And if the whole hindquarters, from the ilium to the toes, of a half-hatched chick could be suddenly enlarged, ossified, and fossilised as they are, they would furnish us with the last step of the transition between Birds and Reptiles; for there would be nothing in their characters to prevent us from referring them to the Dinosauria.
—THOMAS HENRY HUXLEY, FURTHER EVIDENCE OF THE AFFINITY BETWEEN DINOSAURIAN REPTILES AND BIRDS, 1870
THE BIG CHILL IN CHINA
During the Chinese Cultural Revolution from 1966 to 1976, scholars and educated people were purged from most institutions, and many were killed or forced to work in labor camps and undergo indoctrination for not being good communists. Chinese scientists at the Institute for Vertebrate Paleontology and Paleoanthropology (IVPP) were severely affected, and most of them tried to lay low and hope that the authorities would not arrest them. Even if their lives were not threatened, they had almost no contact with the outside world. Almost all research ceased, and Chinese scientists had no access to the scientific work of the rest of the world, nor could they leave China to see other fossils and make comparisons with their own specimens.
Some of the most important Chinese localities include the famous Lower Cretaceous lake shales of the Yixian Formation in Liaoning Province of northeastern China. These shales were deposited at the bottom of a stagnant lake with no oxygen at the bottom. When animals died, they sank but did not decay until they were covered with many fine layers of silt and mud. The lack of oxygen allowed even soft tissues to be preserved. As a result, the Jehol biota from these shales includes many incredible specimens and thousands of leaves, insects, and small animals. More famous are the birds and nonavian dinosaurs with their original feathery coating (some with the original pigment cells preserved) and stomach contents, plus some of the earliest complete fossils (including fur and body outline) of marsupial and placental mammals and other more archaic groups. There are just a handful of these extraordinary localities known anywhere in the world fossil record. Paleontologists call them Lagerstätten, German for “mother lode.”
There was very limited collecting in Liaoning Province in the early twentieth century, and after 1949 China was closed to most Western scientists. This remained true during the dark days of the Cultural Revolution and well into the early 1980s. Specimens kept accumulating in the collections and were studied but not published. In the late 1970s and early 1980s, the political winds in China changed; Mao Zedong died in 1976, and the “Gang of the Four” were overthrown. A more open and practical regime began under Zhou Enlai.
In the late 1980s and 1990s, the floodgates burst, and more and more scientists found and studied these amazing specimens. Chinese scientists were once again allowed to travel and publish, and Western scientists were allowed into China for the first time since the 1940s. In addition, a few Chinese scientists were allowed to travel abroad, study fossils in other museums, attend professional meetings, and present their work. They described their fossils in international journals, and everyone began to see their incredible discoveries.
The Liaoning fossils included hundreds of exquisitely preserved Early Cretaceous birds, some of which were published but many are still being studied. (My former student Dr. Jingmai O’Connor is now a curator at the IVPP, working on enantiornithine birds and publishing many papers each year.) Each fall at the annual Society of Vertebrate Paleontology (SVP) meeting during the 1980s and 1990s, paleontologists were stunned by presentations showing these incredible fossils. Some seeing the light of the scientific world for the first time in 50 years.
In 1996, a local farmer and part-time fossil hunter named Li Yumin found an extraordinary specimen preserved on a slab with nearly all the bones present in a death pose (figure 18.1). He knew his fossil had great value, so he sold the slab and its counterpart (the other half of the split fossil) to two different museums. Ji Qiang, director of the Beijing National Geological Museum, realized it was an important specimen. As luck would have it, Phil Currie of the Tyrrell Museum in Alberta was visiting at the time, having just led a fossil tour of Mongolia. He recognized its great value immediately. As he said later to the New York Times, “When I saw this slab of siltstone mixed with volcanic ash in which the creature is embedded, I was bowled over.” The Chinese scientists immediately began to work on a paper about the specimen and banned anyone from publishing the images until the paper appeared.
