Smithsonian.com

A restoration of Aardonyx. From the Proceedings of the Royal Society B paper.

The sauropod dinosaurs were the largest animals to have ever walked on the earth. They were so incredibly huge, in fact, that they had to move about on four legs—but since the earliest dinosaurs were bipedal, paleontologists have long known that the ancestors of giants like Brachiosaurus and Apatosaurus actually trotted about on two legs. A dinosaur just described in the Proceedings of the Royal Society B sat close to this major transition in sauropod evolution.

Recovered from Early Jurassic (about 183 – 200 million year old) rock in South Africa, Aardonyx celestae was an approximately 20-foot-long dinosaur that combined elements that are both strange and familiar. It had a small head, a long neck, a large body, and a long tail, but it still had relatively short forelimbs compared to its hind legs. While it could occasionally walk on four legs, its limbs indicate that it primarily walked around on two , and an evolutionary analysis that was part of the new study placed it relatively close to the earliest sauropod dinosaurs (thus fitting Aardonyx within the larger category of dinosaurs called sauropodomorphs).

Aardonyx was not actually ancestral to the larger,  four-feet-on-the-floor sauropods—it lived during a time when such dinosaurs already existed—but it preserves some of the transitional features that we would expect to find in the actual ancestor. (Contrary to a headline published by the BBC, it is not a “missing link” and the entire concept of “missing links” is a hopelessly out-of-date idea that was discarded by scientists long ago. The phrase goes back to a time when life was viewed as proceeding from “lower” forms to “higher” ones in a straight line, and scientists have rightly rejected it in favor of a branching bush of evolutionary diversity.)

While not a direct ancestor of dinosaurs like Diplodocus, this new dinosaur will help us better understand how sauropod dinosaurs evolved. If you would like to know more about it check out the blog of the lead author of the new description, Adam Yates, where he summarizes the important details about Aardonyx. It is good to see working paleontologists take a more active role in communicating their discoveries to the public, and I hope that other dinosaur specialists will follow the example made by Yates and others.

The exceptionally-preserved skeleton of Darwinius. From PLoS One.

This week news services were all a-twitter about a 47-million-year-old fossil primate from the famous Messel deposits of Germany. Named Darwinius masillae and described in the journal PLoS One, the lemur-like primate was heralded as being a transitional form between a group of extinct primates called adapids and anthropoid primates (monkeys and apes). As it turns out the fossil may not be all it has been cracked up to be, but it is still a spectacular find that represents one branch of the primate radiation that occurred after the mass extinction that killed off the dinosaurs at the end of the Cretaceous. Creatures like Tyrannosaurus perished, but primates survived.

Tracing the record of the earliest primates is a challenge. Since primates started off small and lived in forested habitats their fossils are extremely rare, and most fossils that are found are teeth. This can make comparisons between these creatures difficult, and the relationships among early primates or primate-like creatures are controversial. The fact that some molecular studies places the origin of primates even further back in the Cretaceous, about 85 million years ago, makes things even more complicated as no verifiable primate fossils have yet been found from that age. Despite these complexities, however, scientists do have a broad outline of early primate evolution.

One of the earliest primate-like creatures was Purgatorius, a tree-shrew-like mammal that lived right around the end of the Cretaceous 65 million years ago. Whether it was one of the first primates or only closely related to the first primates is still controversial, but it does seem to represent what the ancestors of primates were like during the time that dinosaurs were the dominant land-dwelling vertebrates.

After the mass extinction, mammalian evolution exploded. Mammals were no longer under the feet of dinosaurs, and among the groups that diversified were primate-like creatures called plesiadapiformes. Whether these creatures were true primates or just very primate-like is still being debated, but they underwent a boom and bust during the Paleocene (about 65 to 55 million years ago). In many ways these creatures were somewhat squirrel-like, with clawed hands and eyes on the sides of their heads, but at the very least they seem to be the closest extinct relatives to other primates.

The creatures that are regarded as “true” primates flourished during the Eocene (about 55 to 33 million years ago), and can largely be placed into two groups: the adapids and omomyids. The adapids were lemur-like primates, while the omomyids closely resembled living tarsiers, but both had forward-oriented eyes and adaptations to life in the trees. Both these groups are relevant to yesterday’s big announcement.

According to the new paper, Darwinius is an adapid, and many scientists presently regard this group as being more closely related to modern lemurs and lorises than to monkeys or apes. Many paleontologists who study extinct primates favor omomyids and ancient tarsiers as being closer to monkeys and apes, but the authors of the new paper don’t think so. In the paper itself they claim that Darwinius belongs to the same large group of primates, haplorrhines, as tarsiers, monkeys, and apes, thus placing adapids in a position to potentially become our ancestors. This conclusion has caused the scientists involved in the study and the popular media to herald it as a “missing link” that connects us to other primates.

