Oh, Hi, Bohaiornithids!

It's not often that we are introduced to a large new clade of stem-birds*, but a new paper by Wang et al. finds support for just such a thing among the enantiornithes. Named Bohaiornithidae, the family unites a few previously-known similar-looking opposite birds with two brand new species.

Phylogeny of Bohaiornithidae, modified after Wang et al. 2014.

You're Doing It Wrong: CGI Feathered Dinosaurs

YIKES.
Promotional still from When Dinosaur Roamed America,
Discovery Channel 2001

CGI dinosaurs have come a long way since Jurassic Park. Unfortunately, due to the discovery that these animals were far more bird-like than reptile-like, that direction is straight down a seemingly bottomless pit. For many CGI artists and animators, the key concept that is presenting a very steep learning curve is the idea that these animals need to be restored as feathered dinosaurs, not "dinosaurs with feathers." It looks like many people modeling feathered dinosaurs start out by rendering a featherless dinosaur and then using various modeling or rendering tricks to add the feathers. As you'll see below, this never, ever works.

April fools! A bit late but who's counting?

UPDATE!

This is a late-arriving April Fools joke. Got me!

Archaeocursor. The bahariasaurid (yes, new family) with feathers. Commence head explosions.

Paul C. Sereno, Oliver Rauhut, Xing Xu, Wang, Y., Zhu, T., Gao, X. & Gong, D. (2011). "Basalmost theropod with filamentous integumentary structures and new clade of basal 'carnivorous' dinosaurs". Kirtlandia 37: 82-113.

I haven't seen any discussion of this, save that it's been added to Wikipedia. Apparently from the Tiaojishan formation, the same beds that have yielded Anchiornis and Tianyulong. Also, note the scare quotes around "carnivorous." Could their proximity to Limusaurus mean bahariasaurids are partially or wholly herbivorous? Just idle speculation for now. More if/when I get my hands on this paper.

Tearing Up Pteranodon

Above: Male (foreground) and female Geosternbergia sternbergi, mounted casts at the Royal Ontario Museum. Photo by Kenn Chaplin, licensed.

On the PteroGoss front, I just came across a new paper that doesn't seem to have received much press online yet. A new paper by A.W. Kellner has appeared online concerning the taxonomy of the small but well-known pterosaur family Pteranodontidae. The abstract can be found here.

This paper is interesting in that it attempts to reverse some of the trends of the past few decades concerning pterosaur diversity, in some cases (in others it's merely a re-calibration of the old genericometer). Kellner erects two new species and ressurects a genus, Geosternbergia.

I first encountered Pteranodon sternbergi in Dave Peters' awesome picture book A Gallery of Dinosaurs and other Ancient Reptiles (which also probably instilled my OCD towards drawing scale diagrams). It took my young mind a while to register that this huge, tall/broad crested pterosaur belonged to the same genus as the familiar, backward-pointing-crested Pteranodon lonciceps that flew beside it. I have to admit that I though P. sternbergi just looked... cooler. In this kind of side-by-side comparison, they really don't looks like they belong to the same genus. But as always, genera are subjective things, and nobody doubted that P. longiceps and P. sternbergi were each others closest relatives (they even overlapped in time and geologic range).

P. sternbergi was first described by Harksen in 1966 as a species of Pteranodon, based on a skull which differed from other species by its tall, vertical crest. In 1972, Miller placed it rather arbitrarily in its own subgenus, as Pteranodon (Sternbergia) sternbergi. The name Sternbergia turned out to be pre-occupied (as far as I know, subgenenus names compete with genera for priority). Miller amended the name to Geosternbergia in 1978.

However, this designation fell out of favor by the 1990s, when Chris Bennett published a couple of hefty reviews of Pteranodon from the Niobrara and related formations in Kansas. Bennett stramlined Pteranodon taxonomy, taking the several species that had been considered valid up to that time and showing that much of the variation was likely due to age and/or sexual dimorphism. For example, Bennett re-affirmed the idea that some small-crested Pteranodon specimens represent females (and some juveniles) of the same species as the longer-crested adult males. With this variation in mind, he suggested that all Pteranodon specimens could fit into two species: P. lonciceps and P. sternbergi. Because differences between species are limited almost entirely to the skull and crest (though Kellner 2010 suggests that some consistent differences may be found in the skeleton with further study), Bennett had to rely mainly on stratigraphic position to decide which species a specimen belonged to. While the two did overlap in time, it was only for a very brief period, so even though skulls are very rare compared to skeletons, a specimen from the lower Niobrara could be confidently referred P. sternbergi, while one from higher in the formation probably came from P. longiceps. (Image at left: illustration of various Pteranodon skulls by Matt Martyniuk, licensed).

One problem with this method, which Kellner points out in his new paper, is that many specimens (especially those recovered back during the days of Cope and Marsh) lack information about their provenence detailed enough to allow such an assignment. Bennett himself simply referred these to Pteranodon sp., but if Kellner's new work holds up, they'd need to be assigned even more broadly, only to indeterminate Pteranodontidae.

