tag:blogger.com,1999:blog-67047000314131494662024-03-04T20:24:33.333-08:00The Casual PaleoartistJulio's slightly artistic pages.Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.comBlogger70125tag:blogger.com,1999:blog-6704700031413149466.post-74692873341046396752013-01-17T18:43:00.000-08:002013-01-17T18:43:48.462-08:00All Yesterdays Entry: Gay Dinosaurs<div class="separator" style="clear: both; text-align: center;">
<a href="http://fav.me/d5rtlqi"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8V7-0TaFGx3GzKnowfXEEY9r03myikvzWQVD8hhQpMo6P4v6ZAlBOrA3DTObAleieWXtE19Yj5XBhmMe3DULVK4QHqg_mtlcV44qVdDf9aZ3-n3DRcU2rdlcqI8mggimP_jDJS97241ku/s640/chiro.png" width="628" /></a></div>
<br />If you didn't know already, there's a nice contest going on around the paleoartistic community, from the guys behind the marvellous All Yesterdays book. <a href="http://nemo-ramjet.deviantart.com/art/All-Yesterdays-Contest-Apply-Today-346618231">Go check it out!</a><br /><br />So, I felt obligated to participate. The concept of the book is awesome - speculative subjects surrounding extinct animals, from soft-tissue anatomy to unusual behaviours, that wouldn't (probably) fossilize - and so are the artists behind it. The goal of the contest that's been held is to encourage paleoartists to think outside the box when it comes to what their work shows to the public, pursuing concepts that are not so easily deductible from the fossil record but that are perfectly accurate in light of what information we have about extinct and living animals.<br /><br />I though for many a days on what I should portray, and many things came to my mind. I thought about a golden <i>Jinfengopteryx </i>making a crazy jumping dance akin to Lesser Floricans, not-so-peaceful herbivores fighting each other and a hadrosaur with a head pattern that mimics its tail's to confuse the predators, but ultimately none of these came to fruition. Suddenly I thought of something that I've never actually seen in paleoart (although somebody probably did represent it in some form and I'm not aware of it): gay dinosaurs.<br /><br />Homosexualism is a taboo in many countries, and unfortunately prejudice against it is often related to religious beliefs. As such, many people deem it unnatural, something that only deviant humans would engage into. However, since centuries ago, research has shown that same-sex pairings are actually widely common among different species of animals, from worms to dolphins, flamingos to dragonflies. Of course, it's difficult to differentiate when cases of same-sex copulation are something else other than a 'mistake' on the part of the participants, especially when it comes to invertebrates and other animals without more complex neural systems. But when a gay penguin couple steals the eggs of a female and raise the chicks as their own, there's definitely something up right there.<br /><br />Mammals and birds are rather proficient in bisexual and homosexual interactions. Cases of same-sex copulation, both male-male and female-female, have been observed in pretty much most species with well-researched sexual behaviour. While in some cases it doesn't go beyond a quick encounter, in others the animals form monogamous pairs that last for life. Most dolphins and bonobos are apparently bisexual, practicing heterosexual intercourse for breeding purposes but also engaging in homosexual encounters apparently for pleasure and politics, while giraffes have an unusually high rate of male-male sex (in some populations being even more frequent than heterosexual pairs) and many birds, from swans to ducks to flamingos to penguins, constitute gay mating pairs for life and steal or adopt other pairings' eggs to raise well into the offspring maturity, which research has shown can lead to higher rates or survival for the chicks than what is normally observed, perhaps because two males together are more capable of protecting then.<br /><br />While it is needless to say that the exact factors that lead to homosexuality, both in humans and other animals, are far from clear, numerous studies have associated it with aspects of genetic composition, gestation/incubation and hormone levels. It certainly seems that the cause is more biological than simply psychological, especially in light of the variety of creatures that also show homosexual tendencies.<br />
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In short, why not speculate that dinosaurs, especially those so close to the bird lineage, could ocasionally have engaged in gay pairings as well? It certainly fits with what is known from many living animals, including their closest living relatives, but that is not something that could be deduced from fossils, unless something exceptional comes about. In my entry then, I portray a gay pair of caenagnethid oviraptorosaurs, similar to <i>Chirostenotes</i>, cuddling each other in an unfossilizable moment of tenderness.<br /><br />Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com5tag:blogger.com,1999:blog-6704700031413149466.post-69659599869052585232012-12-24T08:19:00.000-08:002012-12-24T08:19:02.631-08:00Merry Christmas!<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIjnU-zzzIpUEAINwIuSTc4-d0VYihNqGTUcLTFi9_cRZGgPK8x579GzS7Poj5pEcDZKM-oCv0flm9VUVIs1uHXBuF0XAjoTJORmma_6WbY4f_nMNBmAgEUhs0kPBwxx3X1EXdEVdFqns7/s1600/christmas.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIjnU-zzzIpUEAINwIuSTc4-d0VYihNqGTUcLTFi9_cRZGgPK8x579GzS7Poj5pEcDZKM-oCv0flm9VUVIs1uHXBuF0XAjoTJORmma_6WbY4f_nMNBmAgEUhs0kPBwxx3X1EXdEVdFqns7/s640/christmas.png" width="640" /></a></div>
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A quick little post to wish all of you readers a Merry Christmas, Hanukkah, or anything you might celebrate at this time of the year. Until 2013!Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-59030418460968064902012-11-01T12:42:00.001-07:002012-11-01T12:42:37.804-07:00The Mongolian Bird-Mimic<div class="separator" style="clear: both; text-align: center;">
<a href="http://karkajou1993.deviantart.com/art/Vanity-331197495"><img border="0" height="426" src="http://fc09.deviantart.net/fs71/i/2012/281/0/1/vanity_by_karkajou1993-d5h6pmf.png" width="640" /></a></div>
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We now know that many traits once thought to be exclusive to birds actually appeared in non-avian dinosaurs, long before true birds had evolved. Feathers, wishbones and pygostyles are all examples of anatomical characteristics that were present in animals that are not classified as birds, and that is something expected given the very gradual and non-linear nature of evolution. This knowledge came from the discovery of many dinosaur fossils showing numerous similarities with birds, culminating with the discovery of fossilized feathers in specimens that were definetely not avian, including the exquisite fossils of feathered dinosaurs from China.<br /><br />One of those findings was the holotype of <i>Avimimus. </i>This mongolian dinosaur, now classified as an oviraptorosaur, was once suggested to be closer to the origin of birds than <i>Archaeopteryx</i> itself. With short arms covered in well-developed feathers, a toothless parrot-like beak and long, slender legs, <i>Avimimus </i>was indeed a very bird-like animal. Its cursorial adaptations suggest this was a fast runner, perhaps using its wings - most likely useless for flight, to steer while running after the small vertebrates it may have considered prey or evading predators. No matter its taxonomical classification, <i>Avimimus, </i>along with its feathered cousins, would surely be informally called "birds", were they alive today.<br /><br />In the image up top, a speedy male darts around the Mongolian floodplains while exposing it's quail-like tail feathers used for attracting mates.</div>
Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-48811548245393084322012-10-30T18:02:00.000-07:002012-10-30T18:02:18.412-07:00Some Oceanic Paleontography<div class="separator" style="clear: both; text-align: center;">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-n60olW-uk-KeTJt8QsebEsKQE0PxGdvF-zftl_mJZxyALe5zvCWTQS362UPvm8Pjgh8sHgMt2RdXPoQ21NQINuVm_B9kEH1KDPdOYwQP89y_h5izbUnfN4YOzGx2-UY-g1IsBMiJTw3h/s1600/what_are_you__by_karkajou1993-d5gfby4.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"></a></div>
As you should know, <a href="http://thecasualpaleoartist.blogspot.com.br/search/label/Oceans">I love the Mesozoic oceans</a>;
the way it was so familiar and yet so alien, and how it tells the story
of terrestrial animals first came back to the oceans in a process that
has been repeated over the eons by such disparate creatures as penguins,
sea turtles and dolphins. Below are more pictures representing the
three major groups of reptiles that inhabited the oceans during the time
of the dinosaurs:<br />
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<a href="http://karkajou1993.deviantart.com/art/What-Are-You-329920060"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-n60olW-uk-KeTJt8QsebEsKQE0PxGdvF-zftl_mJZxyALe5zvCWTQS362UPvm8Pjgh8sHgMt2RdXPoQ21NQINuVm_B9kEH1KDPdOYwQP89y_h5izbUnfN4YOzGx2-UY-g1IsBMiJTw3h/s640/what_are_you__by_karkajou1993-d5gfby4.png" width="426" /></a></div>
<i><br />Stenopterygius trissicus</i>, a dolphin-like genus of Ichthyosaur <a href="http://thecasualpaleoartist.blogspot.com/2012/08/hipster-ichthyosaurs-were-dolphinin.html">which has been covered before</a>;<br />
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<a href="http://karkajou1993.deviantart.com/art/The-Gathering-331452856"><img border="0" height="425" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQG5ZXAtJdGAo6iYyPnnZuCU4FzjSN2VRK7dEVfLdGoIiSuejkyemPB7oOBSQifMQM0d6uBdbON7z8GID4zVSWekKbvwMJ3LOgf0wq9jEOjhYrfRcqX4hTqXuZXL7NuzEyJwsko7n9hiZe/s640/the_gathering_by_karkajou1993-d5hc6ns.png" width="640" /></a></div>
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A swarm of <i>Mosasaurus hoffmannii</i>, the classic marine lizard, gathering after the smell of blood;<br />
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<a href="http://karkajou1993.deviantart.com/art/X-mom-333460779"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhP1JoZE8ufbypSRMu7IPwGBb19iTwfzOg6UlM4QUwJrsgevzV7nrIuGp_8B27iqEZIDlDoL32XROKHoPWB_CfX_L-Pn8de1gU3CbfrxOea_CirvgPtP8Fg83l6b8KaqLWSbqhE5F0lffr/s640/plio2.png" width="640" /></a></div>
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And a mother <i>Pliosaurus funkei</i>, previously known as "Predator X" - the giant pliosaur from Svalbard - giving birth.<br /><br />Expect more paintings of Mesozoic marine life soon, since I can never get enough of them!<br /><br /></div>
Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-74498038861695046882012-10-30T17:43:00.000-07:002012-10-30T17:43:32.059-07:00Testing the Waters<div class="separator" style="clear: both; text-align: justify;">
