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Epidexipteryx hui, another of the small feathered Chinese dinosaurs, is a bit like Scansoriopteryx from a previous entry, with one major exception - it had only simple feathers, with no flight feathers whatsoever, except for four very long ribbon-like tail feathers. They were likely boldly patterned and used for display purposes, though given that we only have one fossil of this species, it's hard to say definitively. They, like Scansoriopteryx, had an elongated third finger, possibly for use in climbing or for reaching insects in small gaps and crevices in tree bark or rotting wood. The lack of flight feathers on the arms, however, suggests that this dinosaur wouldn't have been able to glide if it did climb up into the trees, while its relative may have done so. Instead, this animal may primarily have been a ground-dwelling species.
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Guanlong wucaii, like many of the Chinese dinosaurs, has a very poetic name - "crowned dragon of five colors" - the five colors being the banded sandstone of Wucaiwan, similar to the four corners region of the US' Great Basin desert. Guanlong is a primitive tyrannosaurid from the late Jurassic, and unlike later tyrannosaurs, it has long, robust arms and hands and a tall crest over the top of its relatively slim head. Only two skeletons have been found, but one was a juvenile, with a much shorter crest over the nose, indicating that as individuals of this species matured, the crest grew taller as well as back toward the eyes. While neither skeleton preserved feathers, it is likely that like other known primitive tyrannosauroid dinosaurs, Guanlong would have had a coat of simple hairlike feathers.

I know, I know, I missed yesterday. Somehow on my travels I obtained a strain of Norovirus, or something similar. I'm feeling more functional today, thankfully.
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No fancy title or background on this one today, I'm afraid - I'd like to do more with these guys at some point, though, because what an unusual dinosaur. This is Caudipteryx zhoui, an early Cretaceous oviraptorid. The outward similarity these dinosaurs shared with later chickens and pheasants is a little bit baffling. They had a very chicken-like body shape, with a birdlike short fanned tail. Strangely, no fossils found so far preserve any secondary feathers (the long feathers attached to the arm, as opposed to the hand feathers, which are the primaries) - either they didn't have them, or somehow they simply weren't fossilized, it's difficult to say. They did have teeth inside that beaked mouth, but they may have been vestigial, for as herbivores, they really only needed that beak and the stones they swallowed into their crop to tear up and break down plant matter. Despite this dinosaur looking an awful lot like a bird, they weren't as closely related to them as some of the other small theropods, like the dromaeosaurs - but maybe that doesn't matter so much, given how blurry that dinosaur-bird line is, already.
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Discovered in 2008 along the shores of the inland sea that once filled most of Utah, Talos sampsoni is an important troodontid dinosaur for paleontologists and paleoartists in that it confirmed what was speculated about in the 1960s with regard to limb morphology in these dinosaurs. Unlike the heavier-built dromaeosaurs, troodontids, and Talos in particular, had very long, thin legs, indicating it was a very quick runner, and also relatively short arms - these were definitely not gliders or climbers, but fast, active ground-dwelling hunters. Only one Talos specimen has been found, and it has a cracked, damaged sickle claw on its left foot, suggesting that just like in the dromaeosaurs, and unlike some of their smaller arboreal relatives, troodontids used that claw for combat.
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An exposed slab of late Jurassic mudstone north of Moab, Utah reveals a unique scene of a potential interaction between a few dinosaurs. A large sauropod, possibly a Camarasaurus, turns mid-stride, apparently reacting to a smaller theropod running nearby. A few yards away, an Allosaurus leaves the site with an irregular stride, possibly the result of a limp. Was this a site where an adult Allosaurus and a juvenile tried to tackle a Camarasaurus and were driven off after a conflict? Or was the smaller theropod running past after something else that caused the Camarasaurus to turn and watch it warily as it ran by? There's no way for us to know what the order of these events were, or what even the exact event was, but it lends nicely to some interesting speculation.

Below, photos of the trackway from my visit this morning. )

I will be home tomorrow, so soon we will be back to my regular level of detail in these drawings, or so I hope!
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Another very quick one today. After 590 miles driven, I don't really have the energy for anything complicated. However, I now find myself in New Mexico, which has some great dinosaur history behind it. The state dinosaur is Coelophysis bauri, a small late Triassic theropod. Hundreds of these dinosaurs have been found at the Ghost Ranch Quarry site in this state. Why so many are all in one place is still unknown, however.
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The early history of dinosaur discoveries has always fascinated me. I love comparing modern knowledge to what we knew earlier, to see how ideas develop and change over time with new discoveries, and also because it's fun to think about what we might think we know right now that could turn out in the future to be completely wrong. The story of Megalosaurus bucklandii exemplifies this process. Found in Oxfordshire, England, from the middle Jurassic, in 1676 it became the first dinosaur ever discovered, and was known only from a segment of the thigh bone. Thought to be from a Roman war elephant, or possibly a Biblical giant, an illustration of the bone appeared in Robert Plot's Natural History of Oxfordshire. A hundred years later, the Linnean system of scientific nomenclature was in use, and the illustration reappeared in another book, which was attempting to apply the binomial system to rocks - and thus the fossil took on its first official name, Scrotum humanum.