That's because Kellner has re-assessed the variation within the traditional grouping known as Pteranodon, and found some specimens that seem to represent new species among them. For me, the most interesting is Dawndraco kanzai, or "Kanza Dawn dragon" named for Dawn, apparently an Iroquois sky goddess, not the English word. The type and so far only specimen is UALVP 24238, a really interesting nearly complete skull and skeleton usually attributed to P. sternbergi (as in Bennett, 1994). Aside from being one of the most complete (former) Pteranodon specimens, it has always struck me as very, very odd. One of the primary reasons for making this a new species it its upper jaw. In most Pteranodon skulls (though none are as complete as you may assume based on its ubiquity in paleoart), the jaws can be seen to curve upward toward the tip and taper off into a needle-sharp projection at the tip. In the Dawndraco holotype, the preserved portion of the jaws are extremely long relative to the rest of the skull, but show no signs of tapering. In fact, the top and bottom margins of the upper jaw form essentially completely parallel lines up until the break. Letting your imagination fill in the rest, this must represent either a phenomenally long-billed animal, or one with a very unusual fat, somewhat flattened tip. The bone within this tall, long bill looks like a loose, honeycomb mesh of very thin struts. Taken together, this does seem like it probably comes from something fairly different than Pteranodon proper. (Image at right: Skull of Dawndraco, from Kellner 2010. Scale bar = 500mm).

The next new species is Geosternbergia maysei. Kellner considers Geosternbergia a distinct genus based on its unique skull characteristics, but again, there is currently no analysis to suggest that it is any more or less closely related to Pteranodon than anything else, so it remains a subjective decision (though it would be interesting to see someone perform an analysis using all of Kellner's species and Nyctosaurus). Anyway, G. maysei is named for a partial skull (KUVP 27821) from the South Dakota Sharon Springs formation. It was a large individual that Bennett previously referred to P. longiceps. However, Kellner notes that the crest is inclined further upward than it should be for that species, and that the premaxilla is arranged differently in forming part of the crest. It also appears to have a larger nasoantorbital fenestra, and a lower and larger temporal fenestra, than in G. sternbergi.

How well either of these identifications remains to be seen. I'm more inclined to be convinced by Dawndraco than G. maysei, simply because the very strange bill of the former seems harder to explain by age or gender variation. Kellner has also tended to be the 'leader' of one 'camp' when it comes to pterosaur taxonomy, usually opposed to Dave Unwin -- see their drastically different recent taxonomies of the ornithocheirids, for example. It will be interesting to see not only if these new species are accepted, but by whom.

While on the subject of new pterosaurs, two new species have also just been reported from the mid-Jurassic Tiojishan formation, some with soft tissue: Kunpengopterus sinensis and Darwinopterus linglongtaensis seem to add support for a monophyletic group of Tiaojishan pterosaurs somewhat intermediate between pterodactyloids and "rhamphorhynchoids", the Wukongopteridae. If I have time to read the paper more closely I'll try to follow up with a full post on these guys.

References:
Kellner, A.W.A. (2010. "Comments on the Pteranodontidae (Pterosauria, Pterodactyloidea)
with the description of two new species." Anais da Academia Brasileira de Ciências, 82(4): 1063-1084. doi: 10.1590/S0001-37652010000400025.

Another Burrowing Ornithopod

Above: Type specimen of Koreanoaurus (minus referred pelvis and hindlimbs) from Huh et al. 2010.

Though Bob Bakker had been suggesting that small ornithpods dug burrows for years, on the basis of the kind of sediments the basal ornithopods of Montana were usually found in, we didn't get solid confirmation that these were really burrowing creatures until the discovery of Oryctodromeus. Here was an ornithopod with the same, vaguely burrower-like features as its relatives Orodromeus and Zephyrosaurus, but which was found inside an obvious burrow.

The burrow was the key, because aside from some fairly ambiguous skeletal details, these dinosaurs all had fairly standard ornithpod proportions: elongated necks, long (usually) stiffened tails (but see below), long hind limbs and short front limbs. The overall body plan was that of a bipedal runner, not a dinosaurian wombat.

While still far from mole or wombat like, the new dinosaur Koreanosaurus boseongensis (named by Min Huh, Lee Dae-Gil, Kim Jung-Kyun, Lim Jong-Deock and Pascal Godefroi) is even closer than its relatives. It has very robust forelimbs, and while the humerus is still long, the forearm is short and stout, with a massive scapula and coaracoid, and a big keeled breastbone, all of which indicate attachment sites for powerful muscles useful for digging. Interestingly, the hind limbs are also very specialized. They're relatively short compared to the forelimbs, with a low ratio between the femur and tibia lengths, and with short metatarsals. The length indicates that even if this wasn't a fossorial creature, it was probably a quadruped. The hip is especially interesting. The head of the femur, the bit which fits into the hip socket, is at a 135 degree angle to the rest of the bone. This would have given Koreanosaurus a very un-dinosaurian semi-splaying leg posture, similar to burrowing mammals. The authors speculate that it would have used its legs to brace itself inside an incipient burrow while it used its powerful forelimbs to shovel soil.

So, while the team of scientists was unable to locate any nearby fossil burrows big enough to have been made by this (roughly) meter long ornithopod, the skeletal details are more than enough to suggest a digging lifestyle. But it was no dinosaurian mole, as it still had many features in common with terrestrial dinosaurs, like a long neck and (presumably) long, partly stiffened tail. However, we shouldn't be so quick to assign stiffness to the tail just because this is found in other ornithopods. As I reported before, the Australian Leaellynasaura had an unusual, very long, very flexible tail.

