Thursday, June 9, 2016

Making Dromaeosaurids Nasty Again Part I - Wing Pummeling Abuse

"Night Terrors" Sinornithosaurus by Duane Nash

Making dromaeosaurids nasty again... Yes, there is a bit of a straw man argument in there because many might say they never stopped being nasty. But it is my straw man to make, tear apart, refashion, and burn to smithereens as I will... so while reading these posts on dromaeosaurids always keep in mind the tug of war between past and present interpretations scientific, artistic and popular. Don't forget as well these animals had a long tenure as small to medium sized predators so there is a lot of room for variation in terms of behavior, physiology, and appearance.

Something has happened to dromaeosaurids. They have went from jumping on the back of giant ornithopods to jumping on the back of opossums. They no longer look like the scaly, crazed, methed out gang overlords of the Mesozoic bestiary but instead dapper, attractive fashionistas that glided out of some Mesozoic audobon photo shoot. The psycho reptoid wolf-lizard of the Mesozoic is now the camera friendly fashion model of the Mesozoic.

Probably my favorite ol' school Deinonychus image credit William Stout
New school Deinonychus taking on smaller game in RPR model credit Emily Willoughby

A very attractive, dapper Deinonychus by Emily Willoughby. CC4.0

While the ol' school raptor I grew up with is now nothing more than a nostaligic memory ready to join the ranks of swamp bound brontosaurus I am not entirely at ease with all aspects of this new dapper "ground hawk" model for dromaeosaurids. Something just does not sit well with me.

First things first, the claw. Dat claw. Second to ol' sexy rexy and his chiseled and ruggedly masculine good looks the "killing claw" of dromaeosaurids and especially Deinonychus is probably one of the most emblematic and iconic elements of the theropod predatory arsenal. Are we focusing too much on the "killing claw" in terms of prey dispatch but negating other aspects such as the hand claws and teeth?

A brief review of several of the more pertinent works that have brought us to where we are now.

The Slashing Claw Denied...

While the youngins today have grown up knowing that the killing claw of these animals did not cut scythe like slashes through the hides of dinosaurian megaherbivores I do have to admit to feeling a pinge of let down in my inner fanboi when this was first revealed via the study "Dinosaur killer claws or climbing crampons" way back in 2005. Essentially what Manning et. al. did was build a robotic hydraulic Deinonychus antirrhopus claw and lower leg and attempted to drive it through a pig carcass. Instead of the meter long slashes of lore the results were a little underwhelming. The claw did puncture the carcass but as they attempted to drive it through the flesh tissue simply bunched together below the entry preventing a long slash wound.

In comparing the morphology of the claw they found it most lined up with the claws of climbing animals. Manning et. al. did not totally eschew the notion of dromaosaurids leaping onto the sides of megaherbivores but offered an alternative; the killing claw was now a crampon which allowed the predators to jump onto the side of prey and deliver slashing bites with the jaws.

Jumping on the Flanks of Giant Herbivores Denied...

Seems pretty legit right?

Well the next paper seemingly expunges the use of the claw in climbing onto the back of megarherbivores. Enter the Raptor Prey Restraint model (RPR) which probably needs little introduction to most readers here. Fowler et. al. reject the notion of dromaeosaurids latching onto the flanks of large herbivores and slashing at prey with foot claws or teeth. Instead prey subequal to the size of the dromaeosaur is pinned down beneath the weight of the predator; stability flaps of the "wings" and movement of the beam like tail help maintain an upright position; and prey is essentially eaten alive if it is not killed outright by the feet.

And you know... I like this a lot. It makes sense - there is a good analogy with modern accipitridae and it has a nice little thematic thing going on with the flight exaptation given that dromaosaurids are likely secondarily flightless. The authors also make a very striking contrast between dromaeosaurids and troodontids that suggests a degree of partitioning between the two groups. Dromaeosaurids had shorter but more powerful metatarsals suggesting a larger prey size seized by the feet than troodontids which compromised strength for cursorial ability and a quicker grip on smaller prey.

So ground hawk Deinonychus... what is not to love?

There are some caveats to this model that the authors address that I think warrant repeating:

So, despite the arguments in favor the RPR model for dromaeosaurids and the inherent attractiveness of the model it appears that dromaeosaurids were not >as good at it< as their modern avian counterparts. I am not saying RPR is not a thing and, again, this is from their own paper but it appears that a 50 kg Deinonychus is not equal to a scaled up 50 kg red-tailed hawk in terms of relative grasping power of the feet. Furthermore if you look at the vice like grip that modern raptors can enact in which digit I is rotated completely opposite the other three digits it appears that Deinonychus and other dromaesaurids do not fully rotate the digit opposite the other three for a truly powerful vice like grip.

credit eaglesohio
Again, not trying to imply that RPR is not a thing for dromaeosaurids or that they did not pin and even kill prey with their feet but let us be clear with what the science shows as of now. In dromaeosaurids the RPR model is a relatively less powerful and less efficient version than modern raptors essentially due to the anatomical concessions of retaining some cursorial ability. But I am sure it was still unpleasant...

