tag:blogger.com,1999:blog-34599644280930885072024-03-20T14:39:54.193+01:00Tuesdays are for TyrannosaursHypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-3459964428093088507.post-6769076236199809242012-05-09T01:56:00.000+02:002013-02-26T20:42:14.584+01:00Raptorex' 15 minutes of fameWhen first unveiled <i>Raptorex </i>caused quite a stir. Here was an early Tyrannosauroid that had evolved all the features of <i>T. rex</i>... at 1/100th of it's size.<br />
But it wouldn't be long before these claims would be seriously challenged, ultimately reducing Raptorex to a <i>nomen dubium</i>.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/e/ed/Raptorex_SIZE_01.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="222" src="http://upload.wikimedia.org/wikipedia/commons/e/ed/Raptorex_SIZE_01.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Raptorex kriegsteini</i> compared to a human (image by <a href="http://en.wikipedia.org/wiki/User:Conty" target="_blank">Conty</a>, from Wikipedia)</td></tr>
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<a name='more'></a><i>Raptorex kriegsteini </i>was described by Paul Sereno as a new Tyrannosauroid from the early Cretaceous of China. The specimen was described as a young adult of 3 meters in length and an estimated weight of 65kg. In terms of size and weight that would be comparable to other Late Jurassic/Early Cretaceous Tyrannosauroids like <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/feathers-on-your-tyrannosaurs.html" target="_blank">Dilong </a>and <a href="http://tyrannosaurtuesday.blogspot.com/2012/02/crowned-tyrannosaur.html" target="_blank">Guanlong</a>. But it's bodyplan was radically different, Dilong and Guanlong were much closer to their Coelurosaurian ancestors, with long arms, three-fingered hands and a small head. Raptorex on the other hand was remarkably similar to Late Cretaceous Tyrannosaurids like <i>Tyrannosaurus </i>and <i>Tarbosaurus.</i><br />
This seemed at at the time to shed a new light on Tyrannosaur evolution, Raptorex was according to Sereno an intermediate stage between the small long-armed Tyrannosaurs and the large short-armed Tyrannosaurids.<br />
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<b>A chequered past</b><br />
The fossil that was described already had something of a history, it had already changed hands several times before being sold to Henry Kriegstein as a juvenile Tarbosaurus. Kriegstein had originally planned to use the fossil as <a href="http://dinogoss.blogspot.com/2009/09/raptorex.html" target="_blank">decoration for his living room</a> (money can't buy hapiness, but it can buy a genuine Tyrannosaur fossil!).<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5Tp8aY5EoZ2BDQCD29BA6n0JG0lxt5MSNsrLcgCUhqytqY8hNJ6mCD0RjVzwlloVATJ_MgCe86hsSm5NKJMVqUj2QsIIMFbi5tEd3-XCCsj7pH5PeFTbrlsqu-K-EMGxa2ULEocmuRa5X/s1600/Raptorex.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5Tp8aY5EoZ2BDQCD29BA6n0JG0lxt5MSNsrLcgCUhqytqY8hNJ6mCD0RjVzwlloVATJ_MgCe86hsSm5NKJMVqUj2QsIIMFbi5tEd3-XCCsj7pH5PeFTbrlsqu-K-EMGxa2ULEocmuRa5X/s1600/Raptorex.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Raptorex </i>skull and life reconstruction (with manes!)</td></tr>
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During the preparation palaeontologist Paul Sereno was contacted for advice, he identified it not as a juvenile but as a subadult of <span style="font-family: inherit;">a completely new species. He also convinced Kriegstein to donate the fossil to science.</span><br />
<span style="font-family: inherit;">To date this suddenly new find Sereno used the fossil of a <span style="background-color: white; line-height: 19px;"><i>Lycoptera </i>fish</span><span style="background-color: white; line-height: 19px;"> embedded in the same rock, which meant that it originated from the early Cretaceou</span><span style="background-color: white; line-height: 19px;">s. Sereno also speculated that</span><span style="background-color: white; line-height: 19px;"> the fossil had originally come from the Yixian formation in China, but had been smuggled to Mongolia for sale on the black market. </span></span><br />
<span style="background-color: white;"><span style="background-color: white; font-family: inherit; line-height: 19px;"></span></span><span style="background-color: white;"><span style="font-family: inherit;"><span style="line-height: 19px;">That was not the first U-turn in the identification of the fossil, before it was sold as a juvenile </span></span><i style="font-family: inherit; line-height: 19px;">Tarbosaurus </i><span style="font-family: inherit;"><span style="line-height: 19px;">from Mongolia it had tentatively been considered an </span></span><i style="font-family: inherit; line-height: 19px;"><a href="http://en.wikipedia.org/wiki/Alectrosaurus" target="_blank">Alectrosaurus </a></i><span style="font-family: inherit;"><span style="line-height: 19px;">(a medium-sized Tyrannosauroid from the Late Cretaceous). Such differences is identification are perhaps unsurprising, identifying juvenile specimens is complicated. Like most Dinosaurs Tyrannosaurs underwent major changes to their body during growth, so</span></span><span style="font-family: inherit;"><span style="line-height: 19px;"> a juvenile specimen might look very different from the adult form. Knowing the origin of the fossil would of course narrow things down, but that information is generally lost when the fossil is traded on the black market.</span></span></span><br />
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<span style="background-color: white; line-height: 19px;"><b><span style="font-family: inherit;">The gloves come off</span></b></span><br />
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/3/3c/Raptorex_skull_illustration.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="141" src="http://upload.wikimedia.org/wikipedia/commons/3/3c/Raptorex_skull_illustration.JPG" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Raptorex </i>skull (<a href="http://en.wikipedia.org/wiki/User:Conty" target="_blank">Conty</a>)</td></tr>
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<span style="background-color: white;"><span style="font-family: inherit; line-height: 19px;">There had already been some doubts cast on the description of </span><i style="font-family: inherit; line-height: 19px;">Raptorex </i><span style="font-family: inherit; line-height: 19px;">as a new species when in 2011 a reanalysis of the specimen appeared in </span><a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021376" style="font-family: inherit; line-height: 19px;" target="_blank">PLoS One</a><span style="font-family: inherit;"><span style="line-height: 19px;">. This paper reads like a scientific hatchet job, all of Sereno's original claims were disputed (if not outright dismissed). The specimen was not a 6 year old subadult, but a 3 year old juvenile. The fish found in the rock alongside was not <i>Lycoptera </i>but an undetermined species of a family that was common in China throughout the Cretaceous (and beyond) Tracing back the origin of the fossil showed no evidence that it came from China as Paul Sereno had speculated. The skull was also found to be extremely similar to a </span></span><span style="line-height: 19px;">juvenile</span><span style="font-family: inherit;"><span style="line-height: 19px;"> <i>Tarbosaurus</i> skull of the same size.</span></span></span><br />
<span style="background-color: white;"><span style="font-family: inherit;"><span style="line-height: 19px;">This led to a devastating conlusion: </span></span></span><br />
<blockquote class="tr_bq">
