Archaeocyatha
Archaeocyatha is a taxon of extinct, reef-building marine organisms of warm tropical and subtropical waters that lived during the early Cambrian Period. It is believed that the centre of the Archaeocyatha origin are now located in East Siberia, where they are first known from the beginning of the Tommotian Age of the Cambrian, 525 million years ago. In other regions of the world, they appeared much during the Atdabanian, diversified into over a hundred families, they became the planet's first reef-building animals and are an index fossil for the Lower Cambrian worldwide. The remains of Archaeocyatha are preserved as carbonate structures in a limestone matrix; this means that the fossils cannot be chemically or mechanically isolated, save for some specimens that have eroded out of their matrices, their morphology has to be determined from thin cuts of the stone in which they were preserved. Today, the archaeocyathan families are recognizable by small but consistent differences in their fossilized structures: Some archaeocyathans were built like nested bowls, while others were as long as 300mm.
Some archaeocyaths were solitary organisms. In the beginning of the Toyonian Age around 516 mya, the archaeocyaths went into a sharp decline. All species became extinct by the Middle Cambrian, with the final-known species, Antarcticocyathus webberi, disappearing just prior to the end of the Cambrian period, their rapid decline and disappearance coincided with a rapid diversification of the Demosponges. The archaeocyathids were important reef-builders in the early to middle Cambrian, with reefs becoming rare after the group's extinction until the diversification of new taxa of coral reef-builders in the Ordovician; the typical archaeocyathid resembled a hollow horn coral. Each had a vase-shaped porous skeleton of calcite similar to that of a sponge; the structure appeared like a pair of nested ice cream cones. Their skeletons consisted of either a single porous wall, or more as two concentric porous walls, an inner and outer wall separated by a space. Inside the inner wall was a cavity. At the base, these pleosponges were held to the substrate by a holdfast.
The body occupied the space between the inner and outer shells. Flow tank experiments suggest that archaeocyathan morphology allowed them to exploit flow gradients, either by passively pumping water through the skeleton, or, as in present-day, extant sponges, by drawing water through the pores, removing nutrients, expelling spent water and wastes through the pores into the central space; the archaeocyathans inhabited coastal areas of shallow seas. Their widespread distribution over the entire Cambrian world, as well as the taxonomic diversity of the species, might be explained by surmising that, like true sponges, they had a planktonic larval stage that enabled their wide spread, their phylogenetic affiliation has been subject to changing interpretations, yet the consensus is growing that the archaeocyath was indeed a kind of sponge, thus sometimes called a pleosponge. But some invertebrate paleontologists have placed them in an extinct, separate phylum, known appropriately as the Archaeocyatha.
However, one cladistic analysis suggests that Archaeocyatha is a clade nested within the phylum Porifera. The clade Archaeocyatha have traditionally been divided into Regulares and Irregulares: Hetairacyathida Regulares Monocyathida Capsulocyathida Ajacicyathida Irregulares Thalassocyathida Archaeocyathida KazakhstanicyathidaHowever, who at the time regarded the archaeocyathans as outside of Porifera, divided the phylum in three classes: Phylum Archaeocyatha Vologdin, 1937 Class Monocyathea Okulitch, 1943 Class Archaeocyathea Okulitch, 1943 Class Anthocyathea Okulitch, 1943 Emiliani, Cesare.. Planet Earth: Cosmology, Geology, & the Evolution of Life & the Environment. Cambridge University Press. P 451 Okulitch, V. J. 1955: Part E – Archaeocyatha and Porifera. Archaeocyatha, E1-E20 in Moore, R. C. 1955: Treatise on Invertebrate Paleontology. Geological Society of America & University of Kansas Press, Kansas, 1955, xviii-E122. Knowledge base and interactive key for identification of archaeocyathan genera: http://www.infosyslab.fr/archaeocyatha/ Archaeocyathans Archaeocyatha
Adam Sedgwick
Adam Sedgwick was a British geologist and priest, one of the founders of modern geology. He proposed the Devonian period of the geological timescale. Based on work which he did on Welsh rock strata, he proposed the Cambrian period in 1835, in a joint publication in which Roderick Murchison proposed the Silurian period. In 1840, to resolve what became known as the Great Devonian Controversy about rocks near the boundary between the Silurian and Carboniferous periods, he and Murchison proposed the Devonian period. Though he had guided the young Charles Darwin in his early study of geology and continued to be on friendly terms, Sedgwick was an opponent of Darwin's theory of evolution by means of natural selection. Sedgwick was born in Dent, the third child of an Anglican vicar, he was educated at Trinity College, Cambridge. He studied mathematics and theology, obtained his BA from the University of Cambridge in 1808 and his MA in 1811. On July 20, 1817 he was ordained a deacon a year he was ordained as a priest.