Actually what dromaeosaur foot graspers remind me of is cats claws and paws (gasp!! mammals). No really... anyone who has had a cat "knead" on them (i.e. breadmaking) knows what I am talking about. As the cat's claws clench shut in a semi-opposable fashion the claws actually pin stuff against the lower arm. In dromaesaurids grasping things would be pinned against the bottom of the metatarsus. This is still a pretty good grip and with both legs working together likely very efficient.

Dino Kitty
The Role of the...

I am obviously not the first to ponder this and it is a perplexing issue in many, if not most, predatory theropods - but what were the clawed wing/arms of dromaeosaurids good for anyway? Fowler et. al. posit them as dynamic stabilizers that combined with the fully feathered tails (like Archaeopteryx not Caudipteryx plumes) allowed these predators to maintain vertical superiority via flapping over prey caught in the foot claws. I like this a lot. So please don't misquote me when I argue that there is something to augment this method not completely replace it.

Those big hand claws seem like such a waste if all they did with their arms is use them in stability flapping.

Issues have been raised as far as the practicality in using the hand claws to grasp small prey dexterously or even bring the hands together to grasp small prey with precision. I honestly don't know what the current thinking on this issue is - or if there is any consensus at all? I would love to hear thoughts and input in the comments section... From what I gather on my cursory research things seem a little equivocal. The wikipedia page on Deinonychus mentions papers that support grasping and others that bring forth some practical questions. Some observations that cause me to question fine tune grasping of small prey items include the potential issue of the "wings" getting in the way of each other when brought together. Also and this is my general observation of patterns in clawed grasping animals: it seems reasonable that in order to achieve a powerful and concise grip that the digits and claws work better aligned in a similar plane. Essentially when you look at the grasping claws of a felid, modern avian raptor, or hell... even our own hands what you see is the digits not varying tremendously in terms of length and that they line up together relatively closely when clenched.

This was simply not the case in maniraptorans with extremely divergent digit length. Such spindly, long claws just seem a little less than ideal for enacting a powerful and concise grip on something small that needs precision. Gripping a tree trunk or "bear hugging" an animal that is fairly large yes... but dextrous grabbing and manipulation of small stuff, I don't buy it. Especially with all those feathers in the way. Could hands like the ones below deftly grab and pick up say a scurrying lizard or mammal? 

credit John Conway. Deinoncyhus (L) Archaeopteryx (R) CC3.0
The digit lengths are just different from the pattern we see in other grasping predators even other theropods. For example in Allosaurus fragilis:

Allosaurus hand. credit Domser CC3.0

Another point is that if a dromaeosaurid wanted to reach out and grab a small prey item doing so with the head and mobile neck or even the feet seems more ideal. The arms - like all theropod arms - had limited mobility in the forward plane. Several of the problems in forelimb usage are summarized in a paper by Phil Senter comparing the forelimbs of Bambiraptor and Deinonychus:

For these and other reasons I find  "fine tune grasping of prey" hypothesis more than wanting. Enough so that other hypotheses warrant exploration.

The hypothesis I will offer - not sure if this idea has been explored yet anywhere to tell you the truth - is going to highlight exaptation of the flight stroke and musculature of the maniraptoran arm to a high degree. This is consistent with the strong hypothesis put forth by Gregory S. Paul that dromaeosaurids are secondarily flightless.

The clawed wing arms of dromaeosaurids could potentially act as clawed battering tools that would further bludgeon, wound, and traumatize prey and/or competitors especially that have been pinned by the feet.

Why not? The arms were strong, long, and heavily clawed after all. More so modern birds just love to bludgeon and smack other things around with their wings. Made famous in a series of posts at Tet Zoo(here 1, part 2part 3wrestling birds) by Darren Naish, some wings even have weaponized claws, clubs, and spurs. Dromaeosaurids - likely being secondarily flightless - already had the exaptation to use their wings as bludgeoning tools. All the musculature was already set up for it.

Two Deinonychus have a disagreement. Provided by Robin Liesens (Dontknowwhattodraw94)

As I mentioned earlier the study by Fowler argued quite well that dromaeosaurids were not >as good< as modern raptors in terms of prey dispatch via the foot claws. Other tools might be needed for prey dispatch... Why not use those nice hand claws powered by the incipient flight stroke to further gouge, pummel, and weaken prey that is being grasped by the footclaws and jaws? Not saying stability flapping did not happen just that stability flapping used in conjunction with with wing pummeling might have some merit. Furthermore the need to maintain vertical position over prey might be just a tad overstated - don't forget the fighting dinosaurs!! After all dromaeosaurids had a little bit more liberty in terms of getting down and dirty on the mat as opposed to accipterids which always have to be mindful of getting grounded with a serious wing injury.

CC 2.0 credit Yuya Tamai. Protoceratops & Velociraptor
And modern birds do love to fight and 'rastle!!

Did you check out that eye gouge at about 1:03? Note how right above the eye is nice a ridge of brightly colored, caruncled tissue... remind you of a suggestion I made before?