Koreanosaurus was found in seaside cliffs of Boseong, on the south coast of Korea. It is the first Korean dinosaur known from good remains. It should be noted that another Korean dinosaur (a theropod) had previously been unofficially named "Koreanosaurus," but as this was a nomen nudum, it's no more a valid scientific name than "Sue," and is rightly ignored.

Brontodiplodocus

Above: "Ah love filter feedin' thorugh mah beak! Om nom nom." Apatosaurus louisae (or not?), photo by Tadek Kurpaski, licensed.

Dan Chure on the DML alerted us to this new, privately published monograph published without peer review (probably?) by an independent fossil digging/selling organization. It concerns a pretty damn remarkable looking bonebed from the lower Morrison Formation with several complete diplodocid specimens of various ages. This line from page 21 pretty much sums it up:

"The traditional approach would have provided us with two new species to add to the Morrison list of sauropods. Instead we employed a novel approach by attempting to fit previously reported Morrison fossils within the context of the A. brontodiplodocus sample. The results are astoundingly radical by comparison with previous studies."

I don't know what to say about this paper. It wouldn't surprise me THAT much if something like this were true but... really? Really guys? Fingers crossed that SV-POW or some some other sauropod experts take a look at this bad boy, though the stigma concerning privately held specimens may simply prompt everyone to ignore it. This is what Mike Taylor suggested on the DML, since he (correctly) pointed out that the hypothesis of the paper (all Morrison diplodocids are congeneric) is essentially unverifiable as long as the specimens are in a private collection and haven't been described in a peer-reviewed paper.

As it was independently published, questions about the newly named taxon's validity have been raised. But, really, is this any different from what Cope and Marsh were doing back in the 19th Century? If anything, cheap and easy publication has simply brought us back to those Wild West days of do-it-yourself science, spurious results and all.

Taxonomy aside, the baleobiological conclusions in this thing are... just... fascinating. and probably will NOT help the author's case.

You can read the pdf here:

Galiano, H. and Albersdorfer, R. (2010). "A new basal diplodocid species, Amphicoelias brontodiplodocus, from the Morrison Formation, Big Horn Basin, Wyoming, with taxonomic reevaluation of Diplodocus, Apatosaurus, and other genera." Dinosauria International, LLC. 44pp.

A Guide To Feather Colors

Above: Restoration of Changchengornis by Matt Martyniuk, all rights reserved. Even when the colors of a prehistoric feathered dinosaur haven't been revealed by studies of feather microstructure, there are ways to infer which colors were and were not likely.

The recent discovery of a fossil penguin from Peru, complete with preserved feathers and melanosomes that reveal their color, prompted me to dive a little deeper into this topic. Keep in mind this is an area I'm still learning about myself, so please feel free to add corrections or keep the discussion going in the comments.

For those of us interested in palaeontography,* the recent work by Jakob Vinther (see original post here) and others on reconstructing the life coloration of prehistoric animals has been some of the most exciting paleontology research of the decade. In the carefree halcyon days before fossil melanosomes were recognized, I and other artists were given free reign over the external appearance of our feathered dinosaurs. But since Vinther's paper, I've been inspired to look into exactly what biological factors go into bird coloration. Needless to say, this is something not a lot of others have probably looked at, as most paleoart follows the old philosophy that when it comes to color, anything goes. Apparently though, this was far from true even before Vinther and his colleagues came along.

* Since this is John Conway's term I reckon I'm stuck using the Queen's preferred spelling, sorta like "pycnofibres". Anyway, that's just a fancy way of saying "paleoart".

There are several processes that add color to the feathers of birds and, presumably, other feathered dinosaurs. At the most basic level, these can be divided into structural color and pigmentation (though sometimes it isn't hat simple, as I'll explain down the page).

Structural Colors
Structural colors come from the actual physical structure of the feather. At the microscopic level, feathers exhibiting structural color have a "foamy" texture of tiny spheres or channels which enclose minute air bubbles. Light scatters through these bubbles in various ways depending on the exact arrangement. The development of these extremely complex structures has recently been covered by Dufresne and colleagues (2009), so you can track down that paper for a technical treatment of structural feather colors.

(Right: Structurally colored blue feathers of a Blue-and-yellow Macaw Ara ararauna, by Jörg Groß, licensed.)

Basically, structural colors can do two things: produce colors not found among the various pigments, and enhance or change pigment colors. For example, among amniotes, there is no such thing as a blue biological pigment. The blue feathers of a bird are produced by scattering due to structural colors. Similarly, iridescence as seen in many birds comes from the feather structure. A bird with bright white or pitch black feathers likely uses structural colors to achieve this effect--without them, these colors would be flatter, duller, and less vivid. Structural coloration can act as a filter, combining with pigments to form new colors. In most birds that have them, green feathers are produced by layering yellow pigmentation nodules over a "blue" underlying structure.

Does it fossilize?: You bet! Iridescent feathers have been reported by Vinther, and it's often apparently to the naked eye alone. There are some stunning examples of iridescent insect fossils out there. Structurally colored feathers have been recognized by a distinct arrangement where a thin layer of densely aligned melanin overlies a looser conglomerate of melanosomes. This can be seen even if the overlying keratin scattering layer has degraded away (Vinther et al. 2008). This kind of structure-via-melanin is also found in the dazzlingly iridescent plumage of hummingbirds (Prum, 2006).