Figure 18.1
The original specimen of Sinosauropteryx from the Liaoning beds, showing the complete animal with soft tissues preserved and even the feathers along its back. (Courtesy of Wikimedia Commons)
But Currie and another Chinese scientist, Chen Pei Ji, had photographs of the specimen, which they brought with them to the SVP meeting in the American Museum of Natural History in the fall of 1996. They were not on the program to make an official presentation about the fossil, but rumors about the specimen spread like wildfire through the meeting. Whenever they were standing in the hallways or at receptions, they were mobbed by paleontologists who wanted to see for themselves. I remember this vividly, and it took me several tries before I got my own chance to see the images. This is not unusual for the SVP meetings. Lots of people bring photographs or casts or even original specimens with them to get input and reactions from the qualified specialists at the meeting. This is especially true if they want this feedback before they write up the specimen for publication and presentation at a future meeting. I can’t even count how many times someone has come up to me at SVP, slipped a specimen out of his or her pocket, and asked me for my opinion.
Why were these photographs so shocking and surprising? After more than 25 years of debate about whether birds evolved from dinosaurs, here was the first fossil of a nonbird dinosaur with clear imprints of some kind of feathers, especially the ridge of fluffy down along the spine. All the paleontologists who fought hard to deny any connection between birds and dinosaurs were suddenly and completely discredited. John Ostrom, who had led the battle to accept the fact that birds evolved from dinosaurs, was overjoyed and even in a state of shock. A year after that SVP meeting, Ostrom, Alan Brush (an expert on feather evolution), Peter Wellnhofer (an expert on Archaeopteryx), and Larry Martin (one of the last deniers of the evidence that birds are dinosaurs) met in Beijing to look closely at the specimen and argue about it. By then several additional specimens with even clearer imprints had been found, and over the next 20 years, hundreds of dinosaurs not even close to the branch that led to birds showed evidence of feathers. Published later in 1996 in a small Chinese museum journal, Ji Qiang and Ji Shuan named it Sinosauropteryx, “Chinese lizard wing.” It was the final proof for an idea that had been simmering since a chance discovery in 1861.
“ANCIENT WING”
During the early days of printing, to create a print of a drawing in a book or newspaper, one had to cut an image into a wooden block or etch an image into a block of fine-grained limestone, using wax drawings on a smooth rock surface to prevent the acid from etching the wax-covered part of the limestone. This technique is called lithography (“stone writing” in Greek). In Bavaria in southern Germany, there was a naturally occurring extremely fine-grained rock known as the Solnhofen Limestone, which the stonecutters had been quarrying for centuries. Every once in a while they would find an extraordinarily complete and well-preserved fossil of something that had died and sunk to the bottom of this stagnant, shallow lagoon surrounding an archipelago of islands formed when Late Jurassic seas drowned much of Europe. These creatures were buried without being disturbed by scavengers. All their soft tissues, including skin, were intact, and they were articulated in a death pose. Fossils of marine creatures such as shrimp and horseshoe crabs were found more frequently, but occasionally land animals that had washed out into the lagoon, such as the first pterodactyl specimens, were recovered. Because of their great value on the commercial market, the quarrymen saved these fossil slabs from becoming a lithographic plate or a building stone. In 1860, they found the fossil of a feather, and in 1861, a complete but partially disarticulated specimen of what appeared to be a bird (figure 18.2A). The idea of a bird fossil with feathers was sensational. Before the German authorities could coordinate their funding and make a bid, the British Museum in London had purchased the specimen, and it still resides there today (now known as the “London” specimen).
Figure 18.2
Archaeopteryx lithographica: (A) the “London” specimen, now in the Natural History Museum in London; (B) the “Berlin” specimen, now in the Museum für Naturkunde in Berlin. (Courtesy of Wikimedia Commons)
Naturally, it fell to Richard Owen, the leading paleontologist in England, to describe it (see chapter 3). The discovery was particularly timely as Darwin’s On the Origin of Species had been published a year earlier and was a national sensation. Darwin was overjoyed at the news of a primitive bird that provided a transition between two major groups. The original feather fossil had already been named Archaeopteryx (“ancient wing” in Greek) by Hermann von Meyer. Owen dutifully described the anatomy of the complete but somewhat jumbled “London” specimen as a Jurassic bird. But as an opponent and critic of Darwin, he made no mention of all the archaic dinosaur-like features of this bird, which made it exactly the kind of transitional fossil that Darwin had predicted.
