Smithsonian.com

A reconstructed skeleton of Rapetosaurus on display at the Field Museum of Natural History in Chicago. Image by Lisa Andres, from Wikipedia.

Everyone knows the sauropod body plan: thin at one end, much thicker in the middle, and then thin again at the far end. Yet simply calling these dinosaurs “long necks” or focusing on their often enormous size doesn’t do justice to the diversity of forms within this group. Different sauropods had vacuum-shaped heads, whiplash tails, long bony spines jutting out of their necks, tail clubs and, among other things, armor. Regarding this latter feature, some sauropods within the titanosaur subgroup had bones embedded within their skin—called osteoderms—that would seem to have strengthened their hides against attack. According to a new Nature Communications report by paleontologist Kristina Curry Rogers and colleagues, however, an inside look at two such osteoderms yielded new evidence that these bones might have had a different function.

The pair of osteoderms that are the focus of the new study were found in association with two different specimens of Rapetosaurus, a titanosaur estimated to have reached an adult length of about 50 feet. These dinosaurs lived sometime between 70 million and 65 million years ago on what is now the island of Madagascar. One piece of armor was found next to the tail vertebrae of a juvenile individual. As seen in osteoderms of other animals, the bone had a dense outer layer surrounding spongy bone inside.

When the paleontologists used CT-scanning technology to look inside a larger, approximately 22-inch-long osteoderm found near the hips of an adult Rapetosaurus, however, they found something unusual. The inside of the osteoderm was mostly hollow. What’s more, the thickness of the outer layer of bone varied around the internal cavity, and the microscopic bone structure inside the osteoderm showed signs that bone was actually being resorbed by the body.

Maybe the osteoderms in the adult animals were not actually armor at all. A mostly hollow, relatively thin-walled bone is not exactly the sort of structure that is going to protect a sauropod from attack, especially since Curry Rogers and co-authors suggest that sauropods like Rapetosaurus were probably not fully covered in osteoderms, anyway. Instead, the paleontologists take the bone resorption within the larger osteoderm as a clue that these bones might have been mineral reservoirs for when times got tough or when egg-laying dinosaurs required extra calcium to give their a hard shell. While small Rapetosaurus might have had relatively solid osteoderms, adult individuals may have drawn upon the calcium and phosphorous in these bones to meet the demands of growing, reproducing, or living in an arid environment poor in such minerals. These dinosaur decorations may have had little to do with attack or defense.

References:

Curry Rogers, K., D’Emic, M., Rogers, R., Vickaryous, M., & Cagan, A. (2011). Sauropod dinosaur osteoderms from the Late Cretaceous of Madagascar Nature Communications, 2 DOI: 10.1038/ncomms1578

When I watched the series premiere of Terra Nova in September, I wasn’t entirely sure what to think of it. The first episode was packed with so much awkward exposition that I just wanted the show to wrap up the background and get on with the story. That, and I was eager to see more dinosaurs. What’s the use of setting your science-fiction family drama 85 million years in the past if you’re not going to highlight some of the local fauna?

More than halfway through the first season, I still don’t know what to think of the show. I think the Atlantic Wire’s Richard Lawson hit the proverbial nail squarely on the head when he wrote that Terra Nova is the weirdest show on television right now. Take all the cringeworthy gooshiness of a 1990s family drama; borrow some plot points from LOST; apply liberal spoonfuls of science fiction tidbits from Avatar, ALIENS and Star Trek; then hit “liquefy” and pour out a show that is so overly sweet that you think your teeth are going to fall out of your head.

The components of Terra Nova are not original—from minor characters to plot points, almost everything has been seen before in other shows and films—but the combination creates a weird new hybrid. While the show is trying to build up suspense about the spy in camp and the possibility that evil bureaucrats of the future are going to try to mine Terra Nova for all it’s worth (called it!), the show is so focused on the lives of their primary protagonists, the Shannon family, that it feels as if each episode neatly wraps everything up. The family always overcomes their problems somehow, nothing truly bad ever happens to them, and everyone’s smiling by episode’s end. (Compare that pattern to what happens in the far-superior series The Walking Dead.) This week’s episode, in particular, was especially over-the-top in terms of cuteness. A baby ankylosaur that the Shannon family took in a few episodes prior  is returned to the wild, and a big momma ankylosaur immediately comes tromping out of the jungle to take the little tyke in as the human family looks on, all dewey-eyed. Awwww. This was so saccharine I thought my face was going to melt off, a la Raiders of the Lost Ark.

