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A restoration of Anchiornis by Michael DiGiorgio, showing the color patterns detected in the dinosaur's fossil feathers. This was arguably the most important dinosaur discovery of 2010.

2010 has been a good year for dinosaurs. Numerous new species have been named, long-awaited conference proceedings have been published, new techniques for studying the past have been devised, and scientists finally allowed us to answer one of the most confounding questions in dinosaur science. There was so much new dinosaur science that it was impossible to cover it all here (in fact, an accepted manuscript describing a new, giant horned dinosaur from New Mexico called Titanoceratops was just made available while this post was being prepared), but here is a breakdown of the top discoveries discussed here at Dinosaur Tracking over the past 12 months.

Before the Dinosaurs

There is much that remains unknown about the origin and early evolution of dinosaurs, but several discoveries announced this year have helped to fill in the early history of dinosaurs and their close relatives. Tracks made by the precursors of dinosaurs – the dinosauromorphs – found in the 249-million-year-old rock of Poland suggest that the ancestors and close relatives of the first dinosaurs originated not long after the great Permian mass extinction 251 million years ago. Creatures of this antiquity can be tricky to identify. Azendohsaurus, once thought to be an early dinosaur, was reclassified this year as being only a distant cousin, and the newly-described creature Asilisaurus was somewhat dinosaur-like but not a dinosaur itself.

Funky Theropods

Multiple theropod dinosaurs were described this year, but two exceptional species stand out. One, the carcharodontosaurid Concavenator, had a short sail on its back and may have had tubular bristles growing out of its forearms. The other, the raptor Balaur, had only two fingers on each hand and a double set of hyperextendable sickle claws on each foot. (And, while not as anatomically strange, the first specimens of Linheraptor described this year were absolutely gorgeous.)

Other notable theropod news included the discovery that a specimen of the small predator Juravenator from the famous Jurassic limestone quarries of Germany preserved traces of both scales and feathers, traces of predatory dinosaurs digging after mammals in their burrows found in Utah, and that the idea that Sinornithosaurus was venomous was rightly called into question. Paleontologists also confirmed that many, if not most, coelurosaurs did not exclusively dine on meat, making this group of dinosaurs one of the strangest and most varied of all.

Of course, no list would be complete without mention of some of the studies about that most famous group of theropods, the tyrannosaurs. The Canadian Journal of Earth Sciences devoted a special issue to Albertosaurus, the tyrannosaur Bistahieversor was named, direct evidence was found of cannibalism among Tyrannosaurus, the identity of the purported tyrannosaur from Australia was debated, damaged bones showed that Tarbosaurus could be delicate with its massive jaws, and one study found that Tyrannosaurus and other predatory dinosaurs had some extra “junk in the trunk.”

Year of the Ceratopsians

Although theropod dinosaurs regularly make headlines, 2010 was notable for the exceptional number of new studies about horned dinosaurs. The year’s major story was the formal publication of the idea that the dinosaur called Torosaurus was really an adult stage of Triceratops – an argument which will require further study to resolve – but paleontologists were also thrilled to see the publication of the New Perspectives on Horned Dinosaurs volume, a landmark publication in the study of this group.  Multiple new species of ceratopsians were described this year, as well. In addition to those announced in the conference volume, Koreaceratops, Zhuchengceratops, Utahceratops, Kosmoceratops, Sinoceratops, and Ajkaceratops (the first confirmed ceratopsian from Europe). Our understanding of ceratopsians is rapidly changing, and I am currently working on a formal academic article reviewing the significant discoveries which were announced this year.

Armored Dinosaurs

Multiple new analyses published this year have altered our perspective of the armored stegosaurs and ankylosaurs. Regarding stegosaurs, in particular, an issue of the Swiss Journal of Geoscience included a spate of papers about the relationships and biology of these dinosaurs, including studies on stegosaur soft tissue, their relatively weak jaws, their posture, the history of stegosaur discoveries, and stegosaur diversity in the Late Jurassic of North America. Furthermore, a pair of studies by Phil Senter on the forefeet of Stegosaurus and the ankylosaurs Edmontonia and Peloroplites have shown that these dinosaurs had a semi-tubular arrangement of lower limb bones similar to that seen among some sauropod dinosaurs, changing our understanding of how these armored dinosaurs walked.

Sauropods and Their Kin

The long-necked, large-bodied sauropods are among the most iconic of the dinosaurs, but new discoveries are rapidly changing our understanding of their origin and evolutionary history. The discovery of the sauropodomorph Sarahsaurus from Arizona has helped identify an evolutionary pattern in which these dinosaurs migrated into North America multiple times during the Early Jurassic rather than just being part of a single move northward. Another sauropodomorph described this year, Seitaad, provided further evidence for this hypothesis.

