The Colour and the Shape

Above: Iridescent Peacock feather, from Flickr. A new study shows that patterns, iridescence and even color can be preserved in fossil feathers.

Every dinosaur picture book aimed at kids comes with a disclaimer /slash/ incentive: "We don't really know what colors dinosaurs were." They were often depicted as green and drab, camouflage suited to their 1930s-era stint as lethargic reptilian swamp dwellers. But, the kid's books tantalizingly continue, "they could have been any color, with any pattern, even bright fuscha with purple polka dots!" (I'm guessing these books are to blame for Barney...).

Well, that's mostly true. We now know dinosaurs are more closely related to birds than modern reptiles (and lets not sell those short, many are very brightly colored). Birds have excellent color vision, and often employ bright colors and striking patterns to attract mates. Some artists have taken this concept to the extreme: See the almost day-glo colors employed by Luis Rey. All of this falls within artistic license, though even this bastion of dinosaur mysteries may disappear for some species. Actually, color can be preserved in fossils, and several recent studies have applied this to fossilized feathers, like those found on some dinosaurs.

Above: One of the iridescent feathers studied by Prum and colleagues in the new paper, discussed below. From National Geographic.

Fossils preserving life body patterns or even color are not new. Many fossilized fish and insects have preserved patterning or even hints of iridescence in their wings, shells, and scales. At least one ammonite fossil is even said to preserve the original, blood red coloration, possibly indicating a deep-sea habitat due to similar color in modern animals from that environment.

A new technique has been developed to help determine if color patterns are real or due to preservation. A 2008 paper by Jakob Vinther and colleagues described looking at apparently patterned fossil feathers under a microscope, looking for (and finding) melanosomes, the remnants of pigment present in life. The traditional view held that most fossil feathers which are preserved as dark 'stains' in a halo around the fossil are caused by bacteria, which cover the feathers as they decay. Vinther and colleagues found fault with that interpretation, though. For example, some fossil feathers show both dark and light bands in regular patterns. Why would bacteria only be present in such regular segments of fossil feathers? Vinther reckoned that rather than bacteria, the small nodules associated with these bands and dark spots (seen under a microscope) were pigment cells, and represented the actual dark/light patterning (though not the specific color) that would have been present in the living animal. Vinther and colleagues concluded that in fact almost all fossil feathers are preserved this way.

Above: Figure 1 from Vinther et al. 2008, showing melanosomes preserved in a banded fossil feather.

That's not to say that feathers lacking a dark carbon film lacked melanin in life--further examination is needed. For example, most specimens of Archaeopteryx do not preserve dark, stained feather impressions. Does this mean the feathers were white? No--in fact, close examination shows impressions where melanosomes would have been, but have since been lost or decayed away.

Still, this could have implications for the famous feathered dinosaur fossils from China. Many of these do preserve feathers as dark carbon stains (presumably caused in part by melanin), and do sometimes show a banded pattern. Such banding can be seen in the tail feathers of Caudipteryx. The "ring tailed" appearance of the holotype Sinosauropteryx tail is probably real, given an unpublished study by Nick Longrich and confirmation (via Dinoforum, of course) that the bands match up across both fossil slabs and so can't be an artifact of splitting the rock as originally suggested. Longrich also suggested that the apparent absence of feathers on the underside of Sinosauropteryx doesn't mean they weren't there, but rather that these feathers were white and did not leave a stain in the rock. Whether or not these feather patterns contain melanin is still an open question that, to my knowledge, nobody has really studied.

Above: Sinosauropteryx may have been counter-shaded, with a white belly and ringed tail. Image from a work in progress digital painting by Matt Martyniuk, all rights reserved.

So, we might actually know what kinds of patterns a few dinosaurs had in life, thanks to preservation of feathers and melanin. But what about actual colors? Well, a new study of melanin in fossil feathers (this time from the Eocene Messel deposits of Germany, home of Darwinius) has found that even traces of iridescence and life color can be recovered. In the future, more detailed study of dinosaur feathers might reveal something similar. A few barely-published specimens of Microraptor do have a very beautiful blue sheen to them (see photo above). Preservation artifact, or dromaeosaurid Blue Jays?

Luckily, formal evaluation of the feathered dinosaurs using this technique is in the pipeline. As co-author of the study Richard Prum told NatGeo, "We are eagerly hoping to be able to work on some of the Chinese dinosaur feathers to try to reconstruct the colors of the feathered dinosaurs." So, the days of drawing these dinosaurs with whatever day-glo magenta stripes you like may be over.

Above: Tail feathers of Microraptor specimen TNP0099624, from figure 2 in Xu et al. 2003. Could these show the color in life or iridescence? Future studies will find out.

And does anybody else remember that very old bit of goss from the DML about a Velociraptor specimen with associated feather proteins that could reveal the color...?

