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Flight of the Microraptor

The views expressed are those of the author and are not necessarily those of Scientific American.


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Microraptor gliding in pursuit of a prey item. There are good reasons for thinking that Microraptor really did behave this way, and that it had black, iridescent plumage. Image by Emily Willoughby, used with permission.

Some weeks ago now, myself and a team of colleagues (Gareth Dyke, Roeland de Kat, Colin Palmer, Jacques Van der Kindere and Bharathram Ganapathisubramani) – all of whom are based at the University of Southampton – published the results (in Nature Communications) of our study on the aerodynamic performance of Microraptor, a small, long-winged dromaeosaurid theropod from the Lower Cretaceous of China (Dyke et al. 2013). Several previous analyses have looked at the aerodynamic performance of Microraptor: what makes our study different, and what did we conclude?

The famous Microraptor gui that you've seen a hundred times before. Justifiably famous: it's beautiful thing. The specimen is owned by the Institute of Vertebrate Palaeontology and Palaeoanthropology, Institute of Vertebrate Palaeontology and Palaeoanthropology and is registered as V13352.

Microraptor – first reported from the famous Yixian Formation of China’s Liaoning Province in 2000 – is well known for being a four-winged dinosaur: it has long feathers on its forelimbs, like a bird, but equally long feathers on its hindlimbs. The rest of the animal is thickly covered in plumage as well, and a large, fan-like array of feathers also surrounds the end of its tail.

Microraptor was originally described from a single fragmentary fossil that revealed few of its peculiarities. However, it has since been described from numerous specimens and its osteology, dentition and plumage can now be considered reasonably well known (Hwang et al. 2002, Xu et al. 2003, Hone et al. 2010, Li et al. 2012). Three species have been named (M. zhaoianus, M. gui and M. hanqingi) but it’s been argued that all are synonymous. A fourth species, Cryptovolans pauli, is also generally regarded as synonymous with M. zhaoianus.

Building a Microraptor: controversy and consensus

What, exactly, did we do in our new study? Colin made an accurate, poseable scale model of a Microraptor, kitted out with genuine feathers (from ducks and pigeons) attached in anatomically correct positions and orientations. Those who have been following the development of ideas on the life appearance of non-avian maniraptorans will be interested to note that our model’s head, neck and body has the streamlined look more typical of modern birds than of conventional reconstructions of Mesozoic dinosaurs: an inescapable consequence of our considering the full extent of all the feathering present in these animals.

Our Microraptor model, mounted in a wind tunnel and being subjected to an experiment. The model is mounted upside down, but this makes no difference as goes performance and results. Photo by Darren Naish. CC BY.

Previous reconstructions have sometimes gotten things wrong as goes feather attachment: the hindlimb feathers of Microraptor have asymmetrical vanes (as do the forelimb feathers), showing that they were arranged in a specific way relative to airflow (that is, the narrower side of the vane must have been arranged along the wing’s anterior edge). However, one previous reconstruction has the hindlimb feathers arranged perpendicular to airflow (Xu et al. 2003) and thus is very likely incorrect.

Based on feather and hindlimb anatomy, it seems that Microraptor held its legs such that the long feathers projected laterally or posterolaterally, their leading edges near-perpendicular to the sagittal plane. This raises lots of questions as to how mobile the feathers were: were they fixed in this pose, or were there muscles and ligaments in place that allowed them to be moved and folded away when not in use? We don’t know (yes yes, we’re fully aware that similar feathers are present in some domestic chicken and pigeon breeds). In fact, our understanding of these feathers is in its infancy: we don’t even have a nomenclature for them yet, plus there are all sorts of questions about the genetics involved in the evolution of these structures. Stay tuned.

Our Microraptor - it's called Maurice - in picturesque settings. The hindlimbs are shown here in an unrealisitic near-maximum sprawl. Photo from Dyke et al. (2013).

If the hindlimb feathers of Microraptor were held projecting laterally (remember that the longest feathers are on the metatarsus), this means that we agree approximately with the biplane-type configuration proposed by Chatterjee & Templin (2007) (though it doesn’t follow that the hindlimbs were held pressed together as Chatterjee and Templin supposed). Incidentally, it should be noted that some members of our team tried really hard to check, and test, Chatterjee and Templin’s proposed configuration. As we explain in the paper (Dyke et al. 2013), this is hard because it hasn’t been possible to replicate their methods; furthermore, Chatterjee and Templin didn’t demonstrate how their biplane configuration might generate lift.

