July 10 , 2016

by Duane Nash

Skeksis (singular and plural) Antagonists from Jim Henson's 1982 film The Dark Crystal. Concept artist Brian Froud conceived as "part reptile, part predatory bird, part dragon".

Appearance (from wikipedia):

The Skeksis are tall bipeds combining avian and reptilian characteristics. They wear elaborate but threadbare robes of lace, velvet, and brocade which apparently keep the skeksis' constantly decomposing bodies intact and make them look larger and more intimidating. Their heads are beaked like a vulture's but simultaneously sporting curved fangs. They have enlarged bellies and long reptilian tails, as well as curved quills on their backs. They have two pairs of arms but only one functional the other reduced... despite their frail appearance they are powerful creatures.

It should be no great revelation that this post will serve as the most subjective and probably therefore most controversial in this series. Experience in electing novel soft tissue structures in T. rex and Smilodon has taught me that much...

It should also come as no surprise to readers that I am no great fan of dapper dromaeosaurids - a look that has come into vogue in recent years.

How did this look evolve? It is not too hard to trace a lineage of inspiration from Gregory S. Paul who retooled dromaeosaurids as feathered and decidedly bird like to John Conway who took a lot from Paul's look and made these animals even more birdy to Emily Willoughby one of the leading contemporary dromaeosaurid paleoartists whom has greatly inspired the dominant ground hawk look.

A commonality in all three of these artist's look is the clean cut juncture on the facial region separating feathered from non-feathered parts. This clean cut visage, almost always combined with an attractive feathery countenance lifted from a modern bird of prey (red tailed hawks and peregrine falcons are common suspects). A look that has been consistently aped and imbued itself into the dominate appearance of these animals in paleoart.

Gregory S. Paul hypothesized a "proto-beak" around the mouth of his dromaeosaurids and other maniraptorans. Basically an area free of integument and slightly cornified. See here and here. Essentially it was an inference made on the perceived - and correct - relatedness to modern birds.

The problem is that we do not have any evidence of a proto-beak in dromaeosaurids or any predatory maniraptorans at all for that matter. Nothing, nada, nunca. Nor do we have any evidence of the type of clean cut juncture depicted by Conway & Willoughby which has influenced current depictions.

Mathew Martyniuk discussed this seldom mentioned meme in an excellent post The First Feathered Dinosaurs (In Art):

"Paul essentially invented the latter meme (half feathered faces) in an attempt to make his theropods look more bird like (by suggesting a sort of beak), and while this was his own speculation, many later artists ran with it, including in early drawings of Sinosauropteryx."

While Conway's and Willoughby's renderings do not necessarily imply the sort of "proto-beak" structure that Paul hypothesized both of these artists kept the clean cut dapper "featherline" which Paul used demarcating a solid break from the feathered region of the head and the bitey jaw region. This trope has imbued itself into countless depictions of dromaeosaurids since, to the point that it is in many ways the de-facto way to depict the heads of these animals in many people's minds. Just remember - if you chose to depict dromaesaurs this way you are merely inheriting a trope that has no basis in evidence of either a proto-beak or a defined juncture between feathers and non-feathery covering on the heads of these animals. Not saying it is impossible that some dromies did not have such a juncture just that it is based on a hypothesis of a proto-beak which has not been borne out evidence wise but remains with us as an attractive speculation.

Indeed feathers covering the entirety of the head (except maybe the nostrils left open ala mammal noses) is what might be the more parsimonious interpretation as suggested by Sinornithosaurus and Zhenyuanlong. With no evidence of a proto-beak in these animals there is no reason to assume feathers did not go all the way to the oral region.

This actually opens the doors for a lot more play as goes the facial appearance of these animals. As it should be, because we should not expect a lineage of animals that evolved and lived in diverse conditions for over 100 million years to all look a like. Everywhere from fully feathered to yes, naked skin, or in between.

You know I loves me some vulturine inspired dromies. I really like how the tail display, arm-wings, contrasting white/dark colors, and jaw are all used together in threat display. As I argued in my last post there is at least as much - if not more - to glean from vultures as analogues to many dromaeosaurids as there is from raptorial accipterids. Also note that the feathers are plumaceous like in an ostrich not the stiff venaceous feathers we have often seen in paleoart.