PteroGoss

Above: Mark Witton explains why pterosaurs are so cool. Copyright BBC.

Nothing much to report in the way of good goss lately. It's been quiet in the world of dinosaurology... almost too quiet...

But not so if you're also a big pterodactyl geek. This is not PteroGoss but I'll link to a few awesome stories coming out lately...

Eudimorphodon rosenfeldi has been assigned to a new genus, Carniadactylus, in a sweet paper looking at relationships of primitive pterosaurs. The authors also consider the super-weird Raeticodactylus to actually be a synonym of the contemporary Caviramus. Here's the article from Wikipedia.

Mark Witton describes a new species of Tupuxuara, T. deliradamus! That translates as "crazy diamond," making it officially one of the most awesome pterosaur names that could also be a character in a Guy Ritchie film. Mark also sorted out the priority of Tupuxuaridae vs Thalassodromidae, which you can read about at his blog.

In other Mark Witton news, he's the subject of a new series of videos done by the BBC tracking the construction of several giant pterosaur models for an upcoming British exhibition. Check out TetZoo for more.

Above: Sketch of the upcoming outdoor pterosaur models at the Southbank Centre in London, for the Royal Society exhibition. Copyright BBC.

Lastly, today a new paper announced the discovery of the first known pterosaur landing tracks. The tracks suggest they landed like birds, feet-first, flapping their wings to stall before dropping onto all fours.

My Sauropod is Bigger

There is a new record holder for second-longest dinosaur, longest if you only count bones that currently exist. Skip past the long-winded intro if you want to get to the point!

New mounted skeleton of Mamenchisaurus, in Tokyo, the longest mounted dinosaur skeleton in the world. Image by Shiziuo Kambayashi from the AP.

What is it about pissing contests over the largest dinosaurs? Who cares if Spinosaurus is a few metres longer than Tyrannosaurus? Does it really matter which super long-necked, long tailed giant sauropod is slightly longer than its nearest competitor?

Of course it does!

Well not really, but it can be a fun part of armchair paleontology to keep track of these things. I created the Wikipedia article Dinosaur Size to try and help people keep tabs on this issue using peer-reviewed sources (though for a while there a few too many Internet sources were creeping in, but we've put a stop to that).

Now, everyone gets their shorts in a bunch over the biggest theropod, because even though sauropods are nearly always bigger, they're not the ones who will try to eat Jeff Goldblum. This is evidenced by the fact that one of the biggest theropods in terms of sheer mass, Therizinosaurus, is almost always ignored in these competitions because it was probably herbivorous and looked like a giant porcupine goose with a beer belly. However, despite how cool theropods may be (i.e., extremely cool), sauropods are without a doubt the group where we find the largest dinosaurs.

So which dinosaur was largest? Well, define large. Do you mean length, height, or mass? In modern animals, mass is usually what counts. The African elephant is considered the largest land animal, even though the giraffe is taller and the reticulated python is longer. The most massive, and therefore largest, dinosaur known from decent remains that still exist is a bit of a tie game right now. Traditionally, the largest sauropod known is cited as the titanosaur Argentinosaurus, with rational mass estimates ranging between 78 and 83 tonnes. However, several other titanosaurs were about the same size, if not bigger, including Puertasaurus and the horrifically named Futalognkosaurus (note that the official name even includes a misspelling, yikes!).


Scale diagram showing several of the largest dinosaurs discussed in this post. Green: Diplodocus. Orange: Supersaurus. Purple: Argentinosaurus. Blue: Sauroposeidon. Grey: Bruhathkayosaurus. Red: Amphicoelias. Scale bar = 40m. Image by Matt Martyniuk, licensed.

The new goss here though, to finally get to the reason for this post, is that the record for longest dinosaur has changed... sort of (see final paragraph, below). When I was a kid, I was enthralled by the longest known dinosaur according to several of my books, the "Seismosaurus" (earthquake lizard). This monster diplodocid (whip-tailed sauropod) was said to be over 130ft in length. Well, those initial estimates were a little too hopeful, and based on the mis-identification of a tail bone which threw the estimates off by up to 30%. More reasonable estimates place its total length at a mere 33.5m (110ft), and furthermore, it turned out to likely be just a slightly oversize specimen of Diplodocus anyway.

The downsizing of Seismo--er, Diplodocus left the length champion to its cousin, Supersaurus. As the preparation of a fairly complete skeleton nicknamed "Jimbo" by Scott Hartman showed, Supersaurus probably reached a total length of 34m, or 112ft, surpassing both Diplodocus and weight champion Argentinosaurus by a meter or two (in the process robbing the titanosaurs of their clear victory in both units of measure).

