There are green furry dilophosaurs now?

What a nice model. It's a shame about the bunny hands. I dunno why 95% of modelmakers still get the whole wrist rotation thing wrong.

Hands aside that is one awesome looking Dilophosaur. I want to pet him.

Karl: They think it looks better. It's an asthetic choice they make.

No neck frill and poison sacks? For shame. Neat lookin' though

They think it looks better.

The palms facing each other would look like it's going to get you. That would be a much better aesthetic choice⦠apart from the whole ripping-bones-out-of-joints issue. No, they did it because they don't know better. That's why.

BTW, why does every artist seem to believe that feathers are somehow incapable of growing on snouts and must be replaced by scales when there's no beak? Why? Why?

There's even counterevidence in the form of Eoenantiornis.

Hold fire on this everyone. The model was created in 1997: it is NOT new. Having said all that, please stay tuned...

I wonder if this is in any way related to that imprint made by a sitting Dilophosaurus (or some similar creature) that is said to show traces of feathery integument. IIRC, the last word was that the traces were not made by feathers...

David, personally I draw them like that because it seems like feathers would get gunked up by dried blood, but I admit that's purely an aesthetic choice.

That's an adorably cuddly dino, though.

I don't think that it looks very green.

Liar.....

I didn't think that was a model when i first looked at it - i thought it was CGI, and presumably from either an upcoming episode of Primeval or one of those films like "Night at the Museum". If it's a model, it's an impressive one. Looks more black and white than green tho...

Ok ok, on the colour: (1) this is a scan of a print-out of a scan, (2) my colour vision is poor and, while I can't _see_ that it's green I 'know' that it's green.

it seems like feathers would get gunked up by dried blood

More so than hair on mammalian snouts?

"More so than hair on mammalian snouts?"

I would think so, since feathers have more surface area than fur.

I think the main reason why many artists like to depict the snouts of feathered dinosaurs naked is too illustrate their relationship with their descendants, the birds.

Also, vultures have bare heads for this reason (both New and Old World vulture families), and some other birds of prey have bare facial skin (caracara, secretarybird). Totally bare heads evolved at least twice, and so did just the facial skin -- so it seems pretty reasonable.

There appears to be some sort of skeletal rhino in the back left of the photo,but it doesn't look like an actual rhino head so much as some vaguely steam-punky model.

Anyone know what that is?

"Dave" has feathers on his snout, and everyone's seen that by now, so there's no reason why that shouldn't be reflected in the art.

[from Darren; sorry, delayed by spam filter]

Appears to be the same model as this one:

http://commons.wikimedia.org/wiki/File:Dilophosaurus_wetherilli_3.jpg

http://commons.wikimedia.org/wiki/File:Dilophosaurus_wetherilli_1.jpg

http://commons.wikimedia.org/wiki/File:Dilophosaurus_wetherilli_4.jpg

http://commons.wikimedia.org/wiki/File:Dilophosaurus_wetherilli_2.jpg

With reference to comment 13, it now seems that the short feathers/naked skin on vulture heads and necks are more to do with thermoregulation than messy feeding, see Ward et al. (2008). However, I still think it likely that feathered theropods had reduced/absent feathering on the snout: there's evidence for closely appressed skin and/or rhamphothecae in these areas, plus there's the fact that many basal birds (like ratites) have thinly feathered or bare patches anterior to the eyes, plus it looks less stupid :)

And (comment 4) Eoenantiornis doesn't demonstrate anything either way: like so many birds and mammals with preserved feathers/fur, it's surrounded by a halo of fuzz. All this means is that the integument was sloughing off the body during decomposition: it does not give you a reliable guide to the position of the feathering in life. The skull is also disarticulated, which doesn't help.

Ward, J., McCafferty, D. C. Houston, D. C. & Ruxton, G. D. 2008. Why do vultures have bald heads? The role of postural adjustment and bare skin areas in thermoregulation. Journal of Thermal Biology 33, 168-173.

Why do vultures have such different thermoregulation needs than other birds of similar size and soaring habits?

Speaking of vultures, red-headed turkey vultures in northern California seem especially curious about the sound of rocket balloons, circling low over where they're released. I couldn't tell whether they thought they sounded like another vulture, or dinner.

Seeing as we have a Dilophosaurus here I hope I can be forgiven for asking if anyone knows if any work is being done on the "Dilophosaurus" sinensis specimen(s?) that seem to have been around for ages and seem to be need a new generic name.
Going even further out on a limb is the "Szechuanosaurus" campi specimen ever likely to be renamed/described either?

"What a nice model. It's a shame about the bunny hands. I dunno why 95% of modelmakers still get the whole wrist rotation thing wrong."