His academic mentors at Cambridge were John Dawson. He became a Fellow of Trinity College and Woodwardian Professor of Geology at Cambridge from 1818, holding the chair until his death in 1873, his biography in the Cambridge Alumni database says that upon his acceptance of the position, reverend Sedgwick had no working knowledge of geology. An 1851 portrait of Sedgwick by William Boxall hangs in Trinity's collection. Sedgwick studied the geology of the British Isles and Europe, he founded the system for the classification of Cambrian rocks and with Roderick Murchison worked out the order of the Carboniferous and underlying Devonian strata. These studies were carried out in the 1830s; the investigations into the Devonian meant that Sedgwick was involved with Murchison in a vigorous debate with Henry De la Beche, in what became known as the great Devonian controversy. Sedgwick investigated the phenomena of metamorphism and concretion, was the first to distinguish between stratification and slaty cleavage.
He was elected to Fellow of the Royal Society on 1 February 1821. In 1844, he was elected a Foreign Honorary Member of the American Academy of Sciences; as a co-trustee of the will of Ann Sill, an owner of slaves in plantations in Jamaica, in 1835 Sedgwick was awarded half of £3783 in compensation for 174 slaves, following the abolition of slavery by the British government. A liberal Whig in politics, Sedgwick had long been a passionate supporter of abolition; the Church of England, by no means a fundamentalist or evangelical church, encloses a wide range of beliefs. During Sedgwick's life there developed something of a chasm between the conservative high church believers and the liberal wing. After simmering for some years, the publication of Essays and Reviews by liberal churchmen in 1860 pinpointed the differences. In all this, whose science and faith were intertwined in a natural theology, was on the conservative side, outspoken about it, he told the February 1830 meeting of the Geological Society of London: "No opinion can be heretical, but that, not true....
Conflicting falsehoods we can comprehend. I affirm, that we have nothing to fear from the results of our enquiries, provided they be followed in the laborious but secure road of honest induction. In this way we may rest assured that we shall never arrive at conclusions opposed to any truth, either physical or moral, from whatever source that truth may be derived"; as a geologist in the mid-1820s he supported William Buckland's interpretation of certain superficial deposits loose rocks and gravel, as "diluvium" relating to worldwide floods, in 1825 he published two papers identifying these as due to a "great irregular inundation" from the "waters of a general deluge", Noah's flood. Sedgwick's subsequent investigations and discussions with continental geologists persuaded him that this was problematic. In early 1827, after spending several weeks in Paris, he visited geological features in the Scottish Highlands with Roderick Murchison, he wrote "If I have been converted in part from the diluvian theory...it was...by my own gradual improved experience, by communicating with those about me.
I may date my change of mind from our journey in the Highlands, where there are so many indications of local diluvial operations.... Humboldt ridiculed beyond measure. Prévost lectured against it." In response to Charles Lyell's 1830 publication, Principles of Geology, known for promoting uniformitarian geology Sedgwick talked of floods at various dates on 18 February 1831 when retiring from the Presidency of the Geological Society he recanted his former belief in Buckland's theory. He believed that species of organisms originated in a succession of Divine creative acts throughout the long expanse of history. Any form of development that denied a direct creative action smacked as amoral. For Sedgwick, moral truths were to be distinguished from physical truths, to combine these or blur them together could only lead to disastrous consequences. In fact, one's own hope for immortality may rest on it, he stated in 1830 that Scriptural geologists proposed "a deformed progeny of heretical and fantastical conclusions, by which sober philosophy has been put to open shame, sometimes the charities of life have been exposed to violation."