Sprawling: bad. Legs down: good. Alternatives hindlimb postures tested for Microraptor, from Dyke et al. (2013).

One debate that surrounds the aerodynamic performance of Microraptor concerns hindlimb posture. In the very first study to discuss Microraptor’s possible flight abilities, it was depicted as being capable of a full-on sprawl, its hindlimbs projecting laterally in parallel with its arms (Xu et al. 2003). This sprawling pose was also promoted in another study (Alexander et al. 2010). Given that the form of the theropod femur and hip socket generally prevents the hindlimb from being abducted this far from the sagittal plane (there are proximally placed trochanters on the femur, and supra-acetabular shelves and antritrochanters on the ilium that prevent this sort of posture), this is surely incorrect (Brougham & Brusatte 2010).

However, there have been suggestions that microraptorine dromaeosaurids had a more spherical femoral head than most other theropods, and hence that they were indeed more capable of hindlimb abduction than is typical for this group. While it’s difficult to provide precise measurements on joint orientation, we manipulated our poseable model such that its femora were abducted for the amount that we deemed reasonable based on the fossils (especially those of Hesperonychus, a Canadian relative of Microraptor known from three-dimensional remains (Longrich & Currie 2009)). We didn’t favour the idea that Microraptor could sprawl.

To the wind tunnel!

Where the magic happens: inside one of the University of Southampton's wind tunnels. Photo by Darren Naish. CC BY.

The model was placed in one of the several University of Southampton wind tunnels and subjected to various simulations. In view of the controversy about hindlimb posture, we tested the model’s performance with sprawling limbs, with the limbs projecting straight downwards, and with the hindlimbs entirely removed. Aerodynamic performance was best when the limbs were in the straight-down posture (Dyke et al. 2013) – a satisfying result given that this is the configuration we regard as most likely. The tail operated as a lift-generating structure, meaning that Microraptor can accurately be described as a five-winged flier, not just a four-winged one.

Notably, Microraptor was never an efficient flier: it suffered from extensive drag in all simulations and was aerodynamically unstable, performing best when moving quickly. It was well able to glide no matter what the feather or wing configuration: in fact, we concluded that all Microraptor needed in order to glide effectively was a flat wing surface – feather asymmetry, anatomy and configuration didn’t make that much difference (Dyke et al. 2013), a discovery which supports the view that the evolution of theropod wing and feather anatomy did not occur within an aerodynamic context.

With its legs arranged in the 'legs-down pose' (red line), the model travelled for as much as 40% further than when its legs were in the sprawling pose. From Dyke et al. (2013).

The integrated Microraptor

You’d have to read the paper to appreciate the significance of these graphs: essentially, they show that a flat plate was just as good as a fully feathered wing in aerodynamic performance. From Dyke et al. (2013).

What might this mean for the ecology, biology and behaviour of Microraptor? Like several of the long-feathered Mesozoic paravians, Microraptor is something of an enigma. After all, it seems to combine a ‘typical’ non-bird theropod skeletal bauplan – traditionally associated with terrestriality and cursoriality – with massive, fully vaned feathers that seemingly have hallmarks of aerodynamic function. The fact that Microraptor was a half-decent glider, but not really a great one (it incurs all that drag, don’t forget), suggests that it was an occasional glider that could indulge in this behaviour, but didn’t rely on it as a specialisation: in other words, it wasn’t an aerial specialist, or a ‘flying squirrel dinosaur’ that spent most of its time leaping from tree to tree, relying on arboreal resources.

As we say (Dyke et al. 2013), I think that this is what we would predict based on what we already know about the morphology of Microraptor. It also matches what we know about its diet and lifestyle. There are indications from the claw curvature work that I published with Alexander Birn-Jeffery and colleagues late last year (Birn-Jeffery et al. 2012), for example, that Microraptor could climb, and the idea that Microraptor occasionally ate fish (Xing et al. 2013) is certainly contradictory to the view that it was a specialised, dedicated aerialist.