<span style="font-family: inherit;"><span style="line-height: 21px;">Unless stronger evidence is presented, </span><em style="line-height: 21px;">Raptorex</em><span style="line-height: 21px;"> should be considered a </span><em style="line-height: 21px;">nomen dubium</em><span style="line-height: 21px;">. LH PV18 [the <i>Raptorex </i>fossil] more likely represents the juvenile of a larger tyrannosaurid from the Late Cretaceous of Mongolia, such as </span><em style="line-height: 21px;">Tarbosaurus.</em></span> </blockquote>
And with that "Raptorex" had come almost full-circle. Originally sold to Kriegstein as a juvenile <i>Tarbosaurus </i>it had enjoyed a brief period of fame as a totally new species of Tyrannosaur, but was once again provisionally identified as a juvenile <i>Tarbosaurus</i>.<br />
Of course this is still a very tentative identification, there is no positive evidence linking the specimen to a geological age much less a specific location. Analysis of the rock matrix in which the fossil was embedded might reveal more about the origins of this specimen, but until someone actually goes out and does that any identification will remain speculative.Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com1tag:blogger.com,1999:blog-3459964428093088507.post-56753971645051366072012-04-24T00:02:00.000+02:002012-04-27T14:20:17.985+02:00The paradoxical arms of T. rex<span id="internal-source-marker_0.5314563466235995"><span style="font-family: inherit;"><span style="font-weight: normal; vertical-align: baseline; white-space: pre-wrap;">The puny size of <i>Tyrannosaurus </i>arms is so much a part of it's iconic image there is a Tumblr dedicated to things that <i>T. rex</i> would have been unable to do, because of it`s short arms (<a href="http://trextrying.tumblr.com/" target="_blank">T-Rex Trying</a>). Paradoxically the arms of a T. rex are actually quite robust and would have been rather muscular in life. </span></span></span><br />
<span style="font-family: inherit;"><span style="white-space: pre-wrap;">So were those puny arms merely vestiges </span></span><span style="white-space: pre-wrap;">inherited</span><span style="font-family: inherit;"><span style="white-space: pre-wrap;"> from a longer armed ancestor, or were they actively used.. and if so, what for?</span></span>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6B2LDEMt8fLElgHTwrsGJBgAuVqVUk8UTC2N-kXsM-xhjJ3CbtXKJFmPvpNtBwli5BjRDvMdtqm2Nw5FBCwdioCZvijchmPaoPCBZftYlhx8ZyMqwbDCUDpTw0ImvecXyg1cfbXXSWnFh/s1600/T-Rex+head+and+arms.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="292" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6B2LDEMt8fLElgHTwrsGJBgAuVqVUk8UTC2N-kXsM-xhjJ3CbtXKJFmPvpNtBwli5BjRDvMdtqm2Nw5FBCwdioCZvijchmPaoPCBZftYlhx8ZyMqwbDCUDpTw0ImvecXyg1cfbXXSWnFh/s400/T-Rex+head+and+arms.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>T. rex</i> head & arms (original image from Wikipedia, by user <a href="http://commons.wikimedia.org/wiki/User:FunkMonk" target="_blank">FunkMonk</a>)</td></tr>
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<span style="vertical-align: baseline;"><span style="font-family: inherit;"><span style="white-space: pre-wrap;"><b></b></span></span></span><br />
<a name='more'></a><span style="vertical-align: baseline;"><span style="font-family: inherit;"><span style="white-space: pre-wrap;"><b>Arm musculature</b></span></span></span><br />
<span style="vertical-align: baseline;"><span style="font-family: inherit;"><span style="white-space: pre-wrap;">Recent research on the musculature <i>T. rex</i> arms was done </span></span></span><span style="white-space: pre-wrap;">by Lipkin and Carpenter</span><span style="font-family: inherit;"><span style="white-space: pre-wrap;">. Interestingly they start of by pointing out that no Theropod would have been able to bring it's manus to it's mouth. Perhaps part of our obsession with </span></span><i style="font-family: inherit; white-space: pre-wrap;">T. rex </i><span style="font-family: inherit;"><span style="white-space: pre-wrap;">arms is that for us as primates hands are our most important means of interacting with the </span></span><span style="white-space: pre-wrap;">environment</span><span style="font-family: inherit;"><span style="white-space: pre-wrap;"> (and to </span></span><span style="white-space: pre-wrap;">bring</span><span style="font-family: inherit;"><span style="white-space: pre-wrap;"> food to our mouths).</span></span><br />
<span style="font-family: inherit; font-weight: normal; vertical-align: baseline; white-space: pre-wrap;">This is also suggestive of a certain style of predation, the mouth was most likely the primary weapon for most Theropods (unlike for example felines which primarily attack using their paws).</span>
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<span style="white-space: pre-wrap;">Their actual research focused on creating a model of the musculature of the <i>T. rex</i> they found that the forearm of was both powerful and capable of resisting strong forces and moving quickly, which clearly suggests that they could have been used during predation.</span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/b/b8/Tyrannosauridae_forelimb_anatomy.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="311" src="http://upload.wikimedia.org/wikipedia/commons/b/b8/Tyrannosauridae_forelimb_anatomy.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tyrannosaurus forelimb anatomy (image from Wikipedia, by user <a href="http://en.wikipedia.org/wiki/User:Conty" target="_blank">Conty</a>)</td></tr>
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<span style="white-space: pre-wrap;"><b>Evidence of use</b></span><br />
<span style="white-space: pre-wrap;">In their overview of </span><i style="white-space: pre-wrap;">Tyrannosaurus</i><span style="white-space: pre-wrap;"> pathologies Rothschild and Molnar note that stress fractures affecting the </span><i style="white-space: pre-wrap;">manus </i><span style="white-space: pre-wrap;">are common in T. rex, since such stress fractures occur when large forces are acting on the hand this is evidence that they were actively used. Because such forces are unlikely in routine behavior this is highly suggestive of the arms being used against struggling prey.</span><br />
<span style="white-space: pre-wrap;">Lipkin and Carpenter likewise note that injuries to the furcula (the bone that connects the shoulder blades in many Theropod Dinosaurs) are most likely to be the result from predator-prey interaction.</span><br />
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<span style="white-space: pre-wrap;"><b>What use are small arms then?</b></span><br />
<span style="white-space: pre-wrap;">As seen in the previous paragraph there is good evidence that the arms were actually used when catching prey, although Lipken and Carpenter note that "because of the small size of the forelimb relative to the body size it is unlikely that <i>Tyrannosaurus </i>would use the manus for striking prey".</span><br />
<span style="white-space: pre-wrap;">More likely is that T. rex used it's claws like hooks, sinking them into the flesh of the prey to hold it in place, while the jaws did the grisly work of finishing off the victim.</span><br />
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/ac/Tyrannosaurus_resting_pose.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="138" src="http://upload.wikimedia.org/wikipedia/commons/a/ac/Tyrannosaurus_resting_pose.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>T. rex</i> rising (image from Wikipedia)</td></tr>
