The eleven specimens ofArchaeopteryxare some of the most iconic and enamour fossils in world . The fingers end in chela , the rump is foresightful and bony , and the head – arched back in the throes of death – contains jaggy jaw . But the splayed arm are lined with the faint but unmistakeable outlines of feathers . This was an animal midway between a small flesh - eat dinosaur and a modern bird . In fact , Archaeopteryx is widely heralded as the first bird , occupy a pivotal spatial relation in the root of this group .
ButXing Xufrom Linyi University think that this first bird was nothing of the sort . The Formosan fossilist , who has foundone engrossing dinosaur after another , has identified a new metal money called Xiaotingia that peril to throw out Archaeopteryx from its position .
By comparing Xiaotingia ’s feature with those of Archaeopteryx and other related birds and dinosaur , Xu has draw up a new family tree . In it , Archaeopteryx sit down with Xiaotingia among the deinonychosaurs , a celebrity - fill up radical of small , predatory dinosaurs that includes Deinonychus and Velociraptor . The blood line that lead to modern bird perches on a unlike branch of the tree diagram .
This does n’t change the fact that birds evolved from dinosaur – it just classify Archaeopteryx to the spare-time activity of that process . In its place , species likeEpidexipteryxandEpidendrosaurustake up the mantle of earliest birds . It is a provisionary revise but a bold one ( Xu himself admits that the newfangled family line Sir Herbert Beerbohm Tree is statistically faint ) . “ It ’s been a adept runnel for Archaeopteryx , ” drop a line Larry Witmer in a related column . “ This determination is likely to be met with considerable controversy ( if not straight-out horror ) . ”
Xiaotingia last in China during the tardy Jurassic period , and was about the size of a pigeon . Until of late , its beautifully preserved fossil ride innocuously in the Shandong Tianyu Musuem of Nature , among a thousand - strong ingathering of fledge dinosaur skeleton in the cupboard . Xu noticed it when he visit the museum . “ I immediately recognized that it was something new , but candidly did not expect that the discovery would exchange the dinosaur - bird family tree . ”
Xiaotingia ’s comportment is crucial . When Xu re - ran his analysis with exactly the same species except for his Modern discovery , Archaeopteryx was restored to its original position as a proto - chick . This new specimen has made a bountiful difference .
However , it ’s not the only dodo to have call Archaeopteryx ’s status into question . In recent years , fossil hunting watch have unearthed several species that are either primitive birds ( or close relative of them ) that look very different to Archaeopteryx , includingEpidexipteryx , Jeholornis , Sapenornis .
Meanwhile , others have take note that Archaeopteryx has many feature that are only plant among the deinonychosaurs . For example , they share a distinctive hip bone , and they both have a big trap above their noses ( the “ premaxillary fenestra ” ) that other shuttle and dinosaur lack . Any many of the features that supposedly characterize Archaeopteryx and other birds , such as feathering , a wishing bone and long knock-down forearm , are also bump in deinonychosaurs .
This is more than just a matter of shuffle cards . Archaeopteryx ’s position has been so sacrosanct that its eubstance had guided many of our ideas about the origins of birds . It prime our understanding of this radical . For example , it was previously thought that most primitive shuttlecock and their closest dinosaur relatives had lightly build skull , which might have been useful for flight of stairs . “ alternatively , our subject field suggests that primitive birds had full-bodied and rigid skulls , ” says Xu .
“ Our study also suggests that most rude razzing were herbivorous animals , ” he says . “ premature report which suggested that flight evolved in the [ nitty-gritty - eating ] context ( such as backstage germinate for catching prey ) require second thought . ” Witmer spell , “ understandably , without the guard net of effective former Archaeopteryx at the root of the snort , we ’ve get some fresh piece of work to do . ”
ButGerald Mayr , who meditate fogey birdie at Germany ’s Sneckenburg Museum , is unimpressed with the novel discovery . “ I fear that it is a minute hyped and that the conclusions are not as new as the source claim , ” he says . Mayr is one of several palaeontologist who think that thedeinonychosaurs are in reality razzing themselves . According to him , they ’re flightless penis of a grouping that include Archaeopteryx and modern shuttlecock , like smaller extinct versions of today ’s ostrich and emus .
The trouble is that all of these reconstruction are weak . Mayr admitted as much about his own modelback in 2006 , and Xu say that his Modern family tree diagram only has “ tentative statistical support ” .
Creationists will undoubtedly pounce upon this history and quote - mine articles for supposedly damnatory musical phrase . But revisions and doubt like this are to be expected . As with all big evolutionary shifts , there was n’t a simple linear road from dinosaur to bird . Instead , animals at the time developed a whole range of different body shapes that were finally tested and winnowed by instinctive selection . “ There were lot of experimental trial ” , says Xu .
The fossil record is full of these failed experiment and evolutionary drained - ends , all uphold alongside the success stories that eventually give rise to forward-looking mintage . This crap it very difficult to construct a robust folk tree . Witmer sum it up brilliantly in the ending of his editorial :
“ Just as Xiaotingia moved Archaeopteryx out of the birds , the next find could move it back in – or to somewhere else within this fuzzed tangled knot that makes up the origins of shuttlecock and bird - alike dinosaurs . That allege , during this sesquicentennial day of remembrance of Archaeopteryx , which is being reward with exhibits and commemorative coins , the bitter irony may be that it may not have been the bird we ’ve always thought it was . But Archaeopteryx will stay an icon of evolution , perhaps even more so now , providing compelling evidence that , as we should wait , evolutionary origin are rather mussy affairs . ”
reference book : Xu , You , Du & Han . 2011 . An Archaeopteryx - like theropod from China and the origin of Avialae . Naturehttp://dx.doi.org/10.1038/nature …
This post originally appeared onNot Exactly Rocket Science .
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