Or the above video which actually doesn't feature a stork eagle fight but loads of domestic breeds battling one another (uuurgh there Nash goes with domestics again). Loads of fleshy caruncled faces, face biting, wing pummeling, talon thrusting. In short very awesomebro!! but not necessarily without merit just because it is awesomebro!! You see the pattern - lunges and strikes are made with the head and/or feet. When brought into the line of fire of the wings, pummeling commences.

Tsaagan dispatching Velociraptor. work in progress Duane Nash

This methodology of prey capture/combat is essentially a bit of an inverse of a common tactic used by felids. Anyone who has a pet cat  (or who has a cat that has them?) should be familiar with it. If not simply stroke the vulnerable belly of a said felid and the forelimbs and/or jaw will lock into your arm and the back legs commence clawed kicks. In dromaeosaurids it would be the hindlimbs and jaws locking prey into place and the forelimbs delivering blows and trauma via wing pummeling.

Deinonychus wing pummeling Zephyrosaurus. credit Robin Liesens (Dontknowwhattodraw94)

In addition to the analogy to modern bird wing pummeling the analysis of theropod stress fractures and forelimb avulsions (Rothschild et. al., 2001) came up with some interesting results with regards to Deinonychus limb use: 43 hand bones and 52 foot bones were examined for signs of stress fracture - none were found. However the second phalanx in the second toe (the killing claw) has a healed fracture (YPM 5205). Why is this important? Well it suggests that the hand claws are not hooking into things and holding them tightly such as appears to be the case with Allosaurus which shows multiple manual pathologies - but the healed killing claw suggests that digit II is hooking into and holding struggling prey/combatants to a higher degree. On the other hand it is worth asking why wing pummeling would not create stress fractures? Perhaps with the force being distributed across the whole surface of the wing (including the feathers) stress fractures would not be such a problem? Are stress fractures a problem in modern birds that wing pummel? Could be an avenue of exploration...

Really I am quite surprised that wing pummeling in dromaeosaurids (and other winged dinos/maniraptorans) has not been proposed before... I mean has it? I dunno, can't find any mention and it seems like a pretty logical inference from what I have gathered.

Two potential criticisms I want to address:

"Yes but modern birds use this wing pummeling in antagonistic disputes not predatorial. Birds of prey do not batter their prey with their wings."

True. Remember Fowler quite convincingly argued that dromaeosaurids were not  as relatively >strong< in grasping as accipterids. Does this imply that they were small game specialists? I think not. My contention is bolstered by the "fighting dinosaur" specimen. You will hear some researchers try and explain this situation away as a "rare" or "aberrant" exception to the "baby killer specialist" or "small prey only" model. With all due respect I think that they are mistaken. Not that loads of baby dinosaurs were not munched on, merely that dromaeosaurids and most theropods were not "specialized" for that task.

Given that dromaeosaurid foot grasping was meh compared to modern birds of prey but they were still getting into the thick of things with some pretty rugged combat other lines of attack should be invoked. Those big hand claws seem awfully put to waste in mere stability flapping. Especially when attacking strong retaliatory prey like protoceratopsids.

"Why don't birds of prey pummel prey with their wings?" As I alluded to earlier accipterids differ from dromaeosaurids in that they are dependent on flight. Wing pummeling for them may be selected against as a predatory strategy because they risk an injury, not to mention their feet do the job just fine.

"What about the claws getting stuck in the flesh and skin of the prey during pummeling. Could that be a problem?"

I don't think so. If the downstroke can enmesh the claw in the animal then the upstroke can pull them back out. If claws getting stuck in stuff was so much a problem I guess that implies these animals could not use their claws to climb and clamber in trees as well, because their claws would get stuck in wood, amirite?

Given that; dromaeosaurids are likely secondarily flightless; that their digit morphology is aberrant from other predatory "graspers"; that wings may have got in the way of grasping, especially of objects on the ground; that the fingers remain spread during flexion; that one handed clutching of objects to the chest is just weird; that the elbow can not be fully extended and forelimb mobility is limited;  that extant aves often use their wings - sometimes coupled with knobs, spines, and claws - to pummel other animals; for these reasons I posit the hypothesis that clawed wing pummeling is a promising tactic used in dromaeosaurid predatory, combative, and defensive endeavors.

At the moment I see no reason that the idea of wing pummeling can not be extended to other winged dinosaurs and maniraptorans. Hello wing pummeling GallimimusGigantoraptor, Therizinosaurus, and Deinocheirus!!

Next up: biting, scavenging, scrumming, and bone cracking dromaeosaurids.