I am a little surprised at the blowback I receive in electing naked headed, gnarly faced, caruncle ridden dromaeosaurs as a likely look for many of these animals. But why not? I am fully willing to concede my bias for ugly, uncouth, goblin looking critters duh.... I wear my inspirations on my sleeves baked in bong hit residue, blotter acid, splatter films, and swedish death metal. That does not mean I am in fact wholly wrong. More to the point, I would suggest others are less open than I am in conceding their own biases. Do I suspect that some people really have a penchant for the attractive, elegant, and refined look of dromaeosaurids that has come into vogue? Essentially a grounded peregrine falcon or red-tailed hawk? That such elegant, attractive, and appealing visages have a conscious or subconscious appeal to many of the artists and fans who endorse such a look even going so far as to assert "this is how they looked, period". Wrapped up in a nice little bow because of the RPR hypothesis - which as I have mentioned again and again Fowler stated specifically dromaeosaurids were not as strong graspers as modern accipterids - fueling the typological thinking to dress up a Deinonychus as a grounded red-tailed hawk? And that people who have such a definite and emotional attachment to such a look would be dismissive and threatened by my interpretation asserting a more vulturine influence? Nah, that never could happen snark, snark...

Just to keep in mind I am getting my inspiration from birds too, and not all birds are concerned with looking regal and elegant...

For every grey-crowned crane I can raise you a helmeted hornbill;

Truth is we do not have a lot to go on in terms of facial appearance of the medium to larger dromaeosaurids that lived in open and/or hot & arid environments. Painting with broad strokes I would lean more towards fully feathered heads for smaller dromies/small game specialists especially in closed temperate environments - essentially Liaoning. But for dromies that were out in the open, fighting and competing over carcasses, going toe to toe with carchs, abelisaurids, and tyrant lizards, in hot and/or arid environs a naked head with fleshy adornments is a defensible position. Many of the more famous dromies such as Velociraptor, Deinonychus, Utahraptor, and Dakotaraptor fall in this category.

Large exposed patches of skin on the head and neck can serve a thermoregulatory function and also social signaling. Blood can be flushed into caruncles, necks flaps, and other skin adornments in colorful threat dominance displays as occurs in condors.

Whenever I talk about fleshy skin adornments on theropods - including large lips - there is a consistent critique that people chime in with: "but these areas would be targets for biting by conspecifics and get snipped right off!?!"

Let me offer some rebuttals (takes a deep breath):

1) Losing a chunk or flap of skin is still preferable to losing an eye or getting a bite on the neck or vertebral column which could have fatal results. That being said skin can be amazingly strong, elastic, and (best of all) it grows back. Hyenas, bears, badgers and yes vultures are often noted for the strong and elastic properties of their skin that allow them to suffer abuse that would seriously lacerate lesser skinned animals. Theropods - and especially combative dromies - had all the reason to not only have such thick and elastic skin but abundant skin derived display structures. Just look at the skull of a male andean condor, there is no tell tale osteological signifier that it looked like the mug above.

2) Which brings me to my next point. We already have compelling and irrefutable osteological evidence of display structures on other theropod skulls (Dilophosaurus, Guanlong, Monolophosaurus etc. etc.). That these animals would grow such features in a highly visible and vulnerable part of the body complete with thin struts of bone - and they were not snipped right off - is all the more compelling reason to suspect a more widespread and outlandish panoply of soft tissue structures throughout theropoda (and many dinosaurs in general) that would not preserve. Especially among those theropods that were regularly coming together socially at large carcasses in feeding events/social gatherings. Dromies certainly count in that regard. In fact we should predict such structures.

3) Which leads right into my next point - prediction met (sort of) !! By now many readers have doubtless heard of the (as yet undescribed) evidence of a large distensible gular neck structure on a Tarbosaurus bataar. If this story pans out we do have evidence of a fleshy display structure on a lineage of the most bitey theropods of all time in the most vulnerable part of the body. So putting a highly visible, likely brightly colored display structure on the neck of the most powerfully biting terrestrial tetrapods of all time still panned out in the Darwinian struggle.

4) Such critics have probably never really been in a fight or done poorly in one... really don't take it as an insult because fighting and violence in humans is not really a good trait to endorse. But looking at what professional fighters and strikers do and the tactics that they use can be useful. One common tactic used in boxing is to intentionally offer up a shot that puts your opponent in a vulnerable position by feinting a move and then counter-striking. Let's go through what happens when a "vulnerable" fleshy skin adornment (or large lips) are bitten by another theropod.

I In a dispute one theropod bites the skin flap on the chin of another theropod. Due to the strength and elasticity of this skin it is not simply cleaved right off but instead substantial yanking and pulling would be needed to remove such structures.

II As the theropod that did the biting - let's call it theropod A - pulls and yanks that piece of skin off the bitten theropod - theropod B - and finally cuts clean the skin structure the momentum of the pull off will move theropod A downward and lateral from theropod B.

III At this point it is theropod B - the bitten theropod - that has tactical advantage. Theropod A in the course of yanking off a chunk of skin has put its head and neck inferior to theropod B.

IV Theropod B can now attack theropod A and get a potentially fatal or devastating bite to the back of the neck or head of theropod A. More importantly theropod A can not retaliate when bitten from this position at the back of the neck/skull.