Darwin’s great friend and supporter, Thomas Henry Huxley, had no such reservations. Often nicknamed “Darwin’s Bulldog,” Huxley was already a rising star in paleontology and biology, and after 1859 he spent a lot of his time defending Darwin’s ideas in print and in debates. (Darwin was notoriously shy and retiring and sick much of the time, so he never got into the battle directly.) When Huxley looked at the Archaeopteryx fossil, he could see that most of its bony features suggested that it was a small dinosaur. At a famous presentation in front of the Royal Society in 1863, he proposed that birds were descended from dinosaurs and listed 35 features shared only by nonavian dinosaurs and birds (17 of these are still used by modern paleontologists).
In 1868, he studied another fossil from the Solnhofen Limestone, the first known specimen of the small dinosaur Compsognathus (figure 18.3). This was the basis for the dinosaurs nicknamed “compys” in the Jurassic Park books and movies. It had been found in 1859 and briefly described and named by Johann Wagner, but now it was more important than ever. Huxley immediately noticed how similar its bones were to the bones of Archaeopteryx, convincing him that birds evolved from small dinosaurs. (In 1973, F. X. Mayr found a specimen that had been misidentified as Compsognathus until he saw feather impressions and realized it was Archaeopteryx.) Finally, in 1877 the most famous of the 12 known specimens of Archaeopteryx was found in a perfect death pose with the neck drawn back (figure 18.2B). This fossil is known as the “Berlin” specimen because the German authorities got the money from Wilhelm Siemens to buy it and prevent it from “flying the coop.” Today it is featured in a vault behind bulletproof glass at the Museum für Naturkunde in Berlin.
Figure 18.3
Articulated skeleton of Compsognathus from the Upper Jurassic Solnhofen Limestone. (Courtesy of Wikimedia Commons)
In the late 1800s, the “birds are dinosaurs” idea became less popular, and paleontologist Harry Govier Seeley argued strongly against it. Then, in 1926, paleoartist Gerhard Heilmann proposed that birds arose from some primitive unspecified group of archosaurs (then called “thecodonts”; see chapter 5). His main evidence against the dinosaur origin of birds was that birds have a wishbone formed of two fused collarbones or clavicles, and he claimed that no dinosaur had collarbones. How could birds with collarbones evolve from animals that had already lost their collarbones? It turns out that most dinosaurs did have collarbones (this has been demonstrated in numerous specimens now), but collarbones are small and fragile and are rarely preserved except in the most complete specimens. In 1926, this argument seemed conclusive however, and the “birds are dinosaurs” idea died for decades.
The “birds are dinosaurs” idea was nearly forgotten until the 1970s, when John Ostrom was reexamining and redescribing all the known specimens of Archaeopteryx. He was already struck by the idea that dinosaurs like Deinonychus were active, intelligent predators (see chapter 17). As he looked closer at Archaeopteryx, he realized he was seeing almost the same bony anatomy as in Deinonychus. Not only were the bones almost the same shape, but some strikingly detailed features in the anatomy were shared by Deinonychus and Archaeopteryx. These features were only seen in birds and dromaeosaur dinosaurs such as Deinonychus. For example, some of the wrist bones in these animals are fused into a crescent-moon-shaped bone called the semilunate carpal (figure 18.4). This wrist bone allows dromaeosaurus like Deinonychus to snap their hand in a quick motion forward and down to grab prey—the same motion of the wrist seen in the downward flight stroke of a bird.
Figure 18.4
Anatomy of the wrist bones, including the semilunate carpal (dark bone) found in dromaeosaurs like Velociraptor and in birds like Archaeopteryx. (Redrawn from several sources)
Like all other dinosaurs and pterosaurs, Archaeopteryx and all birds have a mesotarsal joint. Unlike almost all other land animals, the joint in their foot does not hinge between their shinbone and first row of ankle bones (tarsals), but between the first and second row of ankle bones (see figure 5.4B). You can see this any time you are eating a chicken or turkey drumstick. The drumstick bone itself is the shinbone of the bird, and the tiny cap of cartilage on the “handle” of the drumstick is the remnant of the first row of ankle bones. Only birds, dinosaurs, and pterosaurs have this unique configuration of the ankle. Finally, the astragalus bone in the first row of ankle bones (fused to the end of the shinbone) has a spur of bone (called the “ascending process”) that overlaps the front of the lower end of the shin. This feature only occurs in dinosaurs and birds, yet another distinctive evolutionary novelty that can be explained only if birds evolved from dinosaurs.