Fowler DW, Freedman EA, Scannella JB, Kambic RE (2011) The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds. PLoS ONE 6(12): e28964. doi:10.1371/journal.pone.0028964

Manning, PL, Payne, D, Pennicott, J, Barrett, PM, Ennos, RA (2006) Dinosaur killer claws or climbing crampons. Biology Letters (2006) 2 110-112 pdf

Rothschild, B. Tanke, D, Ford, TL (2001) Theropod stress fractures and tendon avulsions as a clue to activity. Mesozoic Vertebrate Life. editor Tanke, D & Carptenter, K. Indiana University Press pp331-336

Senter, Phil (2006) Comparison of forelimb function between Deinonychus and Bambiraptor (Theropoda: Dromaeosauridae). JVP Volume 26 Issue 4 2006

"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

"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deed; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place will never be with those cold and timid souls who neither know victory nor defeat." Theodore Roosevelt

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As I have seen an uptick in traffic and subsequent comments that lower the standard of conversation on this blog I will be moderating the comments section from here on out. I don't have a comment policy other than it is my blog and I will do whatever the hell I want to with it and ban whoever and whatever comments I want. Disagree with my ideas - fine, disagree with me so strongly that you launch smear campaigns and rants against me... fine... go make something original on your own. You will still be banned here.  As several recent commentators now are - banned for life. It should not be too hard to find out who those are from recent posts as I will leave their comments up as fair warning to others.

There is a big ol' internet out there and I don't need you.

Over all though I am happy with the input, differences of opinion, and general intelligence of the commentators. You guys are my "peer review" as much as I can muster at least and have helped me change and refine my own thoughts and perspectives numerous times. Keep it up.

Sorry if you thought that theropod lip post was happening now, a little bait and switch hahaha... some other stuff beforehand that is very interesting to build suspense...  but I am still coming for ya' lizard lipped theropods.


khalil beiting said...

Another great post Duane! I've actually had a similiar thought about wing pummeling Dromaeosaurs. Not because it was based off of any evidence I was reading of, but rather just a sensical analogue to modern day birds. When they fight, you do see them smacking eachother with their wings to a certain extent, albeit really just for trying to balance themselves out whilest in the air. When hawks are pinning down prey, they nearly smack it with their wings while trying to balance themselves out. So seeing as how Dromaeosaurs had massive, beefy claws (that everyone forgets about for some reason), I just assumed they would have used them purposefully or even accidentally when beating their wings to better balance themselves while fighting or tackling prey. And I love your reconstructions of Dromaeousaurids. They always have wattles and caruncles that make perfect sense for their behaviour. I see many people call it too awesomebro, but saying that is the equivelent of calling modern day wattled birds awesomebro. I find nature in itself fairly awesomebro to a certain extent, it's jsut that we never really realize this since we're kind of used to it. No one batts an eye when vultures and junglefowl (including domestic chickens) bite eachother's face's to a point where their wattles are torn up and bitten off, but when the massive, saw toothed, Mesozoic ground raptors (aka Dromaeosaurs and Troodontids) have wattles everyone loses their mind and calls you awesomebro. Living animals are far more aweomsebro than that. Eagles play the world's most terrifying game of chicken when fighting and gripping eachother in the air. Many things from hyenas to skuas eat their prey alive by ripping out their organs. Elephant seals rip eachother's necks and noses off when fighting. There's an Australian species of bee (whoes name I forgot) where the males fight eachother to the death for the right to mate; they will literally bite eachother's heads off. All of this would be labeled as awesomebro if portrayed in paleoart (well, it depends, but on average it's considered awesomebro), yet this is just regular behaviour for many living organisms.

So since Dromaeosaurids, Troodontids and really just most Maniraptoriformes would have used this form of "flap beating", what other groups would have done so? Are their any other Theropods or even Dinosaurs in general that would have done this? Maybe even somehwere in Pterosauria?

Duane Nash said...

Thansk Khalil. I fully agree that something that I believe was explicitly made as a cultural observation by John Conway "awesomebro" has somehow leap frogged into being a legit scientific argument i.e. "that is too awesomebro". Sorry you got to do better than that. Yes nature is full of things that are truly "awesomebro" that does not make them untrue does it? Killer whales flipping pinnipeds 60 feet in the air; pythons swallowing insane sized prey; hyenas eating ungulates alive; lions taking down elephants; eagles pummeling ungulates off of cliff walls. All of these things undeniably awesomebro, all of them undeniably true.

What is ironic about my ugly, ghoulish theropods is that I went explicitly to birds for inspiration. For every peregrine falcon I can raise you lappet-faced vulture; for every golden eagle I can give you a marabou stork. And when we look at birds that do engage with their face a bit in predatorial/combative endeavors there does seem to be a bit of a drift into very fleshy, wattly, caruncle ridden faces. Do I have a personal bias towards the ugly and macabre? Hell to the yes!! Do I believe others have a bias towards sleek, attractive, and dapper looking things that is imbued into their paleoart? Hell to the yes!! Doesn't mean that either option is >more correct< at this point only that both appearances were likely and both artistic hypotheses deserve exploration in paleoart. I would venture that the more elegant dapper look predominates in representation though.

Trilobite Cannibal said...

I once had the Idea of wing slashing to create bleeding wounds, and potentially bacteria coated claws to increase likely hood of infection similar to the bite of komodo dragons

Christian Halliwell said...

Great post! I actually already wrote wing-beating into a story I am writing about Deinonychus, glad to see someone else finds this to be very plausible :).

khalil beiting said...

So since Dromaeosaurids, Troodontids and really just most Maniraptoriformes would have used this form of "flap beating", what other groups would have done so? Are their any other Theropods or even Dinosaurs in general that would have done this? Maybe even somehwere in Pterosauria?