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<span style="white-space: pre-wrap;">A completely different use for the arms has also been suggested. It has been speculated by Stevens, Larson, Wills and Anderson that </span><i style="white-space: pre-wrap;">T. rex</i><span style="white-space: pre-wrap;"> might have used it's arms to rise from a resting position.</span><br />
<span style="white-space: pre-wrap;">While they have convincingly modelled this using computer simulation, this remains highly speculative, very little is known about Dinosaur resting positions. Just because a <i>Tyrannosaurus</i> was physically capable of rising from a resting position by pushing itself upwards doesn't mean it actually slept on it's belly. For all we know <i>T. rex </i>may have only ever rested standing up (for some fascinating speculation on Dinosaur sleep and sleep posture see: <a href="http://saurian.blogspot.com/2012/02/dinosaur-conundrums-how-did-dinosaurs.html" target="_blank">Dinosaur Conundrums - How did Dinosaurs Sleep</a> by Mark Wildman).</span><br />
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<span style="white-space: pre-wrap;"><b>Sources</b></span><br />
<span style="white-space: pre-wrap;">All the articles quoted were published in <i>Tyrannosaurus rex - </i>The Tyrant King by Larson and Carpenter (editors)</span><br />
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<span style="color: white; font-family: Impact, sans-serif;"><span style="font-size: 22px;"><br /></span></span></div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com3tag:blogger.com,1999:blog-3459964428093088507.post-11630060385038306402012-04-18T01:08:00.000+02:002012-04-27T14:21:29.229+02:00Yutyrannus, the fuzzy giantThe first definite feathered Dinosaur was found in 1996 in the <a href="http://en.wikipedia.org/wiki/Liaoning_Province" target="_blank">Liaoning Province</a> in China, since then many more have followed, most of them quite small. Not so <i>Yutyrannus</i>, at 9 meters and an estimated one-and-a-half tonnes it's a giant. And it's a Tyrannosaur to boot albeit distantly related to <i>T. rex</i>.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwq6-Ni3hzM87hU5L680QpxfwYKxuuedL9fzcFIV3pDG6_kyzFFSOTA6zoTCQUnBXDHXF3k0riZUJF5M7hvEnqSRfUJ4AvtkphRAvGfiuFSPYPfZkr04b06X1487dC_4eIOdpkFqS2dMrY/s1600/Yutyrannus_2185949b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="396" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwq6-Ni3hzM87hU5L680QpxfwYKxuuedL9fzcFIV3pDG6_kyzFFSOTA6zoTCQUnBXDHXF3k0riZUJF5M7hvEnqSRfUJ4AvtkphRAvGfiuFSPYPfZkr04b06X1487dC_4eIOdpkFqS2dMrY/s640/Yutyrannus_2185949b.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Yutyrannus</i> dwarfing the two <i>Beipiaosaurus </i>in the foreground</td></tr>
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<i>Yutyrannus </i>wasn't the first feathered Tyrannosaur to be found. That was <i><a href="http://tyrannosaurtuesday.blogspot.com/2012/01/feathers-on-your-tyrannosaurs.html" target="_blank">Dilong</a> </i>a much smaller animal estimated to reach some 2 meters in size (the largest fossil found was a juvenile that was 1,6m long).<i> Yutyrannus </i>was a basal Tyrannosaur like <i>Dilong</i>, that in itself is interesting because other early Tyrannosaurs like <i>Dilong </i>and <i><a href="http://tyrannosaurtuesday.blogspot.com/2012/02/crowned-tyrannosaur.html" target="_blank">Guanlong</a> </i>were much smaller.<br />
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<a name='more'></a><br /><br />
<b>Beautiful feathers?</b><br />
The full name <i>Yutyrannus huali</i> is a mix of mandarin and latin and translates as "beautiful feathered tyrant", but beauty may well be in the eye of the beholder here. While <i>Yutyrannus</i> was undoubtedly covered in a coat of feathers, these were primitive protofeathers and would probably have given the animal a fuzzy, rather than a majestic, look.<br />
It's appearance would have been further enhanced by a crest running along the top of it's snout, this was most likely used for display and so may have been vividly coloured.<br />
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<b>Cretaceous cold</b><br />
The Cretaceous is generally known as a warm period, but <i>Yutyrannus </i>lived during a cold spell, when temperatures dropped worldwide and parts of the earth were covered in ice. That fuzzy coat of feathers would have served it well during cold winters and in the colder regions.<br />
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<b>Close relations</b><br />
Some news reports have claimed that <i>Yutyrannus </i>was closely related to <i>Tyrannosaurus rex</i>, while such things are of course relative "close" is in this case probably over-optimistic. Some 60 <i>million</i> years separate the two (only slightly less than the time that separates us from <i>T. rex!</i>) and while both are members of the larger group Tyrannosauroidea <i>Yutyrannus</i> is more closely related to basal forms like Dilong and Guanlong than with the Tyrannosauridae )the late Cretaceous group that includes <i>T. rex</i>).Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-48314019823302719142012-03-20T23:30:00.000+01:002012-05-21T10:32:14.636+02:00Nanotyrannus, the Tyrannosaur that never was?<i>Nanotyrannus </i>was described in 1988 by Robbert Bakker as a species of pygmy Tyrannosaur that lived alongside <i>T. rex</i> in what is now Montana, but it's status as a valid species is currently disputed.<br />
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/e/e4/Nanotyrannus_lancensis_TQWR_400.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="241" src="http://upload.wikimedia.org/wikipedia/commons/e/e4/Nanotyrannus_lancensis_TQWR_400.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Nanotyrannus </i>life reconstruction (image <a href="http://en.wikipedia.org/wiki/User:Conty" target="_blank">Conty</a>/Wikipedia)</td></tr>
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The skull that formed the basis of Bakker's <i>Nanotyrannus</i> has certainly had an interesting second life as a fossil. When first described in 1946 it was named as a new species of <i>Gorgosaurus</i>, given the specific name <i>lancesis</i> after the Lance Formation in Montana where it was found. Subsequently it was referred to the slightly later Tyrannosaur genus <i>Albertosaurus</i>.<br />
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But it's moment glory would come in 1988 when it was given it's own genus by Robbert Bakker who named it <i>Nanotyrannus </i>because of it's small size compared to other Cretaceous Tyrannosaurs. The total length of <i>N. lancensis</i> was estimated to by about 5 meters in total length, less than half the size of a mature <i>T. rex</i>.</div>
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The status of <i>Nanotyrannus </i>did not go undisputed however, and the discovery of a second specimen in 2001 seemed to bring an end to the status of <i>Nanotyrannus</i> as separate species.</div>
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<a name='more'></a><b><br /></b><br />
<b>A mature <i>Nanotyrannus</i></b></div>
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/4/48/Craneo_nanotyrannus.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="140" src="http://upload.wikimedia.org/wikipedia/commons/4/48/Craneo_nanotyrannus.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cast of the holotype (Wikipedia)</td></tr>
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The status of <i>Nanotyrannus </i>as first a separate species within <i>Gorgosaurus </i>and <i>Albertosaurus</i>, and it´s ultimate elevation to it´s own genus, all relied on one assumption; that the skull belonged to a mature individual.</div>