I think that our conclusions on the aerodynamic performance of this peculiar dinosaur are in agreement with our general ideas on its ecomorphology – and I haven’t discussed all the ramifications and conclusions of our study: those especially interested will want to read the paper. Applying sophisticated (and complex) aerodynamic modelling and the use of wind-tunnels to the study of Microraptor was great fun, but our work is – of course – definitely not the last word on this issue. Furthermore, Microraptor is but one of many: the Mesozoic fossil record has become populated by a growing number of near-bird paravians with particular wing and hindlimb configurations and feather arrangements, and we still know but oh so little.

For previous Tet Zoo articles on non-bird paravians and other maniraptorans, see…

Refs – -

Alexander, D. E., Gong, E., Martin, L. D., Burnham, D. A. & Falk, A. R. 2010. Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui. Proceedings of the National Academy of Science 107, 2972-2976.

Birn-Jeffery, A. V., Miller, C. E., Naish, D., Rayfield, E. J., Hone, D. W. E. 2012. Pedal claw curvature in birds, lizards and Mesozoic dinosaurs – complicated categories and compensating for mass-specific and phylogenetic control. PLoS ONE 7(12): e50555. doi:10.1371/journal.pone.0050555

Brougham, J. & Brusatte, S. L. 2010. Distorted Microraptor specimen is not ideal for understanding the origin of avian flight. Proceedings of the National Academy of Science 107, E155.

Chatterjee, S. & Templin, R. J. 2007. Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui. Proceedings of the National Academy of Sciences 104, 1576-1580.

Dyke, G., de Kat, R., Palmer, C., van der Kindere, J., Naish, D. & Ganapathisubramani, B. 2013. Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight. Nature Communications 4, Article number: 2489 doi:10.1038/ncomms3489

Hone, D. W. E., Tischlinger, H., Xu, X. & Zhang, F. 2010. The extent of the preserved feathers on the four-winged dinosaur Microraptor gui under ultraviolet light. PLoS ONE 5(2): e9223. doi: 10.1371/journal.pone.0009223

Hwang, S. H., Norell, M. A., Ji, Q. & Gao, K. 2002. New specimens of Microraptor zhaoianus (Theropoda: Dromaeosauridae) from northeastern China. American Museum Novitates 3381, 1-44.

Li, Q., Gao, K.-Q., Meng, Q., Clarke, J. A., Shawkey, M. D., D’Alba, L., Pei, R., Ellison, M., Norell, M. A. & Vinther, J. 2012. Reconstruction of Microraptor and the evolution of iridescent plumage. Science 335, 1215-1219.

Longrich, N. R. & Currie, P. J. 2009. A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America. Proceedings of the National Academy of Science 106, 5002-5007.

Xing, L., Persons IV, W. S., Bell, P. R., Xu, X., Zhang, J., Miyashita, T., Wang, F. & Currie, P. J. 2013. Piscivory in the feathered dinosaur Microraptor. Evolution 67, 2441–2445.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. JoseD 11:47 pm 11/18/2013

    Very interesting stuff that remind of a few questions.

    Does this mean that Microraptor was a glider (as opposed to a flapping flier)? Just making sure.

    Does this have anything to do w/Krentz’s Microraptor model (if so, it would explain why said model was reconstructed “legs down”) or Habib et al. 2012 from last year’s SVP meeting? Specifically, what does this mean for the latter’s results (if anything)?

    I was wondering you could explain Habib et al.’s hypothesis to me? I ask b/c I’m not completely sure I follow. Specifically, are they arguing that Microraptor was a glider that used its hindwings for stabilising/steering? I ask b/c it sounds like what the following Gardom/Milner & Holtz quotes are referring to. Is it &, if so, does that mean it’s an old idea that’s only just been tested scientifically?

    Many thanks in advance.

    Quoting Gardom & Milner ( http://www.amazon.com/Natural-History-Museum-Book-Dinosaurs/dp/184442183X/ref=sr_1_1?s=books&ie=UTF8&qid=1384835424&sr=1-1 ): “This has given rise to speculation as to whether there might have been a four-winged gliding stage in flight evolution with the hind wings acting like stabilising canards on an aircraft.”

