August 28, 2012
I adore feathered dinosaurs. It feels a little strange to say that, but it’s true. Few things make me happier than seeing delicately-rendered restorations of theropods covered in fuzz and ceratopsians with some accessory bristles. The various bits of plumage–from quill-like structures to true feathers–make dinosaurs look even more wonderful and fantastic than the drab, scaly monsters I grew up with. And who wouldn’t love a fluffy like dinosaur like Sciurumimus, perhaps the cutest dinosaur of all time?
Of course, not everyone feels the same way. There are some people who want their dinosaurs to be scaly, scaly, scaly, science be damned. They weep, wail and gnash their teeth whenever a new study suggests that another branch of the dinosaur family tree might have been adorned with plumage. It’s as if they expect the Dinosauria to be consistent with an unchanging canon–sci-fi and comic fans suffer a similar apoplexy when one of their favorite characters deviates from their most cherished storyline.
io9′s “We Come From the Future” show recently debated whether science had “ruined” dinosaurs by decorating so many non-avian species with feathers. (Remember–birds are dinosaurs, too, and there have been some very scary birds in the history of life on earth). Granted, some restorations of feathery dinosaurs really do look stupid, and the minor plumes on the heads of Jurassic Park III‘s Velociraptor didn’t really help.
The show’s point-counterpoint debate on the matter isn’t totally serious, and it’s a way to get a tidbit of science out to a wider audience. That’s a good thing. All the same, I’m pretty sick of people who complain that feathers somehow detract from dinosaurian magnificence. How immature can you get? We all love the dinosaurs we first meet as kids, and, for many of us, those leviathans were drab and scaly. But those earlier versions have been slit from stem to stern by more active, colorful and complex dinosaurs, many of which had some kind of feather-like body covering. Which would you prefer? The scaly, sluggish pot-bellied Tyrannosaurus of the mid-20th century, or a svelte, agile predator that has a few patches of fuzz?
Don’t misunderstand me here. I’m not saying that all dinosaurs looked like big chickens. Dinosaurs exhibited an array of body structures–from simple, fuzzy tubes to bristles and full-on flight feathers. Some species, like modern birds, even exhibited several different types of feathers. The weird Beipiaosaurus, for one, had fuzzy protofeathers on much of its body but also had a sort of tail fan created by a different feather type. And “feathered dinosaur” doesn’t mean that the animal was entirely cloaked in plumage. Take Psittacosaurus, for example–this little ceratopsian was a very, very distant relative of birds and had a row of bristles along its tail. The structures were probably visual signals, and I have no doubt that same was true among other dinosaurs. Feathers aren’t just about flight or insulation, but they’re also important in display and communication.
And feathers are the key to dinosaur color. I’m still awestruck that we can recreate the colors of creatures that have been extinct for tens of millions of years. By comparing the microscopic details of prehistoric dinosaur feathers to the feathers of modern birds, we can finally answer that most persistent of paleo questions. That fact, alone, makes feathered dinosaurs especially magnificent.
I’m weary of this Portlandia-esque attitude that dinosaurs are over if they’re feathered. Please. New scientific discoveries are allowing us to gain unprecedented insights into the biology of dinosaurs, including the lives of the fluffy species. Feathers are just part of that bigger picture, and I’m ecstatic that paleontologists are reconstructing dinosaurs in ever-greater detail. The point is this. Feathered dinosaurs are awesome. Deal with it.
July 5, 2012
On Monday, the world met yet another fuzzy dinosaur. The little theropod – named Sciurumimus albersdoerferi – is beautifully preserved in a slab of roughly 150 million year old limestone found in Germany. (These deposits have also brought us Archaeopteryx and the also-fluffy Juravenator.) And, with a little evolutionary context, Sciurumimus hints that filament-like protofeathers were more common among dinosaurs than we previously expected.
Birds – the only surviving lineage of dinosaurs – are covered in plumage. No surprise there. But since 1996, paleontologists have identified about 30 genera of non-avian dinosaurs with feathers. Most of these dinosaurs are coelurosaurs – the major group of theropod dinosaurs that contains tyrannosaurs, the switchblade-clawed deinonychosaurs, the truly weird therizinosaurs, and, among others, birds. As the discoveries accumulated, it seemed that feathers originated at the base of this group, and were inherited by birds. And feathers were not only present an small, especially bird-like dinosaurs. As the recently-described Yutyrannus shows, even 30-foot-long tyrannosaurs were fluffy.
Up until a few years ago, birds and their closest non-avian relatives were the only dinosaurs known to have feathers. Simple enough. But then two ornithischians crashed the party.You see, the dinosaur family tree is split into two halves – the saurischians on one side, and the ornithischians on the other. The split goes back about 230 million years or so, nearly to the origin of the very first dinosaurs.
