On the structure of hind wings

Above: Anchiornis model from NatGeo. Something is wrong with those foot feathers...

With all the recent hubbub over Anchiornis and its coloration, have come several pretty cool life reconstructions showing the animal as it would, supposedly, look in life. I posted one in my blog yesterday on the topic, and NatGeo has a cool 3D model on their site, here (and figured above).

One thing I've noticed about all these images is the very... standard rendering of the infamous hind wings (shared with Microraptor and Pedopenna). Much debate has surrounded these appendages, mainly relating to their ability to glide. A whole Nova special was made showing different attempts to reconstruct gliding posture, from biplane-like, to sprawled-out-sideways, to rear-swept canopy. And especially in that special, the same thing bugged me about the hind wings:

Every configuration required the primary foot feathers to emerge at a different angle from different parts of the limb!

It shouldn't be so hard to figure out how these feathers attached, which would help us suss out their potential uses. First of all, the reconstruction of Anchiornis above, and by extension reconstructions of Microraptor with the legs sprawled out, make little anatomical sense to me. Maybe I'm mistaken, but I think we should look to the example of how front wings are put together to inform on this, as developmentally the two are almost certainly related.

Above: Incorrect, pronated-handed Velociraptor skeletal by Frederik Spindler, licensed. Just where are those primary feathers supposed to be attaching? To the underside of the fingers?

Back in the days of pronated theropod hands, many similary ridiculous renderings of feathered theropods were made, many by me. Of course, we all know how wings 'look' when folded - primary and secondary feathers swept back along the side of the body. The problem is that, if the hand is incorrectly shown as pronated, this arrangement makes no sense. On a pronated hand, the feathers emerge laterally from the edge of the finger and hand, and from the lateral side of the ulna. Only when the hand is not pronated does the proper wing configuration emerge. If real wing anatomy were taken into consideration, artists of bunny-wrist theropods would show the primary feathers sicking out to the side of the animal, not flush with the body, when the arms are folded. Otherwise, the feathers would be attached to the palm of the hand, which is ridiculous.

Above: Probably incorrect rendering of Microraptor. Just how is this animal supposed to sit down?

So why isn't this also true of the foot? My guess: it is. For all intents and purposes, the foot is the same configuration as the hand, only it really is pronated. The toes and metatarsals are equivalent to the fingers and metacarpals. I'll put this to the experts out there, because it's something I've never seen addressed and makes no sense to me. If the hind wing feathers projected posteriorly from the metatarsals, how are these animals supposed to have sat, or brooded their eggs? We have several fossil examples of theropods sitting, sleeping, or brooding, all with metatarsals fully in contact with the ground. If there were very large, rigid feathers pointing straight down from the foot, that would be impossible. Furthermore, developmentally, it seems we would expect the legs to mirror the arms, with primary leg feathers articulating from the top of pedal digit 2 and metacarpal 2. Therefore, sticking straight out to the side when standing.

Above: An animal capable of sitting, with sticky-out hind wings. AMNH.

Now, maybe I missed something so please correct me if any of my reasoning is wrong. But in short, I believe the biplane or semi-biplane model is the only one anatomically feasible, barring some novel adaptation like feathers with a hinge at their base to allow them to deploy outward like an X-Wing from Star Wars. The pedal primaries have to have pointed out to the side, while the tibial primaries of the lower leg would still point backward, as in the model above. So all those recons purporting to show Anchiornis as it really was miss a pretty important point. Not to mention the naked, beak-like snout, doesn't anybody look at fossils anymore? ;)

Above: This pigeon with sticky-out, biplane configured foot feathers is apparently able to sit down.

Another note on this--maybe my whole reasoning about comparing the front to hind wings is off. Can't we then compare to modern hind winged animals? Like the one pictured above? Those foot feathers do not point backward and, as you can see, the animal is therefore able to sit. Imagine those feathers configured like the Anchiornis model at the top of this post. It just doesn't work.

In other news... Anchiornis now in full color!

Above: Left - so close, yet so far away. Right: The actual colors of a dinosaur.

Oh man, I was SO CLOSE! And I've been planning a new digipainting of this guy too, but was hesitant to do so figuring the color would be worked out in a few months. You can all thank me for summoning this study with mind bullets. Thanks to Ed Young pointing this out on his blog!

Li et al. 2010. Plumage Color Patterns of an Extinct Dinosaur. Science http://dx.doi.org/10.1126/science.1186290

P.S. How flipping beautiful is this new specimen? Go to hell Berlin Archaeopteryx specimen ;)

Above: Awesomeness.

Banji the Hunted

Above: Possible extents of oviraptorid beaks, from Jansen's thesis.

Recently, some of my adventures on Wikipedia have addressed the question of oviraptorid beaks. Now, contain yourselves, I know this sounds a little too exciting. But it's really a very rarely addressed topic. It's obvious that oviraptorids had beaks of some kind, with their strong, toothless, pointy jaws that don't quite close right when unsheathed by rhamphotheca (the keratinous covering that forms the beak). But just how these beaks looked and to what extent they covered the jaws hasn't been studied in a lot of detail.