My advice to the show’s creators? Ditch the Shannon family—a pack of Slashers or even a pair of Carnotaurus would do nicely—and make it the Commander Taylor show. Terra Nova’s leader, portrayed by Stephen Lang, is just about the only interesting character in the whole thing. Then you’d get to keep the action and intrigue with an ensemble cast while deep-sixing the gooey family subplots. (Wishful thinking, I know.)

As for the dinosaurs, I feel that Terra Nova falls a bit flat. Before the first episode aired the buzz was that Terra Nova was going to feature lots of beautifully rendered dinosaurs the likes of which we have never seen before. That was part of the point in picking an 85-million-year-old jungle as part of the setting—our knowledge of dinosaurs during that time is relatively limited, leaving creature creators plenty of leeway to invent cool new species. So far, though, the fuzzy, raptor-like Slasher (seen in the trailer for this week’s episode above) is the only dinosaur that the show’s creators have really had fun with. All the other dinosaurs we have seen are either familiar creatures such as Carnotaurus, brachiosaurs and ankylosaurs, or dinosaurs with fictional names, such as Nykoraptor, Ovosaurus and empirosaur, which look just like dinosaurs we already know about.

Maybe that’s because dinosaurs don’t really play that much of a role in the show. They seem to pop up only when there’s a plot point that needs to be moved along, and the majority of dinosaurs in the show are carnivores. In a real ecosystem you’d expect to see far more sauropods, ceratopsians, hadrosaurs or other sorts of herbivorous dinosaurs, but instead the jungle outside Terra Nova seems to be swarming with medium- to large-sized predators. Maybe they’re all eating each other. More than that, the dinosaurs never bring a real sense of danger to the show. You know that anytime one of the main characters meets a dinosaur, they will somehow escape. Even the most vicious of dinosaurs are rendered virtually toothless by the show’s family-centered format.

Dinosaurs are the prehistoric icing on the so-so supermarket sheet cake that is Terra Nova. They’re simply a part of the setting, and for every glimpse of a dinosaur you have to sit through minute after minute of family programming. At least the dinosaurs look pretty good when they appear. There are some really bad anatomical mistakes, such as the Carnotaurus with long, arms, bunny-hands, and feathers at the beginning of the episode “What Remains,” and the dinosaurs still don’t mesh well with the background environments when seen in stark daylight, but in general, the prehistoric creatures are well detailed. And the special effects crew behind Terra Nova certainly deserves credit for putting feathers on a number of theropod dinosaurs. It’s just too bad that we don’t see more of the local fauna. For a show set in a brave new Cretaceous world, very little time is spend actually exploring the wonders that must be outside Terra Nova’s gates. Where’s a herd of ceratopsids or rampaging tyrannosaur when you need one?

Leave it to “The Simpsons” to concisely encapsulate the competing images of dinosaurs in under three minutes.

In last week’s episode, “The Book Job,” the Simpson family takes a trip to the local arena to see “Sitting With Dinosaurs”—a more aptly named send-up of the Walking With Dinosaurs live show in which animatronic dinosaurs stomp around the stage. The seats are packed with children and their families. Kids love dinosaurs, right? And, after all, the show is supposed to be educational. But when the dinosaurs appear, they terrorize the show’s tiny attendees. Families bolt for the exits. Tragically awkward Milhouse protests by throwing his Barney doll—a “kid-friendly” version of Tyrannosaurus—at the more accurate and scary Tyrannosaurus looming over him. Less snarling, more singing.

With most of the crowd gone, the Simpsons sit back and watch the rest of the show. The announcer wraps things up by explaining that the dinosaurs probably went extinct when an asteroid struck the earth a little more than 65 million years ago. Ah, the science-based take-home message.

The episode reminded me of my own early encounters with robotic dinosaurs. When I was five years old, my parents took me to see a traveling “dinomotion” show at a local New Jersey museum, but as much as I adored dinosaurs I was frightened by the mini-sized Tyrannosaurus that jerked and roared in the exhibit. All the facts I had absorbed about dinosaurs at that time—admittedly not very many!—didn’t do me any good when faced with the carnivore itself. My dad walked up to the robot and touched it to show me that nothing bad would happen, but I still stayed behind a nearby doorway until I was absolutely sure that the dinosaur wasn’t just playing a trick.