However, now a new champion emerges by a neck (I'll be here all weekend folks!). A new specimen of the mega-necked Chinese sauropod Mamenchisaurus unearthed in 2001 was initially reported as the largest of its kind at a respectable, but short, 30m (98ft). However, a surprise came when they assembled a reconstructed skeleton for a new exhibition opening in Tokyo: the specimen actually measures a whopping 35m long, or 115ft, beating out Supersaurus for the title of longest known dinosaur. See photo at top of this post.

Extraordinarily accurate (down to the scales) illustration on Mamenchisaurus by Steve OC, licensed.

That is, if you don't count Amphicoelias. This monster, known from a single partial vertebrae that was 8ft tall and would have been 12 if complete, was very similar to Diplodocus and, scaling up from the same bone in that animal, Amphi would have been at the very least 40m long (131ft) and probably in the area of 120 tons, easily trumping all other contenders in every category: length, weight, and height (read the Wiki I started and wrote most of on Amphi here). So far the only contender to that throne is the even more dubious Bruhathkayosaurus, which is known from a poorly preserved, poorly published, and basically never studied leg bone sometimes thought to be a tree trunk, and even if the size the describers said it was is probably vastly overestimated in published surveys. For now, Amphi is the king, but its smaller cousins with better remains are inching closer.

More On Chewy Hadrosaurs

First, thanks to those who commented and emailed regarding my post on the controversial hadrosaur chewing mechanics paper (see "Nom nom nom"). Vince Williams, lead author of the paper in question, was among those who contacted me about it, and he pointed out an error that stems from (yet again) science reporting that isn't all there.

Above: Underside of the skull of Leonardo, the Brachylophosaurus mummy. By Ed T., from Flikr. Licensed.

My last post reiterated a statement from this MSNBC article, that gut contents of the famous hadrosaur mummy "Leonardo" seem to contradict Williams et al.'s findings, because the plant matter was

a) chopped or sheared, not chewed, and
b) mainly coniferous, indicating that hadrosaurs were browsers rather than grazers.

Well, I checked up on the source that MSNBC used for this information (Leonardo is, despite documentaries on the History Channel, not fully studied and published on yet). That lead me to another MSNBC article on Leo, which appears to state the opposite! From the older, cited article:

• "An analysis of the gut contents from an exceptionally well-preserved juvenile dinosaur fossil suggests that the hadrosaur's last meal included plenty of well-chewed leaves digested into tiny bits."
• "An analysis of pollen found in the specimen's gut region revealed a variety of plants, including ferns, conifers and flowering plants. Although the pollen could have been ingested when the dinosaur drank water, the tiny leaf bits, under 5 millimeters (a quarter-inch) in length, indicate that Leonardo was a big browser of plants, Chin said."

So, the gut contents in question actually would seem to support, at least in part, Williams' findings. Even stranger given the apparent lack of cranial kinesis reported last December. Obviously further study is needed on this...

How Mimsy Was Zanabazar?

No, not the early Mongolian Buddhist leader.

Above: Not a troodontid.

Zanabazar is the newly-coined name for the troodontid previously known as Saurornithoides junior. A new review of the genus Saurornithoides by a heap of authors including Mark Norell and Rinchen Barsbold himself (who named S. junior in 1974) found that the evidence linking S. junior to S. mongoliensis as each others closest relatives is lacking, so a new genus name was needed for junior (I would have gone with "Henryjonesius" in honour of Sean Connery).

Above: Zanabazar junior by FunkMonk, licensed.

But wait a second... there's been talk for some time now that S. junior may be synonymous with another small troodont, a contemporary from the Nemegt Formation with one of my personal favourite dino-bird names, Borogovia (after one of the nonsense creatures in Lewis Caroll's poem Jabberwocky.) I haven't read the paper yet so I'm not sure if this issue was addressed, but as it stands now, there still is no overlapping material to directly compare the two troodonts, so it's impossible to prove synonymy at the moment (Borogovia is known from leg and foot bones lacking the rest of the skeleton, Zanabazar is known from a partial skeleton lacking leg and foot bones). But if any further material for either species turns up, and they turn out to be synonyms, Borogovia will win the day as the older name. Not that Zanabazar isn't a cool name in and of itself. But how boss would it be to name a hypothetical new Nemegt therizinosaur (with their long necks, giant claws, and overall freakish appearance) after the Jabberwock itself? A mammal called "Momerathobataar"? "Tovia slithius" the nematode to complete the set? Will, 70 years later, an oviraptorid have to be re-named "Toviamaia"? Too many Nemegt fauna inside jokes? Yeah, I'll stop.

Above: The resemblance is uncanny! Left: Jabberwock by John Tenniel, 1871. Right: Therizinosaurus by Apokryltaros, licensed.