Ryan Dempsey said...

To help contrast all the junky comments you've been getting, I'd just like to let you know that your writing (as well as some of your paleoblogging cohorts) has sparked a new appreciation and fascination with Dinosaurs and paleontology. Dinosaurs have never really been more fascinating and wonderful.

I don't have anything intellectually to throw into the ring (maybe someday), but I'm always lurking and enjoying your work.

Stoked for Part 2!

Duane Nash said...

@Trilobite Cannibal Hey gnarly thought. I am sure there claws had some pretty nasty stuff on them in terms of bacteria.

@Christian Halliwell Nice to see convergence in thought!!

@khalil Other dinos using wing pummeling. Well ornithomimids had "wings" it seems so them, perhaps oviraptors and therizinosaurs too are possibilities.... have not thought about pterosaurs but that extended digit that forms the end of the wing is really robust. Maybe Mark Witton has some better informed thoughts on this topic in pterosaurs. Would be an interesting area to explore. Are there any anatomical characteristic in birds that wing pummelling that can be extended to other animals? I don't know... but it seems to be pretty wide spread in birds too so maybe hard to limit it to a single anatomical characteristic...

@Ryan Dempsey hey thanks for chiming your comment really makes my day!! I've done my share of internet lurking without commenting as well. Nice to hear there are appreciative people out there even if some people just bark louder...

Bk Jeong said...

I actually considered this idea seriously.

Bk Jeong said...

Also, with their grasping foot claws, pummeling wing claws, and bone-saw jaws, dromaeosaurs might be the lb or lb kings and queens of killing among theropods.

D-man said...

Amazing post, agree with most of this (except for, you know, domestic breeds and naked headed raptors).

However I heard something from Emily Willoughby saying they probably did not use their arms for hunting. I quote

"There is surprisingly little evidence to suggest that dromaeosaurs, despite the robust hand-claws, were using their hands in predation at all. Some researchers have suggested that the main function of handclaws may have been to support a partially arboreal lifestyle, at least in juveniles. The function of handclaws in dromaeosaurs is still an open question, as far as I'm concerned.

That said, there is no reason to assume that large hand and arm feathers would preclude mobility and grasping ability in dromaeosaur hands."

Also, all the examples of wing pummeling you put up are from birds that are herbivores and do intraspecific comabt.

The Eurypterid said...

I disagree with the 'raptors have abberrant hand morphology' thing. A cursory glance at four other coelurosaurs- Eotyrannus, Compsognathus, Sinocalliopteryx and Ornitholestes, all being species with known hand material- shows extremely similar hand bones to maniraptors including Microraptor, Sinornithosaurus, Jeholornis, Archeopteryx and Troodon.

Seeing as all four non-maniraptoran coelurosaurs are more primitive than the maniraptors, it is simple to assume that these hand proportions are in fact basal to coelurosaurs. Judging by the fact that all four of these species are small, fast animals, and the fact we've found gut contents of both Sinocalliopteryx and Microraptor that were all small animals, it is safe to assume that this structure is in fact well-adapted for taking small prey. So dromaeosaurs were perfectly normal hunters of small prey in that regard.

What is more notable is that there were three exceptions to this, not included in the above list of maniraptors- Velociraptor, Utahraptor and Deinonychus. (Plus Buitreraptor but that was a piscivore, and its adaptations- small claws, more even finger sizes- are not anything I could talk about.)

These two dinosaurs have three features. One- their arm bones are hypertrophied. In particular, the ulna and radius are much further apart than in other species, providing a wide area for muscle attachment and force application. Two- they had hypertrophied first (thumb) fingers. Velociraptor had an incredibly robust first finger bone, while the entire first finger was robust in Deinonychus and Utahraptor. Three- both Velociraptor and Deinonychus are associated with large prey items, and all three are closely related.

From a look at Darren Naish's work on battering adaptations in recent maniraptors, it showed that fighting adaptations were not, in fact, run along the entire hand. Instead they are focused- with the exception of the club-ibis- on the wrist, the first finger and the leading edge of the palm. Areas here are hypertrophied, as mentioned, in Velociraptor, Utahraptor and Deinonychus.

I would like to hypothesise that predatory battering was not, in fact, a widespread use of the wings in the dromaeosaurs. Instead, I believe that the hands were- as previously suggested- used in the snatching of small prey and for use in balance when running or fighting. However, certain raptors- likely specialised in the predation of large prey- do in fact show adaptations that could imply the wings were better-adapted for predatory battering than others, and the least-adapted- Velociraptor- had a less well-developed adaptation accordingly.

The Eurypterid said...

Oh, and one more point- hitting with the side of the wing is most likely, because hitting with all three fingers would require dragging the wings through the air with them. So the latter two fingers are going to be fairly useless for battering, so they are- as seen- less robust, making them better for grabbing anyway.

Duane Nash said...

Interesting thoughts Eurypterid.