The feathery coelurosaurs belong to the saurischian side of the tree, but paleontologists have also discovered dinosaurs on the other side – on the ornithischian branches – with feather-like structures. In 2002, paleontologists discovered that the archaic ceratopsian dinosaur Psittacosaurus had a brush of bristle-like structures jutting from its tail. And in 2009, another team discovered Tianyulong – another ornithischian dinosaur with a row of similar filaments running down its back. The bristles were not just like the fuzz and feathers seen among the coelurosaurs, but they were structurally similar.
Paleontologists were left with two possibilities. Either protofeathers evolved multiple times in different dinosaur lineages, or simple “dinofuzz” was an ancestral dinosaur feature that was later lost in some lineages. We don’t have enough fossils yet to know for sure, but the discovery of Sciurumimus is a significant clue that most, if not all, dinosaur lineages were at least partially decorated with protofeathers.
Even though Sciurumimus is a theropod dinosaur – part of the saurischian side of the family – it isn’t a coelurosaur. Sciurumimus is a megalosauroid, which is a lineage of dinosaurs that’s closer to the base of the theropod group. In other words, Sciurumimus is a relatively archaic theropod that isn’t very closely related to birds, yet it still has dinofuzz.
Paleontologist Thomas Holtz helped provide some context on Twitter shortly after the new dinosaur was announced. Before Sciurumimus, only coelurosaurs were known to have fuzz. (What the bristles on Psittacosaurus and Tianyulong actually are is still unclear, but no one calls their filaments “fuzz.”) After Sciurumimus, fuzz has been moved down a branch to a group called the Carnosauria.
We are still left with two possibilities. The fuzz on Sciurumimus could have originated independently. But as paleontologists add fuzz to lineages of dinosaurs only distantly-related to birds, it seems less and less likely that protofeathers evolved from scratch in each and every lineage. It’s looking more and more like feathers were a common, ancestral feature of dinosaurs. In this case, Sciurumimus indicates that simple feathers were an early, common theropod trait that evolved close to the origin of the group. The diminutive dinosaur also fits in the wide gap between coelurosaurs and their very distant ornithischian dinosaurs, bringing us a little closer to the idea that dinofuzz was an early, widely-shared dinosaur feature.
And there’s something else. Pterosaurs – the flying archosaurs with leathery wings stretched over elongated wing fingers – were the closest relatives to the Dinosauria as a whole. They had fuzzy body coverings, too. No one knows for sure, but this might mean that wispy plumage was present in the last common ancestor of dinosaurs and pterosaurs, and those simple body coverings were subsequently modified or lost in different lineages as both groups evolved.
We need more fossils to test the idea that dinosaurs started out feathery. Additional fossils preserving fuzz – fluffy baby sauropods, maybe? – would help us understand the spread of feathers and their precursors among dinosaurs. And, even then, we’d still need to find exceptionally-preserved specimens of the earliest dinosaurs to see if they had any kind of filament-like body covering. The trouble is that the high-definition deposits that would even have a chance of preserving feathers are rare. It may be a very long time before we ever know for sure.
Nevertheless, there’s still a possibility that all dinosaur lineages had some kind of bristly or feathery body covering. It’s a hypothesis that needs testing, but not an unreasonable one. Think about this for a moment. Imagine a Stegosaurus with patches of long, stiff filaments covering its body, or a Ceratosaurus with a little splash of brightly-covered fuzz on its already well-decorated head. And I think a huge sauropod – like Apatosaurus – with a partial covering of dinofuzz would look absolutely spectacular. These visions are wholly different than the scaly dinosaurs I grew up with, but they are not so fantastic as to be fiction. We are only just beginning to understand how fuzzy dinosaurs were.
July 3, 2012
Last week, paleontologists at the Argentine Museum of Natural Science in Buenos Aires literally unveiled a new dinosaur. Named Bicentenaria argentina to celebrate the museum’s 200th anniversary and just over two centuries of Argentine independence, the dinosaur was presented in a dramatic mount in which two of the predatory dinosaurs face off against each other.
As yet, there’s not very much to say about the dinosaur. The paper officially describing Bicentenaria has yet to be published. Based on various news reports, though, Bicentenaria appears to be a 90 million year old coelurosaur. This is the major group of theropod dinosaurs that contains tyrannosaurs, deinonychosaurs, therizinosaurs, and birds, among others, and Bicentenaria is reportedly an archaic member of this group that represents what the earliest coelurosaurs might have looked like. It wouldn’t be an ancestor of birds or other coelurosaur groups – by 90 million years ago, birds and other coelurosaurs had already been around for tens of millions of years – but Bicentenaria may have had a conservative body plan that preserved the form of the dinosaurs that set the stage for other coelurosaurs. For now, though, we’re left to admire the impressive skeletal mount until the paper comes out.