I asked about this a few times back on the old version of dinoforum, and some commentors there (especially oviraptorer Jaime Headden) were very helpful in pulling educated guesses based on modern analogues. Jaime's conclusion, IIRC, was that most oviraptorids have been constructed with beaks that are too large or, more specifically, cover too much of the skull and jaws. You can see the difference in two versions of my own ovi profile drawings, old one here with extensive beaks, new one with corrected beak after Headden here. Note also the more subtle difference--the beaks on the newer version meet flush, without the upper beak overlapping the other (what use would that be?) and the beak does not incorporate the nostril, which is the exception, not the rule in modern beaked animals like birds and turtles.

The first real scientific work on this topic has not yet hit the official literature, but an unpublished phD thesis by Stig Jansen addresses this topic. Jansen also has a similar unpublished paper floating around for ornithomimid beaks, I'm sure you're Google-fu will turn it up.

Jansen's thesis comes to essentially the same conclusions as Headden did, and presents two potential extremes for the extent of oviraptorid beaks, illustrated by him above. Interestingly, one of the options has a keratin-less crest. Traditionally, crested oviraptorids or those with tall, pronounced skulls have been restored with horny, cassowary-like casques, though there was never any direct evidence for this, and they could just as well have been covered in skin or feathers.

Above: Skull reconstruction of Banji, note the striations on the crest. Fig. 2 from Xu & Han 2010.

Well, most of them, but maybe not a newly described genus of oviraptorid (named Banji long, or "dragon with striped crest"... this is, incidentally, another case of bad grammar in a binomial. The specific name is supposed to be an adjective, not a noun, which makes for very awkward translations like Mei long, or "dragon, comma, soundly sleeping". Also, it sounds like Benji.). Anyway, Banji reserves some unique vertical striations on its crest. The implications of this feature aren't discussed in the paper, but the first thing that jumps to my mind is that these may form the bases of more pronounced striations in an overlying keratinous crest. As Jansen shows, underlying bony features of a bak often subtly reflect larger features of the keratin, like the keratinous pseudo-teeth on the beaks of some oviraptorids. A future paper will describe Banji and its implications in more detail, so we'll see if this ends up supported by actual study of the fossils, but right now it's a very interesting possibility that may argue for the more extensive beak suggested by Jansen's thesis.

Haplocheirus, the (or one of the?) Jurassic alvarezsaur(s)

Above: Illustration of Haplocheirus, from Stone 2010 (intro article published in Science)

Those coelurosaur ghost lineages just keep getting filled in lately. Today sees the publication of Haplocheirus sollers, the first Jurassic alverezsaur. Unlike its later brethren, this doesn't look very alvarezsaurian at first glance, more like you're typical generic coelurosaur. As Tom Holtz said o the DML, this is the first alvarezsaur that "looks normal"!

However, telltale signs (such as downward-flared basipterygoid processes on the skull) and a phylogenetic analysis shows that this is the earliest and most primitive member of the group. It comes from the Late Jurassic of China, and falls out as a basal maniraptoran, which jibes with the placement of alvarezsaurs in many recent studies, not avialan or ornithomimosaur as previously suspected by some. Interestingly, the teeth are heterodont, which seems to me to give weight to the reent hypothesis that all maniraptorans are ancestrally omnivorous. It's also the largest nkown alvarezsaurid known from good material, indicating that these guys may have started out fairly big and later shrunk to the diminutive sizes seen in the likes of Parvicursor.

But, is this really the earliest alvarezsaur on the radar? Some goss fans may have heard of a supposed alvarezsaur from the Tiaojishan Formation, preserved with feathers, mentioned at last year's SVP. That ain't this, though it would be from roughly the same time period (about 60 Ma ago). Depending on how similar the two species are, we might be looking at a ghost lineage that goes even further back than before, rther than being clipped to the mid-Jurassic. Time will tell.

The White Stripes

Back in August, I posted about a study by Vinther and colleagues looking at fossil bird feathers in an attempt to not only determine color patterns in life, but the actual colors constituting those patterns. That study looked only at Cenozoic birds, but tantalizingly, Vinther and co. promised follow-ups looking at Mesozoic birds and other feathered or proto-feathered dinosaurs.

Well, somebody has beat them to it (though, interestingly, Vinther has responded with skepticism to this newest study which has beat him to the punch though appears to use similar methods, as reported by Ed Young). Specifically, Zhang and colleagues have an online-first paper out in Nature today reporting the presence of melanosomes (pigmentation-bearing cell bits) for the first time in protofeathers. The team looked at Sinosauropteryx, Sinornithosaurus and Confuciusornis, and found pigment in all of them.

This is interesting for a few reasons, not the least of which that children's books can now officially limit their audiences imaginations by saying "no, little Billy, dinosaurs weren't whatever color you can dream of, this one here for example was black with shades of red and white patches thrown in." Firstly, this whole color-patterns-in-dinos thing was (as far as I know) first officially brought up by Nick Longrich at SVP 2002. Longrich pointed out that the thing everybody noticed about Sinosauropteryx (the stripey tail) was not an artifact of preservation, as the describers suggested, but reflected color, in the same way that prehistoric insects and fish fossils can show patterns. Based on Longrich's conclusions, I did the painting of Sinosauropteryx shown above, and this has proven largely correct (I lightened the color a bit to seem lighter browning orange, but the original was pretty close if I may say so!).