Dinosaurs are terrifying when brought back to life, but they are also symbols of deep time, evolution and the scientific understanding of our world. They can be used to scare or educate. How things balance out depends on presentation. It can be difficult to recall the mindset of our younger selves when dinosaurs seemed bigger, toothier and more monstrous. The way I see dinosaurs at 28 is vastly different than how I saw them at five. Childhood monsters, emblems of extinction, objects of scientific scrutiny—dinosaurs are all these things and more.

A reconstructed model of a young Tyrannosaurus at the Natural History Museum of Los Angeles County. Were these little tyrants covered in feathers? Photo by the author.

From museum displays to comic books and feature films, Tyrannosaurus rex has been celebrated as one of the biggest, meanest and ugliest predatory dinosaurs of all time. The image of this long-extinct carnivore as the apex of the apex predators has a nearly unstoppable amount of cultural inertia. Maybe that’s why people get upset when paleontologists and artists suggest that the tyrant dinosaur was at least partly covered in a coat of feathers. (Cracked.com even listed an illustration of a feathered Tyrannosaurus as one of “17 Images That Will Ruin Your Childhood.”) Such images make it seem as if the old “prize-fighter of antiquity” has gone soft—how could such an imposing predator go in for such a silly look? Tyrannosaurus was no turkey, right?

To date, no one has found the fossilized remnants of feathers with a Tyrannosaurus skeleton. A few patches of scaly skin are known from some big tyrannosaur specimens, and those scraps represent about all we know for sure about the body covering of the largest tyrants. So why is Tyrannosaurus so often depicted with a coat of dino-fuzz these days? That has everything to do with the evolutionary relationships of the great tyrannosaur lineage.

Until the early 1990s, paleontologists often placed tyrannosaurus with Allosaurus, Spinosaurus, Torvosaurus and others inside a group called the Carnosauria. These were the biggest of the carnivorous dinosaurs. But the group didn’t make evolutionary sense. As new discoveries were made and old finds were analyzed, paleontologists found that the dinosaurs within the Carnosauria actually belonged to several different and distinct lineages that had branched off from one another relatively early in dinosaur history. The tyrannosaurs were placed within the Coelurosauria, a large and varied group of theropod dinosaurs which includes dromaeosaurs, therizinosaurs, ornithomimosaurs, oviraptorosaurs and others. Almost every single coelurosaur lineage has been found to have feather-covered representatives, including the tyrannosaurs.

In 2004, paleontologist Xing Xu and colleagues described Dilong paradoxus, a small, roughly 130-million-year-old theropod which may be one of the earliest tyrannosauroid dinosaurs known. (The Tyrannosauroidea contains all the big, famous tyrannosaurids, such as Tyrannosaurus and Albertosaurus, as well as their closest relatives.) Small patches of filamentous protofeathers were found along the dinosaur’s neck and tail, indicating that—at least during their early evolutionary history—tyrannosaurs may have been covered in feathers, too. But the relevance of Dilong to the question of feathered tyrannosaurs partially rests on what Dilong turns out to be. The initial description cast the dinosaur as a tyrannosauroid, but subsequent analyses have differed as to whether Dilong is an early tyrannosauroid (as in Carr and Williamson, 2010) or belongs to some other coelurosaur group (as in Turner et al., 2011).

For the sake of argument, though, let’s say that Dilong was not a tyrannosauroid and actually belonged to a different coelurosaurian lineage. Would this mean that tyrannosaurs didn’t have feathers? Certainly not. Feathers were a widespread trait within the coelurosaurs, and simple, fuzzy protofeathers may go back to the last common ancestor of the group. Otherwise feathers would have to have evolved near the base of every lineage, and there is no indication that feathers evolved so many times. The spread of feathers among almost all coelurosaur groups hints at a shared origin.