April 6, 2012
Every kid knows how Easter eggs wind up in their yard. According to the canonical weirdness that is the holiday tradition, the Easter bunny delivers the colorful eggs overnight. But the origin of the eggs themselves is hardly ever mentioned. According to a well-timed press release from the University of Leicester, non-avian dinosaurs are the best candidates for some of the candy eggs hidden away on lawns.
There is some real science behind the silliness. In the latest issue of Palaeontology, researchers Nieves López-Martínez and Enric Vicens described a new type of dinosaur egg discovered in the Cretaceous strata of northeastern Spain. The roughly 70-million-year-old eggs, given the name Sankofa pyrenaica to distinguish them from other egg forms previously found, exhibited a strange combination of features.
Many non-avian dinosaur eggs are more or less symmetrical in shape, regardless of whether they are spherical or elongated. Bird eggs, such as those from hens, often have an asymmetrical, tear-drop shape in which one end of the egg is more pointed and the other more rounded. There is some overlap in form, though. Eggs attributed to the small, sickle-clawed dinosaur Troodon and to the beaked oviraptorosaur Citipati are both elongated and taper to one end, and so seem similar to bird eggs.
The profile of the newly described egg type is most similar to that of archaic birds. But, according to López-Martínez and Vicens, the microscopic structure of the Sankofa eggs shares more in common with those laid by non-avian dinosaurs such as Troodon than with birds. The Sankofa eggs exhibit a mix of characteristics seen in both non-avian dinosaurs and archaic birds. Without fossils of the chicks developing inside the eggs, or even associated bones of adult animals, exactly what sort of creature laid this egg is ambiguous.
As part of the study, López-Martínez and Vicens created a chart of non-avian and avian dinosaur egg shapes. And, while it didn’t resolve the true identity of Sankofa, University of Leicester paleontologist Mark Purnell employed the comparative diagram in an attempt to track what sorts of dinosaur—avian or otherwise—could have laid the colorful eggs offered in England’s shopping districts. While many treats had the traditional hen egg shape, Purnell found, at least one resembled the Sankofa egg shape. I have to wonder if other Easter egg variations fit within the non-avian dinosaur range. Perhaps an expedition to the supermarket is in order.
LÓPEZ-MARTÍNEZ, N., & VICENS, E. (2012). A new peculiar dinosaur egg, Sankofa pyrenaica oogen. nov. oosp. nov. from the Upper Cretaceous coastal deposits of the Aren Formation, south-central Pyrenees, Lleida, Catalonia, Spain Palaeontology, 55 (2), 325-339 DOI: 10.1111/j.1475-4983.2011.01114.x
March 9, 2012
Microraptor was an exquisitely feathered dinosaur. The small, sickle-clawed predator, which lived about 120 million years ago, was covered in well-developed plumage, including long feathers on its arms and legs. But we now know that Microraptor was not only beautiful in an anatomical structure sense. A detailed new study has painted this dinosaur in a glossy black sheen.
The range of the dinosaur palette has been one of the most mysterious aspects of dinosaur biology. For most species, we just don’t know—bones and teeth can’t tell us anything about skin color. But feathered dinosaurs contain evidence of their hues within their feathers. Microscopic organelles called melanosomes are the key. In fossil creatures—just as in living ones—the size, shape, density and distribution of these tiny, pigment-filled blobs created different colors. By studying the characteristics of melanosomes in feathered dinosaurs and comparing the patterns with those that create the colors of modern birds, paleontologists can reconstruct dinosaur feather colors.
Several dinosaurs have already received a color treatment. After establishing that fossil melanosomes are faithful indicators of prehistoric color in ancient birds, paleontologist Jakob Vinther and colleagues restored the full-body coloring of the feathered, non-avian dinosaur Anchiornis. This small dinosaur looked something like a magpie with a bright red splash of feathers on top of its head. Earlier this year, Vinther, Ryan Carney and co-authors determined that the famous feather used to name the earliest known bird—Archaeopteryx—was black. And a different team of researchers, led by paleontologist Fucheng Zhang, hypothesized that the fuzzy Sinosauropteryx had a candy-cane tail ringed in white and rusty red. Paper by paper, dinosaurs are being colored in.
In the case of Microraptor, the dinosaur did not turn out quite like any of the restorations that artists had previously composed. Many Microraptor illustrations envisioned the dinosaur in shades of brown, white and blue. But when Vinther, Quanguo Li and collaborators studied the melanosomes sampled from 26 different locations on a Microraptor specimen designated BMNHC PH881, they didn’t find those colors. Microraptor feathers were iridescent blue-black. In appearance, Vinther said via email, Microraptor would have looked similar to “grackles or a magpie, or indeed a crow.”
