Non-Dinosaur News: Choristoderan Craziness

Above: Hyphalosaurus by Nobu Tamura. Licensed.

This might be the first post where I deviate from the title of my blog... but this was too good to let pass. As first reported by Jocelynn Falconnet on the DML, here are two new papers that just came out about Hyphalosaurus baitaigouensis (a small, long-necked aquatic choristoderan from the Jiufotang Formation) reproduction:

Ji Q., Wu X.-C. & Cheng Y.-N. 2010. Cretaceous choristoderan reptiles gave birth to live young. Naturwissenschaften 97(4): 423-428.
Viviparity (giving birth to live young) in fossil reptiles has been known only in a few marine groups: ichthyosaurs, pachypleurosaurs, and mosasaurs. Here, we report a pregnant specimen of the Early Cretaceous Hyphalosaurus baitaigouensis...

and:

Hou L.-H., Li P.-P., Ksepka D.T., Gao K.-Q. & Norell M.A. In press. Implications of flexible-shelled eggs in a Cretaceous choristoderan reptile. Proceedings of the Royal Society B 277(1685):1235-1239.
Flexible, or soft-shelled, eggs are almost unknown in the fossil record, leaving large gaps in our knowledge of the reproductive biology of many tetrapod clades. Here, we report two flexible-shelled eggs of the hyphalosaurid choristodere Hyphalosaurus baitaigouensis from the Early Cretaceous of China, one containing an embryo and the second associated with a neonate.

To recap, Hou et al. have just reported that a specimen of H. baitaigouensis shows they gave birth to live young. Simultaneously, Ji et al. reported the discovery of unhatched H. baitaigouensis eggs.

I love paleontolgy ;)

Imploding Hadrosaurs and Dubious Nomina Dubia

By now, everybody has heard about Jack Horner's attempt to KILL our beloved Torosaurus.

Above: Look out Toro, Horner's coming and he's packing an AK! Photo by Daniel Hendricks, licensed.

Well, I say "our," but I've never really given much of a thought to Torosaurus, beyond my 10-year-old self trying to get the mechanized DinoRiders toy. But some people seem to feel inexplicably attached to this name, often and incorrectly translated as "bull lizard" (it's got big horns, and was ornery like a raging bull!). In reality it means "perforated lizard", in reference to the holes in its frill. And it's not like the animal will cease to exist, it's just the mature, let's say "silver back" stage of Triceratops. Or should we say, Torosaurus is the mature morph, and Triceratops is the immature morph, of Agathaumas. As I mentioned before, Agathaumas specimens lack diagnostic characters in the context of an environment with multiple taxa from which it must be distinguished. But if there's only one ceratopsian in town, the identity of those generic-looking postcrania is narrowed down to one option, and it's no longer a nomen dubium.

Above: Dear E.D., Please stop naming isolated vertebrae and teeth. kthx. Photo by F. Gutekunst pre-1897, public domain.

Ah, the nomen dubium, or "doubtful name." This is an unofficial* designation given by scientists to names whose type specimens can't be classified because they're too generic. Like many dinosaurs discovered by E.D. Cope, Agathaumas was named based on partial postcranial remains. As more fossils turned up, it turned out that its "unique" postcranial features were actually characteristic of a larger clade, and all ceratopsids have nearly identical torsos and limbs. So Agathaumas lost it's standing as a valid name, because (lacking a skull) it couldn't be determined which species of ceratopsid the bones came from. True, the genus name could have simply been used for all ceratopsid species with this type of postcrania, but modern taxonomists don't roll that way, preferring genera to be mostly monophyletic. For years, Agathaumas remained known as a nomen dubium. It probably belonged to either Triceratops or Torosaurus, the only contemporary contenders known from better remains, but since no skull was found with the type specimen, we could never know for sure which one was the junior synonym.

* The ICZN does not officially recognize any such thing as a nomen dubium, and contrary to popular belief, has no rules to the effect that family names can't be based on dubious taxa, etc. Hence Titanosauridae (=Saltasauridae), Hadrosauridae (=Lambeosauridae), Troodontidae (=Stenonychosauridae), Deinodontidae (=Tyrannosauridae), Podokesauridae (=Coelophysidae) Ceratopsidae (=Chasmosauridae) and yes, Ornithodesmidae (=Dromaeosauridae) are all perfectly valid.

That is, of course, unless the number of potential synonyms is reduced to 1. With Triceratops and Torosaurus recognized as one genus, there is no reason to think that the type specimen of Agathaumas and the type specimen of Triceratops don't come from the same species. If and when another genus of ceratopsid is ever discovered from the well-sampled late Maastrichtian beds of North America, this could always be reversed, but for now the default hypothesis must be that only one was present, rather than an extremely common genus with a wide range of individual variation (Triceratops) and one shadowy mystery genus known only from a post-crania identical to Triceratops but hey, maybe it had like 20 horns or something, who knows?