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If this was indeed a mature individual, it was indeed quite different from <i>T. rex</i> (and <i>Albertosaurus</i> for that matter). Not only was it much smaller, it also had a much more gracile form and narrower snout. The skull overall was much less robust than that of a mature <i>T. rex</i>, with more and smaller teeth. This would mean that it did not have the same <a href="http://tyrannosaurtuesday.blogspot.com/2012/03/more-than-just-bone-crunching-bite.html" target="_blank">bone-crunching bite</a> and probably would have had a different feeding strategy.</div>
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<b>Or a juvenile <i>Tyrannosaurus</i>?</b></div>
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The maturity of the specimen was established by the fusion of bones in the skull, which is generally a sign of maturity. In Tyrannosaurs however the nasal bones fuse early in development, so it is of itself not a good indicator of maturity. Analysis of the bone development also showed that the bone was still growing, suggesting that this was a juvenile animal still undergoing significant growth.</div>
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Perhaps most damning was a paper by Carr in 1999 in which he established that the differences between the skull of <i>Nanotyrannus</i> and that of a mature <i>Tyrannosaurus </i>were best explained by <a href="http://tyrannosaurtuesday.blogspot.com/2012/02/tyrannosaurus-growth.html" target="_blank">ontogeny </a>(the changes across an animal's lifespan).</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/0/01/Jane_rex.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/0/01/Jane_rex.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"Jane" a new <i>Nanotyrannus</i>/juvenile <i>Tyrannosaurus</i> (image FunkMonk/Wikipedia)</td></tr>
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<b>More specimens, more trouble</b></div>
<div>
In 2001 a second specimen was found, nicknamed Jane it was far more complete than the skull that formed the basis of the genus <i>Nanotyrannus</i>. But rather than further cementing the status of <i>Nanotyrannus </i>as a separate species it led to overwhelming support for the theory that "<i>Nanotyrannus</i>" was really a juvenile <i>T. rex</i>, something most palaeontologists now agree with.</div>
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At 6 1/5 metres Jane is actually significantly bigger than the estimated length for <i>Nanotyrannus</i>. Greg Erickson determined her* age to be 11 years, suggesting that the original specimen was younger and thus immature. But other evidence also points to Jane being an immature individual; the arms, legs and feet are disproportionally large compared to the body. Something expected in an immature individual of a larger species, but not in a mature individual of a smaller species. </div>
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<b>The end of <i>Nanotyrannus</i>?</b></div>
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Not all palaeontologists are convinced that "<i>Nanotyrannus</i>" is really a juvenile <i>Tyrannosaurus</i>, most notably Robert Bakker and Peter Larson hold on to the term. And they have recently unveiled a fossil find they named the <a href="http://www.duelingdinos.com/" target="_blank">dueling dinos</a> which shows a <i>Nanotyrannus </i>and an unidentified ceratopsian Dinosaur locked together in a fight, a fight that possibly killed them both.</div>
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It should be noted that since this fossil is on sale there may be an ulterior motive for hanging on to the name for now (their site actually gives "May solve controversy regarding <i>Nanotyrannus</i> vs juvenile <i>T.rex</i>" as a unique selling point).</div>
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* The actual gender of "Jane" is unknown, and probably will never be known.</div>
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</div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-82624337357554785292012-03-13T02:13:00.000+01:002012-03-13T02:13:19.531+01:00More than just a Bone-crunching Bite<i>Tyrannosaurus</i><i> rex</i> had the most powerful bite of any land animal that ever lived, but recent research shows that their was more to it's bite than brute force alone.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFyYMQeA0NHitda5HDwtuu7bFi2a3_iof_kwCC4AoRgoTXCQ9WhkoHK9VX3w9Uo2HZr2V2NhBP1Yc7UBm2dXifQpTcPeSCKUDjlScNWV_btSl8pYf3Sllz-dZyhn0o9ZvHVnoQkvfMrqCa/s1600/Untitled-1+copy.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="155" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFyYMQeA0NHitda5HDwtuu7bFi2a3_iof_kwCC4AoRgoTXCQ9WhkoHK9VX3w9Uo2HZr2V2NhBP1Yc7UBm2dXifQpTcPeSCKUDjlScNWV_btSl8pYf3Sllz-dZyhn0o9ZvHVnoQkvfMrqCa/s400/Untitled-1+copy.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Image via <a href="http://palaeoblog.blogspot.com/2012/03/t-rex-bite-force-calculated.html" target="_blank">Paleoblog</a></td></tr>
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That <i>T. rex</i> had a powerful bite had long been known, a mechanical test of it's biting strength done by Paleontologist G.M. Erickson and engineers from Stanford University built a mechanical rig to replicate the teeth marks found on fossilized <i>T. rex</i> victims. They found a <i>minimum</i> bite strength of 3.300 pounds (~16.000 Newtons).<br />
A recent computer analysis put the bite force even higher, with a minimum bite force of 20.000N and a maximum estimated at an astonishing 57 thousand Newtons. And it should be noted that because of the <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaurus-teeth-crowns-of-king.html" target="_blank">differently sized teeth</a> of Tyrannosaurs the bite force would initially be applied only to the tallest teeth, which would punch their way into the flesh (and any bones they happened to meet) ahead of the rest.<br />
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There is however evidence that <i>T. rex</i> wasn't optimized for brute force alone, and it comes from yet another computer analysis of the <i>T. rex</i> skull. <br />
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<a name='more'></a>For a paper published in 2004 Emily J. Rayfield created a computer-model of a <i>T. rex </i>skull to test how strong the skull really was. The research was based on the observation that the skull of <i>T. rex</i>, like that of most vertebrates, does not consist only of completely fused bones. Instead many of the bones in the skull are connected to each other by '<a href="http://en.wikipedia.org/wiki/Cranial_sutures" target="_blank">sutures</a>', joints that allow limited movement and give the skull a measure of flexibility.<br />
It had long been hypothesised that these sutures would act as "shock-absorbers" taking up some of the stress caused the force of the bite.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMxtEwVBtwFHI2UQH83E0PnjU1DWV8ZSSuJGniVWStJwk6FZuj99pLGosmXC9bAsM3wk-3Gh3yI2XOJm-LcAsQSYDlOK-zY2gid41HbUQg66gGnHTJvIN9PkVOJH7eelF_AMbQqQfrFUer/s1600/Stress.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMxtEwVBtwFHI2UQH83E0PnjU1DWV8ZSSuJGniVWStJwk6FZuj99pLGosmXC9bAsM3wk-3Gh3yI2XOJm-LcAsQSYDlOK-zY2gid41HbUQg66gGnHTJvIN9PkVOJH7eelF_AMbQqQfrFUer/s640/Stress.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stress distribution in a fused (l) and partly fused (r) skull (adapted from Rayfield)</td></tr>
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What Rayfield found was different however, the model of the skull that was not completely fused (as it would have been in reality) could take less force, and thus a weaker bite. The stress caused by the bite however was differently distributed because of the sutures, with more of the load going to the rear of the skull and the tip of the snout. These areas are where the <i>T. rex </i>skulls is reinforced by ridges, hornlets and in the case of the snout fused nasal bones (fused nasals are in fact a defining characteristic of Tyrannosaurs).<div>