Since so many other coelurosaurs had feathers, it is fair to infer that tyrannosaurs also did. This hypothesis is no more unreasonable than saying that close relatives of the earliest mammals such as Morganucodon were covered in fur on the basis of their evolutionary relationships. And, to pick another dinosaurian example, no one has yet described an ornithomimid dinosaur with evidence of feathers, yet we are comfortable attributing feathers to them because they are coelurosaurs. (Maybe their vaguely ostrich-like appearance helps a bit in this regard.) If feathers can reasonably be inferred for ornithomimosaurs on the basis of their family tree, then we can do so for tyrannosaurs.

So, within this evolutionary bracket, what kind of feathers might have clothed Tyrannosaurus and kin? The simple dino-fuzz of Dilong is a fair bet. Perhaps such a body covering would have served for insulation, but then again, the patchy distribution of filaments on Dilong and other coelurosaurs has raised the suggestion that some dinosaurs were only partly coated in feathers. Whatever their distribution on tyrannosaur bodies, though, the feathers probably didn’t look like those which allowed other coelurosaurs to eventually take to the air. After all, feathers were probably used for display and the regulation of body temperature first, and since no tyrannosauroid even came close to flying we should expect for them to have relatively simple feathers related to these functions.

A fuzzy juvenile tyrannosaur puppet at the Natural History Museum of Los Angeles County. Photo by author.

Regarding Tyrannosaurus specifically, the tyrant king may have had feathers only during the early years of life. A fuzzy coat may have helped hatchling and juvenile Tyrannosaurus regulate their body temperature, but as the animals grew, the benefits provided by insulation may have disappeared. (Retaining heat is a problem often faced by small animals, while shedding excess heat is a problem faced by larger animals due to changes in surface-to-volume ratios as animals grow.) Maybe an adult Tyrannosaurus would have patches of protofeathers here and there, as in Peter Schouten’s illustration of the dinosaur, But given the evidence at hand, it is likely that baby Tyrannosaurus would have been fuzzier than their parents.

Frustratingly, though, we may never know for sure what sort of feathers Tyrannosaurus might have had, or during what part of life. Circumstances of fine preservation are required to detect feathers, and even then, sometimes only patches are preserved. The types of environments Tyrannosaurus lived in were not exactly amenable to the kind of rapid, fine-detail preservation required to detect feathers. Even in cases where skin patches are preserved, it is difficult to know whether there might have been protofeathers on other parts of the body, or whether some of those feathers fell off or otherwise eluded preservation. Delicate structures require delicate preservation to detect.

What we can say is that the idea of a feather-covered Tyrannosaurus is a reasonable hypothesis. We still know so little about the body covering of this dinosaur that artists can reasonably restore the dinosaur with scaly skin, a coat of feathers, or a patchwork of both (I would especially like to see more renditions of that third possibility). Perhaps future fossil discoveries will provide us with a clearer picture of what Tyrannosaurus looked like, but the current unknowns are fascinating. Asking what Tyrannosaurus looked like is not just a matter of speculation—obtaining an answer requires that we consider the patterns and processes of evolution, as well as the methods we use to restore creatures that have been dead for millions upon millions of years. Feather-covered or not, though, I wouldn’t want to call Tyrannosaurus a turkey to its face. If I did, I don’t think I could run away fast enough to avoid becoming the dinosaur’s Thanksgiving dinner.

From everyone here at Dinosaur Tracking, we hope that you enjoy your holiday dinosaur and have a warm Thanksgiving.

References:

Carr, T., & Williamson, T. (2010). Bistahieversor sealeyi, gen. et sp. nov., a new tyrannosauroid from New Mexico and the origin of deep snouts in Tyrannosauroidea
Journal of Vertebrate Paleontology, 30 (1), 1-16 DOI: 10.1080/02724630903413032

Turner, A., Pol, D., & Norell, M. (2011). Anatomy of Mahakala omnogovae(Theropoda: Dromaeosauridae), Tögrögiin Shiree, Mongolia American Museum Novitates, 3722 (3722), 1-66 DOI: 10.1206/3722.2

Xu, X., Norell, M., Kuang, X., Wang, X., Zhao, Q., & Jia, C. (2004). Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids Nature, 431 (7009), 680-684 DOI: 10.1038/nature02855

A Microraptor catches a prehistoric bird, based on bird bones found within one Microraptor specimen. Art by Brian Choo and from O'Connor et al., 2011.