    Quoting Holtz ( http://www.geol.umd.edu/~tholtz/G104/lectures/104aves.html ): “Elongate leg feathers may have helped the dinosaurs steer during a dive, just as today some raptorial birds use them to help aim when diving for prey; similarly, the modified eumaniraptoran tail may have helped as a dynamic stabilizer in flight (as well as on the ground, or while in the trees).”

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  2. 2. JoseD 11:48 pm 11/18/2013

    In my previous comment, I meant to say “Very interesting stuff that reminds me of a few questions.” Silly me.

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  3. 3. WillemvanderMerwe 5:07 am 11/19/2013

    What I’d like to know is how well Microraptor could *run* with those long feathers on its legs.

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  4. 4. Jerzy v. 3.0. 6:44 am 11/19/2013

    Darren, congratulations for the publication!

    Why not call these leg feathers hind-primaries, hind-secondaries, hind-tertials, hind-scapulars and hindleg coverts?

    BTW, modern birds, especially songbirds, are able to greatly bend their legs sideways in the tibio-tarsal joint (or however it is called). I wonder if Microraptor could do it, and how it would affect its flight?

    BTW, do I see well that ‘hind-secondaries’ are pale with darker tips?

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  5. 5. Dan1701 6:50 am 11/19/2013

    A habitat and lifestyle that might make some sense for microraptor would be if it was living in very rocky, precipitous terrain. Most of the time it would be a terrestrial hunter, mostly after insects and small animals, and the gliding would be mostly used as a way of getting down from rocks or cliffs, most likely not as an escape mechanism but as an easier way of moving than just jumping.

    That sort of lifestyle also gives an easy evolutionary pathway from “small raptor” to “small raptor that can glide”, without introducing the complexities of turning a tree-climbing specialist into a glider. Living in a very precipitous sort of environment would also limit the numbers of big, cursorial predators in the environment; any animal trying to glide in an environment where there are fast predators wouldn’t get all that far down the evolutionary pathway (you will note here that flying squirrels, gliding lizards, gliding snakes and frogs etc never deliberately head for the ground; the ground is dangerous to an arboreal animal with adaptations also to glide, as on the ground are purely terrestrial predators that are faster than the gliders).

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  6. 6. Dartian 7:45 am 11/19/2013

    Dan1701:
    flying squirrels, gliding lizards, gliding snakes and frogs etc never deliberately head for the ground

    Never say never. Flying squirrels occasionally do land on the ground on purpose, and gliding snakes do that too. In a paper by Socha (2011), there is even a photo of a Chrysopelea taken the moment before it’s about to land on the ground.

    the ground is dangerous to an arboreal animal with adaptations also to glide, as on the ground are purely terrestrial predators that are faster than the gliders

    That may be so, but at least some gliding arboreal vertebrates nevertheless do spend significant amounts of time on the ground – or even in the water. Many flying squirrels, for example, frequently forage on the ground (eating, e.g., fungi). And gliding snakes are excellent swimmers that do not hesitate to swim across long stretches of open sea; Chrysopelea paradisi was, in fact, one of the first non-flying vertebrates to colonise the (at first mostly treeless) Krakatau Islands after the devastating 1883 volcanic eruption (Thornton, 1997).

    References:

    Socha, J.J. 2011. Gliding flight in Chrysopelea: turning a snake into a wing. Integrative and Comparative Biology 51, 969-982.

    Thornton, I.W.B. 1997. Krakatau: The Destruction and Reassembly of an Island Ecosystem. Harvard University Press, Harvard and London.

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  7. 7. naishd 9:08 am 11/19/2013

    Thanks for comments so far. Dan1701: Microraptor did not live in rocky places, so far as we can tell from the fossil record. The numerous specimens now known all come from densely forested, temperate habitats where there are abundant lakes and ponds.