Luckily, Megalosaurus escaped being called that permanently when more bones were discovered in 1827 and the skeleton was officially published in the paleontological literature as the giant iguana-like lizard Megalosaurus bucklandii. Although it is the first dinosaur ever discovered, it remains one of the least well-known, with only portions of the skull, pelvis, one leg, and a few vertebrae and other miscellaneous bones known. Still, that's enough to be able to classify it as a large Tyrannosaur-like theropod - but there's still a lot about its skeleton that we don't actually know for sure.
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Nothronychus graffami, along with its Therizinosaur cousins, is an oddity. They are heavy-set, with thick bones and massive claws on their hands, yet they have beaks and plant-chewing teeth. Their odd skeletons resulted in paleontologists initially thinking they were somehow related to sauropods and that perhaps they burrowed, like badgers, but as more skeletons were discovered it became evident that these were theropods after all - but unlike the vast majority of theropods, which tend to be built for speed and power to hunt prey, these theropods were slow-moving browsers, likely using their huge claws to grasp and shear branches and leaves - a lifestyle and set of adaptations that would be later mirrored in mammals by the giant ground sloth. Most of them have been found in China, but Nothronychus is a North American genus, and N. graffami specifically is from late Cretaceous Utah.

Phew, today marks two weeks of dinosaur drawings! I apologize if they get simpler over the next week or so while I pack up and move across the country. I'll try and continue to draw and upload while traveling, but if I miss a couple days, I apologize!
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So since my Qiliania the other day was so tiny on the snout of that Argentinosaurus, I felt it necessary to give it its own portrait. So here you go, a much closer look at the smallest-known non-extant dinosaur. Like other Enantiothornithines, it has developed a pygostyle instead of a long bony tail, asymmetrical wing feathers, and other traits that make it very similar to modern birds, though it still lacks a beak, and instead has a toothed snout. Whether these guys were capable of true flight, we're not yet sure. Instead, it may have been primarily a ground-dweller, and used its wings for wing-assisted incline running (WAIR). Many ground birds today still do this, using their wings primarily to help propel them up a slope without truly leaving the ground for more than a few seconds, and it has been proposed that the use of WAIR by early winged dinosaurs eventually led to the evolution of powered flight.
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I still remember when I first heard about the discovery of Sinosauropteryx. Gorgeous close-up detailed images of the fossil were released in the March-April 1997 issue of Audubon Magazine. The first dinosaur ever found with feathers, Sinosauropteryx prima - a name that will forever remind people of its significance. Archaeopteryx was birdlike, yes, and in hindsight we see how dinosaur-like it is, too, but before Sinosauropteryx it was understood as a link between birds and reptiles, not dinosaurs specifically. The origin of birds from dinosaurs was a hypothesis that had been proposed already, but the prevailing thought was that birds had evolved from a different archosaur ancestor, something more crocodilian. But Sinosauropteryx was unambiguously a dinosaur - a Compsognathid, specifically - and it had a coat of feathers all over its body that were extremely well-preserved and extremely obvious.

Sinosauropteryx later earned another honor, when in 2010 it was one of the first to have its colors identified - a warm orange-brown, with bold white bands on the tail. It looks a bit like a lemur crossed with a reptile, really. Cute, even, for a predator.
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Any time you see paleoart showing a crested oviraptorid, the chances are it will be labeled Oviraptor - and yet that crested head belongs to an entirely different genus of oviraptorid, named Citipati, as an intact Oviraptor head has never been found. The entire Oviraptorid family is so named because the first one discovered was on a nest, and it was assumed at the time that the dinosaur was literally stealing the eggs, hence its name. Many oviraptorid dinosaurs, including Citipati species, have since been found on nests, and it has become clear that rather than stealing the eggs, they were brooding them, with wings stretched around the perimeter of the nest much like brooding birds today.

Citipati itself is from the late Cretaceous, in what is today the Gobi Desert. It was roughly the same size as today's emus, and certainly superficially resembles another Australian ratite, the Cassowary, with its bony crest and beaked mouth.
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Yutyrannus huali, at 30 feet long and just over 3,000 lbs, is the largest known feathered dinosaur. It is not the first-discovered feathered tyrannosaur - that honor goes to the much smaller and more primitive Dilong, and presumably many tyrannosaurs were feathered as juveniles. However, it had been thought that large dinosaurs wouldn't have or need feathers, as it is likely their primary function for most theropods was insulation, and very large animals usually are able to maintain their body heat more easily. So it was a bit of a surprise when, in 2012, fossils of two gigantic fully-feathered adult tyrannosaurs were found through a Chinese fossil dealer. Yutyrannus did live in a colder climate than most tyrannosaurs did, and so it may genuinely have needed the extra insulation - think of Yutyrannus and T. rex as a wooly mammoth and an elephant, perhaps.
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Last week, a paper was published in PLOS Biology by a team of Oxford scientists who, based on skeletal measurements, calculated the masses of 426 species of dinosaur. The largest, Argentinosaurus, was a massive sauropod weighing in at roughly 90 tons, while the smallest they measured was Qiliania, an Enantiornithine bird that weighed 15 grams, making the weight of the largest dinosaur 6 million times the weight of the smallest non-extant known species (the smallest-ever dinosaur known is the Bee Hummingbird of Cuba which weighs 2 grams). It's suspected that size played a large role (no pun intended) in the survival of the maniraptorans past the mass extinction 65 million years ago, as the smallest dinosaurs may have been able to avoid the worst effects of the asteroid impact by being more generalist, requiring fewer resources, and/or being able to exploit niches not available to larger species.