A presentation at this year’s Geological Society of America meeting caused a stir by claiming to have found tracks of juvenile sauropod dinosaurs running only on their hindlimbs. Paleontologists are awaiting further details about these fossil footprints. Most of the known sauropod tracks are quite a bit larger, and footprints made by some sauropods may have formed deathtraps which later preserved smaller dinosaurs like Guanlong and Limusaurus.

One sauropod nest site in Argentina was found in close proximity to geysers, vents and other features associated with geothermal activity – the dinosaurs selected a naturally-heated nursery. Nesting sites were not always safe, though. A different nest site in India contained the remains of a snake that had been feeding on baby sauropods.

Even well-known sites and old collections are yielding new discoveries. A juvenile Diplodocus skull collected decades ago has helped show how the diets of these dinosaurs changed as they aged. This specimen came from Dinosaur National Monument, and a geologically younger, Early Cretaceous site from the national park also yielded the skulls of a previously-unknown sauropod called Abydosaurus.

Dinosaur Colors

The biggest announcement of the year was that scientists have finally found a way to detect the colors of some dinosaurs. The technique has only been applied to feathered dinosaurs, but by comparing microscopic structures in preserved dinosaur feathers to their counterparts in modern birds, paleontologists have finally been able to fill out parts of the dinosaur palette. The first study, published in Nature, looked at just part of the tail plumage of Sinosauropteryx, while the second study (published the following week in Science by the team that had pioneered the techniques being utilized) reconstructed the entire feather colors of Anchiornis. These were just initial reports in what is sure to become a very active area of research. At long last, scientists will be able to provide answers about what has traditionally thought to be a question incapable of resolution.

Those are just a few selection from stories we covered here during 2010. What were your favorite dinosaur stories from the past year?

See also our list of 2010′s top dinosaur books, and our list of top dinosaur stories from 2009.

Tracks made by an Iguanodon-like dinosaur at the 100 million year old Dinosaur Ridge tracksite. Image from Flickr user Matthew Saunders.

The Cretaceous dinosaur tracks scattered along Morrison, Colorado’s Dinosaur Ridge have persisted in the fossil record for 1o0 million years, but they are now in danger of being lost forever. Exposed on the surface, the tracks are being eroded away bit by bit, and a local controversy over the aesthetics of the Colorado landscape has complicated efforts to preserve these tracks.

The fossil sites of Dinosaur Ridge come from three different time periods. There is a 150-million-year-old dinosaur bone quarry, a 100-million-year-old track site, and a 68-million-year-old track site. It is the 100-million year-old set of tracks, dominated by footprints made by an Iguanodon-like dinosaur, that is at the center of the debate. Regular freeze-thaw cycles and exposure to the elements have been gradually destroying the tracks. According to an article in the Denver Post, the nonprofit group Friends of Dinosaur Ridge has proposed that a canopy of high-tech fabric be erected over the site to help prevent further damage. The trouble is that this proposal runs counter to Jefferson County’s official Front Range Mountain Backdrop policy which forbids structures that would obscure or detract from views of the mountains. An article on the debate from LJWorld.com reports:

“The plan that they came up with includes structures and it just doesn’t work,” said Kathryn Heider, a spokeswoman for Jefferson County, which owns the land where the tracks are located 15 miles from Denver. “It doesn’t mean we don’t want to preserve the footprints. It just means we don’t want structures on the backdrop.”

Discussions about what can be done to save the tracks are ongoing, but there is not much time left. Based upon damage already done to the tracks, the Friends of Dinosaur Ridge project that the tracks have only about 10 to 15 years before they are lost. Their destruction would rob a natural treasure from scientists and the public alike. I hope that an amenable solution to this dilemma can be found soon.

Capitalsaurus Court, marking the location of the dinosaur's discovery in 1898. From Flickr user DC Like a Local.

When I think of North American dinosaurs, my mind immediately jumps to the impressive giants like Diplodocus and Tyrannosaurus scattered in rock formations around the West. But there were East Coast dinosaurs, too. One of them, an enigmatic creature discovered at the close of the 19th century, even serves as the controversial official dinosaur of our nation’s capital.

According to David Weishampel and Luther Young’s book Dinosaurs of the East Coast, in 1898 construction workers found part of a dinosaur vertebra and other bone fragments while excavating a sewer at First and F Streets SE. It was one of several fragmentary dinosaurs found in the approximately 100-million-year-old, Early Cretaceous rock under parts of the city, but there was so little of it that paleontologists are still uncertain as to what this animal actually looked like. The most distinctive bone of the lot—the vertebra, which came from near the base of the tail—indicates that that animal was a large theropod dinosaur, but over the past century it has been bumped from one assignment to another. In 1911 the paleontologist Richard Swann Lull named the dinosaur Creosaurus potens, but this was overturned a decade later when his colleague Charles Gilmore noticed that the name “Creosaurus” was synonymous with Allosaurus. Furthermore, Gilmore proposed that the partial tail bone more closely resembled its counterpart in the New Jersey dinosaur Dryptosaurus, leading him to rename it Dryptosaurus potens.