Black was apparently quite fashionable among feathered dinosaurs. Anchiornis, while overall more colorful, was also predominantly black, and the lone Archaeopteryx feather was also black. Why black was so common for dinosaurs with complex, specialized feathers isn’t clear. Vinther pointed out that the small sample size might be creating this pattern, especially since other, unpublished specimens show different colors. Then again, black and other dark shades might have had something to do with where the animals lived. Citing a phenomenon called Gloger’s rule, Vinther explained that mammals and birds that live in hot, humid environments near the equator have more of the pigment melanin, and therefore appear darker, than those living closer to the poles, though “sample size needs to be increased to make any generalizations like these,” he cautioned.
Vinther is confident that further studies will increase the number of dinosaurs for comparison. “The material is clearly there,” he said. It is only a matter of time before paleontologists can start to understand how color varied between individuals, and possibly even between the sexes. For the moment, though, the handful of dinosaurs that have been restored in color have shown that intricate avian traits existed far back in the past. “We were speculating about how deep iridescent colors might be and we were pretty excited when we realized that Microraptor indeed is iridescent,” Vinther said, and this discovery can tell us something about how feathers and even behaviors evolved among early birds and their dinosaurian kin.
“We can see that the paravian clade,” the group that contains birds and non-avian dinosaurs more closely related to birds than dinosaurs , “has complex feather morphologies and exhibit colors and color patterns for display and even iridescence like in modern birds, so these features are ancient and indeed suggest that at least the derived theropod dinosaurs were more similar in ecology and behavior to birds,” Vinther said. And, as research continues on feathered dinosaurs more distantly related to birds, Vinther suspects that many characteristics of modern birds will be pulled “deep down” the dinosaurian tree. The more we learn about feathered dinosaurs, the further back we can draw traits seen among birds today.
And there are still things to learn about the anatomy of feathered dinosaur plumage. While the iridescent hues of Microraptor are the major finding of the new paper, the study also pointed out that specimen BMNHC PH881 had a specialized set of paired feathers at the end of the tail. Similar feathers had been noted in other Microraptor specimens before, but this fossil had an especially lovely set. The structures are “simply too small and the feathers too spaced to create any lift,” Vinther said, so it’s unlikely that they aided the dinosaur in gliding or flying. Instead, citing the assessment of co-author Julia Clarke, Vinther said that the feathers might have been a display structure. Combined with the flashy feathers, these structures might be another clue that display and visual communication were very important factors in the early evolution of feather anatomy and color.
For most of my life, I was told that we would never know what colors dinosaurs were. Now, amazingly, there is a way to restore the appearances of some dinosaurs with a fidelity never thought possible. But I had to wonder if paleo-artists have felt any aggravation about such discoveries. As new studies establish feather colors for dinosaurs, the realistic palettes for those dinosaurs are constrained. I asked Vinther if he has received any irritated comments from artists about his work. He replied that, to the contrary, his research has been greeted with excitement. And while defining dinosaur colors “might take some of the imagination from the artists,” Vinther said, “I think that their fascination with these beasts gives them a desire to make them more scientifically correct.” The colorfully restored dinosaurs seem to be a hit. “I am struck by awe when I google-image Anchiornis and see forty plus versions of Anchiornis by various artists all over the world and even tattoos of it,” Vinther said. With any luck, the new glossy Microraptor will be just as popular.
Carney, R., Vinther, J., Shawkey, M., D’Alba, L., & Ackermann, J. (2012). New evidence on the colour and nature of the isolated Archaeopteryx feather Nature Communications, 3 DOI: 10.1038/ncomms1642
Li, Q., Gao, K., Vinther, J., Shawkey, M., Clarke, J., D’Alba, L., Meng, Q., Briggs, D., & Prum, R. (2010). Plumage Color Patterns of an Extinct Dinosaur Science, 327 (5971), 1369-1372 DOI: 10.1126/science.1186290
Li, Q., Gao, K., Meng, Q., Clarke, J., Shawkey, M., D’Alba, L., Pei, R., Ellison, M., Norell, M., & Vinther, J. (2012). Reconstruction of Microraptor and the Evolution of Iridescent Plumage Science, 335 (6073), 1215-1219 DOI: 10.1126/science.1213780
Zhang, F., Kearns, S., Orr, P., Benton, M., Zhou, Z., Johnson, D., Xu, X., & Wang, X. (2010). Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds Nature, 463 (7284), 1075-1078 DOI: 10.1038/nature08740