<a href="http://karkajou1993.deviantart.com/art/The-First-Trip-to-the-Beach-329208696"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKEDgrj6Htd2cmNMCdnjSHu08J-DYQ9hnZBUZL86692BnMjlGkV20Hjy-rSLJKwvoWjvbOsMWa39BO9tfq_6jtpMrKrbjIAK_mbYnVQc8dQVwTqDhmBuJJIUtWBbouYQk0bPRwxtvmxYYB/s640/the_first_trip_to_the_beach_by_karkajou1993-d5g0320.png" width="640" /></a></div>
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<br />I've already briefly covered <a href="http://thecasualpaleoartist.blogspot.com.br/2012/06/south-american-stork-mimics.html">unenlagiines</a>, the group of deinonychosaurs thought to be mostly specialized for piscivorous diets. These feathered dinosaurs were basal dromaeosaurids, more primitive relatives of <a href="http://thecasualpaleoartist.blogspot.com/2012/03/finally-black-microraptor-is-done.html"><i>Microraptor</i></a>, <i>Utahraptor</i> and <a href="http://thecasualpaleoartist.blogspot.com/2012/03/nocturnal-dinosaurs.html"><i>Velociraptor</i></a>, but already showed surprising similarities with birds; The basalmost genus of the clade, <i>Rahonavis</i>, was so bird-like that at first it was thought to be a true avian, closely related to <i>Archaeopteryx</i>. Most recent analyses however consider it a sister taxon to <i>Unenlagia</i>, and therefore an unenlagiine itself.<br /><br /><i>Rahonavis</i> was pretty small, measuring about 70 centimeters in lenght. It lived in late cretaceous Magadascar, being a contemporary of other famous malagasy dinosaurs such as <i>Rapetosaurus</i> and <i>Majungasaurus</i>. Paleontologists are still not sure if <i>Rahonavis</i> was capable of flight, although the presence of quill knobs on it's ulna indicates long wing feathers. The general consensus for the moment though, as suggested by it's robust ulna, evidence of strong ligaments on its shoulder bones and prominent quill knobs, is that this little dinosaur could indeed fly, although probably not as gracefully and efficiently as modern birds. Overall, <i>Rahonavis</i> is an example of how diversified and bird-like were many maniraptors (which in turn shows how subjective and gradual is the path separating true birds and some feathered non-avian dinosaurs), and how flight may have evolved and lost multiple times during the evolution of birds. <br /><br />In the image up top, an individual lands on a rock near the shore of a lake or ocean, something that the ancestors of all unenlagiines once did before triggering the evolution of the mesozoic strok-mimics.</div>
Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-23079493395595540792012-09-22T05:49:00.002-07:002012-09-22T05:52:49.747-07:00Getting Up-to-Date<div class="separator" style="clear: both; text-align: center;">
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I've been having trouble recently to keep this blog updated with my latest paleoart; That's in part due to procrastination, but also some lack of time as well as inspiration to write insightful posts. That should change in the future, although my current, busy schedule means I won't be as productive at least for now. But enough talking, let's go to the pictures!</div>
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<a href="http://karkajou1993.deviantart.com/gallery/#/d5dx3uf" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="http://fc02.deviantart.net/fs71/f/2012/250/5/5/torpedoes_by_karkajou1993-d5dx3uf.png" width="426" /></a></div>
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<span style="text-align: start;">A couple (and presumably an off-screen pod) of </span><i style="text-align: start;">Ichthyosaurus, </i><span style="text-align: start;">the classic fish-lizard, swims joyfully, torpedo-style, in the tropical Jurassic oceans.</span></div>
<a href="http://karkajou1993.deviantart.com/gallery/#/d5e0yqk"><img border="0" height="426" src="http://fc02.deviantart.net/fs70/i/2012/251/e/e/washed_ashore__remake__by_karkajou1993-d5e0yqk.png" width="640" /></a><br />
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A remake of a pretty old piece of mine, entitled <a href="http://karkajou1993.deviantart.com/art/Washed-Ashore-211471549">"washed ashore"</a>; A baby <i>Tylosaurus </i>carcass lies on a beach somewhere along the cretaceous Western Interior Seaway, and a lucky <i>Nyctosaurus</i> is the first to spot it.</div>
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<a href="http://karkajou1993.deviantart.com/gallery/#/d5eegli"><img border="0" height="426" src="http://fc01.deviantart.net/fs71/i/2012/254/2/7/the_wandering_musicians_by_karkajou1993-d5eegli.png" width="640" /></a></div>
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Two <i>Lambeosaurus </i>got separated from the main herd during a tyrannosaur attack. They seek shelter from the rain in the woods, and soon will try to reunite with their companions</div>
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<a href="http://karkajou1993.deviantart.com/gallery/#/d5exw1y"><img border="0" height="426" src="http://fc03.deviantart.net/fs70/i/2012/259/3/6/the_flycatcher_by_karkajou1993-d5exw1y.png" width="640" /></a></div>
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Having been inspired by <a href="http://500px.com/photo/10719099">this picture</a>, from photographer Simon Roy, I've made this spring-y piece of an subadult <i>Alioramus</i> playing around, trying to catch some insects.</div>
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<a href="http://karkajou1993.deviantart.com/gallery/#/d5fkcs5"><img border="0" height="426" src="http://fc07.deviantart.net/fs70/i/2012/265/4/9/uneasy_rest_by_karkajou1993-d5fkcs5.png" width="640" /></a></div>
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Finally, a Camptosaurus decides to rest under the hot afternoon sun of the jurassic Morrison Formation, but he can't let his guard down for too long.</div>
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So that's it for now. I have some plans in my mind for good pictures and will try to put them in practice soon. Until then, I hope you enjoyed this image-rich post!<br /><br /></div>
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Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-72597126818644241032012-09-08T19:36:00.003-07:002012-09-08T20:02:07.978-07:00Exquisitus No More!<a href="http://karkajou1993.deviantart.com/art/Exquisite-325296472"><img alt="" border="0" height="427" id="BLOGGER_PHOTO_ID_5786000592067905890" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ-y5h751JQPxQlc6C3Ra_9dXAF4synAe44wQXw6k1A4BpXUAGZ1Yy0_mPLOXNmvOqXtfFCeIeVvzYEKR7uw2qW_Hh9Sg_rrY9SKJYqVVSqDoAcJzDCp_yPT8Mks6pQhaKU78HEIT8OQbI/s640/exquisite_by_karkajou1993-d5do8d4.png" style="display: block; margin: 0px auto 10px; text-align: center;" width="640" /></a><br />
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One of the hardest things to figure out in paleontology is how should a specimen be classified. Do the characteristics seen in that individual fossil are enough to elect a new genus for it? Or does it represent another species of a previously identified genus? Is it instead a case of intraspecific variation, or perhaps of sexual dimorphism? Is it just a juvenile or a mature form of another known animal? These questions are hard to answer even when it comes to modern, living creatures. Only recently, for example, has a new species of elephant been officially recognized as different from the common African Bush Elephant: it has been determined in 2010 that the forest dwelling elephants of the Congo Basin should be classified as <i>Loxodonta cyclotis</i> instead of being lumped with <i>Loxodonta africana</i>.<br />
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But by observing living animals, we have some clues as to how closely related two individuals or populations may be. Although of course the highly subjetive concept of animal classification is created by humans and does not mean much apart from the convenience of taxonomy, there are some rules to go by. We can investigate, for example, if two individuals can mate and produce fertile offspring to determine if they should belong to the same species. We can note subtle differences between two populations separated geographically and classify them as different subspecies. We can analyze a large sample from a population and perceive what is common, intraspecific variation, what is sexual dimorphism, and what is determined by the age of the animal. But when scientists have only bones, and often not-so-greatly fossilized fragments at that, things become much difficult.<br />
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Among extinct dinosaurs, sometimes these questions can't be decisively answered, at least until we have a better sample of fossils to analyse. Such is the case with <i>Torosaurus</i>, which has recently been suggested to be a mature form of <i>Triceratops</i>; <i>Nanotyrannus</i>, which may or may not be a juvenile <i>Tyrannosaurus</i>; and <i>Tarbosaurus bataar</i>, that is sometimes referred to as <i>Tyrannosaurus bataar.</i> In these cases, competing hypothesis challenge each other to try and prove that some particular species should or should not be lumped into another existing one, and often the very concept of what is a species and how it can be determined by bones alone is debated. In other situations though, the extraordinary state of preservation of some specimens may shed some light on the relationships between them, like how both the north american and the asian species of <i>Saurolophus</i> were found with skin impressions that showed significant discrepancies in scale pattern and suggested that those should be indeed different species within the same genus.<br />
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The main character of today's picture is an example of that uncertainty that surrounds dinosaur classification. Described in 2010, <i>Linheraptor exquisitus</i> was a velociraptorine dromaeosaur that lived in what is now Mongolia. This year however, it has been proposed that <i>Linheraptor</i> is actually the same animal as <i>Tsaagan mangas</i>, another dromaeosaur from the same time and place, that was described in 1996. The small differences between the two speciments found, which was at first considered enough to separate them into different genera, has now been suggested to be a combination of individual variation and artifacts of preservation. The matter is not settled yet, but it seems that <i>Linheraptor</i> is <i>exquisitus</i> no more.</div>