The tailbone sat at the Smithsonian for another seven decades, but in 1990 the paleontologist Peter Kranz gave it another look. The tail bone did not closely match that of Dryptosaurus after all, and instead appeared to represent a unique type of dinosaur (which would make sense given that Dryptosaurus lived later during the Cretaceous and Allosaurus had lived earlier during the Jurassic). Little could be said beyond this with certainty, but Kranz called the dinosaur “Capitalsaurus” in a 1990 Washingtonian article and introduced the name, albeit in quotes, into the formal scientific literature in a 1998 review of Washington D.C.’s fossils.

Here’s where things get tricky. Kranz never officially described the fossils according to the standards of modern paleontology, meaning that “Capitalsaurus” is an informal name and not a scientific designation for the dinosaur. This did not stop it from becoming the official dinosaur of Capitol Hill. The same year that Kranz published his review of D.C.’s fossils, he also worked with local schools to make the case to the D.C. Council that “Capitalsaurus” should be the district dinosaur. This passed, even if the body of the bill muddled the science itself, calling “Capitalsaurus” a potential ancestor of Tyrannosaurus while including a skeletal restoration of the distantly related allosauroid Acrocanthosaurus.

Valid or not, “Capitalsaurus” became embedded in the city’s culture. The site of its discovery was renamed Capitalsaurus Court, and January 28 is Capitalsaurus Day to commemorate the date in 1898 when the dinosaur was found. Nevertheless, the name “Capitalsaurus” remains only a popular designation, and without more fossil material it will be impossible to definitively identify this dinosaur. Who knows if further remains will ever be found? The relevant deposits have been built over, although there is the possibility that future construction projects may inadvertently find more fossils. Until then, the true identity of “Capitalsaurus” will have to remain a mystery.

The cover of New Perspectives on Horned Dinosaurs, the most important dinosaur book of 2010.

Another year, another spate of dinosaur books. The following is a brief review of the major dinosaur and dinosaur-related books I reported on during the past year (plus one extra that I have not yet reviewed but that no “best of 2010 dinosaur books” list could be without):

Barnum Brown: The Man Who Discovered Tyrannosaurus Rex

Famous for his fossil-hunting exploits—and a notorious lothario to boot—Brown helped form the foundation of early 20th century paleontology in North America. Although his boss, Henry Fairfield Osborn, would name the monster, it was Brown who found the first pair of Tyrannosaurus rex skeletons, and the halls of the American Museum of Natural History in New York are filled with the spoils of his field expeditions. Written by paleontologists Mark Norell and Lowell Dingus, this biography is an extensive and authoritative look at the adventurous life of one of the most significant figures in American paleontology. (Original review.)

Triassic Life on Land: The Great Transition

A slim, technical volume by paleontologists Hans-Dieter Sues and Nicholas Fraser, Triassic Life on Land is an extensive catalog of the organisms that inhabited the landscape between 250 million and 200 million years ago. As the book’s subtitle indicates, this was a time of great transitions—the precursors of mammals, the synapsids, had nearly been wiped out during the mass extinction that preceded the beginning of the Triassic, and the origin of the dinosaurs can be traced during this time. In many ways, life on land during the Triassic set the stage for evolution during the following 200 million years, and this book is a rich reference for any serious student of the fossil record. (Original review.)

The Second Jurassic Dinosaur Rush

Written by paleontologist and historian Paul Brinkman, The Second Jurassic Dinosaur Rush fills in a significant gap in the history of North American paleontology. The tale of the “Bone Wars”—the intense fossils collecting contest between E.D. Cope and O.C. Marsh from the 1870s through the early 1890s—has been told many times before, but Brinkman focuses on the following period in which turn-of-the-century scientists competed with each other to collect the biggest and most impressive dinosaur skeletons. Doubtlessly of interest to paleontologists, this excellent book will also give more casual readers a detailed look at the search for dinosaur bones.  (Original review.)

The Princeton Field Guide to Dinosaurs

Dinosaurs are being named and described so quickly that it is difficult to keep track of them all, and there is still so much left to find! Fortunately for anyone who feels as if they are drowning in a sea of new dinosaurs, though, The Princeton Field Guide to Dinosaurs by paleontologist and artist Gregory S. Paul serves a sort of yearbook of dinosaurs. Skeletal drawings and fleshed-out restorations abound in this dinosaur catalog. If all you know of dinosaurs is based on the classics like Allosaurus, Stegosaurus, Triceratops and Apatosaurus, you will certainly be surprised by the stunning array of dinosaur diversity that Paul illustrates. Frustratingly, however, Paul has an inconsistent and idiosyncratic way of renaming dinosaurs—lumping some distinct dinosaurs into the same genus while splitting others on minor differences—and so a number of dinosaurs in the book have been improperly renamed. (Original review.)