The skull of <i>Tyrannosaurus</i> is clearly optimized for large bite forces, but it's not perfectly optimised. This means that in life it wouldn't have achieved the maximum theoretically possible bite force.<br /><br />
Perhaps even more significant was another find from this study, which also looked at the capability of the <i>T. rex </i>skull to withstand shear forces. That is, the forces that would be caused by pulling the head backwards while the teeth were embedded in a victim, tearing the through the flesh.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0_CUPZTN5ABpBLqr65ySMzs-xbq-I-8ZLHkpTN8E2gtgKaYDLMGiU9HpNzXxEGEwogRIfajcLQyOE9HmnZ0nh3TXoxyPSfZ4TkFAzU-aLnMZ8U9xoIfeCaZUncAr42uKdoC_oYoUFadn-/s1600/Shear.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0_CUPZTN5ABpBLqr65ySMzs-xbq-I-8ZLHkpTN8E2gtgKaYDLMGiU9HpNzXxEGEwogRIfajcLQyOE9HmnZ0nh3TXoxyPSfZ4TkFAzU-aLnMZ8U9xoIfeCaZUncAr42uKdoC_oYoUFadn-/s640/Shear.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stress distribution caused by biting (l) and tearing (r) (adapted from Rayfield)</td></tr>
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The results showed that the skull of a <i>Tyrannosaurus</i> was equally adapted to tearing as it was to biting, lending support to the idea that <i>T. rex</i> used a unique form of feeding that has been termed 'puncture-pull'.<br />
Puncture-pull is pretty self-explanatory, <i>T. rex </i>would have used it's powerful bite to create a row of puncture and than pulling back with it's strong neck muscles to separate a large chunk of flesh from it's victim. Much like tearing perforated paper.<br />
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<i>References: </i><br />
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Rayfield, E.J. (2004) Cranial mechanics and feeding in Tyrannosaurus rex <i>Proc. R. Soc. Lond.</i><br />
Bates, K. T., Falkingham, P.L. (2012) Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics <i>Biology letters </i>(quoted on <a href="http://palaeoblog.blogspot.com/2012/03/t-rex-bite-force-calculated.html" target="_blank">Paleoblog</a>)</div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-59080811739777159732012-02-28T02:44:00.001+01:002012-03-12T14:37:52.268+01:00A Tyrannosaur of a different branch<i>Alioramus </i>is both very closely related too, and very different from <i>Tyrannosaurus rex</i>. It was found in Mongolia where it lived alongside the giant Tyrannosaur <i>Tarbosaurus.</i><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/7/77/A.altai.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="156" src="http://upload.wikimedia.org/wikipedia/commons/7/77/A.altai.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The fossil remains of <i>Alioramus altus</i> showing it's body in outline (image <a href="http://en.wikipedia.org/wiki/User:Conty" target="_blank">Conty</a>/Wikipedia)</td></tr>
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When discovered in 1976 <i>Alioramus</i> was given the specific name <i>A.</i> <i>remotus</i> because it was thought to be far removed from the large Tyrannosaurs like <i>Tyrannosaurus </i>and <i>Tarbosaurus </i>that lived at the same time. But a recently found <i>Alioramus</i> specimen has shed new light on this relationship.<br />
Discovered in Mongolia in 2001 the new specimen was first described in 2009 and found to be sufficiently different to warrant it's own species name. It was given the specific name <i>A. altai </i>after the Altai mountains in southern Mongolia.<br />
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<b>Long snouts</b><br />
Both species of <i>Alioramus</i> differ significantly from <i>Tyrannosaurus</i> and other large Tyrannosaurs in being smaller, with an estimated adult size of 5 to 6 metres, but also in having a very different skull.<br />
The skull of <i>Alioramus</i> was very long compared to other Tyrannosaurs, with the snout making up two-thirds of the length of the skull. The skull was also much less robust, with more and larger openings contributing to a much lighter skull, as well as being far more ornamented. <i>A. remotus</i> had many small crests on the top of it's snout, but <i>A. altai </i>had no less than 8 disitinct horns including one on each side of the head just below the eyes.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/b/bb/Alioramus_BW.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="227" src="http://upload.wikimedia.org/wikipedia/commons/b/bb/Alioramus_BW.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Artist's impression of <i>A. remotus</i> by Nobu Tamura (note nasal ridges)</td></tr>
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<b>Lifestyle</b><br />
The teeth of <i>Alioramus </i>conform to the <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaurus-teeth-crowns-of-king.html" target="_blank">standard dental plan for advanced Tyrannosaurs</a>, with a set of `scraper` teeth at the front of the upper jaw, followed by larger teeth of differing size and smaller teeth at the back of the jaws. But the teeth are smaller and spread out over a larger area than in large Tyrannosaurs. Combined with a longer, lighter skull it is clear that it could not have used the same hunting tactics as <i>T. rex</i> with it´s bone-crunching bite.<br />
The smaller more gracile form of <i>Alioramus</i> suggests that it may have been a more agile hunter, going after smaller and faster prey. Possibly filling the same ecological niche that in North-America was filled by <a href="http://tyrannosaurtuesday.blogspot.com/2012/02/tyrannosaurus-growth.html" target="_blank"><i>Tyrannosaurus </i>juveniles</a>.<br />
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<b>Famous relatives</b><br />
Because the <i>A. remotus</i> specimen was very incomplete (little more than an incomplete skull and some foot bones) the position of<i> Alioramus </i>within the Tyrannosaur family was long unsure. The geographical age of the specimen mean that it couldn't be a basal Tyrannosaur like <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/feathers-on-your-tyrannosaurs.html" target="_blank">Dilong </a>or <a href="http://tyrannosaurtuesday.blogspot.com/2012/02/crowned-tyrannosaur.html" target="_blank">Guanlong</a>, but it was generally considered to belong to a completely different (and otherwise unknown) branch.<br />
Because the much more complete <i>A. altai</i> fossil showed it to have many features in common with advanced Tyrannosaurs it could now be placed in the Tyrannosaurinae, the group that includes <i>Daspletosaurus, Tarbosaurus</i> and<i> Tyrannosaurus rex. </i>Albeit as a different branch within that group.<br />
This has also made it it possible to infer those parts of the <i>Alioramus</i> anatomy that are not present in the fossils, like a long tail and short two-fingered hands.<br />
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<b>Shared stomping ground</b><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; float: right; margin-bottom: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/5/5e/TarbosaurusDB.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="225" src="http://upload.wikimedia.org/wikipedia/commons/5/5e/TarbosaurusDB.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Artist's impression of Tarbosaurus by Dimitri Bogdanov</td></tr>