Unfortunately, however, the scientists who wrote the paper did not conduct a detailed evolutionary analysis of the new fossil or its relationships to other primates. The fossil is spectacular, the first fossil primate to be find in such a state of exceptional preservation, but it has been oversold by the History Channel (who organized the media hype) and the scientists involved in the study. They simply did not do the work to support the conclusions they drew from the fossil, and the real relationship of Darwinius to other primates will have to wait for further studies.

A pair of Iguanodon on a riverbank, from Current Literature.

Outside of Hollywood films, dinosaurs like Tyrannosaurus and Triceratops never coexisted with humans, and no case can be made that The Flintstones is an accurate depiction of prehistory. That has not stopped young-earth creationists from maintaining otherwise, though, and this has led to some rather silly statements.

Attempts to squeeze paleontology into a literal interpretation of Biblical timelines have a long history. A 1912 issue of Current Literature featured some excerpts from a book about paleontology called Evolution in the Past by H.R. Knipe. The article itself is not terribly interesting, but the captions accompanying the article’s illustrations are. Several dinosaurs and extinct mammals are featured and each caption explains the benefits or dangers these animals would have posed to early humans. The caption beneath a pair of Iguanodon reads:

THE TERROR OF THE RIVERBANK IN THE GEOLOGICAL PAST

The iguanodonts [sic] fought with their tails, and in the course of the combat rendered life precarious in the vicinity for all living creatures. It is difficult to see how prehistoric man could have made his abode along the main streams while these monsters flourished.

In truth, early humans had nothing to fear from Iguanodon. The herbivorous dinosaurs had been extinct for about 114 million years by time the earliest humans evolved in Africa. To suggest otherwise would require some startling evidence indeed! It should be noted that the tone of some of the captions makes it seem like they are not to be taken seriously, but even if this is true they are not out of line with what many creationists truly believe. (Don’t even get me started on their ideas about what Tyrannosaurus would have eaten in the Garden of Eden.)

If humans did live alongside dinosaurs, though, it does raise the question of how our kind survived. Why wouldn’t our species have been consumed by a horde of hungry tyrannosaurs, or our early attempts at agriculture destroyed by herds of sauropods? There is simply no record of any kind of Dinotopia, and most of the “evidence” creationists offer are like Rorschach tests; they see what they want to see. Watching humans flee from dinosaurs might make for exciting cinema, but it is absolutely awful history.

A few months ago my colleague Mark Strauss mentioned the controversy surrounding the state dinosaur of Texas. Previously the state’s patron dinosaur was the sauropod Pleurocoelus, but this has turned out to be a mistake. Pleurocoelus was initially named for bones found in Maryland and the same name was applied to fossils from Texas. As it turns out, however, the Texas bones are distinct enough to merit a different genus name, Paluxysaurus.

The change should have been relatively simple. Texas was not really getting a new dinosaur; the name of the fossils were just being changed. Things got complicated, however, when ten-year-old Shashwatch Murphy petitioned to have the state dinosaur changed to Technosaurus. It was a valiant effort, but unfortunately for Murphy, Technosaurus was actually not a dinosaur at all and could not be considered for the honor of state dinosaur.

Paluxysaurus looked like a shoe-in for the “new” state dinosaur, but the Texas representatives decided to use the opportunity to engage in a little legislative theater. Some of the primary supporters of the resolution, like representatives Mike Hamilton and Mark Homer, put on dinosaur suits to show their support for the name change (even if Hamilton mixed up the words “extinct” and “instinct”). Some of the other representatives gave them a hard time, though. Representative Dan Gattis made known his opposition to the bill as “In accordance with the international fourth-grade spelling bee and grammar rules … the author [of the bill] cannot even spell or pronounce all the words in his resolution.”

If Gattis opposed the bill, he was the only one. The measure passed by a vote of 132 to 1 (even though it still has to pass through the state senate). Unless there are any more shenanigans to be played out, it looks like Paluxysaurus is the new state dinosaur of Texas.

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A skeleton of Gorgosaurus. From Wikipedia.

It may never be possible to create a real-life Jurassic Park, but if I were given the task of picking which dinosaurs to bring back to life, there are a few that would be at the top of my list. I would love to be able to see all dinosaurs in the flesh, of course, but here are five (in no particular order) that I would like to see more than most any others.

1) Amargasaurus

The first time I heard about it I almost couldn’t believe it. A sauropod with sails on its neck? It might sound like a fantasy cooked up by an over-imaginative paleontologist, but the early Cretaceous sauropod Amargasaurus really did have two parallel rows of long spines on its neck. The question is whether these spines were “naked” or carried sails, and something that is difficult to figure out without seeing the living animal.

2) Epidexipteryx

This is a “new” dinosaur, having been described only in October of 2008, but it is one of the most bizarre. It was a small, feathered theropod with a set of teeth organized into a scoop, and four long feathers sticking out of its stumpy tail. As strange as it was, though, it may be one of the dinosaurs most closely related to birds, and has the potential to shake up current hypotheses about bird evolution.