Unfortunately, being a Nature publication, this announcement comes with high prestige and itty bitty page count. The authors here promise more detailed follow-ups with more specific color patterns, and presumably Vinther et al. are also still working on their studies. Vinther's objection, which I mentioned above, is that as they had pointed out, really deciphering fossil animal colors requires a thorough understanding of how different pigment structures create color in modern birds, which is barely understood. So new discoveries with modern animals could overturn some or all of this. But, for now, all good paleoartists will reconstruct Sinosauropteryx as red-brown with a striped tail, and if Longrich was right about the rest, a bit of counter-shading.

Interestingly, the Sinosaur the new study uses is an undescribed specimen. In some news reports like this one, it is stated that Sinosauropteryx had only a feather fringe along the back, implying a partly scaly body. Now, other specimens have shown evidence of feathers on at least the lateral torso, but could this new one show evidence of a more Juravenator-type scalation on the legs and tail base (as I also restored above)? We'll see...

NY Daily News Staff Writers Are Dumb As Bricks

Above: Maybe venomous, but NOT a spitter!

Check out this short piece "attempting" to condense the recent story on potentially venomous sinornithosaurs. The piece was written by New York Daily News staff writer Ethan Sacks, who does not understand one word of the subject he's covering.

The headline:
"Venomous velociraptor: Scientists discover sinornithosaurus dinosaur spit poison at prey"

*HEADDESK*

I can guarantee you with 100% certainty no scientist or press release even remotely said anything like this.

What they probably told him/what he probably read on other news sites: "The dinosaur Sinornithosaurus, a relative of Velociraptor, was venomous, like the spitting dinosaurs in Jurassic Park."

What Sacks heard: "Velociraptor's relatives were venom-spitting dinosaurs, like in Jurassic Park!"

Way to make the world a dumber place, Ethan Sacks.

Venomous Dinosaurs

Above: Illustration of a Sinornithosaurus skull.

A few of you may remember a little 1993 picture called Jurassic Park. In the film as in the novel it was based on, a point was made of showing how unpredictable cloning extinct organisms could be, and that we would not be able to anticipate all the dangers dinosaurs posed just from their fossil remains. To illustrate this, author Michael Crichton invented the idea that the basal theropod Dilophosaurus was venomous. This was, of course, completely fictional and only present to make a philosophical point. There is no evidence whatsoever that this dino had venom, let alone could spit it like a cobra, let alone had a ridiculous display like a rattling frill-neck lizard (added only for the movie).

However, while Dilophosaurus in particular was probably not venomous (and if it was, the late Crichton should be hailed as a prophet for picking that specific dino out of his... orifice), this doesn't rule out the possibility that some dinosaurs were. Poison or venom of come kind exists in a wide selection of modern vertebrates, from amphibians, to lizards (like the gila monster and Komodo dragon) and even birds such as the Hooded Pitohui, which is very aptly named, as the neurotoxins in its feathers cause predators to promptly spit it out.

There has in the past been some goss to the effect that we have evidence for venomous dinosaurs (the difference between venom and poison: poison is ingested or absorbed from prey to predator, venom is injected from predator into prey). A 2 cm long tooth with a longitudinal groove, reported from Mexico in 2001, was suggested to come from a venomous theropod.

Those grooves, which are actually present in most theropod teeth to some extent, are the issue of a new controversy over a paper on the Chinese dromaeosaurid Sinornithosaurus, which we've covered before regarding it's hind wings, or lack therof. A new study looks at the unusually positioned gooves on sinornithosaur teeth, and speculates that these could have delivered venom. The researchers even identify an opening in the upper jaw bone where the venom gland may have been. (left: Sinornithosaurus by FunkMonk. Licensed.)

This is exciting stuff, but take it with a grain of salt. Ed Young does a good job covering the situation at his blog. Basically, it's entirely possible that the grooves are simply features typical of other theropods. Many animals have grooves on their teeth to negate any suction that would occur when pulling the tooth out of flesh. However, Young also reports that Bryan Fry, who discovered the venom of Komodo dragons, has stated that grooved never occur on the posterior side of the tooth surface except in venomous animals, which sounds pretty convincing.

The authors of the new paper cite the length of the grooved teeth as evidence that they were "fangs", but it really just looks like they're out of socket, the way many theropod skulls are mounted in museums. T. rex famously have 6-inch teeth, but that includes the roots. Really, only 2 or three of those inches would protrude from the jaw. Fossils that have been crushed and distorted are also susceptible to out of socket teeth making the dentition look more formidable (and more fang-like) than it really was.

Above: T. rex mount with teeth dangling out of the mouth like it just finished a brutal hockey game. Photo by Quadell from Wikipedia. Licensed.

Obviously more investigation needs to be done, but famous TV personality Dr Tom Holtz is on record saying he evidence is weak, so let's not be too hasty with conclusions here.