<br />Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-19621550150984434482012-09-04T17:14:00.004-07:002012-09-04T17:45:02.887-07:00The Giant Dwarf<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjL_jBZ4nyvxTZkov-Y-EcbyF0Aj8xIjj6HhC_JFep0kzzUYkUyjlk23J_FgvBWukj2fbPYxnzGoSyqTe5mlm9oXtKJj5mJI3Q7Cc082zFUGTBHcLO82JDcrHCYGx8fS3PSdkSza7o9E-_p/s1600/comp.png"><img alt="" border="0" height="427" id="BLOGGER_PHOTO_ID_5784479587366843330" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjL_jBZ4nyvxTZkov-Y-EcbyF0Aj8xIjj6HhC_JFep0kzzUYkUyjlk23J_FgvBWukj2fbPYxnzGoSyqTe5mlm9oXtKJj5mJI3Q7Cc082zFUGTBHcLO82JDcrHCYGx8fS3PSdkSza7o9E-_p/s640/comp.png" style="cursor: pointer; display: block; margin: 0px auto 10px; text-align: center;" width="640" /></a><br />
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Going against the human tendency for organized categorization, nature is a mess. It follows no order, no rules; it is restricted only by it's own limitations. As such, is common to discover something that challenges our previous views of how everything works. That conflict between our charts and nature's confusing web is very noticeable in paleontology, especially if we take into account it's history.<br />
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Throughout many decades, dinosaur classification was very simplistic and straightforward: every sauropod was big, every theropod was carnivorous, every non-theropod was herbivorous, all big theropods were closely related under the category or "carnosaur". Over the years though, things got a little bit complicated: We now know of dwarf sauropods, possibly omnivorous ornitischians and prosauropods, herbivorous theropods and the clear distinction between carnosaurs and coelurosaurs regardless of size. We've found out that <i>Tyrannosaurus </i>was actually a giant representative of a clade of usually small theropods, and we've discovered small relatives of <i>Megalosaurs</i> as well. And talking about size, it's interesting to note how dwarfism and gigantism evolved multiple times across different dinosaurian lineages.<br />
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One example that goes out of the rule when it comes to size is <i>Sinocalliopteryx gigas</i>: the giant compy. Compsognathids are a rather uncertain group of small, basal coelurosaurs. Composed mainly of small and conservative forms, such as <i>Sinosauropteryx</i>, <i>Juravenator</i> and <i>Compsognathus</i> itself, it has <i>Sinocalliopteryx</i> as the biggest member yet found, measuring more than 2m in length. It lived in the chilly forests of Early Cretaceous China, and is remarkable for it's well-preserved fossil speciments; the holotype shows an extensive coat of simple feathers, as do many other dinosaurs found in the Yixian Formation, but many also show preserved meals. From the stomach cavity of different speciments, interesting remains of fossilized prey were recovered: the small dromaeosaur <i>Sinornithosaurus</i> as well as the ancient bird <i>Confuciusornis</i>.<br />
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Just as <i>Tyrannosaurus</i> was a giant amongst tyrannosaroids, a clade that otherwise remained small to medium for most of it's evolutionary history, <i>Sinocalliopteryx</i> was, as it seems, the culmination of size amongst compsognathids. And from what we can tell, this furry predator was wreaking havoc amidst the small animals that scurried along the chinese forests.</div>
<br />Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-46031669476152022382012-08-23T12:34:00.005-07:002012-08-23T13:12:41.413-07:00Rival Brothers<a href="http://karkajou1993.deviantart.com/art/Banarang-322919224"><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5779954531214737266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjc4_cVu7zjnhwmwYyhVuXHm99Ub4Apamcmniagltcf3DvVVM4uq_XBNgMOtU3qnxAXZ8iCT76-Q8P2mFRroosfazvNIxcm699ve6ToUioI6TvggKZ_xT31ienKxlN8mzo8IVuZbMhFfuZd/s640/krono.png" style="display: block; margin: 0px auto 10px; text-align: center;" width="640" /></a><br />
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As you know, the oceans were also teeming with life while dinosaurs walked on land. We've already talked about <a href="http://thecasualpaleoartist.blogspot.com/2012/03/paleo-flashback-marine-monitors.html">Mosasaurs</a>, the marine relatives of monitor lizards, and <a href="http://thecasualpaleoartist.blogspot.com/2012/08/hipster-ichthyosaurs-were-dolphinin.html">Ichthyosaurs</a>, the dolphin-mimics, but there's one major group of mesozoic marine reptiles left to cover: the plesiosaurs.<br />
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While mosasaurs swam by ondulating their tails side-to-side, much like a crocodile, and Ichthyosaurs swam similarly to sharks and other fast-swimming fish, plesiosaurs had a unique form of locomotion. With broad bodies and four long flippers, these animals propelled themselves by moving their limbs up and down in an alternating manner. The closest alternatives for these way of movement are sea turtles and penguins, but none of them use all four limbs for rowing. The way plesiosaurs moved went extinct along with them.<br />
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Being "reptiles", plesiosaurs also have a history of transition. Like every other aquatic tetrapod, their ancestry can be traced back to terrestrial animals that became increasingly amphibious over many generations. The forebears of plesiosaurs were the nothosaurs, otter and seal-like animals with webbed feet that show progressive adaptations to a permanent life in the water: somewhere along the line, they lost the ability to come onto land and could do everything in the water, including mating and giving birth to live young.<br />
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Plesiosaurs can be divided in two major groups: plesiosauroids and pliosauroids. As a general rule, plesiosauroids had long necks and small heads, and were mostly adapted to slow-simming and bottom-feeding. Famous examples include <i>Plesiosaurus</i> itself, <i>Elasmosaurus</i> and <i>Cryptoclidus</i>. Pliosauroids, on the other hand, were short-necked and big-headed predators, with more streamlined shapes. Well-known species include <i>Liopleurodon</i> and the misterious "Predator X". But every rule has it's exceptions, so deviating from this broad categorization are long-necked pliosauroids like <i>Rhomaleosaurus</i> and short-necked plesiosauroids such as <i>Dolichorhynchops.</i><br />
<br />While plesiosauroids produced peculiar forms, with bodies that were once described as similar to "a<span class="st"> snake drawn through the shell of a turtle", pliosauroids culminated in some of the biggest predators on earth, often exceeding 15 meters (50 feet) in length. These successful and diverse animals persisted on the oceans until the very end of the Mesozoic, when they went extinct along with non-avian dinosaurs, pterosaurs and many other fauna.<br /><br />On the image up top, a pair of australian plesiosaurs, the pliosauroid <i>Kronosaurus</i> and the plesiosauroid <i>Woolungasaurus</i>, get ready for a serious confrontation.</span><i></i></div>
<br />Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-79915541428635468102012-08-21T14:56:00.004-07:002012-08-23T12:34:28.186-07:00Deceptive Thunder Lizard<br /><a href="http://karkajou1993.deviantart.com/art/Awakening-of-a-Giant-322549787"><img alt="" id="BLOGGER_PHOTO_ID_5779263786497041986" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlbaMNt5fbMhHnfY4tZMi-Kj3Hr3EGoaawmDkfUt1kM9Zl7eNnH1qaO2OWoEELWgYOoyugDls-CRHTMB_YZXTIMTw1wT4ZGM_-LUR74QxmOCLbnCEj-PVilOvrL5dTPaiVLGfHfgUWlueF/s640/apat.png" style="display: block; margin: 0px auto 10px; text-align: center;" width="640" border="0" height="427" /></a><br /><div align="justify"><i>Apatosaurus </i>is one of the classic sauropods, a symbolic representative of the Jurassic Morrison Formation. But these robust and massively-necked cousin of the slender <a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&ved=0CFIQFjAC&url=http%3A%2F%2Fthecasualpaleoartist.blogspot.com%2F2012%2F03%2Fnew-diplodocus.html&ei=8xE0UNKOB4Tv0gGt9IHQCw&usg=AFQjCNGMAYJgBWtdW8QQ6cfdf5ahFSISzw&sig2=eSGUVILSeGta5iPzYV1Fsg"><i>Diplodocus</i></a> has a confusing history of misclassification.</div><div align="justify"><br />When the first fossils of Apatosaurus were found in 1877, paleontology was still in it's adolescence. After the first dinosaurs were uncovered in Europe, including <i>Iguanodon</i> and <i>Megalosaurus</i>, more prehistoric animals were being discovered in other parts of the world, and the western United States turned out to be a paleontological treasure trove. The notion that enormous, now extinct animals roamed the world before men was sinking into people's minds and stirring up all sorts of scientific theories, and various museums were competing with each other for the best and biggest fossils that could be found. This period, which culminated in the famous Bone Wars, saw many paleontologists going crazy over dinosaur bones, especially Edward Drinker Cope and Othniel Charles Marsh. And while this meant that people were really excited and willing to fund various expeditions to search for fossils, it also represented a fight that involved theft, personal attacks and destruction of rival findings.<br /><br />O. C. Marsh described <i>Apatosaurus ajax</i> on basis of an<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6CAV7YkSbZkHOL33eJb7ID0sSg0S-nYdQNe9ahdYDEYf4FsYvAUFmsFMDRwR0UUacvGEw8zH7jMfLIBlx7mR009Mdh8Aex659V84WbOQZ5FikSWazzsKYC4f33o44qIT00bZbvaw2FK33/s1600/apat3.png"><img style="float: right; margin: 0px 0px 10px 10px; cursor: url("chrome://thumbnailzoomplus/skin/images/tzp-cursor.gif"), crosshair;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6CAV7YkSbZkHOL33eJb7ID0sSg0S-nYdQNe9ahdYDEYf4FsYvAUFmsFMDRwR0UUacvGEw8zH7jMfLIBlx7mR009Mdh8Aex659V84WbOQZ5FikSWazzsKYC4f33o44qIT00bZbvaw2FK33/s400/apat3.png" alt="" id="BLOGGER_PHOTO_ID_5779954133541738146" width="150" border="0" height="150" /></a> incomplete skeleton of a juvenile sauropod, and two years later found another, more complete skeleton which he classified as <i>Brontosaurus excelsus</i>. None of those specimens had a skull though, but in the midst of the ongoing competiton and the urge to present a complete skeleton of such a huge animal, the heads of these animals were speculated to be similar to that of <i>Camarasaurus</i>, another sauropod from the Morrison Formation and the only one with decent skull material at the time. So, for many years, a mount of <i>Brontosaurus excelsus</i> was exposed at the American Museum of Natural History with a <i>Camarasaurus</i> head, as well as a more 'reptilian' posture and dragging tail as was common at the time. Only in 1903 a study made by paleontologist Elmer Riggs concluded that <i>Apatosaurus ajax</i> and <i>Brontosaurus excelsus</i> were similar enough that they should be lumped together in one single genus, and according to the rules of taxonomy, the name <i>"Apatosaurus</i>" had priority for being coined first. Thus, <i>Brontosaurus </i>was considered an invalid genus.<br /><br />But Brontosaurus was already famous by then. For a while it was the biggest dinosaur known, and for many years (and ever since, for that matter), it appeared on dinosaur books, magazines, TV shows and every kind of media. Brontosaurus, the "Thunder Lizard", was so entrenched on people's mind as the lumbering, swamp-bound giant of Jurassic North America that its reclassfication and reformulation did little to its reputation. It was no more a scientific name for a real dinosaur, but it became the timeless representation of what a sauropod <i>is</i>. And although now we know that <i>Apatosaurus</i>, and sauropods in general, were very different from what was believed of them in 1877, Brontosaurus still remains as the sprawling, algae-loving giant, free from scientific rigour since, by all means, it never actually existed.</div><br />Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-2320592876320225492012-08-11T17:32:00.005-07:002012-08-11T18:24:56.540-07:00Hipster Ichthyosaurs Were Dolphinin' Before Dolphins<a href="http://karkajou1993.deviantart.com/art/The-Blue-320371763" title=" "><img alt="" border="0" height="427" id="BLOGGER_PHOTO_ID_5775578079391087314" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFIgXPqjZJMTRkGr7AmODZuYxuA5hcf4ABS9OGN7HebQ5ftu9vbX92SI2vVvR-ReaDgRUH2sO9OMuXKtrz6CNnFVSclPPlTt79ErniSvazoarnT6fNO3moRIViAHqEIgCBOfKhU5VsWswd/s640/steno.png" style="display: block; margin: 0px auto 10px; text-align: center;" title=" " width="640" /></a><br />