3) Gorgosaurus

Gorgosaurus might not be as strange as the previous two dinosaurs, but I do have a soft spot in my heart for it. One of the first dinosaur skeletons I ever saw was the Gorgosaurus mount at the American Museum of Natural History, and this tyrannosaurid has been a favorite of mine ever since. It might not be as famous as its cousin Tyrannosaurus, but it was a much sleeker animal. It would probably be best to view this one from a distance, though.

4) Baryonyx

I know this list is getting a little theropod-heavy, but it is hard to resist Baryonyx. At the time it was discovered it represented a new kind of predatory dinosaur with heavy forelimb claws and a crocodile-like snout. Its relative Spinosaurus was discovered first, but it was only when Baryonyx was found that some previously enigmatic theropod fossils began to make sense. Given that it was probably a fish-eater, it might be a little safer to observe, too.

5) Pachyrhinosaurus

Horned dinosaurs were my favorites when I was a kid, and none seemed as odd as Pachyrhinosaurus. With the huge flattened bosses of bone, it stood out against more familiar forms like Triceratops, and there seemed to be a vigorous debate over whether it had a huge nose horn or a more flattened nose ornament. It seems that the latter hypothesis is more likely, but it still would have been an impressive creature to see!

There are plenty of other dinosaurs I would like to see, but these five are among my favortes. What are yours?

The cover of Fantastic Four #345. From Cover Browser.

I was cleaning out some old boxes yesterday when I happened upon dinosaurs in an unexpected place. A few years ago a cousin of mine gave me all of his old comic books, most of which wound up in a box for safe keeping. When I dug up the dusty old container yesterday, I noticed that some of Marvel’s most famous superheros once fought dinosaurs.

The 345th issue of Fantastic Four might have held a shock for fans of the super-powered team. On the cover of this issue was a Triceratops draped in the torn suits of Mr. Fantastic, the Invisible Woman, the Human Torch, and the Thing with the words “Fantastic Four No More!” Could a herbivorous dinosaur really have been the end of the heroes?

As you might expect, the answer is “no.” Due to a time travel glitch, the Fantastic Four wound up on a mysterious island where American soldiers were already battling it out with dinosaurs. (Gee, that’s an original idea.) The superheros and the soldiers manage to evade the dinosaurs with few casualties, but in order to distract a rampaging Triceratops Mr. Fantastic has to strip to his skivvies. Thankfully he is provided with an extra uniform soon afterwards.

The next issue, #346, picks up the storyline. After fending off a Tyrannosaurus the survivors head out to sea on a wooden raft, and as is comic book convention there is something hungry waiting in the water. Somehow the humans manage to fend off the Kronosaurus and make it back to their own time. I am a little weary of the “dinosaurs on a mysterious island” storyline, though. Why can’t someone think of something a little more original, like “Dinosaurs on a Plane“?

A child poses next to the skeleton of a hadrosauroid dinosaur. From Flickr user Clover 1.

Time is running out for paleontologists studying a Cretaceous fossil site in North Arlington, Texas. As reported by CBS 11, paleontologists from the University of Texas only have about five months to finish their work before they will have to make way for a huge development project. This is unfortunate, especially because the site may hold the remains of a mystery dinosaur.

The 1,700-acre site was discovered in 2003 by Art Sahlstein and his daughter Olivia. It seemed like a promising place to dig, conveniently placed for University of Texas students, but it took about four years before paleontologists received permission to excavate. When they were finally able to search the locality, the paleontologists found that most of the bones belonged to a hadrosauroid dinosaur, perhaps Protohadros. They have yet to find a skull, however, and researchers working the site have stated that finding one is essential to knowing whether these dinosaurs were Protohadros or something new. They only have the summer to find out.

Cavemen and dinosaurs never met, despite this humorous sculpture. From Flickr user sundancekid.

Right about this time in 2007, the creationist cartoonist Johnny Hart, creator of the “The Wizard of ID” and “B.C.,” passed away. While many people have placed cavemen and dinosaurs together out of ignorance or artistic laziness, Hart truly believed that his cartoon B.C. contained at least a minor reflection of reality (even if it ran against all we have learned from paleontology). That’s why I have mixed feelings about plans to honor Hart by placing dinosaurs, and cavemen, around the city of Binghamton, New York.

According to a report released over the weekend, the city of Binghamton is going to honor Hart, who lived nearby, by putting up 100 five-foot-tall sculptures of a caveman riding Gronk the dinosaur in 2010. (Coincidentally, Hart believed that the world might end in 2010. Maybe cavemen riding dinosaurs are a sign of the Apocalypse.) The sculptures will be painted by selected local artists and sponsored by local businesses. If one catches your eye you can even buy one, although it will set you back about $5,000.

I am glad fans of Hart’s art have found a way to celebrate his work, but honestly if I passed by a sculpture of a caveman riding a dinosaur I would cringe a little. I would rather see a display of some beautifully painted feathered dinosaurs, but that might be a harder sell.