I don't beleive that theropod hands wre "locked" in the medially-facing palms position. Ornithomimosaurs could cross their radiae/ulnae and thus pronate the hands. There is an articulated specimen of Ornithomimus (=Struthiomimus) altus that shows the right radius and ulna crossed with the hand pronated. Also, in the complete description of Sinornithomimus dongi, the provided photos show the arms of several of the specimens with pronated hands and strongly crossed radiae/ulnae, with all joints fully articulated. Theropods (or at least ornithomimosaurs) could assume the "bunny hand" position, even if the "bird position" was the natural everyday pose.

References:

Kobayashi, Y., Lü, J.âC., Azuma, Y., Dong, Z.âM., and Barsbold, R. (2001) Bonebed of a new gastrolithâbearing ornithomimid dinosaur from the Upper Cretaceous Ulansuhai Formation of Nei Mongol Autonomous Region, China. Journal of Vertebrate Paleontology 21 (Supplement to 3): 68â69.

Osborn, Henry Fairfield (1917). Skeletal adaptations of Ornitholestes, Struthiomimus, Tyrannosaurus. Bulletin of the American Museum of Natural History 35: 733â771.

1997, Darren?! Now the suspense is REALLY getting to me.

A redescription of "Dilophosaurus" sinensis is in preparation... wait for the paper.

Dilophosaurus sinensis: its placement in Dilophosaurus may not be so daft after all. See Adam Yates's article here.

And - - why do vultures need to worry about thermoregulation more than other big soaring birds? Unlike other big birds, vultures move regularly and rapidly from very high altitudes to the ground, thus experiencing fluctuations of something like 70 deg C. Cameron (= Lord Geekington) might be able to say more: he's written a lot about vultures lately.

>>experiencing fluctuations of something like 70 deg C.

Wow... I always thought vultures' ability to survive (and often even kill by digesting) disease germs in their food was impressive - but I never knew about that!

Darren:

why do vultures need to worry about thermoregulation more than other big soaring birds? Unlike other big birds, vultures move regularly and rapidly from very high altitudes to the ground, thus experiencing fluctuations of something like 70 deg

That may explain the vultures and the condors, but what about the other big, bald-headed birds, notably the storks? The marabou and the adjutant storks Leptoptilos, the jabiru Jabiru mycteria and the wood stork Mycteria americana are all bald. If thermoregulation is the main explanation, then why don't other large, tropical/semi-tropical storks (e.g., the Ephippiorhynchus species) have equally unfeathered heads and necks?

Dartian: no-one said that what goes for vultures has to go for all other birds too (indeed, naked facial patches in some birds have been linked to a role in visual display). Read Ward et al. (2008).

Darren:

no-one said that what goes for vultures has to go for all other birds too

No, and I didn't suggest that either, I was just thinking out loud. As for Ward et al. (2008); unless I missed something, they say nothing at all about storks specifically. That seems to me a surprising omission in this context, considering the scavenging habits of the Leptoptilos species. (After all, isn't the standard textbook explanation for the bald head of the marabou stork the same as that for the vultures?) On page 172, the authors do say that

It is notable that, apart from vultures, many other large birds which live in tropical conditions, may face extreme heat gain from solar and thermal radiation, also show large areas of bare skin on the head, neck and legs: e.g. ostriches Struthio camelusm [sic], emus Dromaius novaehollandiae, cassowaries Casuarius casuarius, hoatzin Opistocomus hoazin, turkeys and secretary birds Sagittarius serpentarius. In many bird groups, the skin surface area is often increased by elaborate wattles or skin folds: e.g. turkeys, macaws and guans. Whilst these are often assumed to have evolved due to sexual selection, it is notable that in many bird groups such as parrots, plovers and starlings it is only the largest species which tend to show these increased bare skin areas (P. Ward pers. com.), although we know of no study that has investigated this across taxonomic groups.

(Emphasis mine.)

In other words, Ward et al. do at least hint at thermoregulation being a more generally applicable potential explanation for avian bald-headed-ness. So my question - which perhaps needs to be re-phrased - remains: why do some large tropical storks (e.g., marabou, jabiru) have lost their head and neck plumage when other equally large or even larger ones (e.g., saddle-billed stork) have retained theirs? If there are some ecological and/or behavioural factors at play here, they are not immidiately obvious (not to me, anyway).

there's evidence for closely appressed skin and/or rhamphothecae in these areas,

Like what?

plus it looks less stupid :)

IMNSHO it looks a lot more stupid. It looks like someone tried to simulate a beak and didn't understand that scales aren't the same thing as a beak, and further that feathers go all the way to the beak in most birds.