    Darren

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  8. 8. MMartyniuk 9:22 am 11/19/2013

    Great research Darren, and it seems to fit in line with everything we’re seeing in the osteology regarding only marginal at best ability to climb trees.

    however, i’d also be curious to see more research on paravian pectoral girdle arrangement. The standard thinking seems to be that these things couldn’t elevate the arms to flap (e.g. Senter), but the relevant studies always seem to be on larger, more obviously terrestrial species like Deinonychus. IIRC Agnolin and Novas in “Avian Ancestors” suggested the glenoid was more dorsal than usually stated, for some reason (don’t have copy handy) but I don’t think they elaborated on this…

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  9. 9. Raptormimus456 10:42 am 11/19/2013

    Considering Microraptor seems to have fish on the menu, maybe it used it’s wings to lure fish in (presumably spreading them fully and hovering them above the water to generate shade, which the fish would be drawn towards and subsequently into Microraptor’s neck range).

    Considering it’s subpar gliding capabilties it’s probably not hunting flying insects like moths or flies (unless it somehow ambushes them), so it seems fish and mammals probably made up the majority of the Microraptor diet, possibly with some fruit tossed in. Also, as Darren said; “The numerous specimens now known all come from densely forested, temperate habitats where there are abundant lakes and ponds”, which means it really only has a couple of niches that make sense; a bad-at-gliding shiny black opsrey, a shiny black heron or a tiny version of a phorosrachid that preyed on other small animals. That was also shiny black. And knew how to swim.

    I do wonder when Darren will ever cover those fruit-loving crocodylians the TetZoo tenants hold so dear on the new blog (if he hasn’t already), considering they generated as much comments as they did on V2, but of course Darren’s the one deciding our TetZoo content, not me, so I have no say in such matters. :P

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  10. 10. JoseD 10:58 am 11/19/2013

    WillemvanderMerwe: “What I’d like to know is how well Microraptor could *run* with those long feathers on its legs.”

    I’ll 2nd that.

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  11. 11. Gigantala 12:25 pm 11/19/2013

    So, we are to take that wing feather asymmetry did not evolve in response to aerial locomotion? Is there any circumstances where wing feather asymmetry would evolve other than powered flight?

    Does this study take into consideration Agnolin and Novas 2013, where it is shown that Microraptor both had a more dorsal glenoid and a bastard wing? Or have their observations being dismissed?

    For the moment, it doesn’t make any sense for Microraptor to be a usually flightless animal that occasionally glided, though it could maybe reflect a lifestyle akin to that of dimorphodontids, fowl and woodpeckers, spending most time on the ground and using quick flights.

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  12. 12. andrewwright73 3:07 pm 11/19/2013

    Chrysopelea definitely head for ground. I startled one that was coiled in a dead tree next to my school’s football pitch in Bangkok, and it glided to the grass (about 3m distance in height) and shot off into the bushes. We used to work in a leafy area in Bangkok and this has happened at least four times to teachers at our schools. If you corner one they will turn and strike, but their preference is for cover, including holes in the ground (aerial, scansorial and fossorial!).

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  13. 13. Jerzy v. 3.0. 3:27 pm 11/19/2013

    Just a quick thought, that hindleg wings of Microraptor might have no special function in flight, and be display ornaments. Which would fit with the iridescent plumage, peculiar double tail and likely feathered crest. Microraptor would then be an analogue of argus pheasant.

    I also wonder if supposed nocturnal adaptations may be interpreted as living in the dim rainforest floor. Some modern birds living in the forest undergrowth (like thrushes or kagus) have extremely big eyes.

    So I can put a provocative prediction: that some of smaller specimens of Microraptor upon closer inspection, will lack hindleg wings, and be juveniles or females.

    And some talented artist (hint) might even estimate how Microraptor could stretch its limbs and reconstruct a display posture. It may be similar to some birds of paradise like parotias and sicklebills. There, elongated feathers on different parts of the body come together, and create a single peculiar shape, like a circle (parotias) or a flag or a long panel (sicklebills).

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  14. 14. MMartyniuk 4:12 pm 11/19/2013

    @Gigantala: The holotype of Microraptor gui clearly has long pennaceous feathers on the first manual digit that seem like they would correspond to an alula. This is clearly visible even in low-res photos. I think the significance if generally downplayed because many paravians are known to have feathers covering the fingers to the claw, contrary to much of the art out there, and the homology is not entirely clear as Confuciusornis appears not to have significant feathering on most of digit I. Lack of alula in C. sanctus is probably real given the sample size. It may have been lost secondarily, but that alone could argue these early bastard wings were not used for an aerodynamic purpose as in modern birds, but are leftovers from a streamlining or insulating role.