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Sergei Kurzanov the Russian palaeontologist who described <i>A. remotus</i> suggested that it probably lived alongside "the Asian T-Rex" <i>Tarbosaurus, </i>the specimen of <i>A. altai</i> lends further support to this idea. The geographical age and location of the fossil confirm that <i>Alioramus </i>and <i>Tarbosaurus</i> lived at the same time in the same area. Because of their different feeding habits these two Tyrannosaurs could probably co-exist because they occupied different ecological niches.<br />
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</div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-64819765988677828482012-02-13T23:24:00.000+01:002012-05-21T10:23:42.386+02:00Tyrannosaurus growthDinosaurs grew very large in a relatively short period of time, and their bodies changed as they matured. This happened in <i>T. rex</i> too, but with a twist.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/5/56/Jane_TRex_Burpee.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="290" src="http://upload.wikimedia.org/wikipedia/commons/5/56/Jane_TRex_Burpee.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"Jane" a <a href="http://www.blogger.com/goog_1641441177">Juvenile </a><i><a href="http://tyrannosaurtuesday.blogspot.com/2012/03/nanotyrannus-tyrannosaur-that-never-was.html" target="_blank">Tyrannosaurus</a> </i>(image Wikipedia)</td></tr>
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That Dinosaurs could grow to enormous size is common knowledge, but they were surprisingly small when they hatched. Even the largest known Dinosaur egg is no more that 25 by 30 centimetres. No <i>T. rex </i>egg is known, so we don't know exactly how big they were when hatching, but they were probably about the size of a chicken.<br />
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The growth pattern of Dinosaurs can be roughly summarized as a number of years of slow growth, followed by rapid growth until maturity and gradual growth until death. Depending on the size of the Dinosaur it could take anywhere from 2 years for the smallest species, to 15 years for the gigantic Sauropods to reach maturity (quite amazing if you consider the size of the largest Sauropods). </div>
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<i>Tyrannosaurus</i> had a surprising twist on this pattern. Much like humans <i>T. rex </i>did not start its fast growth until around twelve years old, and would then grow rapidly until reaching maturity at 18 or 19 years old. Compare that to the basal Tyrannosaurid <i><a href="http://tyrannosaurtuesday.blogspot.com/2012/02/crowned-tyrannosaur.html" target="_blank">Guanlong</a> </i>which was found to have been mature at a mere seven years of age.<br />
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It has been suggested that the reason that <i>Tyrannosaurus</i> enjoyed such a long infancy and adolescence was that the juveniles filled the ecological niche normally occupied by medium-sized predators. So far no medium-sized carnivores have been found that shared an environment with <i>T. rex.</i> The "King the Tyrant Lizards" was definitely the top-predator in it's environment, it was probably also the dominant medium-sized predator.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/9/94/Tyrannosaurus_4040.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/9/94/Tyrannosaurus_4040.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"Sue" a mature <i>Tyrannosaurus </i>(image Wikipedia)</td></tr>
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Despite the long years of youth <i>Tyrannosaurus</i> was not a particularly long-lived species. Sue, the oldest known specimen, was 28 years old when she died. A ripe old age for a <i>T. rex</i>. Over half the known fossils were animals that had died within six years of reaching maturity.<br />
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Like most Dinosaurs <i>Tyrannosaurus rex</i> grew fast, and died young.</div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-44225065875623209302012-02-08T01:15:00.000+01:002012-03-12T14:42:01.390+01:00The Crowned Tyrannosaur<i>Tyrannosaurus Rex</i> may have been the 'king of the Dinosaurs', but it was one of it's ancestors that wore a crown.<br />
Found in the China this early Tyrannosaurid from the Late Jurassic was named <i>Guanlong </i>(Crowned Dragon) because of it's distinctive crest.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/7/74/Guanlong_wucaii_head.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="241" src="http://upload.wikimedia.org/wikipedia/commons/7/74/Guanlong_wucaii_head.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="background-color: white; font-family: sans-serif; line-height: 19px; text-align: -webkit-auto;">Pencil drawing of the head of </span><i style="background-color: white; font-family: sans-serif; line-height: 19px; text-align: -webkit-auto;"><a class="external text" href="http://en.wikipedia.org/wiki/Guanlong" style="background-attachment: initial; background-clip: initial; background-color: initial; background-image: url(data:image/png; background-origin: initial; background-position: 100% 50%; background-repeat: no-repeat no-repeat; color: #663366; padding-right: 13px; text-decoration: none;">Guanlong wucaii</a> by Renato Santos</i></td></tr>
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<i>Guanlong </i>is the oldest relative of <i>Tyrannosaurus</i> yet found, older even than <i><a href="http://tyrannosaurtuesday.blogspot.com/2012/01/feathers-on-your-tyrannosaurs.html" target="_blank">Dilong</a>. </i>It is therefore a very basal Tyrannosaurid with the slender build, long arms (with three-fingered hands), and a long narrow snout common to most Coelurosaurs.<br />
It did however have a number of specializations that put it clearly in the Tyrannosaur clade. Like <i>T. rex </i>and all other Tyrannosaurs<i> Guanlong</i> had <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaurus-teeth-crowns-of-king.html" target="_blank">two types of teeth</a>, with the smaller front teeth being shaped like scrapers. The foremost bone of the jaw was also very high, giving <i>Guanlong</i> the relatively blunt snout common to all Tyrannosaurs.<br />
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<a href="http://upload.wikimedia.org/wikipedia/commons/4/43/Guanlong_SIZE.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br /><img border="0" height="139" src="http://upload.wikimedia.org/wikipedia/commons/4/43/Guanlong_SIZE.png" width="200" /></a></div>
Unlike it's famous relative<i> Guanlong </i>was not the dominant predator in it's enviroment, being only 3 meters long and with a hip-height of no more than a metre.<br />
It was still an active hunter despite sporting a fragile crest, which has lead some to suggest it may be an example of "the handicap principle": where males show their superiority by achieving success despite an obvious handicap. It may also have played a more directly role in courtship or species-recognition, in which case it was probably brightly coloured.<br />
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<a href="http://upload.wikimedia.org/wikipedia/commons/b/b6/Guanlong_fossil.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="133" src="http://upload.wikimedia.org/wikipedia/commons/b/b6/Guanlong_fossil.jpg" width="200" /></a></div>
Feathers are an inferred attribute of <i>Guanlong, </i>no feathers were found with either of the skeletons that have so far been found. But because feathers were found with the later <i><a href="http://tyrannosaurtuesday.blogspot.com/2012/01/feathers-on-your-tyrannosaurs.html" target="_blank">Dilong</a> </i>and are found in many other groups of Coelurosaurs making it extremely probable that <i>Guanlong</i> also sported a coat of (proto)feathers.<br />
