It has been a good year for dinosaurs. Every month multiple new, interesting discoveries have been announced that either introduce us to new dinosaurs or tell us something new about those already familiar to us. I have been able to cover only a small fraction of all these stories here on Dinosaur Tracking, but here are some of my favorite dinosaur discoveries of 2009.
"Bone-Headed" Dinosaurs Reshaped Their Skulls. A few years ago it was announced that there was some evidence that what were once thought to be three distinct "bone-headed" dinosaurs were really just growth stages of Pachychephalosaurus. The research supporting this hypothesis was published this year, and while it is still being debated, it has opened up questions about the identity of other dinosaurs, too.
Miragaia, the Long-Necked Stegosaur. Stegosaurus was one weird dinosaur, but its long-necked relative Miragaia was even stranger.
New early dinosaurs. Questions about the early evolution of dinosaurs have perplexed scientists for years, but two new dinosaurs announced this year help fill in gaps in our understanding. The predatory dinosaur Tawa hallae and the early sauropod relative Panphagia protos have given paleontologists a new look at what early dinosaurs were like and how the giants of the Jurassic and Cretaceous got their start.
Tianyulong, an Unexpectedly Fuzzy Dinosaur. New specimens of feathered dinosaurs almost always make the news, but Tianyulong was extra-special. It was a dinosaur only very distantly related to birds that was preserved with simple, quill-like structures on its body, supporting the idea that many different dinosaurs might have had body coverings. Tianyulong is not to be confused with Tianyuraptor, a small predatory dinosaur found in the same region of China and also announced this year.
Gooey Hadrosaurs. Hadrosaurs are among the most useful dinosaurs for studying questions about dinosaur biology because they were so numerous and there are a number of exceptionally preserved specimens that give us a look at what their soft tissues were like. This year one team of paleontologists described the preserved skin of a hadrosaur nicknamed "Dakota" and another team studied remnants of blood vessels in a Brachylophosaurus. No doubt we will hear more about the soft tissues of hadrosaurs from both groups in the future.
Year of the Tyrants. It has been an excellent year for anyone who loves tyrannosaurs. Even if tyrannosaurs did not regularly chew on bones they did fight quite a bit (and maybe even ate each other), and their lack of dental hygiene might have assisted the spread of harmful microorganisms among the tyrant dinosaurs that still afflict birds today. And, on top of all that, several new members were welcomed into the tyrannosaur family, including two long-snouted killers and a miniature relative of Tyrannosaurus that will provide new insights into the evolution of some of the largest predatory dinosaurs that ever lived.
This is by no means a comprehensive list. There were plenty of other new discoveries and excellent studies published this year. What were some of your favorites?