What it means for dinobirds: Blue, green, jet black and bright white can't be present in dinobirds that lack structural color in their feathers. I've said before that structural colors are impossible in the monofilament integument of primitive coelurosaurs. However, I'm not so sure that's true. The main difference between hair and feathers isn't the structure of the filaments, it's the structure of the underlying molecules. Hair is alpha-keratin, a helix-shaped molecule like DNA. beta-keratin, which makes up feathers, has a layered and pleated underlying molecular structure more conducive to structural scattering. So a blue-fuzzed Struthiomimus may be possible. However, in the iridescent fossil feathers studied by Vinther et al. (2008), the structural color was restricted to the barbules, which are not present in many primitive feathered dinosaurs.

Pigments
Most bird colors are due in whole or in part to pigmentation, or lack thereof. There are several different kinds of pigments, with the two most common being melanins and carotenoids.

Melanins are what all the hubbub is about. Not only are these easily identified in fossil feathers, but their shape and concentration can tell you what color they gave their feathers. Melanins are responsible for black (though not deep, solid black, which require an extra push from structural color), gray, and a wide variety of browns through rufous orange colors. Melanins are the main pigment in mammalian hair, so think of the spectrum of mammal colors when imagining what shades are possible with melanin. A lack of melanin will produce white.

(Right: Different types of melanin in the feather of a Zebra Finch Taeniopygia guttata, from Not Exactly Rocket Science/Zhang et al. 2010).

Does it fossilize?: Of course! I've discussed the relevant melanosome papers in the past, posts linked below.

What it means for dinobirds: For carnivorous dinobirds, these are where the action is. Pure carnivores will usually lack the dietary requirements for carotenoids, so structural colors plus melanin are all they've got (and maybe porphyrins, see below). It seems odd that of the three described prehistoric dinobirds with color, they all seem to have the same color palate. Sinosauropteryx (rufous and white), Anchiornis (gray, black, white, brown, and rufous), and now Inkayacu (gray, white, and rufous-brown). These are all carnivorous/fish eating species, so it makes sense that they don't exhibit any more exciting colors. However, it's also possible that we're missing something: In their 2009 Anchiornis paper, Li and colleagues specifically noted that they didn't test for carotenoids. However, I would imagine that given their prior 2008 paper, they did look for structural color or at least iridescence in fossil feathers.

Carotenoids are, by and large, what give birds their characteristically bright colors. The trick is that carotenoids can't be directly synthesized by the body in animals (some can, but there need to be other types of carotenoids present to convert). Carotenoids come almost exclusive from a diet of plants or, secondarily, of things that sequester a lot of carotenoids in their body tissues (like plant-eating invertebrates and some fish). Gulls living near salmon farms have begun shown hints of pink in their feathers: this is because farm-raised salmon are fed artificial carotenoid sources to make their flesh pink, and these are transferred to the birds. The most unusual source of carotenoids, this time among a carnivorous species, is the Egyptian Vulture Neophron percnopterus, which gets its bright yellow facial skin by eating the droppings of ungulates, dropping which yield no significant nutritional value and appear to be eaten only for the carotenoids (McGraw, 2006)! Indeed, while carnivores aren't usually brightly colored, McGraw noted that there may be selective pressures in some species to add weird things to a diet in order to become more colorful.

(Right: Egyptian Vulture, photo by Dezidor, licensed.)

Does it fossilize? Yes, but it looks the same as melanin, and unlike melanin, you can't tell a carotenoid by its shape. According to Li et al. (2009), special chemical tests would have to be run to determine if a melanosome is really a carotenoid, and what color it was.

What it means for dinobirds: Even though we haven't yet identified carotenoids in fossils, we know that they can only be present in animals that are herbivores or feed on herbivorous insects. Scansoriopterygids, for example, could have been brightly colored by carotenoids, since they presumably ate tree-dwelling arthropods. Alvarezsaurids would probably lack carotenoids if they are mainly termites and other social, non-colorful bugs, as has been suggested in the lit. Jeholornis and Jinfengopteryx, two dinobirds with direct evidence of seed eating, are prime candidates for reds, oranges, and yellows (or even greens, with added structural color). Also, keep in mind that red carotenoids from crustaceans, when eaten by birds with otherwise melanin-free feathers, are what give pink wading birds like flamingos their distinctive colors. This is why many artists restore some ctenochasmatid pterosaurs, especially Pterodaustro, as pink (though how all this applies to pycnofibres is still anyone's guess).

(Right: Speculative restoration of Jeholornis prima with red and yellow carotenoid crown by Matt Martyniuk, licensed.)

Carotenoids are often used by modern birds as a sign of fitness when choosing a mate. Because carotenoids have to be eaten, a bird with a poor diet will be drabber than a bird that is very successful at finding food. A flamingo kept in a zoo will turn white if its diet isn't artificially supplemented with red carotenoids.

Carotenoids can also impact the eye color of a bird, as well as beak color and the color of the scales on its feet... even the yellow yolk of a chicken egg is due to carotenoids (some birds use Flavin for yolk color, see below). Keep in mind that adding orange, yellow or green feathers, or red, orange or yellow beaks, implies your dinosaur is eating a diet containing carotenoids.