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One of the most interesting concepts seen in evolution is convergence: the tendency for organisms filling similar niches to evolve similar anatomy and behaviour independently from each other. It's a phenomenon that can be seen throughout the animal kindgom: bats and birds developed parallel ways to fly although by different ways; many marsupials are comparable to the more widespread placental mammals in shape and size; some coral species look like plants because both are sessile organisms that generally need high surface areas to acquire/metabolize nutrients. Similar needs equal similar adaptations, simply because it works.<br />
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If you're an animal trying to move efficiently in the water, you have a few ways to go through: you can move by propulsion - generating forward movement by pushing water in the opposite direction - either slowly and rather randomly like jellyfish or quickly and precisely like squids. Or you can move by undulating your body up-and-down or side-to-side like sea snakes, crocodiles and aquatic worms. Or yet you can use paddles or fins, like sea turtles and manta rays, as well as any combination of the above mechanisms and yet others that nature came up with. The point is, in this case natural selection favours those that can move more efficiently and therefore survive and reproduce, and there are only so many ways that you can achieve that. That's why the oceans are a great environment to observe how different animals evolved convergently: if they need to swim well, they'll follow similar routes. And, as often mentioned here, extinct creatures followed the same basic biological rules as extant ones, and an often mentioned animal group associated with convergent evolution are ichthyosaurs.<br />
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Ichthyosaurs were marine reptiles, descendent from an as-yet unknown terrestrial group that went back to the water the same way cetaceans would do millions of years later. Just like cetaceans, their lineage produced more specialized forms over time, abandoning the early lizard-like bauplan for a permanent and active life in the seas. Seeing as they both went through analogous evolutionary histories, it's no wonder that the 'final' result was also remarkably resemblant. Along with sharks, ichthyosaurs and dolphins prove that a winning formula is often reutilized: with fusiform bodies, crescent shaped tails fins, estabilizing dorsal fins, paddles used for maneuverability and the ability to give birth to live young without going onto land to lay eggs, these were animals perfected for a life in the water.<br />
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But apart from the basic shape, ichthyosaurs were also very diverse. There were huge leviathans with small teeth and big eyes, like <i>Shastasaurus</i> and <a href="http://thecasualpaleoartist.blogspot.com/2012/03/triassic-leviathan.html"><i>Shunosaurus</i></a>, that may have lived like Sperm whales - diving to great depths in search of soft-bodied invertebrates such as the already-present squids. Others were elongated and serpent-like, as <i>Cymbospondylus</i> and <i>Leptonectes</i> and finally, more derived forms like the europeans <i>Ichthyosaurus</i> itself and <i>Stenopterygius</i>, featured on the image up-top, had many millions of years to get the shark and dolphin-like shape, ideal for swimming in high speeds after schooling fish and cephalopods. Together, they are one more example of how extinct organisms were just as well-adapted to their world at one time as our familiar fauna is today.<br /><br /></div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-45695723134867269182012-08-05T17:40:00.004-07:002012-08-05T18:18:07.194-07:00Deadly Gluttony<div align="justify"><a href="http://karkajou1993.deviantart.com/art/Gluttony-319222413"><img title="" style="float: left; margin: 0px 10px 10px 0px; cursor: pointer; width: 267px; height: 400px;" src="http://3.bp.blogspot.com/-6qcSaag1RHM/UB8TAsSbA1I/AAAAAAAABHI/-3T6VG7Uhvo/s400/hat.png" alt="" id="BLOGGER_PHOTO_ID_5773354149921620818" border="0" /></a>As my mom used to say (in Portuguese), "some people have eyes bigger than their bellies". And that was usually directed towards me, while I was struggling to shove the last spoonful of the huge puddin I ordered inside my mouth. But, although gluttony is one of the seven deadly sins, it is arguably not exclusive to people - and sometimes it can be fatal. There are several cases of animals dying from asphyxiation after trying to swallow prey bigger than their throats can handle, ranging from fish to snakes to herons and indeed even humans. I remember a photograph that circulated around the internet a couple years ago in which a reticulated python burst open after trying to swallow an alligator in the Everglades, while another famous series of photographs depict a grey heron eating a rabbit that was so relatively big that I still can't wrap my head around it, and although that one survived, <a href="http://scienceblogs.com/tetrapodzoology/2009/12/06/heron-vs-big-lamprey/">others of it's kind weren't so lucky.</a><br /><br />As usual, while contemplating such weird behaviours seen throughout the animal kingdom, I tried to envision if and how the same thing would happen in the Earth's past and in doing so, pterosaurs immediately came to mind. Particularly azdharchids, the giant pterosaurs which heyday was the late Cretaceous, seemed like good candidates to gluttons that would die by their stomachs - in recent years scientists found out more about how these animals lived and behaved, and they seem to have been good analogues for herons and storks: although able to fly, they likely spent more time on the ground, walking around and grabbing baby dinosaurs by their heads to swallow them whole.<br /><br />Hence, the illustration for this post came into being. In it, the romanian azdharchid <i>Hatzegopteryx</i>, one of the apex predators in Cretaceous <a href="http://thecasualpaleoartist.blogspot.com/2012/06/islanders.html">Hateg Island</a>, collapses on the ground after dying by choking on a young <i>Elopteryx</i>, a slender troodontid, that was just too big for it to swallow. A sad and futile end to an incredible piece of biological engineering.<br /><br /></div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-5461328537840990222012-08-02T18:27:00.005-07:002012-08-02T19:23:59.784-07:00The King in the North<a href="http://karkajou1993.deviantart.com/art/The-King-in-the-North-318647067" title=" "><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5772252585948181474" src="http://3.bp.blogspot.com/-WbOR1Wk4x7E/UBspJOtFc-I/AAAAAAAABGE/zFaPmA2U0yk/s640/alaska2.png" style="display: block; margin: 0px auto 10px; text-align: center;" title=" " width="640" /></a><br />
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<i>Troodon </i>is one of the most famous dinosaurs, classically known as the smartest of them all. It gave rise to the concept of dinosaurs evolving into sapient, civilized beings had they not died by the end of the Cretaceous period, symbolized by the infamous and overly human-like "dinosauroid" which was always present in dinosaur books from the last few decades. Although it's brain-to-body ratio was larger than most non-avian dinosaurs, in reality trodoontids likely weren't much smarter than most modern birds. But even if they weren't as intelligent as most people think, they were surely remarkable: remains of <i>Troodon</i> have been found in North America from as south as New Mexico all the way up to Canada. It's doubtful that all these fossils represent the same species (<i>T. formosus</i>) due to the vast span in time and space from which they are recovered, but it is obvious that they come from very similar animals that must have been doing something right to be so successful.<br />
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Recent studies suggest that trodoontids may have <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQZMGJplWGhHCl1OClXm4aqiWzwWiQlnbxr6A2H7Lm47Lk2TBj4ri3YAOX-xXCyAVFSgOaYEDHahpI2djM4OwT8IBCTQ1glJJUs_aObviOFZa2qQH30fh_nnOMyRQGr5iez89yoPFb8rKI/s1600/alaska3.png"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5772266388720020242" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQZMGJplWGhHCl1OClXm4aqiWzwWiQlnbxr6A2H7Lm47Lk2TBj4ri3YAOX-xXCyAVFSgOaYEDHahpI2djM4OwT8IBCTQ1glJJUs_aObviOFZa2qQH30fh_nnOMyRQGr5iez89yoPFb8rKI/s1600/alaska3.png" style="float: right; margin: 0px 0px 10px 10px;" title=" " /></a>been omnivorous, since while they had the famous sickle claws shared with their dromaeosaur cousins, their teeth were unusual amongst theropods in being similar to those of herbivorous reptiles such as iguanas. This indicates that <i>Troodon</i> and it's kin could take advantage of more food sources than their contemporaries. Their eyes were also exceptionally big, wich indicates that they may have been adapted to nocturnal or crepuscular life, and faced slightly forward, which gave them a degree of binocular vision. There is also some evidence that <i>Troodon</i> favoured cool climates, since it's remains are more abundant in northern than southern areas, including arctic regions. And there was one particular place where <i>Troodon </i>reigned supreme: Alaska.<br />