Nom nom nom

Above: Edmontosaurus skull, note teeth in back of jaw. Photo: Ballista / Wikipedia, licensed

Did hadrosaurs chew? A recently named lambeosaur called Angulomastacator ("angle chewer") would have us think so. So would a new paper by Williams et al. on an intensive study of hadrosaur tooth wear. As this article reports, the direction of hundreds of scratches were mapped in 3D to suss out what type of chewing method was used by hadrosaurs. The authors found that they employed an extinct form of chewing unlike any living animals, in which the natural kinesis (joints between the skull bones found in modern reptiles) forced the bones of the upper jaw outward, causing the tooth batteries to slide against each other in a sideways motion.

Sounds very interesting and a great step to resolving the ecologies of this well-known dinosaur group... or is it? A major paper that came out in the December issue of JVP argued convincingly that dinosaur skulls such as this didn't actually have any kinesis at all! As David Marjanovic summed up on the DML, the argument there was that people who have spent their careers studying modern reptiles and their kinetic skulls have assumed that dinosaurs followed the same pattern, and have grasped at straws to find evidence of kinesis where it doesn't actually exist (that is, that dinosaurs lost cranial kinesis at some point in their evolution from other reptiles, or never had it, meaning it's a novel feature of lizards and snakes). If that's the case, than the underlying assumption of this new hadrosaur paper is wrong. Another blow against their conclusions, as noted in the article above, is that reports of fossil stomach contents from hadrosaur mummies show food that had been sheared, not chewed. Gut contents also suggest a diet predominantly of conifers (pine trees etc.), while the tooth wear study suggests food was cropped close to the ground and may have been rich in silica, suggesting a diet primarily of ferns and horsetails.

Above: Edmontosaurus tooth battery, which was studied for wear patterns. Photo: Vince Williams / Univ. of Leicester

So then, how to explain the unique wear patterns on hadrosaur teeth? How can we rectify the conflicting evidence regarding diet? Surely another salvo in this controversy will appear in print in a few months.

Tracy Ford and the Kingdom of the Embellished Skull

It's a catch-phrase for Indiana Jones and a rallying cry for paleontologists and archaeologists alike...

"It belongs in a museum!"

Unfortunately, there are plenty of private collectors out there who don't heed Indy's sage-like advice. Many important fossils are lost every year to private individuals who rarely disclose specimens to experts for study. Even if specimens in private hands are offered to experts, many refuse to publish on them, partly because they see it as simply unethical and partly because most important provenance data (what rocks formation the bones came from, etc.) has already been lost by that point.


Take the case of the Mongolian tyrannosaurid Alioramus. This dinosaur is officially known from only a single decently preserved skull, though several more complete skulls are known to exist in private collections, making them all but worthless to science unless the collectors bequeath them to museums in their wills later on. Mongolia is notorious for losing specimens to collectors, and apparently many, many excellent, potentially very important finds and new species will never become known to the public for this reason.

Back to Alioramus. One such 'lost' skull was recently sold at auction in New York to an undisclosed buyer for over US$200,000 (story here). Photos of this specimen were posted to the Dinosaur Mailing List after the auction finished (see DML post here for links to all the photos. One is reproduced above).

This seems like a tragic sale, because the skull appears to be beautifully complete, so it would be quite a loss for it to end up under a glass case in some millionaire's bedroom. I say would, because it looks like the joke's on him or her...

Often ignored in the sale of private specimens inaccessible to science is that they're inaccessible to science. That means that embellishments often added to black market fossils can't be caught by trained eyes. Now, at first glance, even most experts wouldn't notice the enhancements to the skull pictured above without studying the fossil up close. Enter Tracy Ford: the original armchair paleontologist, he has made a name for himself in offering a subscription-based online dinosaur database, as well as producing numerous publications on dinosaur life anatomy, books on how to draw dinosaurs, etc. Ford is also an active member of DinoForum, and noticed something very familiar about the auctioned-off Alioramus skull. He'd seen it before, at the infamous Tuscon Gem and Mineral Show. Tuscon is a Mecca for fossil collectors and under-the-table deals on shady specimens. The show regularly attracts even pros, who can often come across amazing new finds.

Ford had seen this very skull at the show, and, as he reported on DinoForum:

• "I can saw with total confindance that this specimen is more than 80 percent reconstructed. The reason why I know this is that it was at the Tucson Rock Show about 3 or 4 years ago and I took several photo's of the specmen, which at the time was just the premaxilla, maxilla and tip of the dentary. Nether of the bones complete. So, just to get it sold they reconstructed it into its current state. Not as good as they claim it to be."

Others were astounded that someone would pay over 200 grand for a specimen that hadn't been checked for reconstruction or forgery. "Completing" partial skulls is common even in museums when prepping specimens for display, but you'd reckon this would significantly decrease the value of a specimen at auction, and I'd be very surprised if the buyer knew that only the ends of the jaws were composed of real bone. Here's a photo Ford took of the specimen years ago in Tuscon. Worth $200,000? You be the judge.