I don't beleive that theropod hands wre "locked" in the medially-facing palms position. Ornithomimosaurs could cross their radiae/ulnae and thus pronate the hands.

Interesting. If you have any pictures of ornithomimosaur forearms, please share! (I'll check out the description of Sinornithosaurus; what you cited is not the description, it's the abstract of the talk that announced the discovery at an SVP meeting several years earlier.)

In all other theropods I've seen, though, it's not possible without ripping joints apart or breaking bones. There are detailed descriptions of the forelimbs (and biomechanics thereof) of Deinonychus and Allosaurus, for instance.

I'm sure it varied across taxa, but as mentioned above, the Dave specimen clearly shows feathers ending only slightly posterior to the naris. The feathers here don't look halo-like or displaced to me.

http://www.azhdarcho.com/sinornith_head_feathers.png

I think the main mistake artists make is in conforming to the style invented by Greg Paul, with feathers invariably ending just before the aof (which is the case again in the dilophosaur model).

Some coelurosaurs seem to have feathers along most of the snout (Sinornithosaurus), some seem to have bald faces (Beipiaosaurus), some unknown (The preparators stopped prepping just before the aof in Sinosauropteryx so the true extent is unknown... another GSP influence?)

"Interesting. If you have any pictures of ornithomimosaur forearms, please share!"

Sharing.

In this one, the right arm is not entirely out of the matrix, but the hand is certainly pronated and the radius and ulna seem to be crossed (or would be if we could see the whole thing). Now, I'm basing my assertions on much more than this mind you, but it's all I got right now. If I recover the pics I lost while debugging my computer, I'll share them.

"(I'll check out the description of Sinornithosaurus; what you cited is not the description, it's the abstract of the talk that announced the discovery at an SVP meeting several years earlier.)"

Ooops, my bad. I copy-pasted the wrong citation! (That's what you get for being lazy...)

"In all other theropods I've seen, though, it's not possible without ripping joints apart or breaking bones. There are detailed descriptions of the forelimbs (and biomechanics thereof) of Deinonychus and Allosaurus, for instance."

Yeah, most theropods probably could not cross the radius and ulna. They could pronate the hands, but only by splaying out the humerus.

However, Ken Carpenter showed that Deinonychus could actually pronate the hand without crossing the radius/ulna or abducting the humerus from the body. The pronation involved the wrist only. Pretty cool stuff. (Note: If Ken's work has been disproved/rebutted, please let me know!)

References:

Carpenter, K. (2002). Forelimb biomechanics of nonavian theropod dinosaurs in predation. Senckenbergiana Lethaea 82: 59â76.

[note from Darren: please embed links with html if possible; the formatting gets screwed up otherwise (the urls often exceed column width)]

Oh, and here's the PDF of Carpenter (20020, just in case you don't have it.

Re: evidence for rhamphothecae/tightly appressed skin on snouts of coelurosaurs (see comment 28 and previous)... the pitted surface texture on the maxillae and other facial bones of Sinornithosaurus, the anastomosing channels preserved on the facial bones of some troodontids and ostrich dinosaurs, and the surface texture of the premaxillae and dentaries in oviraptorosaurs, therizinosaurs and others suggest tightly appressed facial skin and/or rhamphothecae. 'Dave' seems to have integument preserved along the dorsal midline of the snout; it does not show that feathering was present on the sides of the snout, and integumentary structures are also lacking from the sides of the snout of the Sinosauropteryx specimens - this despite the fact that NIGP 127587 at least has structures preserved across much of the back of the skull, including adjacent to the quadrate, paroccipital process, articular and back of mandible.

At the moment, I think that snouts were indeed partly (note: partly) unfeathered in coelurosaurs, but this is a hypothesis and it would only be right to doubt it.

And having looked in close detail at ornithomimosaur forelimbs while pondering the possibility of pronation, I don't think that they could do it.

"[note from Darren: please embed links with html if possible; the formatting gets screwed up otherwise (the urls often exceed column width)]"

Sure, no problem.

"Re: evidence for rhamphothecae/tightly appressed skin on snouts of coelurosaurs (see comment 28 and previous)... the pitted surface texture on the maxillae and other facial bones of Sinornithosaurus, the anastomosing channels preserved on the facial bones of some troodontids and ostrich dinosaurs, and the surface texture of the premaxillae and dentaries in oviraptorosaurs, therizinosaurs and others suggest tightly appressed facial skin and/or rhamphothecae."

True. I'd say your hypothesis that the snouts of coelurosaurs were partly unfeathered is pretty well grounded.

