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Pegomastax africana is a heterodontosaur from the early Jurassic period in South Africa. It was an exceptionally tiny dinosaur, measuring no more than 60 cm from beak to tail tip - or, about 2 feet long. With its parrot-like beak and large flat teeth it was clearly an herbivore, but it also held a pair of fangs or tusks on both the upper and lower jaws, possibly for interspecific combat or possibly for helping to pry up roots to eat. But its most remarkable feature is the dense coat of quills this dinosaur had. As should be unsurprising to any of you by now, we don't quite know what purpose they held. Were they for defense, like in today's porcupines, or perhaps for camouflage, or were they brightly colored or patterned and used in communication? Given their small size the former seems plausible, but we can't really say for sure.

The Pegomastax fossil was unearthed back in the 1960s but was never actually described and published until 2012. There are undoubtedly many other species currently suffering this same fate - sitting in museum cabinets, already collected but still waiting to truly be discovered. And dinosaurs of course aren't the only ones this happens to - new species of extant animals, as well as new anthropological discoveries, are still being found on a regular basis out of old overlooked museum collections.
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This hulking brute is Minotaurasaurus ramachandrani, a Late Cretaceous ankylosaur from... Well, we actually don't know for sure. The dinosaur is known only from its fossilized head, which was purchased by famed neuroscientist V. S. Ramachandran from a Japanese fossil dealer based in Arizona for $10,000. It likely originated in the Gobi Desert, but was collected and sold illegally and, as such, belongs properly to China - however, Dr. Ramachandran refuses to turn it over to the Chinese without any proof that it truly belongs to them. It was made available for study at a museum in California in 2007, and was thus officially described and named in 2009, but it is now once again held privately, and the outcome of the battle over ownership is still undecided.
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This enormous pterosaur is Quetzalcoatlus northropi, one of the largest flying animals to have ever existed, with an estimated 33-36 foot wingspan and an estimated weight of 440-550 pounds, and an approximate height while standing of around 16 feet. While Quetzalcoatlus could undoubtedly fly, it likely would have required good thermals to soar on much like today's largest birds - maintaining flight through its own power would have been extremely energetically costly.

Quetzalcoatlus though, like the rest of the azhdarchid pterosaurs, likely spent much of its time on the ground, where it would have stalked ground-dwelling prey like an enormous stork. With legs built like today's ungulates, it could probably have run quite well, and its long beak would enable it to pluck animals up without having to bend down too low. Essentially, imagine a predatory giraffe that could fly - that's Quetzalcoatlus, undoubtedly a terrifying predator to the smaller dinosaurs of Late Cretaceous North America.
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Psittacosaurus mongoliensis is, like Edmontosaurus, one of those dinosaurs we thought we knew everything about until recently. There are actually at least ten species of Psittacosaurus known, and many are known from very complete skeletons. These are the predecessors of the horned Ceratopsians - hornless and frilless, bipedal, but beaked and herbivorous like their descendants. Skin impressions show similar skin to the Ceratopsians, with many hard round scales covering the body. But in 2002 a well-preserved individual was found with long quills attached to the tail. Whether these are related to the quills of feathers, or whether they're an entirely different sort of structure, is still unknown - they may be for display, or they may have, as some have speculated, supported a fish-like fin if that species of Psittacosaurus was somewhat aquatic. If they were related to feathers, then it opens up the possibility for other Ceratopsians to have body feathers as well, and suggests that the ancestor of all dinosaurs (or even further back, the ancestor of many archosaurs) might have been covered in fuzzy protofeathers like many early dinosaurs and even pterosaurs were.
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Daemonosaurus chauliodus was a Late Triassic theropod from New Mexico's Ghost Ranch site. During the Triassic, it was a dense forest, and now a thick layer of coal lines the rocks where Daemonosaurus and its contemporaries were found. Most Triassic theropods have long, narrow snouts, so Daemonosaurus, with its short rounded snout and buck teeth, was a very unique find when it was discovered in 2011. Unlike Coelophysis, fossils of which have been found in the hundreds in this area, we only have one Daemonosaurus skeleton on record so far, but it seems to have died similarly, trapped in a flash flood during one of the region's severe monsoons.
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My grandmother's 93rd birthday is coming up next week and I told her I would do some art as a gift. Little old ladies, my grandmother included, typically prefer extant dinosaurs to extinct ones, and she's a fan of hummingbirds, which she has lately been trying to attract to her yard. Rufous Hummingbirds (Selasphorus rufus) are a common sight here in the Pacific Northwest, and while they're drawn to a wide range of flowers, western red columbines (Aquilegia formosa) are one of their favorites.

