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A reconstruction of Albertosaurus. From Wikipedia.

Last week kicked off the 2010 Winter Olympics in Vancouver, Canada, and as we all know Canada has some really fantastic dinosaur deposits. In fact, one of my favorite dinosaurs, the tyrannosaur Albertosaurus, hails from the province right next door to the one in which this year’s Olympics are being held. Maybe it is a bit of a stretch, but I can’t help but wonder which Olympic event Albertosaurus might excel at if it could compete.

I don’t imagine that curling or luge would allow Albertosaurus to make the best of its talents, and the biathalon might be dangerous since the other competitors would be packing heat, but if the dinosaur could pull it off I think Albertosaurus could deliver one of the most fantastic figure skating routines ever seen. The stride of Albertosaurus might give it an edge in the cross-country skiing event, too, although judges would have to make sure none of the other competitors mysteriously disappear.

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Logo of the "feathered dinosaur protest movment", from I Heart Chaos.

Time and again I have used this blog to describe what I think is one of the most fascinating recent discoveries in paleontology: that birds are dinosaurs.

Not everyone is happy with this fact, though. The blog io9 recently posted sample images from a feathered dinosaur protest group who prefer their dinosaurs to be scaly. According to the “skeptics”: “Dinosaurs are naked, leathery killing machines. They’re not Brazilian Carnivale queens.” Never mind that feathered dinosaurs are a fact (the fossils don’t lie); if you want to join the movement you can get stickers to show your support here.

The poster for the first Jurassic Park film. Will there be a fourth? (Image from Wikipedia)

It is hard to know what to believe about the Jurassic Park franchise anymore. About 15 months ago the rumor was that the series had been dropped, but half a year later a studio exec stated that the prospect of bringing the dinosaurs back was still on life support. According to Hollywood scuttlebutt, producers were hoping to take the series in a new direction and were not going to make a move until they had something fresh.

In fact, a few years ago the studio had something that may have departed a little too far from the previous films. A leaked script for an early version of Jurassic Park IV featured super-smart, gun-toting raptors as main characters, and it definitely would have been one of the strangest big-budget films ever made.

But as revealed by the director of Jurassic Park III, Joe Johnston, that idea was scrapped long ago. Making the rounds to promote his new film, The Wolfman, Johnston mentioned to HitFix that ideas for a fourth dino-blockbuster are starting to come together:

Is [the gun-toting dinosaurs idea] still in the offing, or have you moved on now to a new idea?

Johnston: We have. There is an idea now for number four that is different from the first three, and that is more or less the beginning of a new triology, in that it sends the whole franchise off in a new direction. It’s not about the dinosaur park anymore. It’s about all-new characters. So Steven [Spielberg is] busy right now with the stuff he’s doing and I’ve got to do “Captain America,” but hopefully afterwards, we’ll find time to develop it. And really… it’s something different that we haven’t seen before in the “Jurassic Park” world.

So, if this is accurate, Johnston might very well be back as the director for a fourth installment, which itself will be something of a reboot for the whole franchise. What could these new ideas be? We probably won’t find out for a while. The Captain America movie is not slated to come out until the summer of 2011, and who knows when Spielberg will be available again. It will probably be another few years before the dinosaurs come back.

An exquisitely-preserved specimen of Microraptor. From Wikipedia.

The chicken on the table, the pigeon on the street, the parrot in the zoo: all of them are living descendants of dinosaurs. Over the past ten years a flood of fossil evidence, from evidence of bird-like breathing apparatus to remnants of pigments in preserved feathers, has confirmed beyond a reasonable doubt that birds are dinosaurs. Tyrannosaurus and a turkey have more in common with each other than either does with a crocodile or lizard.

But some scientists are not pleased with this consensus. Way back in the 1920s it was thought that birds and dinosaurs were independent offshoots of a more ancient common stock. This hypothesis eventually was tossed out, but some researchers still believe it is true. This week in the journal PNAS, for example, scientist John Ruben says not only that birds evolved independently of dinosaurs, but that some creatures we now call dinosaurs were actually descendants of early birds.

While Ruben’s article has been much ballyhooed by media outlets, it is actually only a commentary, or the equivalent of an opinion piece. In it Ruben states that the discovery of the feathered Deinonychus-relative Microraptor refutes the idea that birds evolved from feathered dinosaurs, as Microraptor appears to have been adapted to jumping out of trees to glide. Other dinosaur specialists have previously hypothesized that flight evolved in dinosaurs that ran and jumped off the ground. If creatures such as Microraptor represent how flight evolved, then, dinosaurs that lived on the ground would either become irrelevant to understanding bird origins or, as Ruben argues, would have to be considered birds that lost their ability to fly.