In 1834 he continued, "They have committed the folly and SIN of dogmatizing," having "sinned against plain sense," and "of
Wales
Wales is a country, part of the United Kingdom and the island of Great Britain. It is bordered by England to the east, the Irish Sea to the north and west, the Bristol Channel to the south, it had a population in 2011 of 3,063,456 and has a total area of 20,779 km2. Wales has over 1,680 miles of coastline and is mountainous, with its higher peaks in the north and central areas, including Snowdon, its highest summit; the country has a changeable, maritime climate. Welsh national identity emerged among the Britons after the Roman withdrawal from Britain in the 5th century, Wales is regarded as one of the modern Celtic nations. Llywelyn ap Gruffudd's death in 1282 marked the completion of Edward I of England's conquest of Wales, though Owain Glyndŵr restored independence to Wales in the early 15th century; the whole of Wales was annexed by England and incorporated within the English legal system under the Laws in Wales Acts 1535 and 1542. Distinctive Welsh politics developed in the 19th century. Welsh liberalism, exemplified in the early 20th century by Lloyd George, was displaced by the growth of socialism and the Labour Party.
Welsh national feeling grew over the century. Established under the Government of Wales Act 1998, the National Assembly for Wales holds responsibility for a range of devolved policy matters. At the dawn of the Industrial Revolution, development of the mining and metallurgical industries transformed the country from an agricultural society into an industrial nation. Two-thirds of the population live in South Wales, including Cardiff, Swansea and the nearby valleys. Now that the country's traditional extractive and heavy industries have gone or are in decline, Wales' economy depends on the public sector and service industries and tourism. Although Wales shares its political and social history with the rest of Great Britain, a majority of the population in most areas speaks English as a first language, the country has retained a distinct cultural identity and is bilingual. Over 560,000 Welsh language speakers live in Wales, the language is spoken by a majority of the population in parts of the north and west.
From the late 19th century onwards, Wales acquired its popular image as the "land of song", in part due to the eisteddfod tradition. At many international sporting events, such as the FIFA World Cup, Rugby World Cup and the Commonwealth Games, Wales has its own national teams, though at the Olympic Games, Welsh athletes compete as part of a Great Britain team. Rugby union is seen as an expression of national consciousness; the English words "Wales" and "Welsh" derive from the same Germanic root, itself derived from the name of the Gaulish people known to the Romans as Volcae and which came to refer indiscriminately to all non-Germanic peoples. The Old English-speaking Anglo-Saxons came to use the term Wælisc when referring to the Britons in particular, Wēalas when referring to their lands; the modern names for some Continental European lands and peoples have a similar etymology. In Britain, the words were not restricted to modern Wales or to the Welsh but were used to refer to anything that the Anglo-Saxons associated with the Britons, including other non-Germanic territories in Britain and places in Anglo-Saxon territory associated with Britons, as well as items associated with non-Germanic Europeans, such as the walnut.
The modern Welsh name for themselves is Cymry, Cymru is the Welsh name for Wales. These words are descended from the Brythonic word combrogi, meaning "fellow-countrymen"; the use of the word Cymry as a self-designation derives from the location in the post-Roman Era of the Welsh people in modern Wales as well as in northern England and southern Scotland. It emphasised that the Welsh in modern Wales and in the Hen Ogledd were one people, different from other peoples. In particular, the term was not applied to the Cornish or the Breton peoples, who are of similar heritage and language to the Welsh; the word came into use as a self-description before the 7th century. It is attested in a praise poem to Cadwallon ap Cadfan c. 633. In Welsh literature, the word Cymry was used throughout the Middle Ages to describe the Welsh, though the older, more generic term Brythoniaid continued to be used to describe any of the Britonnic peoples and was the more common literary term until c. 1200. Thereafter Cymry prevailed as a reference to the Welsh.