Sarcasm aside, the concept of nomina dubia has become a bit crazy over the years. Jaime Headden has recently been on a mini-crusade to this point on the DML, questioning some pretty well ingrained and yet pretty flimsy concepts of what is and isn't "non-diagnostic". Let's come to our senses and realize that stratigraphic, ecological and temporal considerations also need to be taken into account. Yes, Agathaumas is non-diagnostic relative to, say, Chasmosaurus. But those two were not contemporaries, and barring the use of a time machine, the other ceratopsians that could potentially be synonyms of Agathaumas could not have existed in the same time and place as it did. Except for one, Triceratops, which by rights should go the way or either Brontosaurus (abandonment) or Coelophysis (official conservation).

Above: The dinosaur Rioarribasaurus had its name changed to Coelophysis by mistake. It turns out the original Coelophysis was not only a different species, it wasn't even a dinosaur. The original is now known as Euceolophysis, or "true Coelophysis." Photo by Ballista, licensed.

Which brings me to the promised hadrosaur implosion. Thanks largely to the work of Nicolas Campione, the taxonomy of Late Cretaceous hadrosaurs is finally being untangled after nearly two centuries of confusion. Contrary to conventional wisdom, the short-snouted type species Edmontosaurus regalis appears to be present only in the Campanian Horseshoe Canyon Formation, not the end-Mesozoic Lance, Hell Creek, etc. All the long-snouted "edmontosaurs" in the late Maastrichtian formations can be assigned to either Edmontosaurus annectens (previously Anatosaurus) or the truly duck-billed form Anatotian. Whether or not E. annectens should therefore be kept as Edmontosaurus or re-classified back to Anatosaurus is a matter of personal preference.

Above: The hadrosaur of many names, lately Anatotitan, the once and future Thespesius? Photo by Claire Houck, licensed.

But there's another monkey wrench here. Campione, in his un-published abstracts and talks so far, has been agnostic on the validity of Anatotitan as a separate species. In the past it's been suggested that the "duck-bill" is merely a preservational artifact, a crushed skull. But, there are several specimens that show this feature, and one that appears to be transitional between narrow and duck-snouted forms. On the DML, Greg Paul has asserted that there is only one species of late Maastrictian edmontosaur, and that the flat-billed versions are the mature growth stage. They even fit the pattern of growth seen in the earlier E. regalis populations, reaching the same maximum size, but then also sprouting the duckbill.

So, it looks like Anatotian is about to go the way of Torosaurus. Except, now the newly low-diversity late Maastrictian dinosaur fauna threatens to resurrect another long-dead name. Thespesius is known only from vertebrae. Those vertebrae could theoretically have come from any hadrosaur... if all hadrosaurs were immortal highlanders. In reality, though, there appears to have been only one hadrosaur species in this ecosystem. And in that case, it can have only one name. And that name is Thespesius occidentalis, "western wondrous one." That name is not Trachodon annectens, because I think the type specimen of Trachodon mirabilis is a ceratopsian. But I'm looking into that one.

Above: Some of these teeth may or may not belong to Trachodon mirabilis. From Leidy, 1860, public domain.

To continue crushing the dreams of myself in 1988 and fans of Jurassic Park everywhere, I'll next try to research whether or not Manospondylus is really a nomen oblitum like everybody is assuming (and everyone does simply assume this, because can you imagine if it weren't?). Outlook probably not so good.

Dinogoss: Trendsetting

One more really short post... Because it's time to claim tenuous credit for starting a trend!

This is another image that caught my attention today as I finally took some time to catch up on my Google Reader blog subscriptions. Also at Michael Ryan's Palaeoblog, I found the above size comparison of the cool new sauropodomorph Seitaad with a human. But not just any human, it's the Pioneer Dork's girlfriend!

Above: The Dork poses dorkily with the smallest dinosaur, Anchiornis huxleyi. Say, "Hi dork!" Image by Matt Martyniuk, licensed.

The Pioneer Dork is of course the male figure from the gold plaque sent along with the Pioneer probes 10 and 11. When I first started doing size comparison diagrams for Wikipedia in 2006 or '07, I used this public domain image for the human and have done so since (and so have a few others). We Wiki editors lovingly referred to him as the 'Dork', due to, well, his dorky pose. Several Wiki readers have posted comments on talk pages noting how hilarious it is to depict a happy, waving man inches away from the maw of a charging Albertosaurus. But they just don't understand the Dork's simple charm. There was a brief push to replace the Dork with something a bit edgier, namely a silhouette of Catherine Zeta Jones. Cooler heads prevailed and pointed out that dammit, Jim, this is an encyclopaedia, not a trucker's mud flaps! (I, however, have opted to use her in the scale charts I make for my own site).

I choose to believe the Dork's female counterpart was done as an homage to those Wiki scale charts and will not listen if somebody comes up with an alternate explanation. Note that this must be a press release only image, as the skeletal in the free open-access paper lacks a human figure. Bummer. Maybe the next paper can include CZJ to make up for it.