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  15. 15. MMartyniuk 4:18 pm 11/19/2013

    @Jerzy v. 3.0.
    The M. gui fossil in the article here appears to be the cast on display at the travelling Jehol museum exhibit. The feathers are painted on and don’t match the original all that closely.

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  16. 16. naishd 5:06 pm 11/19/2013

    I should note that we’re aware of the alula present in Microraptor – I wanted Colin to add it since I knew that people would mention it – but it was left out since it was not relevant to the specific experiments we ran.

    As for the idea that hindlimb (and forelimb?) feathering in these dinosaurs is driven by a display role… yes, a very interesting possibility that we hint at in parts of the paper. Some readers here will know of my involvement in work on sexual selection and the evolution of complex feathers. We’ll come back to the subject in time…

    Darren

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  17. 17. Gigantala 5:21 pm 11/19/2013

    @MMartyniuk: Fair enough, though I still think there should be some comparisions between thumb feathers in availiable specimens that have them.

    @Hindwings as display devices: Shouldn’t they be less aerodynamic and more akin to those of Pedopenna, though?

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  18. 18. llewelly 8:32 pm 11/19/2013

    Vertical tailfins in modern aircraft often serve both as display and as stabilizers.

    Why couldn’t microraptor’s leg feathers do both as well?

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  19. 19. David Marjanović 12:34 am 11/20/2013

    Dan1701: Microraptor did not live in rocky places, so far as we can tell from the fossil record. The numerous specimens now known all come from densely forested, temperate habitats where there are abundant lakes and ponds.

    …and the occasional Yutyrannus.

    I also wonder if supposed nocturnal adaptations may be interpreted as living in the dim rainforest floor.

    Forest, yes, but it wasn’t tropical at all. Note the complete absence of semiaquatic crocodiles.

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  20. 20. Jerzy v. 3.0. 8:12 am 11/20/2013

    “@Hindwings as display devices: Shouldn’t they be less aerodynamic and more akin to those of Pedopenna, though?”

    In living birds there are both cases. Long secondaries of male argus pheasant are used for display and reduce the ability to fly, but they are still aerodynamic flight feathers.

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  21. 21. Jerzy v. 3.0. 9:11 am 11/20/2013

    Random news of the day: reptile cognition article. Tracking down the original papers may be worthwhile, esp. the evidence of social learning in tortoises.

    http://www.nytimes.com/2013/11/19/science/coldblooded-does-not-mean-stupid.html?smid=pl-share&_r=0

    I had a pet water turtle when I was young, and once had an idea to teach it to ring a bell for food. In two hours or so it learned.

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  22. 22. Mike from Ottawa 2:28 pm 11/20/2013

    As someone who doesn’t have the knowledge to contribute to the substance of the discussions here at TetZoo, reading a post here is a two part process. First I read Darren’t post. Then I wait a day or two to let the usual crew of erudite commenters contribute and I read the comments.

    I’m very grateful not only to Darren for the post, but to the commenters who add so much to the TetZoo experience, so thank you very much guys!

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  23. 23. Heteromeles 3:00 pm 11/20/2013

    So, based on diet and such, could we call this thing a four-winged proto-crow, at least ecologically?

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  24. 24. EWilloughby 7:57 pm 11/20/2013

    “And some talented artist (hint) might even estimate how Microraptor could stretch its limbs and reconstruct a display posture. It may be similar to some birds of paradise like parotias and sicklebills. There, elongated feathers on different parts of the body come together, and create a single peculiar shape, like a circle (parotias) or a flag or a long panel (sicklebills).”

    Well, I drew this a while back: http://emilywilloughby.com/gallery/paleoart/microraptor-threat-display

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  25. 25. Jerzy v. 3.0. 7:14 am 11/21/2013

    “how well Microraptor could *run* with those long feathers on its legs”

    I propose non-avian maniraptorians had erector muscles in the skin. These muscles are used by modern birds to raise and lower feathers. The bird thermoregulates by puffing or lowering feathers, or in display raises and lowers a crest, ruff etc.