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There are abundant fossils of teeth attributed to <i>Troodon</i> in northern Alaska, dating from the Campanian-Maastrichian. During this time, Alaska was already inside the artic circle, and experienced very low temperatures and long periods of darkness in winter. Other american dinosaurs are known from arctic regions, such as <i>Edmontosaurus</i> and <a href="http://thecasualpaleoartist.blogspot.com/2012/02/boreal-dinosaurs.html"><i>Pachyrhinosaurus</i></a>, but the farther north you go, the less theropod species are present. And there's a special thing about the alaskan <i>Troodon</i> teeth: they are twice the usual size. It seems that in the absence of large predators, especially tyrannosaurs, the northernmost variety of <i>Troodon</i> climbed to the top of the food chain, becoming the apex predator of the polar environment and preying upon the alaskan hadrosaurids. Its generalized bodyplan and hability to cope with low-light conditions allowed it to thrive during the months were the sun wouldn't rise, and these adaptations may be a sign that the alaskan <i>Troodon</i> didn't necessarily migrate south in winter and was instead a permanent resident.<br />
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In the image up top, and Alaskan <i>Troodon</i> (of undetermined species) witnesses the beauty of the aurora borealis.<br /></div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-37142768818952228682012-07-27T16:40:00.001-07:002012-07-27T16:55:58.098-07:00Pterosaur Couples<div class="separator" style="clear: both; text-align: center;"><a href="http://karkajou1993.deviantart.com/art/Courtship-317358459?q=gallery%3Akarkajou1993%2F16095506&qo=0" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img style="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5yJ4exQaCxXZBBle4zMc5b-BK4Y21udmJvKhioOq6tUEn33QZmARbmZrNefNeHLLdivuf-rp-3GvF6az_Q5xp0lag-gMfiVUM1hG7__FSivT9dNc8fFYGvj372PIg-dxhBieY3FXXd1Tu/s640/ptera.png" title=" " width="640" border="0" height="426" /></a></div><br /><div align="justify">It's been quite a while since the last time I've done a pterosaur illustration and, seeing as they're some of my favourite prehistoric groups, I promptly fixed the situation by producing these two pieces, based around the concept of pterosaur couples (I'm a romantic guy).<br /><br />The first one, seen up top, features the now-called <i>Geosternbergia sternbergi</i>. This animal, which was formerly classified as a species of <i>Pteranodon</i> (<i>P. sternbergi</i>), was given it's own genus after a 2010 study concluded the differences between it and the other species belonging to the genus <i>Pteranodon</i> were enough to warrant this taxonomic reformulation.<br /></div><br /><div align="justify">Having lived around the Western Interior Seaway, in what is now central USA, <i>Geosternbergia </i>seems to have been sexually dimorphic. Two morphs are present: the biggest morph appears to be the male, being up to three times the size of the smaller morph and sporting a big, laterally flattened crest atop it's head upon sexual maturity. The smaller morphs, presumed to represent females, are twice as abundant and possess much smaller crests and proportionally larger and wider pelvic bones, that represent the birth canal from which the eggs were laid. From these lines of evidence, it is possible to hypothesize that the species was polygynous, that males competed amongst themselves for the right to mate with a number of females and that they took no part in taking care of the eggs and young, since such behaviour is unheard of in modern polygynous males that have many young at once.<br /></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://karkajou1993.deviantart.com/art/Returning-Home-317017170?q=gallery%3Akarkajou1993%2F16095506&qo=1" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img style="cursor: url("chrome://thumbnailzoomplus/skin/images/tzp-cursor.gif"), crosshair;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5MH78ZgveGWxszEcz1T2_Kl7ThV9GAVY0U08S0nQBw21VTarMWCgIrecnRUew-NoNvwojh6cti-92yel4lbMm-h_6fdMBm0EXzPdtR1USwmalBvohrRwZkkoAJoXJU8BkuiBPJjjOOIbq/s640/cneto.png" title=" " width="640" border="0" height="426" /></a></div><br /><div align="justify">The second image features a flying pair of <i>Ctenochasma elegans</i>, a species known from the famous Solnhofen Limestone of Germany, as well as eastern France. <i>Ctenochasma</i> is a close relative of the argentinian <i>Pterodaustro</i>, and like it's south american counterpart, it sported hundreds of thin, elongated teeth, that were used to filter small invertebrates from the water in a similar way to whales and flamingos do today. Unlike <i>Pterodaustro</i> though, <i>Ctenochasma </i>is a more primitive form with fewer and less specialized teeth, indicating a more varied and generalized diet.<br /><br />A recent study used a technique consisting of comparing the structure of the scleral rings in extinct archosaurs, including two species of <i>Ctenochasma</i>, and modern birds and reptiles found evidence of nocturnal activity in these animals. They may have behaved like modern nocturnal seabirds and anseriforms, feeding on shallow waters at night and resting throughout the day, indicating a case of niche partitioning with other pterosaurs from Solnhofen that were found to have been diurnal, like <i>Pterodactylus</i> and <i>Scaphognathus</i>.<br /><br /><br /></div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com3tag:blogger.com,1999:blog-6704700031413149466.post-69997165008865810402012-07-22T12:44:00.001-07:002012-07-22T12:44:38.289-07:00Teaser of the Week<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMNPDBl_74Yq97jlSDxXxZj9ZxpHt-Ub3zGlgREdWLlz5iTAF1y-Tfho9wItUcjmjjZkYrIn4NYPU6gpScoli0pSkRFS4RF2rJAK50qBdpYt0ZPO9XVdxgiGGTQj_L1sV7HbIQkzcokB0Z/s1600/anom.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMNPDBl_74Yq97jlSDxXxZj9ZxpHt-Ub3zGlgREdWLlz5iTAF1y-Tfho9wItUcjmjjZkYrIn4NYPU6gpScoli0pSkRFS4RF2rJAK50qBdpYt0ZPO9XVdxgiGGTQj_L1sV7HbIQkzcokB0Z/s1600/anom.png" title=" " /></a></div>
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Some strange shrimp are coming to the aquarium..</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-88680298929275971132012-07-16T20:19:00.003-07:002012-07-16T21:08:15.460-07:00Entombed in Sand<a href="http://karkajou1993.deviantart.com/art/Hide-yo-eggs-315153485"><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5765974071940860866" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrf4mzj1opiQ-Imrcrkz_QTOo74RINyUwL-XBOGnxecK_xxifwzqr7GOU3cQX-obYZZez3Phr2cbaxd4sPeW9bmVq7FpP-gCy1JZAqQCqm9XIXeWSRqb2_umgAMoIbfmZOHtXH5y7PDJIP/s640/citi2.png" style="display: block; margin: 0px auto 10px; text-align: center;" title=" " width="640" /></a><br />
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Mother Nature has many ways to express her power, and such phenomena are as old as Earth itself. Every year, hurricanes, tsunamis, earthquakes and forest fires take their toll and there's not much we can do to protect ourselves, except be prepared for them. One such phenomenon is the sandstorm, the equivalent of an avalanche of sand, that is common in arid in semi-arid regions. Sandstorms are a combination of strong winds and small particles, forming often enormous walls of dust travelling at incredible speeds, blocking sunlight and killing both flora and fauna that stand on their way. These storms can be so big as to be seen from space - there are records of sandstorms on Mars - and carry big quantities of sand and dust across entire oceans, causing disruption in global weather patterns and great economical impact. But sandstorms are also responsible for some great discoveries on the paleontological field.<br />
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Sand is a good material for fossilization, since it forms sedimentary layers that cover the remains of dead animals and plants and protects them against scavengers and erosion, increasing their chance of becoming well-preserved fossils. Usually, fossils found on arenite layers represent animals that died and were transported to rivers, lakes and oceans and covered by the sediments on the bottom, but these fossils are often disarticulated due to the water currents and the process of being transported from the place of death to the final destination. Sandstorms, on the other hand, are so quick that the animals caught in them are often preserved in the same position they were in by the time of death, providing an amazing insight into the behaviour and anatomy of the victims.<br />
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Two famous fossils created due to the power of sandstorms (or<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUEsvAuOhncS1qzc3VVPcro96dhk_XJzqSayWA9W0UyDVhlwijtDwudxoOJiTXf3P7I2nrOQV0a95AJVDl-T0bdQWsNk1gfDlut0M3_Lk1M1v1-H3I7p6ulQcTox9LgfP3EzlMCHDRHEl-/s1600/citi3.png"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5765984596272636002" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUEsvAuOhncS1qzc3VVPcro96dhk_XJzqSayWA9W0UyDVhlwijtDwudxoOJiTXf3P7I2nrOQV0a95AJVDl-T0bdQWsNk1gfDlut0M3_Lk1M1v1-H3I7p6ulQcTox9LgfP3EzlMCHDRHEl-/s1600/citi3.png" style="float: right; margin: 0px 0px 10px 10px;" title=" " /></a> alternatively, sandslides) are the famous "fighting dinosaurs" - A mostly complete and articulated duo of a <span style="font-style: italic;">Protoceratops andrewsi</span> and a <span style="font-style: italic;">Velociraptor mongoliensis</span> locked in combat - and the partial skeleton of a <span style="font-style: italic;">Citipati osmolskae</span>, an oviraptorid historically mistaken for <span style="font-style: italic;">Oviraptor</span> itself, sitting on top of it's eggs in a way remarkably similar to brooding birds today. This fossil was very important for two reasons: firstly, it helped clear out the confusion that gave <span style="font-style: italic;">Oviraptor</span> it's name - when it was first discovered, <span style="font-style: italic;">Oviraptor</span> was associated with a clutch of eggs originally believed to have belonged to <span style="font-style: italic;">Protoceratops</span>, which led the paleontologists to believe that it was an egg-eater, while the <span style="font-style: italic;">Citipati </span>fossil showed that the eggs were actually it's own - and it represented an important hint of the then hotly debated relationship between dinosaurs and birds, since it clearly showed a very bird-like behaviour and the possibility of it having arm feathers to cover it's eggs.<br />
