510 million years ago, during what is now called the Cambrian Period - the name reflecting the fact that rocks of this age were first recognised and named in Wales by the early 19th-century geologists. Porth-y-rhaw is one of a small number of sites in Wales where Cambrian fossils are reasonably well-preserved and easy to find, and in addition to Salter's giant trilobite it also yields many other kinds of these extinct marine arthropods of more usual dimensions (2-3 cm long). A National fossil for Wales The formal scientific name given by Salter to the giant trilobite is Paradoxides davidis, named after his friend David Homfray, an amateur fossil collector from Porth-madog. This trilobite is now one of the best-known from Britain, and is illustrated in numerous publications; choice specimens are among the prize possessions of many of our major museums, including the National Museum of Wales. Indeed, if there were to be a 'national fossil' for Wales, Paradoxides davidis would be the prime contender. Worldwide Fame Many specimens of Paradoxides davidis also occur in the Avalon Peninsula of south-east Newfoundland, in rocks of exactly the same age as those exposed in Porth-y-rhaw. In this context, it is important to understand that in the Cambrian Period, the distribution of continents and oceans was quite different from that of the present day. At that time, Wales, England and south-east Newfoundland all lay on the southern side of an ancient ocean, called Iapetus, and were separated from Scotland and north-west Newfoundland, as shown on the accompanying map. While the same kinds of trilobites occur in Wales and south-east Newfoundland, quite different ones are common to Scotland and north-west Newfoundland, providing evidence that they once formed parts of different continents. Snowdon is born Around 480 million years ago, movements in the Earth's interior caused the ancient Iapetus Ocean to narrow gradually and finally to disappear as two continental masses collided, leading to the formation of a high mountain range of which the Welsh, Scottish, Scandinavian and Appalachian mountains are the present day remnants. The new Atlantic Ocean Much later in Earth history, between 200 and 65 million years ago, the two continents began to pull apart again, leading to the formation of a new ocean that was to become the present day Atlantic. However, the new split was not along quite the same line as that along which Iapetus had closed, and left south-east Newfoundland with its 'Welsh' trilobites anchored to the rest of Newfoundland and North America, with Scotland and its 'North American' trilobites attached to the rest of the British Isles. The occurrence of these same trilobites in areas that today are geographically remote emphasises the need for geologists to study fossils far afield if they are to interpret fully the ancient history of their own local pieces of the Earth's crust.
Dinosaur relatives swam in south Wales 26 July 2007 Amgueddfa Cymru holds fine specimens of prehistoric marine animals, related to the dinosaurs, that swam off the coast of south Wales. Specimens from Dorset illustrate how, once, an ancient sea linked the two areas. Reconstruction of an ichthyosaur chasing its squid-like prey Tropical Wales About 210 million years ago the small part of the Earth's crust that is now Wales lay well to the south of its present latitude, probably close to the northern tropics, where the land formed part of a huge supercontinent called Pangaea. Our climate was hot and humid, with much of Wales comprising barren uplands surrounded by desert-like mudflats. To the south, and spreading far across into Europe, was a series of large lakes. Wales drowns As the continents drifted northwards the crust broke up and at various times the seas rose and spread across the land. With these spreading seas came new marine animals that we now see fossilised in the rock record. Some of the most beautiful and spectacular are the marine reptiles known as ichthyosaurs (literally, 'fish lizards'), which were distant cousins of the land-living dinosaurs. By 200 million years ago, early in the Jurassic Period of geological time, the sea covered southernmost Wales. On the sea-floor, a blanket of fine lime sands and muds was deposited, which have since been compacted into the horizontally bedded mudstones and limestones forming the familiar cliffs in the Lavernock area and extending westwards from Barry to Southerndown. Abundant fossils Ichthyosaur remains are not uncommon in these rocks, although they are mostly found as isolated teeth and bones. The fragmentation took place following the death of the animals, when the skeletons were broken up by currents and wave action. Only rarely have more complete specimens been found in south Wales. In contrast, rocks of the same age in Somerset and Dorset have long been known as a rich source of complete or almost complete ichthyosaur skeletons. The early Jurassic sea extended from the shoreline area of southern Wales across south-west England and beyond to central Europe. In the progressively offshore, deeper-water areas to the south, wave action and coastal currents were weaker, so skeletons were more likely to sink to the sea floor and remain more or less intact. Even so, such skeletons are still found only comparatively rarely today, so we are very lucky to have several almost complete ichthyosaurs in our collections from Lyme Regis in Dorset. Some of the most impressive are on display in the exhibition Evolution of Wales at National Museum Cardiff. The fact that 200 million years ago the sea was continuous from south Wales across to Dorset means that we can use these beautiful fossils to illustrate part of the history of our area. The Dorset fossils are the same species as those found in the Glamorgan cliffs, and the animals would have been swimming freely between the two regions. The specimens on display show beautifully the streamlined, dolphin-like shape of the ichthyosaurs. They were adapted superbly for rapid swimming, with propulsion by a large, vertical tail and steering with four flipper-like paddles. Their diet probably consisted mostly of fish and squid.