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With it's distinctive crest and coat of feathers <i>Guanlong</i> must have made quite a distinctive appearance.<br />
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[Images via <a href="http://en.wikipedia.org/wiki/Guanlong" target="_blank">Wikipedia</a>]<br />
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<br />Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-15714662093637823232012-01-31T00:01:00.000+01:002012-03-12T14:42:54.438+01:00Tyrannosaurus Teeth - The crowns of a king<div>
The teeth of Tyrannosaurus are unlike any other, they are highly specialized for killing and eating other Dinosaurs. They are not only famously large and recurved (or "banana-shaped"), but they are also placed for maximum effect.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEim9E83JEYQlfG28fVXa_J3ZRCah9AYuqorI97g4MBuL1_a79O5xPWwoh5WDPeauYOp1l13ezq0bPtgDScLsrYBYZ6KWBfxqSMHIvKp3f83JOxNfi915Zp49Wq4wQjr2QVt_aIuoYIu4hWz/s1600/TTeeth.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="173" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEim9E83JEYQlfG28fVXa_J3ZRCah9AYuqorI97g4MBuL1_a79O5xPWwoh5WDPeauYOp1l13ezq0bPtgDScLsrYBYZ6KWBfxqSMHIvKp3f83JOxNfi915Zp49Wq4wQjr2QVt_aIuoYIu4hWz/s400/TTeeth.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Teeth of <i>Tyrannosaurus Rex</i></td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheWGOOLVV5kwG1Dqf-kl7D-Ypwe5yCmt0YkfIxwjD_aj08L65Wu-2PtE_AM0iWSHqrMEFhqoHijwWVTe7s9Q0eGvxZ8Fyg1uoZKxcqgMCCqYKfCxdtZgkK6yCrZCs4sA7EH3ezbuYuUU5A/s1600/Allosaurus_T-Rex_Skulls.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheWGOOLVV5kwG1Dqf-kl7D-Ypwe5yCmt0YkfIxwjD_aj08L65Wu-2PtE_AM0iWSHqrMEFhqoHijwWVTe7s9Q0eGvxZ8Fyg1uoZKxcqgMCCqYKfCxdtZgkK6yCrZCs4sA7EH3ezbuYuUU5A/s200/Allosaurus_T-Rex_Skulls.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Allosaurus </i>and <i>T. rex</i> (not to scale)</td></tr>
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<i>Tyrannosaurus </i>did not have the hatched-shaped head common to most Theropods, rather the head of a <i>T. rex</i> was comparatively wide ending in a blunt snout.<br />
The teeth of a Tyrannosaur were also different in shape from those of other Theropods. Where almost all Theropods had flat blade-like teeth for slicing through meat, Tyrannosaurs had teeth that were decidedly more rounded (in some teeth almost circular) for punching through flesh and crushing bone. <i>Tyrannosaurus </i>in fact had three distinct types of teeth in it's jaws.<br />
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The upper front jaw of a <i>T. rex </i>was U-shaped and densely packed with smaller teeth. Small, curved backward and with flat tips these closely spaced teeth were ideal for shearing pieces of meat from an animal, living or dead, and for <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaurs-used-their-mouths-to.html" target="_blank">scraping the meat of the bones</a> once the prey is down.<br />
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The middle teeth of <i>Tyrannosaurus </i>were actually the largest, with some being as tall as 30 centimetres total length. That does however include the massive root, which was disproportionally large in Tyrannosaurs (as much as two-thirds of the total length of the tooth!).<br />
A good sized T-Rex tooth might have a crown of over 10 centimetres, but it should be noted that <i>T. rex</i> teeth differ extremely in size, even within the middle part of the jaw. The longest teeth would initially have the full pressure of the bite behind them, helping them to sink deeply into the flesh of the prey, and even crushing bones that happened to get in their way. These teeth were recurved and reinforced with ridges to withstand the extreme pressure of a bite, and they had serrations to even better cut through flesh.<br />
The middle teeth would not only have inflicted massive puncture wounds to it's victims, but with their massive roots they would have been ideal for coping with the stresses of holding on to a struggling prey as well.<br />
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/2/27/B-rex_teeth.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="212" src="http://upload.wikimedia.org/wikipedia/commons/2/27/B-rex_teeth.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Differently-sized teeth of <i>Tyrannosaurus</i>, note the clearly visible line marking the crown</td></tr>
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At the rear of it's jaw <i>T. rex</i> had smaller even more robust teeth, these could be clamped together to deliver particularly crushing bites. This would have been used to deliver devastating bite/forces (in one famous case even biting the horn of a <i>Triceratops</i> in two) and to crush the bones of smaller prey so it could swallow them along with the rest of the animal. As attested by the crushed bones of a young Dinosaur found in a <i>Tyrannosaurus </i><a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaur-droppings-tyrannosaur.html" target="_blank">coprolite</a>,<br />
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That <i>Tyrannosaurus</i> could deliver a bone-crushing bite didn't mean that it deliberately crushed bones to get at the marrow (as seen in modern scavengers, like Hyena's). The existing <a href="http://archosaurmusings.wordpress.com/2010/07/13/so-tyrannosaurs-were-scavengers-then/" target="_blank">evidence for Tyrannosaur scavenging</a> shows that the Tyrannosaur in question deliberately ate around the bones, leaving the bone undamaged except from where it grazed them while scarping of the flesh.<br />
<br /></div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-44545640150459616742012-01-25T01:05:00.000+01:002012-03-12T15:39:24.506+01:00<br />
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<b>Tyrannosaurs used their mouths to manipulate their food</b><br />
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Everyone knows Tyrannosaurs, especially <i>Tyrannosaurus Rex</i>, had tiny arms compared to the size of their bodies. Although counter-intuitive for humans who do almost all their manipulation with their hands, the Tyrannosaurs could use their mouths as an all-purpose tool for feeding.</div>
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/a8/Fossil_Tyranausaurus_Rex_at_the_Royal_Tyrell_Museum,_Alberta,_Canada.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="http://upload.wikimedia.org/wikipedia/commons/a/a8/Fossil_Tyranausaurus_Rex_at_the_Royal_Tyrell_Museum,_Alberta,_Canada.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>T. rex</i> cast, showing it's massive jaws and puny arms (Wikipedia)</td></tr>
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Not only could they bite of chunks of meat with their powerful jaws, there is fossil evidence that shows that they used their mouths to turn over the their food to get at the rest of the meat.<br />
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<i>From the remains of a hadrosaur that was partly eaten by a Tarbosaur (a close relative of T-rex) it is clear that the Tyrannosaur extensively manipulated the carcass with their teeth. </i></blockquote>
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<i>Tyrannosaurs did not just rip apart carcasses and crunch through bones even though they could. Sure on some occasions they did, but not always. They could, and did, chose how to feed and could be relatively delicate.</i></blockquote>
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Dave Hone, <a href="http://archosaurmusings.wordpress.com/2010/07/14/selective-feeding-by-tyrannosaurs/" target="_blank">Selective feeding by Tyrannosaurs</a> </blockquote>