Porphyrins are perhaps most famous for lending blood its red color and leaves their green (both heme and chlorophyl are porphyrins), but it can also color feathers, adding browns and reds (and green, but only in the turacoverdin pigments found in Turacos). Interestingly, porphyrins may have a role in temperature regulation. In addition to insulating eggs (see below), they are mainly found in the downy feathers of nocturnal birds like owls, and those that are active in colder temperatures.

The blue of American Robin eggs is created by porphyrins, as is most other egg coloration. In fact, some researchers note a correlation between porphyrin in eggshells and nesting behavior. Pure white eggs are only found in birds which nest in shelter like under foliage, and which constantly attend their eggs. Species which leave the eggs partly exposed to the elements have colorful porphyrin-containing shells, possibly because of the supposed temperature regulating effect. Paleoartists might want to consider this when drawing various dinosaur nests.

Does it fossilize?: I'm guessing no, as we're dealing at the molecular level here. However, I wonder if porphyrins could be detected via chemical analysis, like the one used to detect beta keratin in the feathers of Shuvuuia deserti.

(Right: The juvenile Black-shouldered Kite Elanus axillarus uses porphyrins to achieve a red-brown color not found in adults. Photo by Mdk572, licensed.)

What it means for dinobirds: This one is the big question mark. I've never seen references that describe a method to detect porphyrins in fossils. Luckily, they're mainly only brown and dull red, colors that could conceivably be found with melanin alone. If anything, porphyrins give us license to add some extra reddish splashes to purely carnivorous dinobirds, especially those that may have been active at night or in cold climates, like troodontids.

Uncommon pigments: There are a variety of minor pigments that can color a bird's feathers. Pterins are responsible for the yellow, red, white, and orange colors of some bird eyes (in humans, eye color is controlled by melanin; low melanin results in blue eyes, and some babies eyes darken as the melanin levels increase). Flavin pigments cause many egg yolks to be yellow.

(Right: The feathers of a Yellow-headed Amazon Amazona oratrix. Parrots are so stingy with their carotenoids they had to evolve an entirely new pigment to color their feathers. Photo by Rei, licensed.)

Psittacofulvins are found only in (you guessed it) parrots, and create yellows oranges and reds in place of carotenoids, which parrots have evolved to sequester, possibly for nutritional reasons. There are some undescribed pigments known only in penguins that add florescence to their yellow display feathers.

The take-home message:
When you add color to a feathered dinosaur restoration, you're presenting an implicit hypothesis about its diet, lifestyle, and soft tissue anatomy. when doing serious paleoart, keep these constraints in mind, and use them to make your art more interesting and your science more rigorous. Nobody can tell you not to draw a Utahraptor with a bright red face, but if you're trying to make paleontography and not just a bit of fun, why not depict it munching on a big, red fish or a pile of Sauroposeidon poop?

References:
* Dufresne, Eric R., Heeso Noh, Vinodkumar Saranathan, Simon G. J. Mochrie, Hui Cao and Richard O. Prum (2009). "Self-assembly of amorphous biophotonic nanostructures by phase separation." Soft Matter, 5: 1792-179

* McGraw, K.J. and Nogare, M.C. (2004). "Carotenoid pigments and the selectivity of psittacofulvin-based coloration systems in parrots." Comparative Biochemistry and Physiology B, 138: 229–233.

* Li, Q., Gao, K.-Q., Vinther, J., Shawkey, M.D., Clarke, J.A., D'Alba, L., Meng, Q., Briggs, D.E.G. and Prum, R.O. (2009). "Plumage color patterns of an extinct dinosaur." Science, 327(5971): 1369 - 1372

* McGraw, K.J. (2006). "Mechanics of Carotenoid-Based Coloration." Pp. 177-242 in Hill, G.E. and McGraw, K.J. (eds.), Bird coloration, Volume I: Mechanisms and Measurements. Harvard University Press.

* McGraw, K.J. (2006). "Mechanics of Uncommon Colors: Pterins, Porphyrins, and Psittacofluvins." Pp. 354-398 in Hill, G.E. and McGraw, K.J. (eds.), Bird coloration, Volume I: Mechanisms and Measurements. Harvard University Press.

* Prum, R.O. (2006). "Anatomy, Physics, and Evolution of Structural Colors." In Hill, G.E. and McGraw, K.J. (eds.), Bird coloration, Volume I: Mechanisms and Measurements. Harvard University Press.
* Vinther, Jakob, Derek E.G. Briggs, Julia Clarke, Gerald Mayr and Richard O. Prum (2008). "Structural coloration in a fossil feather." Biology Letters, 6(1): 128-131.

* Zhang, F., Kearns, S.L., Orr, P.J., Benton, M.J., Zhou, Z., Johnson, D., Xu, X. and Wang, X. (2010). "Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds." Nature, 463: 1075-1078.

Balaur's Gate

Ok, I know everyone and their moms is going to be posting on this but, as many of you have noted, I'm heavily biased towards maniraptorans and this is one of the coolest of the decade.

Hyperbolic Jurassic Park fanboys, meet Balaur bondoc, the dromaeosaurid with not one, but two sickle claws on each foot.

Above: Boom. From NatGeo.