As Ostrom revived Huxley’s idea that birds are dinosaurs during the 1970s and 1980s, he faced resistance from scientists who were used to the old way of thinking. But along with the Dinosaur Renaissance, largely started by Ostrom, the momentum for “birds are dinosaurs” quickly built as more and more evidence accumulated to support it. By the time of Jacques Gauthier’s pioneering analysis of archosaurian relationships in 1986, hundreds of unique anatomical specializations supported the idea that birds evolved from dromaeosaurs such as Velociraptor and Deinonychus. The discovery of Sinosauropteryx in 1996, and the many other feathered nonbird dinosaurs found since then, should have been the final nail in the coffin of the “birds are not dinosaurs” (BAND) idea, but even this was not enough.
Entrenched beliefs don’t die easily, especially for something as radical as arguing that birds are just modified dinosaurs. Some of the deniers simply didn’t like or understand cladistics or realize the importance of the evidence of unique evolutionary specializations. Others tried to nitpick one or two of the anatomical lines of evidence, ignoring the fact that there were hundreds of features supporting the argument that birds are dinosaurs. They were stuck on rigid older ideas such as “birds have feathers, reptiles don’t” and “feathers evolved for flight.” More and more feathered nonflying nonbird dinosaurs were discovered, showing that feathers first evolved for insulation—and most of the down feathers on a bird still function that way today. The development of certain feathers into airfoils that create lift was a late event in feather evolution, taking advantage of a feature that was already present on the bodies of birds and of the dinosaurs.
Many of the deniers were obsessed with the idea that birds turned into flyers by gliding down from trees, and they could not imagine birds developing flight from the ground up. Ostrom showed that many ground birds propel themselves by flapping as they run across the ground, and this is still seen in ground birds such as the chicken, turkeys, pheasants, and quail. These birds fly just well enough to escape a ground predator, but they cannot fly very fast or very far. A study by Ken Dial in 2002 on chukar partridges found that feathered wings were very good for assisting in scrambling up steep inclines, even though chukars rarely actually fly. It is now thought that birds probably evolved flight feathers primarily for short escape flights and for climbing up surfaces, eventually finding a way to use them to glide and fly longer distances.
The dino deniers often used extreme language in their battle against the wave of evidence against them. Ornithologist Alan Feduccia wrote in Science that “the theropod origin of birds will be the greatest embarrassment of paleontology in the 20th century.” In his book, Unearthing the Dragon, American Museum paleontologist Mark Norell goes over the weird debate in detail (226–235). As he writes, the “birds are not dinosaurs,” and the gang “have never quite gotten it that the origin of flight and feathers is decoupled from the origin of birds. To them, if it has feathers it is an avian. They have odd ideas about how all this relates to flight. As Feduccia claims, ‘It is biophysically impossible to evolve fight from such large bipeds with foreshortened limbs and heavy, balancing tails.’ Before more discussion about feathers, the point of about large bipeds incapable of climbing trees is clearly falsified by the presence of so many nonavian dinosaurs in the Jehol fauna” (227).
As the debate dragged on, the BAND band kept “moving the goalposts.” Whenever one piece of evidence showed the dino deniers were wrong, they’d quickly abandon their old argument and grasp at straws to find another attack that maintained their position. As Kristopher Kripchak posted, “As soon as one theory on why birds cannot be dinosaurs is demolished by a new discovery, the BAND crowd comes up with a new theory that is even less plausible than their previous one. Over the past few years, these folks have adopted more positions than the Kama Sutra” (quoted in Norell, 235).
The debate was more intense than most scientific arguments for another reason—it made a good spectacle in the media. In 2005, David Fastovsky and David Weishampel wrote: “The debate has been unnaturally prolonged by media attention. The origin of birds has been a topic of great public interest for the past twenty years, so much so that the leading proponents are frequently interviewed for newspaper articles and TV specials. The rules of journalism require that ‘equal time’ is given to representatives of each viewpoint. So the supports of the basal diapsid origin of birds often have as much airtime as the supporters of birds as dinosaurs, even though the latter represent probably more than 99 percent of working vertebrate paleontologists.”