And I think this bit of art stands as an interesting contrast to the rest of the dinosaurs, too - just look at how highly modified they've become over the last several million years! From one line of small theropods came an extremely wide diversity of modern birds with an astounding variety of shapes, sizes, and special adaptations for filling almost every niche on the planet.
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Amargasaurus cazaui, from Argentina's late Jurassic period, may be familiar to some of you who played the latest generation of the Pokemon games. Amaura and Aurorus were based off of this species of sauropod, which carries twin rows of spikes down its neck. It was formerly thought that these spikes supported sails of skin, but analyses have shown that if that was the case, Amargasaurus' sails would have rendered its neck inflexible, making it unlikely. Instead, they were probably free spines, and would have served the sauropod well both for display and also for intimidation and defense. One paleontologist has even suggested that the spikes, which were probably covered in a thick sheath of keratin, could have been used as a sound display. The Amargasaurus could shake its neck and cause the spikes to rattle against each other, creating a clacking sound not unlike a very large set of bamboo chimes.
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Sanjuansaurus gordilloi is a very primitive dinosaur from the late Triassic period in Argentina. During the Triassic, large agile crocodiles were the dominant terrestrial predators. Early dinosaurs, still very lizard-like with their small hands, four-toed feet, and general lack of diversification into the fantastic body shapes later eras saw, were prey more often than predators. They were small and unimpressive, and scampered about searching for insects and other small reptiles to eat.

Sanjuansaurus' habitat was, at the time, volcanically active. While much of it was covered by forests, fresh lava flows occurred regularly. Small, mobile predators like Sanjuansaurus might have been able to take advantage of these dramatically-altered ecosystems and hunt between the rocks for early colonizers such as spiders and lizards.
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Yandangornis longicaudus is, as the name ("ornis") implies, a bird. We think. It's actually very hard to say. Like birds, it is fully-feathered and has a beak with no teeth. However, it also has a long bony tail, a short fourth toe, and other skeletal features that make it more similar to dinosaurs. Since birds are dinosaurs, the distinction is purely one of interest to taxonomists, who work to figure out which species are more closely related to which other species. From a taxonomic perspective, Yandangornis is a dinosaur, as are all birds - but whether or not it can be called a bird for sure is still up for debate. Discovered in Zhejiang Province, China in 1999 from a largely intact skeleton, we do know that it was more adapted for ground-dwelling than aerial or arboreal life, and was similar in size and habit to today's roadrunners, likely chasing down insects, small reptiles, and primitive mammals on foot.

As a heads up, updates will be spotty over the next couple weeks as I finish my thesis and prepare my defense. I'll try not to go full hiatus on you guys!
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Sinornithomimus dongi was found in the highlands of Mongolia in 2003. Late Cretaceous Mongolia wasn't all that unlike the Mongolia of today, and these ostrich-like theropods, which lived in small herds of similarly-aged individuals, would have had to pass through expansive desert areas to reach pockets of water once snowmelt became scarce in the summer. Many of the individuals we have fossils of include some of the most complete dinosaur skeletons, found having evidently been trapped in the mud at a water hole.
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Pachycephalosaurus wyomingensis ought to be a familiar name to most of you. Discovered in Wyoming in 1931, it has long been famous as the dinosaur with the domed bony head, supposedly used by males in territorial and breeding disputes much like bighorn sheep today, by charging and then headbutting each other in a test of endurance and strength. Recently that thought has been disputed, as the skull likely could not have sustained such blows, nor could the neck, and no evidence of scarring or other damage on the heads of pachycephalosaurs that would result from this kind of combat has been found. They may instead have headbutted the side or flank of competing males, or of potential predators in self-defense.

Juveniles had far more extensive head spines than did adults, which initially caused paleontologists to think they were different species - Stygimoloch spinifer and Dracorex hogwartsia (what a name!). It now seems that the horns on young Pachycephalosaurus were absorbed into the heavy head dome as bone grew around them during the aging process.

Pachycephalosaurus were beaked but had small leaf-shaped teeth - unlike their relatives the ceratopsians, they must have eaten leaves, nuts, soft fruits, and/or insects, rather than tough cycads and grasses. The end of the Cretaceous had plenty of soft leafy plants and flowers for them to eat, making them less similar to cows and more like today's deer in terms of diet.
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Ceratosaurus nasicornis is a late Cretaceous theropod from western North America. Discovered in 1884, its original describer felt that the unusually large (for a theropod, anyway) horns on its face were deadly weapons, in line with the general sentiment at the time that dinosaurs were absurdly brutish and violent compared to modern animals. Today, paleontologists feel that the horns might have been used in male-male combat over territory or females, or that possibly the horns were purely for display purposes. Males and females may have had differently-colored or differently-sized horns, or they may have been useful in species recognition, as Ceratosaurus was not the only large theropod in its habitat.
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Tupandactylus imperator is one of Brazil's many fantastically-crested pterosaurs from the Cretaceous period. The skull itself only has a prong of bone reaching above the bill and another that juts out behind the eye, but skin impressions reveal that skin and keratin was stretched between these two prongs to form the large triangular crest. It had a keratinous beak somewhat like a bird's, and was covered in small feather-like fibers, as many pterosaurs were now known to be.