Despite the credulous repetition of this story, however, Ruben’s argument is cut down by several flaws. The first problem is that we cannot be sure that Microraptor is a good example of how flight evolved. By the time it lived, 120 million years ago, there had been birds for millions of years, and it lived at the same time as early birds like Confuciusornis. Combined with what we know about its close relatives, it appears that Microraptor was a unique kind of specialized raptor that independently evolved the ability to glide, and perhaps even fly. Whether its mode of gliding can inform us about how birds evolved flight will depend upon which group of feathered dinosaurs turns out to be most closely related to the first birds (which may be strange forms like Epidexipteryx).

Secondly, the “trees down” versus “ground up” debate about the origin of flight is no longer useful in addressing the evolution of birds. So many feathered dinosaurs have been found, and continue to be discovered, that paleontologists are continually having to reassess ideas about how the first birds evolved. Perhaps some of the old hypotheses will turn out to be correct, or perhaps flight evolved in a way we did not expect, but framing things in terms of two mutually-exclusive hypotheses hinders discussion over avian origins rather than helps it.

Furthermore, there is no compelling reason to regard dinosaurs such as Velociraptor as flightless birds. This proposal has often been made by critics of the “dinosaur-bird” connection in order to made sense of the many feathered dinosaurs that have been found. It is a sort of taxonomic reshuffling that removes anything bird-like away from dinosaurs despite all the characteristics these animals have in common with other dinosaurs.

Simply put, Ruben’s hypothesis does not stand up to scrutiny, but what I find even more frustrating is the repetition of such fantastic claims by news outlets. In this increasingly fragmented media landscape, knowledgeable science writers who recognize a fishy story when they see one are getting outnumbered. More often, websites and newspapers simply reprint press releases issued by universities and museums (science writers call this “churnalism”), and this policy sometimes lets questionable science slip through the cracks.

A restoration of the spinosaurid Suchomimus. From Wikipedia.

In 1986, paleontologists described a dinosaur unlike any that had been seen before. Named Baryonyx walkeri, it was a theropod with a long, crocodile-like snout and arms tipped in huge claws. Some preserved stomach contents confirmed that it was a fish-eater. It showed some similarities to another dinosaur that had been found decades before, Spinosaurus, and as similar dinosaurs came to light they all appeared to show adaptations for eating fish. They did not have the recurved tearing teeth of other large predatory dinosaurs, but instead had more conical teeth better-suited for grabbing prey before swallowing it, just like in living crocodiles. Despite these anatomical clues, however, it has been difficult to find more evidence of how these dinosaurs lived, but a new study published in the journal Geology suggests that they might have been spending much of their time in the water.

We are often in awe of dinosaur skeletons, but it is easy to forget that the basic materials for building their bony architecture came from their environment. Living dinosaurs took in oxygen, carbon and other elements, and isotopes of these elements became part of their bodies. An animal that primarily eats grass will have a different carbon isotope signature than one that eats leaves, for example, and an animal that spends much of its time in the water will have different oxygen isotope levels than one that spends all of its time on dry land. In some instances these isotopes can remain preserved in parts of fossil skeletons, most often teeth, and paleontologists have used these istopes to study things like what kind of plants prehistoric horses ate and how much time early whales spent in the water. The researchers behind the new Geology paper have now extended these techniques to dinosaurs in an attempt to find out how much time spinosaurids were spending in the water.

To test the semi-aquatic spinosaurid hypothesis, the researchers looked at the oxygen isotope levels in the teeth of spinosaurids, other large theropods and crocodiles (as well as some turtle shell bones). If spinosaurids were spending much of their time in the water then their oxygen isotope signatures would be closer to those of the semi-aquatic turtles and crocodiles and most different from land-dwelling theropods. This is because the oxygen isotope values of semi-aquatic animals are less prone to fluctuations as they are regularly coming into contact with oxygen in the surrounding water; an animal that has to find water to drink is more likely to have more widely-varying values.

The results of the test showed that spinosaurids did have oxygen isotope values closer to turtles and crocodiles than to other large theropods. This supports the hypothesis that they were semi-aquatic, opportunistic predators that probably specialized in hunting fish but would not turn down larger dinosaurian prey it they could get it. The precise details of their lives at the water’s edge are still being discussed and debated, but if this new study is correct then spinosaurids were even stranger than previously thought.

Amiot, R., Buffetaut, E., Lecuyer, C., Wang, X., Boudad, L., Ding, Z., Fourel, F., Hutt, S., Martineau, F., Medeiros, M., Mo, J., Simon, L., Suteethorn, V., Sweetman, S., Tong, H., Zhang, F., & Zhou, Z. (2010). Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods Geology, 38 (2), 139-142 DOI: 10.1130/G30402.1