Note that the two sickle claws are on digits one and two, and digit one is essentially anti-retroverted, pointing forwards as in therizinosaurs. Balaur also has a lot of fusion in the hand, with digit two and three fused together and digit 3 reduced, as in caudipterids. Balaur lived on the island of Hateg in Maastrichtian (latest Cretaceous) Transylvania, a location known for its insular dwarfism among herbivorous dinosaurs, including the dwarf sauropod Magyarosaurus and dwarf hadrosaur Telmatosaurus. While Balaur is about the size of the larger contemporary dromaeosaurs at around 2 meters in length, its unique suite of derived skeletal characters also fits into the "island rule," according to Sues in an accompanying write-up to the official paper. While herbivorous forms tend to "shrink" on islands to conserve resources, predators often grow larger to better exploit the dwarf herbivores, relatives of which would be out of their league elsewhere. A good example of this are the famously small, extinct Stegodon dwarf elephants of Flores (or indeed the apparently dwarf humans, Homo floresiensis), and the contemporary giant monitor lizards like the Komodo dragon. However, no teeth of any carnivore larger than Balaur have been found in the Hateg basin deposits. Teeth are usually the most numerous and obvious indicators of the local carnivore population, so Balaur was probably the largest predator in its ecosystem. This would seem to fit with its stocky build and double sickle claw: here was an animal that truly met the popular image of dromaeosaurs grappling with prey larger than themselves. The extra claws and solid build of Balaur would have come in handy when taking down a hadrosaur or sauropod.

You can read more on this find at National Geographic.

Update: It seems like there's some confusion about the name. Tom Holtz on the DML, and some parts of the above NatGeo article, reported it as Baldaur bondac. Others (and other parts of the linked article) use Balaur bondoc. The later is he correct spelling.

Kayentavenator lives!

Took long enough eh?

Congrats to old forum friend Rob Gay on finally seeing his baby hit print. You may know Rob for his work on cannibalism (or lack thereof) in Coelophysis. But those of you old-guard denizens of paleontology-related forums may know him better as Guy Stabbing a Pineapple. (See portrait to the left: Rob is on the right.)

Rob helped create a very early piece of DinoGoss by leaking his own planned name for this new find on a private forum. Kayentavenator elysiae is named for the Kayenta Formation, where it was found, and for Rob's now-wife. It's a potential basal tetanuran, though some have already cast doubt on that interpretation. I'm still working on getting the paper so details will have to be left to other blogs for now. I'll leave you with this 2005 entry in my Hallucinogene series of comic-style paleo-art depicting Kayentavenator looking over a stylized southwestern landscape.

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.

Raptorex. For serious, that's a real dinosaur now.

Above: Paul Sereno with a model and skull cast of Raptorex, possibly the most ridiculously named dinosaur of all time. Photo from Chicago Tribune by Nancy Stone.

Headline: DeviantArtist Honoured with Dinosaur Name

Well not really, but surely raptorex must be stoked that his (let's face it), fun but pretty ridiculous username is now the name of a real life dinosaur, Raptorex kriegsteini.

The mini-tyrannosaur is from the Yixian ash beds (not the more famous lake sediments that preserve feathers), and is a bit improbable in other ways than its name. It looks like a mini-Tarbosaurus, with short, two-fingered hands and long, running legs, all things expected from a juvenile tyrannosaurid, rather than a (supposed) primitive tyrannosauroid like Dilong or Guanlong. I wonder if this has implications for their position as basal tyrannosaurs--the paper, supposedly released in the online edition of Science today, is nowhere to be found, for my part.

Raptorex also has a sordid past. Apparently, the fossil was smuggled out of China and sold at (where else) the Tuscon fossil show to a private collector for tens of thousands of dollars. The collector, ophthalmologist Henry Kriegstein (whose family name is honored in the specific name of the new dino), had specialists in Utah prep it out of its matrix so he could mount it in his Massachusetts living room. Upon discovering the specimen was not a juvi tarb as advertised, but rather a full-grown individual, Paul Sereno (so that explains the name!) was called in for further advice, and recognized it as an important discovery. Kriegstein soon agreed to relinquish his purchase to science (with a bonus in the form of naming rights, of course. At least he wasn't a big Bambi fan).

In a bit of taxonomic goss, Bill Parker over at Chinleana notes that, as Kriegstein technically named the genus for his parents, not himself (which is frowned upon), the ICZN mandates that the species name needs to be emended to kriegsteinorum, so watch for that change in the future, likely published by George Olshevsky or a similar stickler for proper Latin.

And, of course, Jack Horner has weighed in. In an email to Wired.com, Horner explained that he thinks the small, fleet-footed Raptorex, because it has the same body plan as larger tyrannosaurs, somehow proves that tyrannosaurs evolved into pure scavengers early on, and that the authors are jumping to conclusions in thinking that long, speed-designed legs somehow imply "predator." Keep on keepin' on, Horner.

Oh Giraffatitan, where art thou?

Above: Skull of Brachiosaurus altithorax (right, from Carpenter & Tidwell, 1998) and "B." brancai (left, by Gunner Rias, licensed).

A curious bit of goss, and potential drama?, teased out Mike Taylor and crew at SV-POW.

In recent posts about a new brachiosaurid announced last week, Qiaowanlong (or is it a brachiosaurid? See SV-POW for in-depth coverage), Mike Taylor consistently reffers to the genus "Brachiosaurus" brancai.