Above: Yowza.

Holy !@#$ this is awesome

Many of you may be familiar with one of the most awesome pieces of paleoart ever done for an '80s toy line.

Spotted this at Michael Ryan's blog: Probably my new favorite piece of awesome, though profoundly lacking in Rulons, paleoart.

By the killer Raul Martin. Albertosaurus attacked by Deinosuchus as some (ichthyornithid?) ornithurans scatter.

You're Doing It Wrong #1: Archaeopteryx

Above: What has mankind done to deserve this?

Sorry for the lack of posts lately. Just moved countries again (itchy feet need scratching) and settling into a new full-time teaching job. Also, any free time I've had over the last week or so has been spent on drawing, rather than blogging, dinosaurs. Rest assured those two will overlap. I've been meaning for a while to put together a guide to the wing anatomy of Mesozoic birds which will probably first appear on DinoGoss. This is for the good of the world, since it's insanely rare even in this day and age of the exquisitely preserved Jehol biota to find amateur (or sometimes professional!) paleoartists getting prehistoric birds right. I think they suffer from 'background syndrome'--birds, like pterosaurs, usually appear in the background in paintings starring more glamorous megafauna. Thus artists don't pay them much attention, thus they're prone to getting basic details wrong, which everyone else copies.

Actually, maybe that's the more important point. The copying, that is. Google Image Search syndrome is plaguing paleoart. Do a search for any prehistoric bird/basal aviremigian, and the first page of hits will all be inaccurate drawings. People looking for references but not wanting to do actual research will copy those mistakes, and they keep getting perpetuated, which keeps the same inaccuracies on the top Google hits, forever. Depressing, no? For example, on one forum, a young artist recently showed off a really well made, life-sized sculpture of Caudipteryx. Unfortunately, his research was obviously done by browsing Google, and he used this terribly inaccurate illustration as the basis for the model.

Thus, the reason for this new series, "You're Doing It Wrong." That and it's something I can write up quickly using only Google research. I'll start with one of the worst dinobird Google offenders, and the one for which there is the absolute least amount of wiggle room for excuses: Archaeopteryx.

1. How Bad Is It?

Google Image search "Archaeopteryx," and of the first 18 hits, 5 are photos of specimens, 2 are diagrams with labelled anatomy, and the rest are artist's impressions. Of those 11 illustrations, 0 are anatomically accurate. Count 'em: ZERO! That's pretty bad you guys.

2. What's the problem?

Some are better than others. Three of the images, one by pro Todd Marshall, get minor details wrong. In the Marshall one, all the proportions looks correct, it's just that the primary feathers seem to be coming off the wrist rather than the finger. This is a common mistake, but at least an entire, ill-proportioned, scaly hand isn't poking anteriorly from a feathered wing where the feathers apparently anchor to nothing, like some of the other results. The second "ok" one has the same problem, plus the presence of tertial feathers. If you're posing your Archie with an outstretched humerus, there should be a gap in between the wing and the body. This is even true of most modern birds! Yet it's probably the number one common mistake in drawing Mesozoic avialans. The third, by T. Mike Keesey, has the arms lifted too high above the body, an anatomical impossibility.

This model, from Wikipedia, is pretty good minus the naked legs. We know now that Archie actually had quite long feathers on the legs down at least to the ankle. (UPDATE: I had originally included "blue iridescent color on the head" as an error here. However, recent research suggests that the apparent filamentous nature of the contour feathers in many fossils is probably a taphonomic artifact, so it's entirely possible Archie had pennaceous body and head feathers, allowing iridescence and other structural colors).

Some suffer from more than minor inaccuracies. Images like those above should not be allowed in the 21st Century. Reversed hallux, hands decoupled from the wing, scaly head and neck, etc. Then there's this one, that even says Archaeopteryx had a horny beak... wtf?

3. What's the excuse?

There isn't one. Entire papers have been published explaining the anatomy and plumage of Archaeopteryx in great detail. It's one of the best-studied, if not THE best-studied, Mesozoic bird, period. Aside from color, we know just about everything there is to know about this creatures appearance. Not to mention, one of the top Google hits is a fairly acceptable diagram showing how the feathers attached and the proportions of all the bones. Of course, this is counter-acted by a completely crap diagram further down the page that barely looks like a theropod, let alone Archaeopteryx. Of course, this is on a much more popular web page, and ostensibly an "educational" one, Enchanted Learning.

4. What's to be done?

Research, I should hope! Get a good photo of the fossil, or even better, a copy of Christiansen & Bonde's 2004 paper "Body plumage in Archaeopteryx: a review, and new evidence from the Berlin specimen." Stop copying the images done in the past, even if by notable artists--they're probably wrong in at least some minor respect. And study the drawings done by Reichel in the 1940s, which are still extremely accurate, especially in terms of plumage arrangement.

Till next time gosshounds!

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.