And having looked over the skulls of Allosaurus and Velociraptor in detail, I'd say there is also significant evidence for some sort of squamate-like "lip" structures on theropods - despite the common paleoart convention to restore the teeth as "naked" like those of crocodilians.

"'Dave' seems to have integument preserved along the dorsal midline of the snout; it does not show that feathering was present on the sides of the snout"

Really? It looks like there's some kind of integument preserved inside the AOF in the slab figured in the paper. And isn't the skull split down the middle anyway, so we're looking at the inside, or am I misinterpreting how the slabs are separated?

I wonder why we so seldom see countershading (light-colored undersides) in reconstructed animal colors. It's so common as basic concealment, it ought to be the "best guess" for just about everything air-breathing and most shallow-water fishes.

Armadillos, which burrow into or under large carcases, have almost no fur, and people I know have seen vultures thrusting their heads up the anus of a dead animal, so I just assumed we had bald being easier to clean. I was surprised to find that storks had bald patches, too, although the "bald" is usually a small amount of red skin. Of course, the bald patches could be good for more than one thing, e.g. handy for eating / good for keeping cool or signalling or vice versa.

Monado:

I was surprised to find that storks had bald patches, too, although the "bald" is usually a small amount of red skin.

In this South American jabiru Jabiru mycteria, for instance, the naked patch is neither small nor (wholly) red.

[from Darren: delayed by spam-filter]

While I'm at it... An ad hoc list of other "bald" birds, in addition to those already mentioned in comments #25 and #27:

-The one African and the two Asian species of Mycteria storks have naked, red-skinned faces.

-Some ibises (notably Therskiornis, which includes the African sacred ibis T. aethiopicus and its kin) and spoonbills have bald heads/necks/faces.

-Most cranes have conspicious bald patches on their heads - these can be rather extensive, as in this white-naped crane Grus vipio. These bald spots are found both in tropical and in non-tropical (and even in sub-arctic) crane species.

-Among galliforms, turkeys, guineafowl, the Australian brush turkey Alectoris lathami (which, of course, is a megapode and not a turkey) and some pheasants (notably the argus pheasant Argusianus) have partially or wholly naked heads.

-Ground hornbills, as all regular readers of Tet Zoo know, have large unfeathered patches on their heads and necks.

-Towards the end of that long Limusaurus thread here on Tet Zoo last summer, I and a few others mentioned a number of passerine species with extensive unfeathered patches on their heads.

-And, of course, many more birds than can/need to be mentioned have smaller naked patches around their eyes or at the base of their bills, or have unfeathered wattles or throat pouches.

David, don't think I'm unaware of that. As soon as I hit post I knew someone would bring up that point.

Then again, mammal predators mostly have short, fine facial hair on the snout, the next best thing to bare skin. Maybe it's more difficult for mammals to have evolved a gene to shut off hair growth on the snout alone without also losing it in other places (from the way hair comes in on embryonic puppies, I'm guessing they'd also lack hair on the paws and underside) where they'd need it. Mammals would need to shut down hair production (after passing through stages as small, all-furry insectivores), whereas dinosaurs would be turning it on - I'm probably not explaining this well. Mammals might indeed be better off with hairless snouts. Look how disgustingly fetid long hair on the muzzle gets with long-furred dogs. That they have hair there at all may just be one of those 'good enough, but not perfect' things.

Is there any info on how long and flexible dino tongues might have been? That might have been a factor in their ability to groom themselves.

"Is there any info on how long and flexible dino tongues might have been?"

The tongues of dinosaurs were like those of crocs, lizards, and birds - stiff and fleshy. Exeptions would be the fat, muscular, tortoise-like toungues of ceratopsians and iguanodontians, and the darting anteater-like toungues of ankylosaurs.

"That might have been a factor in their ability to groom themselves."

Only feathered dinosaurs would have needed to groom themselves and they would have done this by preening like birds, most certainly not by licking themselves like cats.

Mammals would need to shut down hair production (after passing through stages as small, all-furry insectivores), whereas dinosaurs would be turning it on - I'm probably not explaining this well.

You are explaining it well; I'm just not sure if you're right. :-)

darting anteater-like toungues of ankylosaurs

???

"darting anteater-like toungues of ankylosaurs

???"

Maryanska, T. 1977. Ankylosauridae (Dinosauria) from Mongolia. Palaeontol. Pol. 37: 85 - 151.

Yeah. I've never understood where MaryaÅska got the idea that herbivores with tiny (but fully enameled and long-rooted and worn!) teeth are somehow impossible. I've also never understood where she got the idea to ignore that broad beak.

I haven't asked her, but I bet she doesn't believe that herself anymore.