As Norell put it, “When more evidence is garnered, whether through the analysis of additional characters, through the discovery of new specimens, or by pointing out errors and problems with the original data sets, new trees can be calculated. If these new trees better explain the data (taking fewer evolutionary transformations), they supplant the previous trees. You might not always like what comes out, but you have to accept it. Any real systematist (or scientist in general) has to be ready to heave all that he or she has believed in, consider it crap, and move on, in the face of new evidence. That is how we differ from clerics.”
Today the debate has largely ended within the paleontological community. The late Larry Martin was the last major denier among vertebrate paleontologists, so no one at SVP is still beating this dead horse. There are still some deniers among ornithologists, who are not familiar with dinosaurs or the evidence or still object to cladistic methods, but they have no influence on the future direction of bird and dinosaur research. Some arguments in science (the debate over what caused the extinction of nonavian dinosaurs at the end of the Cretaceous, or whether dinosaurs were endotherms) are stuck forever in the unresolved, “It’s complicated” category. Fortunately, the debate about whether birds are dinosaurs is over.
FEATHERS, FEATHERS, EVERYWHERE
The discovery of Sinosauropteryx was the first of hundreds of additional specimens from the Liaoning Province, and other places in China, that produced evidence of feathers in nonbird dinosaurs. In fact, Sinosauropteryx is not that closely related to birds at all. It turns out that it is a close relative of Compsognathus, which Huxley first featured in 1868 (figure 18.3) and is a very primitive branch of theropods related to allosaurs, megalosaurs, and spinosaurs. As mentioned previously, none of these nonbird dinosaurs have flight feathers. Instead their feathers are simple shafts (like the pin feathers of modern birds) or downy coverings, or possibly larger feathers that can be used for coloration, display, and courtship.
Prum and Brush published an analysis of the evolution of feathers in 2003 (figure 18.5). First of all, they showed that feathers were not (as dogma had taught) modified reptilian scales but come from a different embryonic primordium with a different developmental pathway. What they call Type 1 feathers are simple, hollow pointed shafts. These occur in the most primitive dinosaurs and appeared in the Ornithischia as well. In other words, all dinosaurs have some kind of feathery covering on some parts of their bodies, even if they are just simple quills. What Prum and Brush called Type 2 feathers are simple down with no vanes in the center. This is what excited paleontologists at SVP in 1996 when they first saw photos of Sinosauropteryx. Type 3 feathers have a vane and a shaft, but the vanes are not linked by hook-like barbules sticking them together like Velcro. This is the kind of feathers found in the Chinese tyrannosaur Yutyrannus and its close relatives, so that would mean Tyrannosaurus rex had feathers of the Type 3 category. Both Type 2 and 3 feathers were found in the large therizinosaur Beipiaosaurus. This shows that most of the advanced theropods related to the therizinosaurs, such as ornithomimids and dromaeosaurs, must have had such feathers.
Figure 18.5
The evolution of feather types from simple pinshafts to down plumes to complex flight feathers with asymmetric vanes and shaft. On the basis of their appearance in various feathered nonflying dinosaurs from Liaoning, we can demonstrate that most predatory dinosaurs (including T. rex) probably had feathers of some sort.
According to Prum and Brush, their Type 4 feathers have barbules that link the vanes of the feather into a continuous surface, but the shaft is symmetrical down the middle of the feather. We find feathers like this in the advanced theropod Caudipteryx, which suggests that these occurred in all the advanced theropods related to it, such as the oviraptorids and the dromaeosaurs. Finally, the most familiar type of feather is the asymmetric flight feather with the shaft near the leading edge of the vane, making an airfoil. Feathers like this first occur in Archaeopteryx and in a few of its close relatives, and many paleontologists think Archaeopteryx was one of the first dinosaurs to actually be able to truly fly and not just glide.
THE “ARCHAEORAPTOR” HOAX
The market for specimens from the Liaoning beds is so lucrative that many farmers spend most of their time quarrying local outcrops of the Yixian Formation in hopes of finding a great specimen that will pay far more than farming. Making the specimen more attractive and preparing it to show all of its good features increases the pressure—and pressure to “enhance” the specimen so it will fetch a better price is also felt. Paleontologists who work with these fossils, particularly those not quarried by scientists and that come from questionable private sources, have learned to watch out for these problems.