    If so, leg feathers of Microraptor could be neatly pressed against the tarsus in the running animal, and spread in display and after death.

    @EWilloughby – nice!

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  26. 26. Gigantala 10:13 am 11/21/2013

    “So, based on diet and such, could we call this thing a four-winged proto-crow, at least ecologically?”

    More like a proto-pheasant, based on it’s lifestyle, volant or not.

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  27. 27. Heteromeles 10:33 am 11/21/2013

    Pheasants eat fish?

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  28. 28. Yodelling Cyclist 11:29 am 11/21/2013

    Many congratulations on the paper. Am currently saving up for what appears (based on Twitter) to be “Darren Naish: Life, All Of It(No Excuses)”.

    Another display of ignorance: I appreciate (thanks to Darren’s podcast comments)that it is hard to phylogenetically resolve the relationships of these basal winged therapods (I’m being deliberately vague here), but is it possible that multiple lineages attempted aerial activities with the aid of feathers (prior to being winnowed to just present day birds)? Such inherently high drag features strike me as being prone to adaptation and selection under (literal) aerodynamic pressures.

    Points based on the paper: a.) centre of mass is indicated, where is centre of pressure for the varying configurations(am I just blind)?

    b.) Based on a human skeleton, would you predict Jean Claude Vann Damme’s (spelling may well be wrong) splits?

    c.) Just an observation, but the below wing-plane stabiliser arrangement is the same as for a predator drone, which looks a bit microraptor-y now.

    Regards
    Yod

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  29. 29. Gigantala 1:50 pm 11/21/2013

    “Pheasants eat fish?”

    Yes, though opportunistically. Green Peafowl in wetland areas do feed on several aquatic invertebrates, so fish is not a stretch.

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  30. 30. THoltz 3:03 pm 11/21/2013

    You can infer humans can do splits because we, like many mammals, have a ball-and-socket joint between the femoral head and the acetabulum. Dinosaurs (including Microraptor and birds) have a different form of articulation: more of a roller-joint than a ball-and-socket.

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  31. 31. Heteromeles 4:44 pm 11/21/2013

    “Pheasants eat fish?”

    Yes, though opportunistically. Green Peafowl in wetland areas do feed on several aquatic invertebrates, so fish is not a stretch.

    Um, I do have to point out that green peafowl eating aquatic inverts is not quite the same as pheasants eating fish. On a bigger scale, the angiosperm grains and fruits that pheasants normally ate were only starting to evolve when Microraptor was galumphing around, so it’s more than a stretch to talk about a pheasant niche in the middle mesozoic.

    What I’m talking about is a smallish generalist forager and scavenger that happens to be black. Presumably the black color is functional in some way, not just random? That sounds like a crow to me. Admittedly, the fit is bad, because I doubt Microraptor had the brains for the social antics and problem solving that crows demonstrate, but it’s the best I can think of at the moment.

    Link to this
  32. 32. Tayo Bethel 5:18 pm 11/21/2013

    @Heteromeles

    Small generalistpredator/scavenger sounds about right not only for Microraptor but for many small maniraptorans.

    Question: Dowe know whether Microraptor had contour feathers all over the body or if it had down feathers on the head and body combined with largelimb feathers?

    Link to this
  33. 33. Yodelling Cyclist 6:45 pm 11/21/2013

    THoltz: thank you for the reply.

    I have another question: could Microraptor have ground launched?

    Link to this
  34. 34. Biology in Motion 12:25 am 11/22/2013

    JoseD: Thanks for the interest in the work that I presented with my colleagues at SVP in 2012. What we set out to do was quite similar to what Darren and his colleagues have done, except that we looked at the problem from a theory standpoint, rather than an experimental standpoint. Our point was that vertically-oriented hind limbs (or nearly vertical ones) could still be aerodynamically active in an advantageous sense, by generating large moments in roll and yaw that could control the flight path of the animal. We demonstrated, algebraically, that the expected improvement in turning radius by using vertically oriented hind limbs (in Microraptor) would be substantial. This would apply to any type of flight path: a steady glide, flapping flight, or a rapid descent/pouncing scenario. This result removes yet another argument for sprawling models (they had been previously suggested to be the only way to produce an aerodynamically active hindwing – we showed that this is not the case).