In life, Microraptor gui must have been an elegant dinosaur. This small, sickle-clawed dromaeosaurid was covered in plumage, including long feathers along its arms and legs. We know this thanks to the exquisite preservation of multiple Microraptor specimens found in the roughly 120-million-year-old strata of northeastern China. But feathers aren’t the only delicate dinosaur features that remained intact during the process of death, burial and fossilization. In at least one Microraptor specimen, paleontologists have found scraps of the dinosaur’s last meal.

Attendees to the 71st annual Society of Vertebrate Paleontology meeting in Las Vegas, Nevada earlier this month got a preview of the specimen during one of the conference’s poster sessions. Now the full paper describing the fossil, written by Jingmai O’Connor, Zhonghe Zhou and Xing Xu of Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology, has been published in PNAS. There are a few notable details of the feathery dinosaur.

The skeleton of this Microraptor, like others, is arched into the classic dinosaur death pose with the head arched back and the tail angled upwards. Whether the trigger for this posture turns out to be death throes, a result of immersion, or something else, the posture may be a clue to how the dinosaurs died or were rapidly buried. This Microraptor is also of interest because the dinosaur’s skull appears to be more complete and less crushed than some of the other specimens published so far, though the authors note that this specimen is relatively poorly preserved and therefore difficult to study. As for feathers, only a few tufts were preserved along the dinosaur’s head, neck and back. But the focus in the new paper isn’t on the dinosaur’s skeleton or outside appearance. The study is about what was inside the dinosaur’s body cavity when it died. There, hidden beneath the ribs, are parts of the wing and feet of a Cretaceous bird.

Exactly what genus of bird Microraptor consumed is impossible to say at the moment. Even so, anatomical characteristics of the bird feet allowed O’Connor and colleagues to classify the unfortunate avian as an enantiornithine, a form of archaic and now extinct bird. The position of this bird’s remains within the dinosaur is as good an indication as any that the feathered, non-avian dinosaur Microraptor at least sometimes consumed its distant avian cousins. But what happened just before the Microraptor swallowed the bird?

According to O’Connor and co-authors, the position of the bird bones within the Microraptor indicate predation rather than scavenging. The fact that the feet of the bird are closer to the front end of the dinosaur indicate that the prey was swallowed head first. The paleontologists cite this hypothesis as evidence that Microraptor was an arboreal dinosaur. Since the avian prey had anatomical specializations for life in the trees, and Microraptor supposedly caught the bird while the prey was still alive, then Microraptor must have been a skilled climber if not a regular tree-dweller.

Strangely, however, the paleontologists did not explore other scenarios for what might have happened in the moments before the Microraptor consumed the bird. Scavenging is briefly mentioned and dismissed as a possibility, but otherwise the idea that Microraptor scrambled up trees to catch birds is taken as the primary hypothesis. We know the facts—that a Microraptor swallowed a bird—but there is more than one pathway to that point.

Let’s assume that Microraptor truly did capture a live bird. But there is no indication whether the prey was caught on the ground or in the trees. In fact, as I sit here writing this, my cat Teddy is sitting in front of the window watching chickadees forage on the ground on my front lawn. Anatomically, the birds in my yard are specialized for life in the trees, but they do spend a considerable amount of time on the ground, and birds are often caught by cats and other terrestrial predators when the birds come down from their perches. Perhaps early birds also foraged on the ground, and when doing so they would have been vulnerable to attack by dinosaurs such as Microraptor.

Furthermore, there is nothing that tells us whether the bird was alive or dead when the dinosaur consumed it. Perhaps the bird died, fell to the ground, and the Microraptor was the recipient of a relatively fresh, free meal. All we know is that the bird was probably intact when the dinosaur ate it, but we can’t tell whether the bird was alive or recently deceased at the time.

We don’t know exactly what happened to the little bird, and therefore the association between the dinosaur and its prey can’t be cited as supporting either a ground- or tree-dwelling lifestyle for Microraptor. Nevertheless, the discovery that Microraptor ate birds adds one more piece to our understanding of this peculiar dinosaur, and I, for one, am a little tickled by the description of an avian dinosaur within a feathered non-avian dinosaur just prior to Thanksgiving. Turducken, anyone?

References:

O’Connor, J., Zhou, Z., & Xu, X. (2011). Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1117727108