May 14, 2013 ? An international team of scientists have revealed a new species of ichthyosaur (a dolphin-like marine reptile from the age of dinosaurs) from Iraq, which revolutionises our understanding of the evolution and extinction of these ancient marine reptiles.
The results, produced by a collaboration of researchers from universities and museums in Belgium and the UK and published today (May 15) in Biology Letters, contradict previous theories that suggest the ichthyosaurs of the Cretaceous period (the span of time between 145 and 66 million years ago) were the last survivors of a group on the decline.
Ichthyosaurs are marine reptiles known from hundreds of fossils from the time of the dinosaurs. "They ranged in size from less than one to over 20 metres in length. All gave birth to live young at sea, and some were fast-swimming, deep-diving animals with enormous eyeballs and a so-called warm-blooded physiology," says lead author Dr Valentin Fischer of the University of Liege in Belgium.
Until recently, it was thought that ichthyosaurs declined gradually in diversity through multiple extinction events during the Jurassic period. These successive events were thought to have killed off all ichthyosaurs except those strongly adapted for fast-swimming life in the open ocean. Due to this pattern, it has been assumed that ichthyosaurs were constantly and rapidly evolving to be ever-faster open-water swimmers; seemingly, there was no 'stasis' in their long evolutionary history.
However, an entirely new ichthyosaur from the Kurdistan region of Iraq substantially alters this view of the group. The specimen concerned was found during the 1950s by British petroleum geologists. "The fossil -- a well-preserved partial skeleton that consists of much of the front half of the animal -- wasn't exactly being treated with the respect it deserves. Preserved within a large, flat slab of rock, it was being used as a stepping stone on a mule track," says co-author Darren Naish of the University of Southampton. "Luckily, the geologists realized its potential importance and took it back to the UK, where it remains today," adds Dr Naish, who is based at the National Oceanography Centre, Southampton.
Study of the specimen began during the 1970s with ichthyosaur expert Robert Appleby, then of University College, Cardiff. "Robert Appleby recognised that the specimen was significant, but unfortunately died before resolving the precise age of the fossil, which he realised was critical," says Jeff Liston of National Museums Scotland and manager of the research project. "So continuation of the study fell to a new generation of researchers."
In the new study (which properly includes Appleby as an author), researchers name it Malawania anachronus, which means 'out of time swimmer'. Despite being Cretaceous in age, Malawania represents the last-known member of a kind of ichthyosaur long believed to have gone extinct during the Early Jurassic, more than 66 million years earlier. Remarkably, this kind of archaic ichthyosaur appears characterised by an evolutionary stasis: they seem not to have changed much between the Early Jurassic and the Cretaceous, a very rare feat in the evolution of marine reptiles.
"Malawania's discovery is similar to that of the coelacanth in the 1930s: it represents an animal that seems 'out of time' for its age. This 'living fossil' of its time demonstrates the existence of a lineage that we had never even imagined. Maybe the existence of such Jurassic-style ichthyosaurs in the Cretaceous has been missed because they always lived in the Middle-East, a region that has previously yielded only a single, very fragmentary ichthyosaur fossil," adds Dr Fischer.
Thanks to both their study of microscopic spores and pollen preserved on the same slab as Malawania, and to their several analyses of the ichthyosaur family tree, Fischer and his colleagues retraced the evolutionary history of Cretaceous ichthyosaurs. In fact, the team was able to show that numerous ichthyosaur groups that appeared during the Triassic and Jurassic ichthyosaur survived into the Cretaceous. It means that the supposed end of Jurassic extinction event did not ever occur for ichthyosaurs, a fact that makes their fossil record quite different from that of other marine reptile groups.
When viewed together with the discovery of another ichthyosaur by the same team in 2012 and named Acamptonectes densus, the discovery of Malawania constitutes a 'revolution' in how we imagine ichthyosaur evolution and extinction. It now seems that ichthyosaurs were still important and diverse during the early part of the Cretaceous. The final extinction of the ichthyosaurs -- an event that occurred about 95 million years ago (long before the major meteorite-driven extinction event that ended the Cretaceous) -- is now even more confusing than previously assumed.
Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/AJiqMUCMt0E/130514213154.htm
weightless ellen degeneres jcpenney yeardley love nba all star reserves rock center christine christine
“Power is a lot like real estate. It’s all about location, location, location.” — Frank Underwood, House of Cards At this very moment, Mark Zuckerberg’s political lobby, FWD.us, is probably taken aback at how reviled it has become, both from the public and its own members. After all, there are countless political technology lobbies, including Facebook’s own Political Action Committee, which routinely offer Republican candidates campaign cash for quid pro quo political favor. So, why, after discovering FWD.us indirectly supporting the controversial Keystone Pipeline initiative, have would-be supporters flooded their Facebook page with scathing comments, and its A-list supporters, such as Tesla’s Elon Musk, ditched the group? Unlike other lobbies, FWD.us burst on to the scene with a very public op-ed from its celebrity founder, promising to?galvanize?the latent civic passions of Silicon Vally’s netizens in a noble crusade to advance the knowledge society. While one hand extended towards grassroots supporters, the other reached into its wallet pocket and discretely doled out funds to controversial candidates. There’s a reason most lobbies don’t bother with grassroots activism: communities don’t get excited about?the kinds of soul-crushing moral compromise necessary in DC politics. So, when FWD.us rolled up with millions in hand claiming to be the voice of the technologists, those who felt?misrepresented?freaked out. Even more confusing, when confronted, FWD.us chose to do something no other major organization in technology has done: it?remained?silent. Even the notoriously tight-lipped Apple holds a press conference after public uproar. Californians haven’t become jaded to the kinds of secrecy common for Wall Street banks and campaign SuperPACs. The unfazed backdoor dealings caricatured in Netflix’s (addicting) House of Cards series may work for lobbies based in our nation’s capitol, but Californians evidently won’t tolerate it in their backyard. “I revised the parameters of my promise.” – Frank Underwood Twitter co-founder Evan Williams tweeted a link to a scathing blog post from former Branch CEO, Josh Miller, explaining, “In service of noble causes, FWD.us is employing questionable lobbying techniques, misleading supporters, and not being transparent about the underlying values and long-term intentions of the organization. More discouragingly, the leaders of the technology industry (and of FWD.us) have built their careers on bringing meaningful change to the world. They should be doing the same in Washington.” FWD.us would-be grassroots supporters agree, “Will Fwd.us prostitute climate destruction & other values to get a few engineers hired & get immigration reform??, wrote one commenter