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In the image up top is my interpretation of this possible scenario: a <span style="font-style: italic;">Citipati</span> responds to it's parental instinct by sitting on top of it's nest, hoping that this would protect it from the incoming sandstorm, in an effort that would ultimately be fatal for it and the eggs, but fruitful for the human paleontologists who discovered them millions of years later, in what is now Mongolia.</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-81453430764803431132012-07-09T10:43:00.003-07:002012-07-10T07:04:56.159-07:00The Last of the Titans<div class="separator" style="clear: both; text-align: center;">
<a href="http://karkajou1993.deviantart.com/art/iBuenos-Dias-313582723"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLG7BuvUtJkLMj2I0FIqewOlAoyYFGnvZqHUBQEm8lnmqfZg0xSYCNTLrLMSDWHZEVEuQBpcLumRlAsMYIde2B0oTSd2JmnPqQGmkqwPnuYs5ttg_4S2b6ufMbyrAlKZBkvUMtkiubsu9y/s640/brach2.png" width="640" /></a></div>
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Sauropods - the group of four-legged, long-necked and long-tailed herbivore dinosaurs - were truly giants. While some exceptions such as <span style="font-style: italic;">Europasaurus</span> and <span style="font-style: italic;">Magyarosaurus</span>, which were the result of <a href="http://thecasualpaleoartist.blogspot.com/2012/06/islanders.html">island dwarfism</a>, were not much bigger than an elephant, most derived sauropods were in the size range of rorqual whales, the biggest animals alive today. This amazing creatures had a lot of special adaptations that allowed such large sizes, from structurally efficient skeletons to a system of air sacks, not unlike those seen in birds, that greatly reduced their weight in comparison to a mammal of the same size. And, while at one hand they were very dependant on stable ecosystems to have enough space and food to survive, the group as a whole survived in every continent until the end of the age of non-avian dinosaus.<br />
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No doubt, the hey-day of sauropods was the Jurassic period: in the Morrison Formation alone, dozens of genera coexisted, such as <span style="font-style: italic;">Amphicoelias, Apatosaurus, Barosaurus, Brachiosaurus, Camarasaurus, Diplodocus </span>and <span style="font-style: italic;">Seismosaurus</span>. Such an abundance of enormous herbivores is a sign of how lush was the Jurassic world, and how adaptable were the sauropods to occupy different niches in the same environment. However, for reasons not yet fully understood, sauropods apparently underwent a decline in diversity in North America and Europe after the Jurassic-Cretaceous boundary; while there were usually one or some taxa at any given Cretaceous formation, most of those being titanosaurs, the giants were evidently rarer. Perhaps changing climate, unsuitable geography and competiton from other herbivores diminished their numbers, or maybe such apparent rarity is an illusion due to lack of well-preserved fossils. Nevertheless, one sauropod in particular proves that there were still titans roaming T-rex territory: <span style="font-style: italic;">Alamosaurus.</span><br />
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<span style="font-style: italic;">Alamosaurus sanjuanensis</span> was a titanosaur, the most abundant kind of sauropod during the Cretaceous period. This lineage produced truly huge animals, like <span style="font-style: italic;">Argentinosaurus</span> from South America and <span style="font-style: italic;">Paralititan</span> from Egypt, both of which are thought to have exceeded 100 tons. <span style="font-style: italic;">Alamosaurus</span> itself rivaled these in size, being the biggest sauropod known from North America. This species was found in both New Mexico and Texas, that during the Cretaceous were the southern part of Laramidia (the landmass that consisted of the western half of North America, then divided by a shallow sea running through it's center). While apparently absent from the northern areas, they still likely coexisted with <span style="font-style: italic;">Tyrannosaurus</span>, <span style="font-style: italic;">Edmontosaurus</span> and <span style="font-style: italic;">Troodon</span> in their southern ranges, and might have been some of the only sauropods that witnessed the collision of the asteroid that symbolises the K-T boundary.<br />
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In the image up top, a pair of <span style="font-style: italic;">Alamosaurus </span>passes by while a group of <span style="font-style: italic;">Ojoceratops</span>, close relatives of the better-known <span style="font-style: italic;">Triceratops</span>, munch on low-lying vegetation while the sun rises.</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com3tag:blogger.com,1999:blog-6704700031413149466.post-56421208782384271242012-06-21T16:40:00.009-07:002012-07-09T15:32:10.678-07:00South-American Stork Mimics<a href="http://karkajou1993.deviantart.com/art/I-Found-It-It-s-Mine-309794134"><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5756645457100820738" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgilvX73PutRSYOt_KqCIYPbscJTlt4gUY_LslgAe4kE-YJRtFxAquYawiMOUm0RMEraLiO-oXHqyH2Qv8qm23jQ9bUXaWKI_SePsNfOfCVPtRyXaL_NV8Ij3_oiv7LAun6CE80kJ3OYAyh/s640/unen2.png" style="display: block; margin: 0px auto 10px; text-align: center;" width="640" /></a><br />
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When one thinks of dromaeosaurs - or, more casually, "raptors", the classic taxa come to mind: <span style="font-style: italic;">Velociraptor</span>, <span style="font-style: italic;">Deinonychus</span>, and for the "bigger is better" people, there's of course <span style="font-style: italic;">Utahraptor</span>. Although in recent years the notion that these animals were fully or mostly feathered (including the biggest species) is much more widespread due to some hard fossil evidence, there's still a stereotype regarding their lifestyles and the way they acted in life. Many people would think of them as (not-quite)avian wolves, living in packs and hunting big game. However, it is becoming increasingly clear that, not only is the "feathered wolves" idea not so realistic after all, but also that dromaeosaurs were a much more diverse group of dinosaurs.</div>
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Deinonychosaurs come in all shapes and sizes. Some were incredibly small by Mesozoic standards, such as the raven-sized <span style="font-style: italic;">Microraptor</span>, while others rivaled tyrannosaurids in size, like <span style="font-style: italic;">Achillobator</span>. Most troodontids and some small, arboreal dromaeosaurs are now thought to have been omnivorous, including seeds, fruit and leaves in their diets, and amongst the likely hypercarnivorous forms, the size difference alone is enough to ascertain that different species ate different things. Regardless of being pack-hunters or not, it is now believed that these animals would not prey on dinosaurs several times their size. Dromaeosaurs were not sauropod-hunters, and the big ceratopsians and hadrosaurs were probably off their menu as well. Yet, not every 'raptor' was running after small ornithopods or little mammals - a specialized group of mostly south-american forms was eating something quite different: fish.<br />
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<a href="http://karkajou1993.deviantart.com/art/Come-Here-Fishy-Fishy-278890043" title=""><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5756645230498275970" src="http://3.bp.blogspot.com/-1_9zVDP1O2Q/T-O2Vk3L4oI/AAAAAAAABCQ/JCr3aIbGIFI/s640/3f6y4hep.png" style="display: block; margin: 0px auto 10px; text-align: center;" title="" width="640" /></a><br />
The Unenlagiines were a basal group of dromaeosaurus known from South America and Madagascar (presumably having lived in other parts of Africa as well). Already very bird-like, most of the well-known species appear to have been fish-eaters: while <span style="font-style: italic;">Rahonavis</span> was likely arboreal and preyed on small vertebrates, <span style="font-style: italic;"></span><span style="font-style: italic;">Buitreraptor</span>, <span style="font-style: italic;">Austroraptor</span> and possibly <span style="font-style: italic;">Unenlagia </span>show adaptations for a piscivorous diet such as big claws and long snouts filled with conical teeth.<br />
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Little is actually known about this group, but it's likely that they form an early off-shoot of deinonychosaurs descendent from <span style="font-style: italic;">Rahonavis</span>-like, flying ancestors that engaged in a more terrestrial lifestyle, much akin to what troodontids, eodromaeosaurs and other feathered dinosaur lineages went trough. Instead of evolving towards omnivory, big game hunting or mammal-killing, some unenlagiines went for the waters where fish were an abundant food source. These were apparently the herons and storks of Mesozoic South America.</div>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxmQa4GW8QAQVmHUuKwA-yZP4ZHq6ptiA4TMSeUa0F7Ro8U3sjKj28RtoNxnupoBQH49sPaYTOAwLgCeLtSxQVxROYenULRxXe_slnvIH6mbSwo-H9bTUf5FVGiww5qkb54TN_ykmuoRu5/s1600/3f6y4hep.png"><br /></a>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com2tag:blogger.com,1999:blog-6704700031413149466.post-26980034509632474212012-06-15T15:23:00.004-07:002012-07-09T15:07:03.237-07:00The Islanders<a href="http://karkajou1993.deviantart.com/art/The-Edge-of-the-World-308410800"><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5754393094159063906" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilUCCii-FPC_DMalOOUTAw4YKPk6Tf9vF-gV9WZLy9APklcOsa4GUM6ZF6VKB5umIhK2t6qZCD-pRjEqrYoSo_X0X4UkmGgJo0eiCBz12HW6Go3RtaYjzxftdbvtIksaE2LFO1zGNOIGr-/s640/balaur2.png" style="display: block; margin: 0px auto 10px; text-align: center;" width="640" /></a><br />
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As Mr. Charles Darwin would have said, "islands are a laboratory for evolution". The reduced and isolated space found in these regions result in limited and peculiar populations of both animals and plants that need to adapt and evolve very differently from their mainland counterparts. Several evolutionary phenomena related to islands are known to affect the process of speciation, such as the tendency for small animals to get bigger and big animals to get smaller after several generations (island gigantism and dwarfism respectively, as dictated by the Foster's rule) that can be observed in giant tortoises and rodents and dwarf mammoths and even hominids. Other singular characteristics can arise from the lack of predators and abundance of food, which can be seen in the several lineages of birds that became large and flightless when isolated. But this strage effect that islands have on evolution is not by any means something new; the fossil record shows that the Mesozoic experienced some interesting cases of isolated evolution.<br />