There are also pressures on the media to find flashier and flashier stories to grab readers’ attention and sell magazines or newspapers (or these days to get more clicks on a story). This is even more true now that most media are commercial ventures owned by big corporations, driven to make a profit, not to publish a well-checked truth. Together these two forces combined to make the most famous hoax since Piltdown man. This contrasts with most scientific journals, which require careful fact-checking and critiques by scientific peers to sniff out problems and weed out bad research.
In 1997, a farmer in Xiasanjiazi, China, found a specimen of a toothed bird, but the slab was broken into several pieces. In a nearby pit, he found another fossil with a feathered tail and legs that complemented the front end of the animal found in the first slab. He cemented the pieces together, thinking they were parts of the same animal, and sold them to a dealer in June 1998. The dealer then smuggled the contraband specimen to the United States. (It’s illegal to export any fossils from China. Once they are out of China, however, they are freely marketed with no worries about their illegal source.) Note that the original finder of the fossil was not deliberately trying to hoax the scientific world or the public; he was simply “enhancing” his “art object” to fetch a better price.
When I attended the SVP meeting in October 1998 in Snowbird, Utah, the gossip was flying about an extraordinary specimen with a toothed bill and feathered body and feathered tail that was being circulated among the commercial dealers in a national mineral and gem show. (This was just after Sinosauropteryx was first published, and very few other feathered dinosaurs had been found.) The word reached paleoartists Steve and Sylvia Czerkas, who got their patrons to spend $80,000 to buy the fossil for their museum so it would not become another specimen lost to rich collectors. Meanwhile a writer from National Geographic magazine became interested and was anxious to get the scoop on the scientific journals and write a cover story about this amazing feathered dinosaur.
Various parties told Steve and Sylvia Czerkas that they needed to have experts look at it, so they asked Phil Currie of the Royal Tyrrell Museum in Drumheller, Alberta, and Xu Xing from IVPP to come and study it on March 6, 1999. Right away Currie noticed that the left and right halves of the top part of the animal were mirror images, so the fossil had been made by gluing the slab and its counterpart together side by side. He also noticed that the tail and hind legs did not match the top of the specimen, and there was no evidence they had ever belonged together. They got Tim Rowe of the University of Texas to CAT scan it, and the scan showed the pieces didn’t belong together. Nevertheless, Steve and Sylvia Czerkas refused to listen to the paleontologists, and National Geographic didn’t want its scoop in the next issue to be delayed while waiting for careful analysis and publication in a peer-reviewed scientific journal. They ran their article on October 15, 1999. National Geographic held a big press conference to announce their discovery, and it appeared in the November 1999 issue with the name “Archaeoraptor.”
When the article appeared, it sparked outrage among paleontologists. First of all, publishing a new scientific name in a popular magazine rather than in a scientific journal is a strict no-no. (In retrospect this was lucky. After the hoax was discovered, the naming mistake meant that scientists didn’t have to formally deal with the name—it is invalid.) More important, other people began to agree with Currie and Xu that the specimen appeared to be a composite of more than one animal. Xu returned to the collecting area, interviewed many of the Chinese collectors, and soon located the site where the tail and hind legs had been found. Eventually, he found the counterpart slab that matched the lower half of the “Archaeoraptor” fossil; it even had a matching yellow iron oxide stain. Yet the rest of the slab did not have parts that matched the top of “Archaeoraptor.” Soon several people followed Xu and Currie in announcing that it was a composite of several specimens. National Geographic launched their own investigation, and in October 2000 it was finally concluded that “Archaeoraptor” was a hoax.
What are we to learn from this? The BAND band always points to “Archaeoraptor” when they refuse to accept new specimens that prove them wrong. Even creationists bring up “Archaeoraptor” as proof than no fossil is real—they are all hoaxes cooked up by paleontologists to prove evolution. It is important to note that the hoax was discovered as soon as qualified paleontologists looked at it. Amateur paleoartists Steve and Sylvia Czerkas did not have the years of experience and anatomical training required to know what is real and what is not. Moreover, the hoax would never have gotten so far if National Geographic hadn’t tried to “scoop” everyone and rushed to publication before proper scientific analysis and review were completed.