The goss stems form use of the quotes. As we all know, when discussing scientific names, the genus and species are always put in italics. The exception to this are nomina nuda, which are names not properly described or coined. Another exception is when a genus and species combo is found to be invalid for whatever reason. For example, the name Ingenia, for an oviraptorid, is preoccupied and has not yet been renamed. But the species name yanshini is still valid. So, when we talk about this species, we might write it as "Ingenia" yanshini to indicate that the genus name is going to change.

Similarly, this same notation is used for species previously assigned to one genus but are no longer considered related to that genus' type, and are pending reclassification under a new genus name. For example, the species "Dilophosaurus" sinensis is probably not closely related to Dilophosaurus wetherilli, so it gets quotes until a replacement name is chosen. This is also the current situation with "Brachiosaurus" brancai. Many people have suspected that this African sauropod is not the closest relative of the North american type species, Brachiosaurus altithorax, given that a B. altithorax skull has been identified that differs from the African species (see photos above), among other differences in skeletal shape and proportion.

So what's wrong with using quotes when talking about "B." brancai? The African version has already been given a new name! In a 1988 paper, Greg Paul coined the name Giraffatitan for a distinct "subgenus" containing the African species. This was later formalized as a genus name, I believe by Olshevsky in his Mesozoic Meanderings, but correct me if I'm wrong.

So wy write "Brachiosaurus" brancai when, if considering this a separate genus, it should rightly be Giraffatitan brancai? I asked Mike about it, and apparently a paper explaining will be coming out in a week or so. The goss at SV-POW for quite some time has been that the SV-POWsketeers favor a separate genus for "B." brancai, but the assumption was always that this would be Giraffatitan. Mike is playing coy for now--is it simply that the authors don't like the name Giraffatitan? Mike says this is the only paper he's seen in which the acknowledgments contain an apology, so it sure sounds like that is close to the truth...

But a valid name can't be rejected simply because an author doesn't like the sound of it. It would have to be argued away on technical grounds. Is the fact that Giraffatitan was originally a subgenus, not a proper genus, coming into play and allowing Giraffatitan to be re-named? Is the apology directed towards George Olshevsky (maybe the authors don't consider his self-publications valid?). I don't know the ins and outs of priority when it comes to subgenera and subspecies. But we'll know shortly...

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.

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.

Empire of the Shark Teeth

Today saw the publication online of a paper finally re-describing Chilantaisaurus maortuensis, a theropod from mid-Cretaceous China. This species was assigned to the genus Chilantaisaurus in 1964 by Hu, and has been all over the map since then. Authors have variously considered it a tyrannosaur, an allosaur (linking allosaurs and tyrannosaurs, actually), and even a maniraptoran coelurosaur. While the exact identity of Chilantaisaurus proper remains a bit uncertain (latest word is that it may be a spinosaur), the new paper is pretty sure of its conclusion: C. maortuensis isn't Chilantaisaurus at all, but the first known Asian carcharodontosaur!

As the story goes (and as Steve Brusatte reported in a guest post at Archosaur Musings), during some down time in Beijing, and while working on his PhD thesis on tyrannosaurs, he got wind of this possibly tyrannosaurian specimen at a Beijing museum. It was immediately apparent to his eye that this was not a tyrannosaur, but a carch, which he and his colleagues finally renamed as Shaochilong maortuensis.

Not only is this the first Asian carch, but it fills a glaring hole in the Asian fossil record. Basal tetanurans dominated the large carnivore roles of Asia in the Jurassic, and tyrannosaurs like Tarbosaurus and Alioramus dominated in the Late Cretaceous. But what was going on in the mean time? Apparently, carcharodontosaurs, which were previously only known from the Americas, Europe, and Africa. This means that tyrannosaurs didn't arrive on the scene until the very end of the Cretaceous, much later than previously thought. Part of this has to do with the dating of the Ulansuhai Formation where Shaochilong was found. Previously thought to be Aptian-Albian in age, dating of underlying rocks shows that it must be at least Turonian (92 Ma), pushing the arrival of tyrannosaurs well into the Late Cretaceous.

So, did tyrannosaurs arise in Asia, migrate to North America, then migrate back to dominate Asia in the LK? We'll need more fossils to know the whole story. Given the Cretaceous age of Shaochilong, we can't be sure whether carcharodontosaurs originated in Asia or migrated there from Europe, Africa, or North America, all of which have earlier carch species. But, as a special bonus as Steve points out on the blog linked above, this presents the first evidence that carcharodontosaurs could have battled ceratopsoids (in the form of Turanoceratops), horning in (haha, get it?) even further on traditional tyrannosaur territory.

Speaking of Asian tyrannosaurs, have you heard about that gorgeous complete Alioramus skull recently auctioned off to a private collector and thus lost to science for probably ever? Well don't cry too much over it. More to come...

[Image: Chilantaisaurus from here.]

Thai One On

Here's a blast from the past:
If you follow ostrich dinosaurs (and really, who doesn't?), you may have heard of a genus called "Ginnareemimus." This name has been popping up on genus lists enclosed in quotation marks for years. That's because, while the remains were found in Thailand over a decade ago, they have never been described and the name has only cropped up in a caption in some obscure journal published in 2000.