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What is now Europe was a series of archipelagos during much of the Mesozoic era, due to the absent or reduced polar ice caps causing higher sea levels. Countries like England, France and Germany were mostly submerged at the time resulting in a tropical collection of islands, each with unique ecosystems, and one of the most strange and well-studied of these was Ha<span style="font-weight: bold;">ț</span>eg Island, which was part on modern Romania. The fauna in this location was an interesting collection of known families with a quirk: <span style="font-style: italic;">Rhabdodon </span>and <span style="font-style: italic;">Telmatosaurus</span> were relatively small ornithopods; <span style="font-style: italic;">Magyarosaurus </span>was evidently a dwarf sauropod; <span style="font-style: italic;">Hatzegopteryx</span> was a giant pterosaur relative to <span style="font-style: italic;">Quetzalcoatlus</span> and probably one of the apex predators in the island; and perhaps the oddest of the Romanian dinosaurs, <span style="font-style: italic;">Balaur bondoc</span> was a highly specialized dromaeosaur.<br />
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<span style="font-style: italic;">Balaur</span> had the basic bodyplan of a dromaeosaur like <span style="font-style: italic;">Velociraptor</span>, of which is thought to be a close relative. But the "dodo-raptor", as it is sometimes called, had very interesting autapomorphies. Apart from being relatively more robust and compact, <span style="font-style: italic;">Balaur </span>had an enlarged pubis, a hypertrophied and sickle-clawed first toe (which is normally reduced in most theropods) and a highly reduced and non-functional third manual digit. It is believed that <span style="font-style: italic;">B. bondoc</span> was one of the top predators of it's insular ecosystem, relying more on strenght and less on speed than usual for dromaeosaurids, but the exact reasons for all the strange adaptations are not completely understood. Nevertheless, it is clear that this was just one more example of a very singular animal shaped by evolution in isolation.<br />
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On the image up top, a <span style="font-style: italic;">Balaur</span> stands on a beach observing the Tethys Sea in the horizon, the very edge of his known world, not knowing that by global standards, they were the oddities.</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-25723563121639729602012-05-20T09:24:00.009-07:002012-07-09T15:07:43.930-07:00The Mother of all Extinctions<a href="http://karkajou1993.deviantart.com/art/The-Great-Dying-303170991"><img alt="" border="0" height="426" id="BLOGGER_PHOTO_ID_5744652818899146882" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5hjytlY7_BbqaNuA7Z3_XakX_fXW0NSc2K4vzdlxOXr6x6IVqiXpL1XZq-nv2Nu9EzXrp6zrZmW_EzBjrNijKlQEWsqdRrQMopYtmb-Kryea0UKNPnNYFZqTfy-ILIsbRMoIuBMjz0pVX/s640/inos2.png" style="display: block; margin: 0px auto 10px; text-align: center;" width="640" /></a><br />
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As a paleoartist, I must say I rarely venture outside of the Mesozoic. I don't know why, but dinosaurs and their contemporaries always had the softest spot in my heart. As time goes by, however, I see how I was suffering from the same blindness that affects the general public - the mainstream media being arguably the main culprit. Many people seem to think that unicellular organisms promptly became dinosaurs as soon as they came out of the primordial swamps, and those would later me immediately replaced (or even evolve into) smilodons and neanderthals. This narrow vision of the prehistoric world really makes us miss how incredibly complex the web of life really is and was throughout the Earth's history, and so I am now trying to learn more about what lies between the Carboniferous amphibians and the Triassic crurotarsians.<br />
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While searching for something non-Mesozoic to illustrate, I thought at first about the period that comes immediately before it: the Permian. This period was the last of the Paleozoic era, which is marked by the emergence and diversification of tetrapods, and ended in the greatest extinction event known to date; The Permian-Triassic mass extinction was responsible for the disappearance of whooping 96% of all marine organisms and 70% of terrestrial vertebrates. Whatever happened at that time, 252 million years ago, hit Earth really hard, and the abundance of open niches in a global scale was a perfect scenario for the boom in diversity that followed, including the emergence of dinosaurs in the Triassic. Therefore, the Permian is a period in which the ancestors of our beloved Mesozoic fauna (mammals included) were getting established.<br />
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The region that is now Siberia, the northern part of Russia, has provided an insight into this misterious extinction event. The area kown as Siberian Traps, which covers an area of about 2 million km², is an enormous deposit of basalt. Coupled with deposits of silica and tuff, these geological formations hint at one of the biggest known volcanic events that might have taken place over the course of one or two million years, dating exactly to the Permian-Triassic boundary. The abundance of active volcanos in Siberia at the time released tons of lava and, most importantly, great clouds of pulverized debris and poisonous gases that, similarly to the asteroid collision thought to have occured at the K-T boundary, blocked sunlight for long periods of time and dropped the global temperatures considerably, while also contaminating the land and oceans in the form of acidic rain and disrupting heavily the food webs worldwide. This event alone might not have been the sole responsible for the disappearance of so many animal and plant species, but it certaintly was a major contributor.<br />
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Just as <span style="font-style: italic;">Tyrannosaurus rex</span> and it's kin were dethroned by an asteroid at<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvuSQ9OVmvap2Yhl9Wf6METZblZPVN7PkoUcZV4a0zAqk2GiRt682Zt2j8wUkQvhRdNcfE40SuXltecmit2wFanFFlR1ZFLB6vIWotcJZN8ISxVi_ZgJCwU58Xkn6OrfwFOOQkklOfU5Oj/s1600/inos3.png"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5744672928489402946" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvuSQ9OVmvap2Yhl9Wf6METZblZPVN7PkoUcZV4a0zAqk2GiRt682Zt2j8wUkQvhRdNcfE40SuXltecmit2wFanFFlR1ZFLB6vIWotcJZN8ISxVi_ZgJCwU58Xkn6OrfwFOOQkklOfU5Oj/s400/inos3.png" style="cursor: pointer; float: right; height: 151px; margin: 0pt 0pt 10px 10px; width: 151px;" /></a> the end of the Cretaceous, major predators lost their reign in the late Permian. Among these, the largest forms were gorgonopsids, a diverse group of therapids that filled many carnivorous niches, from fox to bear-like animals. The gorgonopsids were once known as "mammal-like reptiles" due to their relationship with the first mammals (and the fact that whatever big tetrapod living at that time was called a "reptile"). Indeed, these animals were more closely related to us than to dinosaurs or birds, although they were not our direct ancestors. They shared many mammalian traits, including heterodonty, fully developed temporal fenestrae and erect limb posture, and might as well have had fur and mammary glands.<br />
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<span style="font-style: italic;">Inostrancevia alexandri</span> was one of the biggest gorgonopsids, living at the very end of the Permian. Being the size of a bear, it was the apex predator of it's environment and represents the classical gorgonopsid, with saber-like teeth and a rather feline silhouette. The last individuals of this species likely witnessed (and perished because of) the sucessive volcanic eruptions and lava spills of the Siberian traps, which is the scenario explored in the image up top: a surprised <span style="font-style: italic;">Inostrancevia</span> gets surrounded by a cloud of dust and poisonous gases raised by a brief earthquake that preceded the thundering sound of a volcano awakening.<br />
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<br /></div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-89430301777381784372012-05-18T19:40:00.003-07:002012-05-18T19:40:43.906-07:00Teaser of the Week, guise!<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-VUVX2iI25No/T7cHyiX39RI/AAAAAAAABA0/-24j3fC24UU/s1600/inos.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-VUVX2iI25No/T7cHyiX39RI/AAAAAAAABA0/-24j3fC24UU/s1600/inos.png" /></a></div>
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<br />Long time no teaser, huh? Now what could this whiskery thing be?..</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-39745371910230295502012-04-21T11:28:00.005-07:002012-07-09T15:09:12.672-07:00The Giant Penguins<div style="text-align: justify;">
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<a href="http://karkajou1993.deviantart.com/gallery/#/d4wepor"><img border="0" height="424" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZFoeDEz4MGH4zNjt_JSPxoeY_Eabdnw56IWeIIw_rjwwhzhb7SYt_hFodmLWEOYzMM-5LASKY0ORUdRLHskH2JHclovAJV4Vmtpb1qyEjJ70f4UHDH-0FRi9pimwrko1qu9mMJ9NrGcBG/s640/the_aquarium__12_by_karkajou1993-d4wepor.png" width="640" /></a></div>
<br />Today, penguins are easily recognizable animals; their upright stance, fusiform bodies, flipper wings and usual black and white colouration makes them not only distinct but also charismatic, looking like little people dressed in tuxedoes. And while the biggest penguin species, the King and Emperor Penguins, can grow to more than 1m in height, these birds are usually fairly small. But the fossil record shows that penguin evolution, as is the case with many other animals, was not a straight-forward march and has produced many different lineages.</div>
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The relationship between penguins and other bird orders is not very well understood; It seems that they are probably related to seabirds and other water-going birds such as storks and rails, but studies on the subject remain mostly inconclusive. Beyond that though, we have a pretty clear record of penguin evolution and diversification: following the evolutionary path of the flightless grebes, loons and cormorants as well as cretaceous hesperornithids and the very similar great auks that became extint in recent times, penguins descend from flight-capable birds that became specialized in catching marine prey up to a point where flight was lost in favour of swimming adaptations. The oldest known fossil penguin, <i>Waimanu manneringi </i>from<i> </i>New Zealand<i>, </i>was already flightless and loon-like in lifestyle at 62 mya, showing that the penguin ancestors were probably already established by the late Cretaceous. By 45 mya, penguins had already crossed Antarctica and were arriving at the South American coast<i><span style="font-style: italic;"></span>s, </i>and the same was happening in Africa.<br />