This episode once again reminds us of the serious threat to paleontology represented by the commercial market for fossils. Yes, many of these specimens are authentic, and sometimes these fossils end up in the hands of scientific institutions where they can be studied by qualified people instead of decorating someone’s living room. But as we saw with the skull of Irritator (chapter 13), many of the fossils are “enhanced” or even faked to improve their selling price. Even worse, no fossil from China or Mongolia should ever leave its home country except on a short-term loan. But smuggling and poaching operations are so out control that the market is flooded with these illegal fossils. Any fossil from a commercial dealer is automatically suspect, not only because it lacks the data describing where the fossil was collected and what rock layer it came from but because it may be a fake. In addition, there’s a good chance that the fossil was poached (see chapter 14 about the Mongolian tarbosaur poachers or chapter 16 about the therizinosaurs that were poached). Even when good-quality authentic specimens (such as the primate fossil called Darwinius, which came from a private collector) are announced, paleontologists are wary. Not only might the locality data be faked or lost, but they are also encouraging poaching by buying it. Worst of all, the fossil might be illegal or even a hoax.
One of the major problems with the public concept of dinosaurs is that they take the images presented in the media and in merchandising too seriously. Kids often ask me questions like “What color were dinosaurs?”For years, I could only tell them “No one knows.” The general public doesn’t realize that we usually have only the skeletons, so most of the muscles, tendons, skin textures, and coloration are pure guesswork supplied by the artist who reconstructs the dinosaur and is not based on direct scientific evidence. (A handful of dinosaurs also have skin impressions, but they don’t begin to represent all the dinosaurs that are reconstructed.) Most of the sounds and behaviors animators provide for their subjects are pure guesswork, often informed by very little scientific evidence.
Dinosaur reconstructions come in a complete range of colors, from the various drab greens and browns, based on most animals in nature today, to brightly colored patterns that seem almost psychedelic. The possible colors for dinosaurs are limited only by the artist’s imagination because there was no fossil evidence one way or another. Skin only rarely preserves in dinosaurs, muscles even less often, and color and texture of the skin surfaces seemed to have no fossilization potential.
At least that was the story until 2010. Then a startling article came out in Nature, the leading British science journal, which described a specimen of a small feathered dinosaur, Anchiornis, from the Liaoning beds, which is a close relative of the dromaeosaurs. This beautiful specimen had feather impressions that were so well preserved that they also included some of the melanosomes, the color-determining pigments that give feathers their hues. From this specimen, we can now say with confidence that Anchiornis had a red head, black and white stripes and blotches on its body and wings, and a black tail.
Figure 18.6
Color patterns of Sinosauropteryx based on melanosomes in the specimen. (Courtesy of N. Tamura)
Sinosauropteryx (now represented by many more specimens than the original found in 1996) was recently analyzed. It was even more gaudy (figure 18.6). Even though it’s a small ground runner related to Compsognathus, its body was covered by orange feathers, its tail had black rings around it, and the head had white, orange, and red blotches. Now there are specimens of dromaeosaurs including Caudipteryx, Microraptor, and Sinornithosaurus with color impressions, along with a bunch of birds, such as Confuciusornis, and a number of Early Cretaceous birds that preserve their color patterns. Even the colors of Archaeopteryx have been deciphered.
It is no longer guesswork to say that dinosaurs had feathers and to guess what color they were. I never imagined that this day would ever come to paleontology.
FOR FURTHER READING
Chiappe, Luis, and Meng Qingin. Birds of Stone: Chinese Avian Fossils from the Age of Dinosaurs. Baltimore, Md.: Johns Hopkins University Press, 2016.
Long, John A., and Peter Schouten. Feathered Dinosaurs: The Origin of Birds. Oxford: Oxford University Press, 2008.
Martinyuk, Matthew A. A Field Guide to Mesozoic Birds and Other Winged Dinosaurs. New York: Pan Aves, 2012.
Mayr, Gerald. Avian Evolution: The Fossil Record of Birds and Its Paleobiological Significance. New York: Wiley-Blackwell, 2016.
Norell, Mark. Unearthing the Dragon: The Great Feathered Dinosaur Discovery. New York: Pi Press, 2005.
Pickrell, John. Flying Dinosaurs: How Fearsome Reptiles Became Birds. New York: Columbia University Press, 2014.
Shipman, Pat. Taking Wing: Archaeopteryx and the Evolution of Bird Flight. New York: Simon & Schuster, 1999.
Wellnhofer, Peter. Archaeopteryx: The Icon of Evolution. Berlin: Dr. Friedrich Pfeil, 2009.