I do have to admit to being a little less than sold on the notion of theropods reaching out and grabbing things - especially small things - with their hands. Just seems like the head and neck being further forward and more mobile would be the first to engage with prey. Another issue I find is that the hands are a bit out of the line of sight of the eyes preventing good hand/eye coordination. Lack of forward mobility as well is an often cited issue... Just too many peculiarities for the front paws to be good at deftly grabbing and striking at things the way let's say felids do. In all above cases the head at the end of a long mobile neck seems to be a superior option.

Good points about Eotyrannus, and other coelurosaurs having similar morphology. Again, I am not sold on these animals being great at reaching down and grabbing things with their paws as well. I do think that the hands in these animals could "bear hug" larger prey items/combatants after the head grabbed something. Coarse raking is an option.

Point taken regarding hypertrophied ulna and first finger in certain large dromaeosaurs. Indeed these animals might be >better at it< than other dinosaurs but loads of birds engage in wing battering not just the ones with specific adaptations to it.

The Eurypterid said...

Thanks for the compliments. :)

For alternatives on the hand structure, what about to limit available directions for prey to travel? For example, in this video:

the hare is able to jink to the sides to escape. The structure of the maniraptor hand- two long, close fingers with a thumb for gripping- would be a good design for snatching at prey that tries to turn too closely, keeping the prey in lunging range for longer. The short humerus and large grasping surface would be good for this, allowing the hands to be flicked inwards once they've caught on something.

That sort of thing would also work after being grabbed- for example, an Eotyrannus chasing a heterodontosaur would probably catch that long tail first, allowing the animal to turn around and gore the predator. The hands would be able to grab the body without needing to let go- again, the short humerus and large grasping surface are good for manipulating things under the body.

And as a point against wing-battering, dromaeosaurs lack one other trait that modern birds have, that make wing battering that much more effective- their arms are situated on the sides of their bodies, not the top. This, combined with their shorter arms, makes it harder to effectively get them to the top of the body to attack with vertical blows.

Overall, whatever most dromaeosaurs were doing- I think it woukd have been very similar to what every other coelurosaur did. Was wing battering likely? Yes. Any strong, forceful body part is going to be used to fight when it comes down to it. But it's unlikely to have been any more central to their hunting or fighting strategy than in any other coelurosaurs- in fact the wing feather probably even hindered them in that regard, weighing the arms down and hampering their non-raking slashes.

So wing battering was certainly a thing in dromaeosaurs, but it was likely not any more major to them than in any other long-armed theropod. A Coelophysis would be just as good at it.

Jonathan Atkinson said...

I'm kinda surprised you didn't mention roadrunners or secretary birds as they are both examples of highly terresial predators, granted both are more small game specialized and have their flight feathers to worry about (more the secretary bird then the roadrunner), still it is a place for investigation.

Also Andrea cau made a article Last year about trex arms and their functionality and cited a paper by Carpenter and Smith in 2001. (Pardon if you have read this paper already). The paper compares a "homo", deinonychus, allosaurus, and trex arms across a spectrum of speed/ fast grasping and flexibility vs strength and resistance to force. As you might have guessed the human and denio are towards the extreme of speed and having relativily flexible arms compared to the allosaurus and very stiff plus firm trex arm. Sadly cau's article is about the trex arm and not the deinonychus so he doesn't talk about its roles in prey use etc. ( the name of cau' article is "what is the trex arm").

But what seems to be a recurring theme that I have noticed in all of this is that maniraptorians do seem to be more small game focused for anything smaller then velcioraptor/tsaagan based off of your results and everything i'ved seen in the pass six years on raptors and their arms. Shrugs shoulders.

Anonymous said...

@Jonathan Atkinson what about seriamas? They barely fly.

D-man said...

The idea does merit further investigation, and seems would be helpful with prey of similar size, but it seems more likely that they probably went with the Thigh Ripping/ Supinated Slashing Technique when taking on bigger prey (Utahraptor/Iguanacolossus; Deinonychus/juvenile Tenontosaurus).

"given that dromaosaurids are likely secondarily flightless."
Actually this is quite questionable. Mahakala shows an animal that was more primitive than Microraptor (despite living later) yet it had small wings. Xioatingia is said to be proof of ancestral aerial dromaeosaurids, but later studies show it is an avialan like Archaeopteryx.

Christian Halliwell said...

@D-man Which animals are basal troodontids, basal avialans, or basal dromaeosaurs is very uncertain because they are all incredibly similar. However, it seems all three groups were flightless to begin with. Large wings are a common feature at least in avialans and dromaeosaurs, and probably troodontids as well, even in species that couldn't fly (Archaeopteryx, Velociraptor, Zhenyuanlong, Anchiornis, etc.).

Alessio said...

Yeah, the fact dromies had (apparently) dexterous hand fingers "embedded" in wings always looked weird to me, and the theory you propose really seem to clear things up... Plus, hawks and eagles as analogues for these guys doesn't sounds completely right; i mean, as long as i began to seriously look at dromies skeletons, i immediately imagined 'em like some sort of mesozoic vultures (at least the more ground-dwelling taxa like Velociraptor, Deinonychus and such), in terms of appearance if not behaviour. Some of them (Dromaeosaurus albertensis, i'm lookin' at ya!) have skulls which even resemble Griffin or condor's ones (look at the skull roof, the curvature of the snout, etc)!