In this case the Tyrannosaur most likely tore the bone from the rest of the carcass and scraped the meat off, using the front teeth in it's upper jaw. The U-shape of the upper jaw meant that Tyrannosaurs had<a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaurus-teeth-crowns-of-king.html" target="_blank"> a relatively straight row of teeth</a> at the front, perfect for scraping meat of bones.</div>
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With smaller prey Tyrannosaurs weren't this precise, a Tyrannosaurus <a href="http://tyrannosaurtuesday.blogspot.com/2012/01/tyrannosaur-droppings-tyrannosaur.html" target="_blank">coprolite</a> found in Canada was filled with the crushed bones of a young Dinosaur. The Tyrannosaurus had simply gobbled it's prey, crushing and swallowed the bones along with the rest of the animal.</div>
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<i>The paper on selective feeding by Hone and Watabe is available online: <span style="font-family: Verdana, sans-serif; font-size: 11px; text-align: left;"><a href="http://www.app.pan.pl/article/item/app20090133.html" target="_blank">New information on scavenging and selective feeding behaviour of tyrannosaurs</a></span></i></div>
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<br /></div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-17056463941856824272012-01-17T01:48:00.000+01:002012-03-12T16:04:09.599+01:00Feathers on your Tyrannosaurs<br />
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<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/b/b1/Dilong_paradoxus_VQER_35.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="222" src="http://upload.wikimedia.org/wikipedia/commons/b/b1/Dilong_paradoxus_VQER_35.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Life restoration of <i>Dilong paradoxus</i></td></tr>
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Ever since Archaeopteryx was discovered 150 years ago there has been speculation about the connection between dinosaurs and birds, this relationship has now become so well established that birds are considered to be a subset of dinosaurs.<br />
During the 1990s this was further cemented by the find of many unusually well-preserved dinosaur fossils in the Chinese province of Liaoning that showed them to have feathers. The feathered dinosaurs found were small Theropods, and among them was an early member of the Tyrannosauridea.<br />
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<b>The Emperor Dragon</b><br />
The distant cousin of Tyrannosaurus rex found in china was <i>Dilong (Di </i>for emperor and<i> long </i>for dragon, a suffix often used for Chinese dinosaurs) an early member of the Tyrannosaurids. It was also quite small, with the adult size estimated to about 2 meters.<br />
The feathers found on the <i>Dilong </i>fossil were different from the feathers found in modern birds and are better described as protofeathers, Wikipedia notes that<span style="font-family: sans-serif; font-size: x-small; line-height: 19px;"> "t</span><span style="font-family: inherit; line-height: 19px;"><a href="http://en.wikipedia.org/wiki/Dilong_(dinosaur)" target="_blank">hey could not have enabled flight</a><span style="font-size: x-small;">".</span></span><span style="font-family: sans-serif; line-height: 19px;"> </span><span style="font-family: inherit;"><span style="line-height: 19px;">Which may seem </span></span><span style="line-height: 19px;">superfluous as this animal had no</span><span style="font-family: inherit;"><span style="line-height: 19px;"> wings, but it reinforces the notion that feathers were not originally developed for flight,</span></span><br />
<span style="font-family: inherit;"><span style="line-height: 19px;">Most likely the protofeathers formed an insulating coat, similar to fur in mammals. </span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 19px;"><b>Was T-Rex a big chicken?</b></span></span><br />
<span style="font-family: inherit;"><span style="line-height: 19px;">It has often been suggested, generally <a href="http://ncsu.edu/newsletter/archive/2008/05/t-rex.php" target="_blank">firmly tongue-in-cheek</a>, that <i>Tyrannosaurus rex </i>was akin to a big chicken (or turkey, depending on the season) because it is closely related to modern birds. </span></span><br />
<span style="font-family: inherit;"><span style="line-height: 19px;">So did <i>T. rex </i>have feathers as well? That question doesn't have a definite answer yet. </span></span><br />
<span style="font-family: inherit;"><span style="line-height: 19px;">Only a few skin imprints of Tyrannosaurs are known, and they all show scales. But they are only partial imprints. Tyrannosaurus may have had both scales and feathers, just like modern birds still have scales on their legs.</span></span><br />
<span style="font-family: inherit;"><span style="line-height: 19px;">One hypothesis, derived from the fact that all feathered dinosaurs found so far are small Ther</span></span><span style="font-family: inherit; line-height: 19px;">opods, is that may not have needed feathers to keep warm. According to that hypothesis large Theropods like <i>T. rex</i> would not have had feathers, or only in their juvenile form when they were much smaller.</span><br />
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<span style="font-family: inherit; line-height: 19px;">[image from <a href="http://en.wikipedia.org/wiki/Dilong_(dinosaur)" target="_blank">Wikipedia</a>]</span>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0tag:blogger.com,1999:blog-3459964428093088507.post-30410075082486514842012-01-10T11:32:00.000+01:002012-05-08T02:09:51.830+02:00Dinosaur Droppings<div style="text-align: center;">
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At 12 meters tall and weighing in over 6 tonnes <i>Tyrannosaurus rex</i> was truly a giant, and so were it's droppings. The fossilized dinosaur droppings (known as a coprolite) in the picture are half a meter long and have a volume of two litres.
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<tr><td style="text-align: center;"><span style="margin-left: auto; margin-right: auto;"><a href="http://www.blogger.com/goog_641957807"><img border="0" height="265" src="http://upload.wikimedia.org/wikipedia/commons/e/e4/Coprolite.jpg" width="400" /></a></span></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://en.wikipedia.org/wiki/Coprolite" target="_blank">Tyrannosaur coprolite from Saskatchewan (image Wikipedia)</a></td></tr>
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But there is more to this stone dung than sheer size. They tell us something about the life-style of the animal that left it. These particular droppings were a filled with bones, <a href="http://www.nature.com/nature/journal/v393/n6686/full/393680a0.html" target="_blank"><span id="goog_641957813"></span>30 to 50% of this coprolite</a> is made up of bones. These bones belonged to a subadult dinosaur, perhaps not surprising. Juveniles were <a href="http://archosaurmusings.wordpress.com/2009/08/04/baby-killers-hunting-and-feeding-behaviours-of-large-theropods/" target="_blank">the most likely prey</a> even for the largest of carnivores.</div>
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The large amount of bones (and even fossilized pieces of undigested flesh) found in <i>Tyrannosaurus </i>coprolites also suggest that it was <a href="http://blogs.smithsonianmag.com/dinosaur/2011/03/tyrannosaurus-scat/" target="_blank">an active eater</a>, quickly moving from meal to meal.</div>
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<br /></div>Hypnotosovhttp://www.blogger.com/profile/11469293434683944221noreply@blogger.com0