Until c. 1560 the word was spelt Kymry or Cymry, regardless of whether it referred to the people or their homeland. The Latinised forms of these names, Cambrian and Cambria, survive as lesser-used alternative names for Wales and the Welsh people. Examples include the Cambrian Mountains, the newspaper Cambrian News, the organisations Cambrian Airways, Cambrian Railways, Cambrian Archaeological Association and the Royal Cambrian Academy of Art. Outside Wales, a related form survives as the name Cumbria in North West England, once a part of Yr Hen Ogledd; the Cumbric language, thought to
Ordovician radiation
The Ordovician radiation, or the great Ordovician biodiversification event, was an evolutionary radiation of animal life throughout the Ordovician period, 40 million years after the Cambrian explosion, whereby the distinctive Cambrian fauna fizzled out to be replaced with a Paleozoic fauna rich in suspension feeder and pelagic animals. It followed a series of Cambrian–Ordovician extinction events, the resulting fauna went on to dominate the Palaeozoic unchanged. Marine diversity increased to levels typical of the Palaeozoic, morphological disparity was similar to today's; the diversity increase was neither instantaneous. There is unlikely to be a simple or straightforward explanation for the event. Possible causes include changes in palaeogeography or tectonic activity, as well as a modified nutrient supply; the dispersed positions of the continents, high level of tectonic/volcanic activity, warm climate, high CO2 levels would have created a large, nutrient-rich ecospace, favoring diversification.
In addition, the changing geography led to a more diverse landscape, with more different and isolated environments. On the other hand, global cooling has been offered as a cause of the radiation, another alternative is that the breakup of an asteroid led to the Earth being pummelled by meteorites, such as the proposed Ordovician meteor event; the above triggers would have been amplified by ecological escalation, whereby any new species would co-evolve with others, creating new niches through niche partitioning, trophic layering, or by providing a new habitat. As with the Cambrian Explosion, it is that environmental changes drove the diversification of plankton, which permitted an increase in diversity and abundance of plankton-feeding lifeforms, including suspension feeders on the sea floor, nektonic organisms in the water column. After the SPICE event about 500 million years ago, the extinction in the ocean would have opened up new niches for photosynthetic plankton, who would absorb CO2 from the atmosphere and release large amount of oxygen.
More oxygen and a more diversified photosynthetic plankton as the bottom of the food chain, would have affected the diversity of higher marine organisms and their ecosystems. If the Cambrian Explosion is thought of as producing the modern phyla, the GOBE can be considered as the "filling out" of these phyla with the modern classes and lower-level taxa; the GOBE is considered to be one of the most potent speciation events of the Phanerozoic era increasing global diversity severalfold. Notable taxonomic diversity explosions during this period include that of articulated brachiopods and bivalves. Taxonomic diversity increased manifold. In addition to a diversification, the event marked an increase in the complexity of both organisms and food webs. Taxa began to have localized ranges, with different faunas at different parts of the globe. Communities in reefs and deeper water began to take on a character of their own, becoming more distinct from other marine ecosystems, and as ecosystems became more diverse, with more species being squeezed into the food web, a more complex tangle of ecological interactions resulted, promoting strategies such as ecological tiering.
The global fauna that emerged during the GOBE went on to be remarkably stable until the catastrophic end-Permian extinction and the ensuing Mesozoic Marine Revolution. The acritarch record displays the Ordovician radiation beautifully; the warm waters and high sea level permitted large numbers of phytoplankton to prosper. The planktonic realm was invaded as never before, with several invertebrate lineages colonising the open waters and initiating new food chains at the end of the Cambrian into the early Ordovician. Cambrian explosion Evolutionary fauna Mesozoic–Cenozoic Radiation