D-man said...

@Alessio yeah. Dromaeosaurus, Atrociraptor, Dakotaraptor, and Sauronitholestes seem to be very vulture like in niche (I'm not sure on appearence).

Jonathan Atkinson said...

So I think I must recant on the whole secretary bird idea as being a good example. The reason is because the secretary bird is just clearly too much of a specialized small game hunter. The thing is four feet tall yet it weighs no more then your average golden eagle( that is no velociraptor or deinonychus). Two its feet while used in what could be a very dino-raptor like fashion still have more of a flying perching style/raptorial foot instead of a more generalized foot as you mentioned Duane. Lastly a 10 pound/ 5 kg bird isn't much help for describing the larger taxa of dino raptors.(but with that said maybe secretary birds could be an example of alvarezsaurids as small game hunters)

Seriema's though are much better albeit with some caveats. For one they have a legitimate dino raptor like claw, its not all the way there like a troodon claw but it still is a dino raptor claw. Also this may go against the dino-raptor claw test but Wikipedia says that the seriema when stuck with prey to big to swallow whole "will be ripped into smaller pieces with a sickle claw by holding the prey in the beak and tearing it apart with the claw." If a small bird can use it's fairly unserrated/sharp claw to rip admittedly small and restrained prey, then couldn't dino- raptors do the same with their claws with the right sized subdued prey.(not taking in to account the large mouth full of teeth). Lastly for the Seriema is that it also has a specialization for taking small prey and having less need to maintain flight capability.

Alright last big paragraph but it seems all of our conclusions come down to dromaeosaurs having relatively inflexible fingers, having very limited arm movement while having some of the best theropods for arm movement/flexibility, their small origins with wings and a possibility of being arboreal, could the earliest of raptors been turkey style flight capable predators? kinda like gliding cats :b

picture of a secretary bird with raised foot with a sorta raptor claw,d.aXo&psig=AFQjCNEoAO3-I_EckSCwLIl5S-Q6vR2Xrg&ust=1466084462335593

Here is a Seriema claw all nice and posed,d.aXo&psig=AFQjCNHXg2t14M_FLvuhgG68bXS4uLi-Sw&ust=1466084805997949

lastly heres a velociraptor skeleton for comparisons
swallow whole "will be ripped into smaller pieces with a sickle claw by holding the prey in the beak and tearing it apart with the claw." If a small bird can uses it claw

picture of a secretary bird with raised foot with a sorta raptor claw,d.aXo&psig=AFQjCNEoAO3-I_EckSCwLIl5S-Q6vR2Xrg&ust=1466084462335593

Here is a Seriema claw all nice and posed,d.aXo&psig=AFQjCNHXg2t14M_FLvuhgG68bXS4uLi-Sw&ust=1466084805997949

Duane Nash said...

Good ummmmm points Jonathan.

Seriema's do warrant a mention and I recall reading that wikipedia thing about them breaking prey into bits with their claws and even seeing a video somewhere of that behavior. For me though it makes more sense for the teeth in dromaeosaurids to do the prey tearing while the feet did the restraining and pinning. This makes sense with the serrations being more robust on the back (lingual) side of the tooth.

"Could the earliest raptors been turkey style flight capable predators? Kinda like gliding cats?"

Sure this is probably what microraptorines were like anyways...

Pedro Bear said...

Hey, just gonna leave my thoughts on seriemas here.

"Also this may go against the dino-raptor claw test but Wikipedia says that the seriema when stuck with prey to big to swallow whole "will be ripped into smaller pieces with a sickle claw by holding the prey in the beak and tearing it apart with the claw."

Surprised there isnt a paper dealing with seriema second digit use(though theres one on phorusrhacids and some mentions on others papers that deal with seriemas)... The best ive ever found of them using it is this pic:

"Lastly for the Seriema is that it also has a specialization for taking small prey and having less need to maintain flight capability."

Yeah, there was a paper that mentioned both, Chunga and Cariama, stomach content:

"stomachs of the Red-legged Seriema contain grasshoppers, Atta ants,
beetles, larval insects, a few small fruit, and tree gum (Burmeister 1938,
Miranda-Ribeiro 1938). This species also eats snakes and other reptiles,
small birds, and small mammals (Sick 1984). In the wild and in captivity
Cariarna grabs small vertebrates in its beak and beats them against the
ground before dismembering them with its beak and claws (MirandaRibeiro
1938, Santos 1979, Sick 1984). "

"The Black-legged Seriema has similar food habits. In Tucuman, Argentina
they were often observed foraging near cattle and horse dung.
The gizzards of 4 individuals contained beetles, locusts, green leaves, and
grass with a few hard seeds and the body of an entire rat or young cavy. Black-legged Seriemas in captivity greedily fed on the bodies of rats and
birds. As was the case with the Red-legged Seriema, the prey was beaten
on the ground before being consumed (Boyle 1917)."

"Seriema's do warrant a mention and I recall reading that wikipedia thing about them breaking prey into bits with their claws and even seeing a video somewhere of that behavior."

Do you still have this video? Id like to see it.