New Perspectives on Horned Dinosaurs

I saved the best for last. New Perspectives on Horned Dinosaurs is the single most significant dinosaur book published this year. Not only are several new horned dinosaurs, such as Diabloceratops and Medusaceratops, described for the first time within its pages, but it also acts as a much-needed update to our understanding of this peculiar group of well-ornamented dinosaurs. Since 2010 has been so rich in horned dinosaur discoveries, this technical volume is required reading for anyone who wants to get up to speed on what we currently understand about ceratopsians. (Full review forthcoming.)

So that’s my list. Did I miss something? Speak up in the comments.

(Ed. Note — We’ll speak up! Brian is way too modest and ignored his own book, Written in Stone: Evolution, the Fossil Record, and Our Place in Nature. We loved it and published an excerpt about whale evolution on Smithsonian.com — read and enjoy!)

Several bones from juvenile hadrosaurs found in a bonebed along Alaska's Colville River. From Fiorillo et al., 2010.

In northern Alaska, along the banks of the Colville River, a series of fossil bonebeds preserve remnants of the Late Cretaceous world. These ancient environments were quite different from those found farther south.

Even though the climate of Cretaceous Alaska was warmer than that of today, areas near the Colville River deposits were cold enough to support permafrost and ice fields. This area was not a tropical paradise, but a cooler environment where the average annual temperature was only about 41 degrees Fahrenheit. Nevertheless, the multiple fossil sites show that this place was home to a wide variety of dinosaurs including tyrannosaurs, ceratopsians, hadrosaurs and pachycephalosaurs.

The discovery of such rich assemblages of polar dinosaurs is relatively new. The fact that there were dinosaur fossils in northern Alaska became known only in the 1980s, and excavations since that time have found multiple bonebeds along a 27-mile stretch of the Colville. The diversity of dinosaurs and the number of rich fossil sites was not expected, but what could have caused the formation of so many bonebeds so close to each other?

According to a Palaeogeography, Palaeoclimatology, Palaeoecology paper published this year by Anthony Fiorillo, Paul McCarthy and Peter Flaig, the answer might be found in the colder areas that bordered the environments represented by the bonebeds. As reconstructed by the paleontologists, the dinosaur-bearing deposits are indicative of a relatively warm coastal plain. Right next door, however, the Brooks Range mountains were being pushed up, creating a colder environment where permafrost and snow regularly formed during the coldest part of the year. When summer returned, the ice and snow of the Brooks Range melted, sending floods down into the coastal area where the dinosaurs dwelt.

The jumbles of bones along the Colville are consistent with this scenario. Paleontologists working these sites are not finding beautifully-articulated skeletons, but are instead discovering many bones thrown together, some of which are associated (that is, came from the same animal even though they have fallen out of their natural placement). The bones don’t show signs of cracking that would indicate that they were lying exposed on the ground for long periods of time before being buried, nor do they show signs of damage caused by being transported by water over long distances.

Based on the geology of the area and the details of the bones, the bonebeds along the Colville appear to have been created by intense, seasonal floods that quickly killed and buried dinosaurs living on the coastal plain. As the authors themselves state, “The Cretaceous arctic of northern Alaska may have witnessed the coastal plain being a seasonal killing field.”

Curiously, however, the way the bonebeds were created caused some dinosaurs to become preserved more often than others. Juvenile dinosaurs appear to have been especially vulnerable. Young dinosaurs are quite common in these assemblages, and this may indicate that the seasonal floods struck during a time of year when young dinosaurs were particularly abundant. This is an important fact. Rather than migrating in during the warmest months, young dinosaurs were probably born and grew up in this place, meaning that dinosaurs were probably living hear year-round. Though we often think of dinosaurs as inhabitants of warm, tropical environments, these polar dinosaurs almost certainly experienced snow. Imagine: herds of hadrosaurs trudging across the plain as snow falls, while a tyrannosaur stalks them from a distance. The dinosaurs did not just barely hang on in this cold place; they thrived there.

And with visions of snowbound dinosaurs dancing in our heads, all of us here at Dinosaur Tracking want to wish you happy holidays!

References:

Fiorillo, A., McCarthy, P., & Flaig, P. (2010). Taphonomic and sedimentologic interpretations of the dinosaur-bearing Upper Cretaceous Strata of the Prince Creek Formation, Northern Alaska: Insights from an ancient high-latitude terrestrial ecosystem Palaeogeography, Palaeoclimatology, Palaeoecology, 295 (3-4), 376-388 DOI: 10.1016/j.palaeo.2010.02.029