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By the Late Eocene and Early Oligocene, around 40-30 mya, some penguin lineages got really big. The Peruvian <span style="font-style: italic;">Icadypes salasi</span> measured 1.5m, while <i>Anthropornis nordenskjoldi </i>from Antarctica stood at 1.7m in height. But those birds were not giant versions of today's penguins. Many had very long beaks not seen in any modern species, and the primitive morphology of the wings in many taxa suggest that they were not as good in diving. The discovery of pigmentation in <span style="font-style: italic;">Inkayaku paracasensis</span> from Peru, trough the same process that revealed the colours of <span style="font-style: italic;">Anchiornis</span>, <span style="font-style: italic;">Sinosauropteryx</span> and <span style="font-style: italic;">Microraptor</span>, showed that instead of the usual black and white pattern this penguin was mostly grey with a reddish-brown belly and suggests that early penguins may have been more diverse in colouration than their modern monochromatic counterparts.<br />
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Penguins are mostly endemic to the southern hemisphere. While some species such as the Galapagos and Jackass Penguins might go as far as the Equator, they all are specialized to live in cold waters and the aforementioned species depend on the cold Humboldt and Benguela and Agulhas currents to survive in their northern ranges. It seems that their specialized morphology doesn't allow penguins to cross the warm waters directly north of the Equator to reach the suitable conditions in the Arctic, where the same niche is filled by other birds such as the auks. Such isolation has produced an interesting case of convergent evolution; the extint Great Auk was so similar to penguins that the name "penguin" itself was fistly given to it before the western civilizations knew about the southern birds. When the portuguese and spanish sailors found it's twins in Africa and South America, the same name was given to them, while a few centuries later, in 1820, the last of the original penguins was seen off the coast of Canada.<br />
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In the image up top, one more from the Aquarium Series, you can see a <span style="font-style: italic;">Inkayaku</span>, the Giant Red-bellied Penguin. <span style="font-style: italic;"></span><i><br /></i></div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-4332803856210260322012-04-15T10:27:00.001-07:002012-04-15T10:27:26.035-07:00Teaser of The Week<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoUaOZptVa-P9kHeGFJVtZ_nMzozpliw6oNh1jTHG-rm8a_L-jftas0JJVzi3dt0X1zxbwODSKp_kt8FVRbA0ieLNCC-ODNm7E_iejzNQjpcAs2K8kVWSK3XubOKxhQ4pAu8hz1GuVvjKA/s1600/penguin.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoUaOZptVa-P9kHeGFJVtZ_nMzozpliw6oNh1jTHG-rm8a_L-jftas0JJVzi3dt0X1zxbwODSKp_kt8FVRbA0ieLNCC-ODNm7E_iejzNQjpcAs2K8kVWSK3XubOKxhQ4pAu8hz1GuVvjKA/s1600/penguin.png" border="0" /></a></div><br /><div style="text-align: center;">Somewhat old, somewhat new, somewhat feathered, somewhat blue.</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com1tag:blogger.com,1999:blog-6704700031413149466.post-30944340883062770052012-04-12T12:25:00.007-07:002012-07-09T15:19:42.687-07:00My Take On The Feathered Tyrant<div style="text-align: justify;">
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<a href="http://karkajou1993.deviantart.com/art/Catching-Snowflakes-295564475" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNQMHoiYpfq4iwwfPfig03e0a7pACZPnVpE67fZJDmLp2Va7l6D6qzsMF2D9Bg3FzoI9axSlsDT8auaRXs_nEfYWJRcmuxWmqeWdFGoxL4Gl0ucLdD9FugKNMbqzzaYJn4yTGuEi1131kA/s640/catching_snowflakes_by_karkajou1993-d4vyz0b.png" width="426" /></a></div>
After the recent discovery of the confirmedly feather-covered tyrannosauroid <span style="font-style: italic;">Yutyrannus huali</span> from China, turmoil has been established among paleo-lovers (if you didn't know about this species by now, you either don't care about dinosaurs or live under a paleontology-proof rock). This theropod was around 9m long, roughly the same size as the north american <span style="font-style: italic;">Gorgosaurus libratus</span>, but the fossils of three specimens (one adult and two juveniles) show clear signs of feather covering through most of the body. The presence of feathers in the tyrannosaur lineage was already confirmed by the primitive <span style="font-style: italic;">Dilong paradoxus</span>, also from China, but the presence of such a wide integumentary cover in big tyrants was but speculation (There has been some speculation that it was actuallu a carnosaur, the order to which <span style="font-style: italic;">Allosaurus</span> and <span style="font-style: italic;">Charcarodontosaurus </span>belong to, in which case the feathers would be totally unprecedent for te group. The general consensus though is that it was indeed a tyrannosauroid, representing a sort of transition between <span style="font-style: italic;">Sinotyrannus</span> and <span style="font-style: italic;">Eotyrannus</span>). <span style="font-style: italic;">Yutyrannus</span> now holds the record of biggest confirmedly feathered dinosaur, previously hold by the 2m long therizinosaur <span style="font-style: italic;">Beipiaosaurus inexpectus</span>, and although it's flufiness is likely a consequence of the relatively cold environment in which it lived in, there's even more evidence now that bigger, more derived tyrannosaurs, including <span style="font-style: italic;">Tyrannosaurus rex</span> itself, could have had some sort of feather covering. Perhaps <span style="font-style: italic;">Yutyrannus</span> was to <span style="font-style: italic;">Tyrannosaurus</span> what the extinct whooly mamoths were to modern elephants; that is, a fluffier cousin living in colder climates. In any case, this is so far the greatest dinosaur discovery of the year (and we need something fantastic to beat it until december), and as such the casual paleoartists, such as myself, were all eager to illustrate it. After waiting for a while for the dust to settle down (as the hipster that I am), here's my contribution to the most illustrated dinosaur of the month.<br />
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<span style="font-style: italic;">Yutyrannus</span> had peculiar knobs and protusions over the snout, a trait shared by other tyrants - from the crest of <span style="font-style: italic;">Guanlong wucaii</span> to the brow horns of <span style="font-style: italic;">Daspletosaurus torosus</span>. While these structures could very well have been brighlty coloured, I chose to depict a young female in wich the display colours weren't or had not yet been developed. The white feathers could as well be a bit of a stretch; while Jehol represents an environment with clear seasons and possibly frost and snowfall in winter, it's likely that there would not be so much snow to make a white camouflage necessary. But hey, <a href="http://karkajou1993.deviantart.com/art/Royal-Wedding-278043199">I love white fluffy theropods</a> so bear with me.<br />
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So there it is, one more <span style="font-style: italic;">Yutyrannus</span> picture in the internet. This was actually my first illustration following a recently announced dinosaur discovery (well, not counting the <span style="font-style: italic;">Microraptor</span> colour study, but that was not a whole new dinosaur) and it was very fun to draw it at the same time as a whole lot of other people and share our versions over at DeviantArt. Let's see what more 2012 has in store for us!</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0tag:blogger.com,1999:blog-6704700031413149466.post-56317721737687286002012-04-12T12:11:00.007-07:002012-07-09T15:21:08.503-07:00The Pterosaur Extravaganza ContinuesLet's keep ourselves updated with more pterosaur-related illustrations:<br />
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<a href="http://karkajou1993.deviantart.com/art/Golden-Hour-291958962"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFlAZDQWlW1YD8bJI569weknxx96nIzDTW-pi0-7kt6CNVgsKmUgp-E4xrwWMIOR11S-GFIEdEX7WA58quCvuLmnn22hN9_HE7AqbY49YX1XYBmJZNOPGanaAz1QX1p1TUhi69AWhAK-3e/s640/golden_hour_by_karkajou1993-d4ttoz6.png" width="640" /></a></div>
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<span style="font-style: italic;">Pteranodon longiceps</span>, one of the quintessential pterosaurs, flies back to the rocky shelters at sunset.<br />
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<a href="http://karkajou1993.deviantart.com/art/Feeding-off-a-Mirror-294683835"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmApgFhkO3P-r7vfCedvzKET2u6skKKkRFVwsEN0WoOxmTcHHeoIDqt68sRe8zSburKTCHCIx1v2_KX4rEYS3QKTijTJxohsJ_ZyRbZ3MqgJ21ey72A6nlJk83q1iNej7Kvvnc_-0kzE7n/s640/feeding_off_a_mirror_by_karkajou1993-d4vg3i3.png" width="640" /></a></div>
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<span style="font-style: italic;">Pterodaustro</span>, the peculiar filter-feeding cnetochasmatid from Argentina, which aparently was actually a nocturnal animal. (Note that it deviates from the flamingo-pink <span style="font-style: italic;">Pterodaustro</span> meme due to the probable impossibility of pycnofibers to have been pink)<br />
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<a href="http://karkajou1993.deviantart.com/art/Who-Are-You-Callin-Ugly-294893700"><img border="0" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhglKxptaQGmKnkCMFZWDK5lK87EYuRz6czhGVEtinGMnJtOwuEBOvuHdtCdAloBvoE5ZkZBVjkykDK-ZtTWjcA9J1onGLbMT3fFIpdD1nCK6Xdmj1crAbXX2gRExgoO2pwoZKbcC9Hw-9r/s640/who_are_you_callin___ugly__by_karkajou1993-d4vklfo.png" width="640" /></a></div>
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And lastly <span style="font-style: italic;">Dsungaripterus</span>, the so-called "Ugliest Pterosaur", sporting a more pleasant appearance for a change.<br />
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Now since I know you guys are probably tired of seeing so many pterosaurs, let me work on some aquatic critters.. See ya!</div>Julio Lacerdahttp://www.blogger.com/profile/09075439567916698811noreply@blogger.com0