Warren JB said...

Let's just check if I'm 'banned for life' already. Not that it makes much difference anyway, because...

"As I have seen an uptick in traffic and subsequent comments that lower the standard of conversation on this blog I will be moderating the comments section from here on out. I don't have a comment policy other than it is my blog and I will do whatever the hell I want to with it and ban whoever and whatever comments I want. Disagree with my ideas - fine, disagree with me so strongly that you launch smear campaigns and rants against me... fine... go make something original on your own. You will still be banned here. As several recent commentators now are - banned for life. It should not be too hard to find out who those are from recent posts as I will leave their comments up as fair warning to others.

There is a big ol' internet out there and I don't need you."

This whole rant ensured that Antediluvian Salad will be gone from my bookmarks. I've said it before, but now I'll be a bit more blunt about it: the problem's not so much your ideas, it's the whole aggressive victim complex that you express them with, that is IMO the real cause of the lower standard of conversation in this blog. (I laugh at that, the way I laughed at commentators elsewhere who mentioned your desire to see less aggression to awesomebros. Being aggressive is your whole schtick!) You throw the theories out with not so much an admittance but a wallowing pride in your biases, and accuse others of the same. (If there's a bias in depicting 'dapper' dromaeosaurs, it's likely to counter the inexpert depictions of 'lizard-faced monsters in gorilla suits' that first popped up when feathered dinos went mainstream) Then you top your self-compromised theories with quotes from smarter men, as if it makes you smart and right by association. You say that it's only a 'viable interpretation', but the above quote demonstrates what happens when someone disputes how right you are and triggers your persecution complex.
You try to fashion yourself as the free-thinking rebel in palaeo circles, the unofficial heir to Gregory S. Paul or something. Possibly, but I think you're racing far ahead of the 'proven right' phase and straight into the 'cranky old man trying to impose his will on the internet' phase.

Big ol' internet, is it? You're just making it smaller for yourself. I still think most of your interpretations are interesting and thought-provoking, as I did when I stumbled across your plesiosaur series, but I don't think they're worth watching you throw your toys out of the pram each time, much less crushing all dissent to your 'free exchange of ideas'. It's a big ol' internet out there, and it doesn't need you.

Duane Nash said...

Hi Warren JB,

"Let's just check if I'm banned for life already" Although I recognize your name from past comments I don't see you as a problem commentator so no I was not addressing you specifically, sorry if you took it that way Warren. Several other (just 2 really) commentators that have been smearing me - even going so far as to tie me into neo-creationist thinkers, a new fangled David Peters, and other charlatans. SHould not be to hard to find these commentators still up from big lip sabertooth post and the recent one on T. rex. So, no I don't feel bad or guilty about giving them banned for life badges, I am under no obligation to devote my time or energy to them and if you read their comments you will see why it is a fruitless voyage to give my energy to them.

"being aggressive is your whole schtick" I really don't find that fair. I honestly get very peeved when my ideas are misquoted or people simply don't read the whole post and/or leave out pertinent information. I think that would anger most people however and I don't really think that I am exceptionally angry or aggressive about it. I don't for instance do twitter or get into countless flame wars in social media forums to the extent that many do. In fact I try to limit my discussions at this point to the blog itself and have recently actively went away from sharing new posts in other forums i.e. facebook groups as keeping up with the comments was tiresome and fruitless. Sometimes I think people confuse passionate and excited with aggressive as well.

"Then you top your self-compromised theories with quotes from smarter men, as if it makes you smart and right by association" I probably do quote lots of "smarter" men and women here - so what? This is very subjective and you have not given me any example that I can learn by and better myself so... who is ranting now? Smart is very subjective in my estimation - some can be artistic geniuses but lack common sense, autistic math geniuses that can't hold a conversation, we can't all be experts at everything. I never made a claim to be the smartest man or women out there. I do think I have a gift for spotting interpretations and ideas that others - for whatever reasons - miss and i will continue to do this. It does not mean I am in fact smarter than them. In fact they are probably vastly superior to me in many arenas of the paleo/biological/intellectual game. But I will continue to just keep doing what I am doing even if it turns some off.

I do keep this blog going as a document of my own thoughts and ideas for as much intellectual growth as personal growth - I am happy to make mistakes and just leave them out there for the world to see warts and all. I can see how some have came to the conclusion I have jumped the shark into the "ol' crank" realm. However they are mistaken as I am growing and changing all the time. No longer am I invested in the outcome, merely the process. The big assumption some have is that I am doing all this for fame or to get love. That stuff is fine if it comes, but to really get down to why I do this is purely selfish and artistic reasons. I want to discuss the ideas and thoughts that I don't see out there, I want to draw the things out there that I don't yet see. That is why I don't take requests for posts and write in my own language/style.

"You try to fashion yourself as the free-thinking rebel in palaeo circles, the unofficial heir to Gregory S. Paul or something."
You said it, not me. I'm just being me. If my name is put in the same sentence as GSP for right or wrong reasons... hey I'm flattered.

"This whole rant ensured that Antediluvian Salad will be gone from my bookmarks" Again, sorry you feel this way. C ya!!

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