Update: today (5/16/14) a team of paleontologists in Argentina announced they've found a new sauropod species that may be even bigger than Argentinosaurus, and estimate its weight at 100 tons. Should be interesting to see what comes of this new discovery.
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Troodon formosus was one of the first North American dinosaurs discovered. They lived in the late Cretaceous, and ranged throughout most of western North America, all the way up to the north slope of Alaska. Although Cretaceous Alaska was warmer than it is today, and covered in temperate forest similar to the current ecosystem around Juneau, deep snow likely still occurred in the harsher winter months. Alaska was farther north then as well, resulting in four months of nearly complete darkness in the winters, with only a glimpse of sunlight breaking over the horizon around noon.

Troodon, however, was well-adapted for these tough conditions, with its large eyes, excellent hearing, and likely a thick feather coat. In this image, a pair steps out from the edge of the forest into the noon sunlight, looking for any sign of prey in the open area.
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Confuciusornis is a genus of four to six known pigeon-sized theropods (at least two may represent the same species) from Jurassic China that appear to be more closely related to true birds than Archaeopteryx is. They are the oldest-known birds with beaks instead of scaly snouts, they have no teeth, and they have a pygostyle instead of the long bony dinosaur-like tail. They have very long pointed wings and asymmetrical flight feathers, making them altogether more like modern birds than any other known creature of their time, but skeletons indicate they weren't capable of powerful flapping flight and may instead have been gliders.

Fossils of this genus have been found in vast quantities, and places where entire flocks of hundreds of birds were preserved simultaneously have been found. They are so abundant that long before they were known to science, several hundred had been collected and sold in Chinese street markets - and this, in fact, is how the first Confuciusornis to be described in the scientific literature was initially found. The colors in this drawing are accurate, but the pattern is not - I was able to find several references that they were gray, brown, orange/red, black, and white, and that the wings were mostly white, but I couldn't find anywhere that showed the exact pattern of how these colors were laid out on the body.
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Anchiornis huxleyi is a famous little dinosaur, and one of the best-known, with several hundred fossils in collections worldwide - all found since its discovery in 2009 in northeastern China. The third Anchiornis found was exceptionally well-preserved, showing that it had a fully-feathered body except for the very tip of its snout. It, like Microraptor, has four wings, one on each limb, but the "flight" feathers on Anchiornis are far more primitive in that they are shorter, rounded at the ends, and symmetrical, unlike modern birds' flight feathers which are asymmetrical and pointed. The pigment-containing melanosomes within those feathers were the first of any dinosaur melanosomes to be analyzed, and as a result, Anchiornis became the first dinosaur whose true colors were known. What we don't fully know yet is where they fit with the rest of the dinosaurs - they've been placed with the troodontids, but may be more closely related to Archaeopteryx.

As a result, they're one of the most popular dinosaurs in paleoart, and I couldn't resist, either. These were tiny little guys, only a few feet long, and this one has awoken at its roost in a ginkgo to preen in the early morning sunlight.
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Jinfengopteryx is a troodontid, though when it was first discovered it was considered a bird and a relative of Archaeopteryx. Troodontids have an unusual feature shared only with owls and no other known animal - their ears are asymmetrical, with one ear higher on the skull than the other. This allows for a much easier time pinpointing the location of something the animal hears, and this, plus the large eyes in this family, suggest that troodontids, like owls, may have been nocturnal or crepuscular predators - although the most complete Jinfengopteryx skeleton had seeds in its digestive tract, and based on tooth shape, it and other troodontids may have been omnivorous.
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Last one for today: a Microraptor gui, in true color.



I've written about these little guys before. We know they were a glossy iridescent black, and we know they were either very common or lived in large flocks, or both. They seem to be the Cretaceous' answer to crows or blackbirds.
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Just a quick one this morning, mostly a result of me trying to picture how those funny arms Mononykus/Shuvuuia and their relatives have could be actually useful for getting at food.

Edit: I re-cropped the image and added a touch of color via some gradients. Just playing around but I think I like this version better. The original drawing is within the cut.



Click for original version )

Drawing rotting stumps is actually pretty fun, I've decided.

I think Microraptor will be next. Drawing iridescence should be interesting.
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Alvarezsaur, based on Mononykus/Shuvuuia. While these insectivores are speculated to have used their claws to tear open logs in search of termites, they were also fast, agile runners and likely would have taken opportunity of a passing dragonfly.
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