Skulls of this and other tapejarid pterosaurs reveal that they had large visual centers of the brain, even moreso than other pterosaurs, suggesting that they may have relied almost exclusively on eyesight to hunt, rather than scent or hearing. What exactly they ate, however, is still unknown.
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Balaur bondoc was an apex predator on Hateg Island, the late Cretaceous portion of Romania from which we know so much about the effects of island life on dinosaur evolution. Balaur was roughly the size of a turkey, with unusual proportions for a dromaeosaur - short, robust arms and legs, only two fingers on its hand, and with not just one but two sickle claws on each foot due to a highly modified inner toe. It wasn't a graceful sprinter like its relatives, but it was powerful and likely capable of taking down prey larger than itself. This one has caught a juvenile Zalmoxes robustus, an iguanodontid, still young enough to have a coat of down. Like Magyarosaurus and other Hateg dinosaurs, Zalmoxes grew much smaller than its relatives, an example of island dwarfism. As an adult, it would not have exceeded 7-10 feet in length, considerably smaller than the nearby Iguanodon species of continental Europe which reached 30-40 feet long as adults.

And with this I am officially back from my hiatus! It was longer than I'd anticipated it being, but that's thesis work for you sometimes.
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Finally heard back from my thesis advisor on edits, so I have some work to do. I'll be back to drawing shortly, don't worry!
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Buitreraptor gonzalezorum is a unenlagiine dromaeosaur from Cretaceous Argentina. Unlike more typical dromaeosaurs, it had very long, thin legs, as well as a long slender snout filled with small, strongly recurved and grooved teeth. Rather than hunting larger animals or living in packs, it appears likely that Buitreraptor captured smaller animals - mammals, lizards, and amphibians, for example. Others, however, including Scott Hartman, a well-known skeletal restoration artist, have speculated that Buitreraptor's proportions and tooth shape suggest it may primarily have been piscivorous, making it the prehistoric equivalent of a heron or egret.
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I often run out of time to draw on weekends, and the one I started for today, I already know I won't be able to finish on time and be happy with it. So I'm going to try something new, where instead of still posting daily on Friday-Saturday-Sunday, I work on one bigger detailed piece over a few days and post it when I finish on Sunday. Should make my weekend schedule more flexible. I still intend to post one daily on Monday through Thursday for the time being. Thanks for being patient!

In return, here, have a small preview:

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Ouranosaurus nigeriensis is a basal hadrosaur from, as the name implies, what is today Nigeria. While I've given it a sail for display (and possibly thermoregulation as well) here, the odd shape of the vertebrae, with them becoming wider and flatter toward the tips, suggest a large fat-storing hump might also have been possible. As a hadrosaur, it was herbivorous, and like some other hadrosaurs, the first two toes on the front feet were flattened and thick at the ends, forming a hoof. Unlike Edmontosaurus, which I drew previously, Ouranosaurus retained its fourth and fifth fingers separate from the hoof, and the fifth finger especially seemed to remain flexible, possibly enabling the animal to grab onto hard-to-reach plants while shifting to a temporary bipedal stance. Like other hadrosaurs, such as Iguanodon, the thumb was modified into a spike, possibly for defense against predators and/or combat with other Ouranosaurs during territorial or breeding disputes.
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Concavenator corcovatus is a carcharodontosaur, one of several medium-to-large carnivores from Cretaceous Southern Europe. Discovered in Spain in 2010, it is the only known carnosaur with a sail on its back. This sail is unlike those of the early synapsid Dimetrodon, or the spinosaurs, in that rather than being tall and thin, it was low and likely wide at the base - possibly for display, possibly for fat storage such as in today's camels, or potentially for both purposes.

Concavenator also has large bumps on its forearm bones that appear to be quill knobs, and skin impressions show that its body was covered in large alligator-like scales.
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Archaeopteryx lithographica has, until recently, enjoyed its place in the spotlight as the link between dinosaurs and birds. When it was discovered in 1861, it was regarded as a bird, but one with unusually dinosaur-like characteristics, including a long bony tail, clawed hands on the wings, and a toothed snout. As more specimens have been recovered, however, and with more and more feathered theropods being found every year, it has become evident that Archaeopteryx may not be the all-important transitional stage we once thought it to be. While some paleontologists maintain that it belongs in Avialae, others have suggested it may in fact be a troodontid or other maniraptoran, and therefore still a close relative of birds, but no more so than a species like Velociraptor, rather than a likely ancestor of modern birds. Whatever the case may be, it was certainly an important discovery in its time, and remains a well-known public ambassador for the evolutionary history of birds.
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