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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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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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Didn't quite have time to finish last night, so here it is this morning. This is Edmontosaurus annectens, one of the best-known dinosaurs in existence. On top of having found hundreds of very complete skeletons of adults and juveniles, we have a few very complete mummies as well, which have allowed us to know the skin texture (loose and scaly, with round tuberculous scales more like a gila monster than a snake), and diet (lots of seeds, conifers and gymnosperms, based on gut contents and isotope ratios in the teeth). We have skeletons that show signs of scar tissue, damaged vertebrae and hips, and tooth marks, showing that they were preyed upon by large tyrranosaurs, as well as skeletons that show bone damage from other ailments such as cancer. Skeletons have been found from Alaska to Colorado, a huge range for any dinosaur, and some have suggested they may have been migratory like today's caribou, heading south to avoid the arctic winters. Their front toes were even developed into hoof-like structures, with the hard-scaled skin fully enclosing flattened toe bones. And they definitely lived in herds, some of which may have numbered thousands of Edmontosaurs.

Despite everything we do know, we're still finding out new information about this and other Edmotosaurus species. At the end of 2013, one specimen was discovered that preserved impressions of soft tissue around the head, which revealed for the first time that Edmontosaurus had a fleshy rooster-like comb on top of its head - something we never could have seen from skeletons alone. Just one more reminder of how little we know, even when it comes to a species we think we know so much about.
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Lambeosaurus magnicristatus is a giant hadrosaur from the late Cretaceous which ranged all over coastal regions of North America. They likely filled a niche similar to bovids today, as large, herd-living, migratory grazers. Many hadrosaurs, including this species, also possessed large bony crests, which probably served in display and sexual selection but which also incorporate the nasal passages, meaning that air passing in through the nostrils then traveled through the crest before exiting - and the size and shape of the crests of various lambeosaurine species probably resulted in each species having its own unique trumpet-like call for communicating with the rest of the herd.

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Lauren Helton

September 2014

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