Well, this month the paper finally came out, only the name is... wait for it... Kinnareemimus! Subtle change to avoid (or because of) Jim Jenson's fate (see previous post for more on that)? Nah, some intrepid poster to the DML found the spelling "Kinnareemimus" in a Thai language journal article, from 1998 or 1999, so "Ginnareemimus" may just have been a typo all along (EDIT: Or, as mentioned in the comments, an alternate transliteration of Thai characters). The Thai article, if you're curious, can be downloaded here as a pdf. The crack team of dino fans at Wikipedia have already been able to translate the relevent bits. The journal is "Reports of the Annual Meeting of the Geology-something" (hey I said "crack team of dino fans" not "linguists") and the author appears to be Sasithorn Kamsupha.

So that's the saga of Ginnaree, err, Kinnareemimus. For all that, the remains aren't anything spectacular, just post-cranial bits including a severely pinched arctometatarsalian foot (i.e., it was probably a good runner). The authors found it to be more advanced within ornithomimosaurs than Harpymimus due to this, though its early Cretaceous age would make it the oldest known ornithomimosaur. However, Mickey Mortimer reckons it's not diagnostic enough of that group and might be a different kind of coelurosaur entirely. Still, it is kinda cool to get more of the Thai dinosaur record, which until now has consisted mostly of the possible spinosaur Siamosaurus and some tiny little eggs with an embryo that must have been laid by an unknown scansoriopterygid or something equally small in size.

[The image at left shows the metatarsals of Kinnareemimus khonkaenensis, from Buffetaut et al. 2009 and is copyright The Geological Society of London. Check out the severely pinched middle MT.]

The Story of Lori

The origin of birds has always been a dicey subject. If you define "bird" as the clade including Archaeopteryx and modern species, as most paleonotolgists currently do, then the Late Jurassic Archaeopteryx ("Archie"--all the really cool and/or important fossils need a good nickname!) has always been the first bird, and because of the definition, probably always will be unless some of it's very close cousins are ever unearthed. The problem is that the closest supposed relatives of birds, the deinonychosaurs ("raptors" and relatives) should naturally pre-date Archie, if they're generally ancestral to it. Unfortunately, fossils from this group come almost exclusively from the Cretaceous period, well after Archie went extinct. The dwindling bird-are-not-dinosaurs crowd (BANDits) has historically seized on this as an attempted "gotcha" to rational human beings. After all, if birds evolved from dinosaurs, how come all the bird-like dinosaurs lived after the first birds?

It's true that the fossil record of pre-Archie maniraptorans is pretty slim, but paleontologists infer they must exist based on ghost lineages (see previous post on this topic). In that previous post, I mentioned the case of "Lori", the pre-publication nickname Scott Hartman has given to his (wait for it) Late Jurassic troodontid! Found in the Morrison Formation (not exactly known for its small dinosaur preservation, its more of an 8-foot vertebrae kinda spot), Lori would have lived at roughly the same time as Archaeopteryx, not early enough to be ancestral, but still enough to shoot down the old ghost lineage problem pretty thoroughly.

Scott (pic at right) first started discussing this find in more private venues like Gondolend, but it's safe to say the goss has spread far and wide in the years since then. He's provided some of us with an exclusive sneak peak at his own skeletals (he's pretty much a skeletal illustration guru, check out his awesome Web site), but the years have gone by and Lori has still not seen print nor a proper name.

Well, inside sources have sent the goss stunning evidence that a name has indeed been chosen, and possibly, that an official publication is getting close (it appears to be a cladogram for the paper, with the old Lori skeletal clearly labelled with its shiny new genus name). Far be it from me to leak the name pre-pub and risk creating sticky nomen nudum situations (I'm sure Scott doesn't envy Jim Jensen), but rest assured it preserves a traditional troodontid naming convention, as well as bearing some similarity to a recent dromaeosaurid name.

I wanted to post some of the great reconstructions of Lori that have already been produced and shared by members of the private boards where it's a well-known subject, but I can't seem to find any online. Scott is a pretty active member of these communities so it's only natural people are showing his find a little more discretion than would be normal for exciting, unpublished dinosaurs. I feel the same way, so the censored clipping of my source is all you're getting out of me. I'm sure a 3-year backlog of killer illustrations will appear out of the woodwork once it's officially published (didn't we even do a Lori draw-off at some point?) so as Tom Holtz would say, W4TP...

(pic above right: Jim Jensen with his Ultrasauros. He probably would have preferred to use a 'u' at the end there instead of an 'o', but the goss got a little out of hand).

Not Deinocheirus, but still pretty cool

Along with Xiongguanlong, another new theropod was announced today in Proceedings B: A giant ornithomimosaur!

(not Deinocheirus).

No, it's not the quasi-mythical giant-armed wonder, but it's still a pretty big ornithomime. Named Beishanlong grandis, is not only big, but fairly primitive as ornithomimes go. It's similar to Harpymimus, though without a skull, we can't tell whether or not it had teeth and to what extent. Clues from the post-cranial skeleton, however, place it in between Shenzhousaurus and Garudamimus. This is pretty interesting as it shows that ornithomimids evolved very large size at least three times (and depending on where Deinocheirus falls out, maybe four). Other large ornithomimes include Gallimimus bullatus from Mongolia, and Struthiomimus sedens from Canada. Beishanlong was larger than both of these, weighing in at 626 kg compared to 440 kg for Gallimimus. By my reckoning that makes it the largest ornithomimosaur known (except, of course, big D.).

Image here is from the FMNH press kit.