V Theropod B has lost a piece of skin that can potentially grow back. Theropod A has in its miscalculations put itself in a vulnerable position and although it successfully inflicted non-fatal damage by removing a chunk of skin it may potentially lose its life because in doing so it left the back of its head and neck open.

One final word on theropod facial biting/skirmishes. I suspect the vast majority of bites were not the bone scraping/puncturing potentially fatal traces we see in the fossil record. The overwhelming majority of interactions that went beyond theatrical displays and gesticulations were probably the fast little nips and non-committal bites we see among canids and social feeding birds. Many of these bites would not even break the skin.

A Long History Of Dromaeosaurid Evolution Lots of Room For Variation

If we accept a middle Jurassic origin for dromies of about 167 mya that gives us more than 100 million years of dromaeosaurid tenure of small and medium sized carnivorous theropod. That is longer than felids or canids have been around. More importantly that is longer than ratites have been around.

I really want to drive home the ratite comparison because dromaeosaurids are increasingly likely secondarily flightless - probably evolving from something like Microraptor that could glide if not fly in a limited capacity. So if we look at ratites it becomes apparent that they have done all sorts of weird things with their feathers once they became permanently grounded. Especially so with their flight feathers. Ostriches no longer have the stiffened vennaceous wing feathers of flighted birds but more open plumaceous ones. Cassowaries have quilled wings. These options are real possibilities for dromaeosaurids but should be analyzed and imbued within a likely evolutionary/ecological framework.

In my last post I depicted a Dakotaraptor that veered very far away from other restorations. What I put in that rendering is quilled tail feathers. No need to incur drag when you are that cursorially adaptated. No longer a flighted animal or even one that could glide at that size I posited quills on the tail as a weaponized exaptation useful for whipping around at theropod dinner parties and also for rattling in threat display. Visual, auditory, and physical threat and intimidation displays should all be on the table when considering dromies. They were likely some of the most gruesomely theatrical animals when gathered in group feeding bouts in the history of terrestrial carnivores.

I also gave Dakotaraptor a striking white feather patch on the front of its chest for bold display and intimidation. Such bold white patches - when contrasted against darker integument - are common in birds of prey and also some mammals such as various species of Asiatic bear.

I took this notion of feather disuse and even extreme reduction further in a rendering showcasing a Dromaeosaurus feeding scrum on a non-descript chasmosaurine ceratopsid. An azhdarchid and a troodon are looking on waiting for scraps.

As you can see I really took the hyena analogy to the extreme even to the spotted scruffy coat. I reduced the wing feathering and eschewed tail feathers completely as this ground based, running, scavenging dromie had little need for them.

100 million years of terrestrial evolution from likely flighted ancestors allowed for substantial variation in appearance and function of dromaeosaurids; modern flightless birds show that flight feathers can become plumaceous or quilled; aggressively combative, usurping, and scavenging dromaeosaurids especially in hot and/or arid environs likely featured large areas of the head, neck, and chest bare or with feather reductions; such areas could have sported extreme skin adaptations that offered thermoregulatory, protective, social, and intimidatory benefits; for these dromaeosaurids new world vultures (cathartidae) and old world vultures (accipteridae) might offer more useful analogue behaviorally and physically than raptorial birds of prey (accipteridae); feathers could additionally have been arranged in coarse manes or thick tufts around the neck for protection as well as bold white/dark contrasting areas for intimidation.

One final note and this has to do with anthropomorphism - the ascription of human values, conceits, and emotions onto animals. One charge I have seen leveled at me is that I, to paraphrase, "depict many of my animals intentionally weird, ugly, or unattractive". To which I reply "duh, goal achieved".

I have always been transparent with my inspirations culturally on this blog - informed as I am by ugly music and ugly movies. I think it important that researchers be transparent with their inspirations, not just their scientific ones, to most reveal potential biases. We are all primarily cultural critters and it would be naive to think even the strictest and staunchest scientists are not first and foremost cultural creatures.

So when one looks at vultures gobbling and skirmishing over a carcass or the scruffy, uncouth appearance of hyenas and their cackles and the words "horrific", "disturbing", "ugly", and "revolting" are bandied about is this a cultural reaction or a more intrinsic, base natural one? Let us flip our way of thinking about combative scavengers... do we think about them with these conceits in our mind because of culture, or, because we ourselves are animals and most animals want to move away from the sight of such animals feeding? That is the that the shock, the visual awe, the intimidation we feel at the sight of these feeding events is the same gut level emotional response other animals feel: "I don't want to get near this cancerous looking, tumor faced, loud, shrill, dominating, repellent, and combative animal not because of some cultural tradition but because I too am an animal and I react on a visceral level to this display?"

"A Long habit of not thinking a thing wrong, gives it a superficial appearance of being right, and raises at first a formidable outcry in defense of custom". Thomas Paine

http://antediluviansalad.blogspot.ru/2016/07/making-dromaeosaurids-nasty-again-part.html