    Link to this
  35. 35. Dartian 2:29 am 11/22/2013

    Yodelling Cyclist:
    Jean Claude Vann Damme’s (spelling may well be wrong)

    A hyphen is missing and there’s an extra ‘n’ there, but otherwise it’s right; it’s Jean-Claude Van Damme. (Which, incidentally, is just his stage name. According to Wikipedia, his real name is Jean-Claude Camille François Van Varenberg.)

    Heteromeles:
    the angiosperm grains and fruits that pheasants normally ate were only starting to evolve when Microraptor was galumphing around, so it’s more than a stretch to talk about a pheasant niche in the middle mesozoic.

    Good point.

    Presumably the black color is functional in some way, not just random? That sounds like a crow to me.

    Why are crows black? Interesting question. I’d guess that their blackness is primarily related to social or behavioural reasons rather than ecological or physiological ones (blackness certainly doesn’t make crows more cryptic and inconspicuous, for instance) – but that’s just my guess.

    As for extant birds with wholly black plumage living on the (rain)forest floor, cassowaries come to mind. Although apart from colour, I can’t think of any obvious morphological similarities between cassowaries and Microraptor.

    Link to this
  36. 36. llewelly 7:13 am 11/22/2013

    Hm. Black, you say?

    Black to bird eyes, which see with four primary colors, and typically have strong color vision, or black to mammal eyes, which have only two primary colors, and many non-color capable rods on their retinas?

    For micro-raptor, I fear the answer is unknown, but if it could be determined, it would be very interesting, as it might imply something about the importance of small mammals in its diet … or, much less likely, that it figured in the diet of an as yet undiscovered predatory mesozoic mammal.

    For crows, and for cassowaries, the answer I am sure is known, but I don’t know it, and I hope somone here does.

    Link to this
  37. 37. llewelly 7:16 am 11/22/2013

    (Oops. I forgot a parenthetical note about the three primary colors most old-world and some new world monkeys see with. But perhaps that isn’t relevant to the Mesozoic … )

    Link to this
  38. 38. Gigantala 9:17 am 11/22/2013

    “Um, I do have to point out that green peafowl eating aquatic inverts is not quite the same as pheasants eating fish. On a bigger scale, the angiosperm grains and fruits that pheasants normally ate were only starting to evolve when Microraptor was galumphing around, so it’s more than a stretch to talk about a pheasant niche in the middle mesozoic.”

    Angiosperms were rare, but other plants, like podocarps, gingkos and bennettitales would have provided seeds and “fruits”. Jinfengopteryx was found with seeds within, after all, which suggests pheasant like “granivory” was occuring to some extent among early maniraptors.

    The point is more that Microraptor was a terrestrial omnivore which probably relied on short flights, which is not compatible with a corvid-like ecological niche.

    Link to this
  39. 39. Heteromeles 11:07 am 11/22/2013

    @gigantala: We’ll have to agree to disagree then. I generally see crows and ravens foraging on the ground, as well as eating fruits from trees. As for podocarps, gingkos, and bennettitales (and cycads), we can get in an endless argument about whether the fruits of these woody plants are equivalent in size, foraging pattern, nutrition, and toxicity to the grass seeds and small berries favored by modern pheasants. We can also argue endlessly about whether the hypothetical flights on microraptor were equivalent in function to the fast take off, short distance flights that pheasants specialize in.

    As for the color, for all I know, black feathers are stronger, and the color may be a side effect of a need to have longer-lasting feathers for some reason.

    Link to this
  40. 40. naishd 12:25 pm 11/22/2013

    With respect to last comment, there is indeed some work showing that melanosomes help feathers to withstand abrasion – to ‘make them stronger’. I at least mentioned this in one of the petrel articles from 2012.

    Darren

    Link to this
  41. 41. David Marjanović 8:04 am 11/23/2013

    Black to bird eyes, which see with four primary colors, and typically have strong color vision, or black to mammal eyes, which have only two primary colors, and many non-color capable rods on their retinas?

    Indeed: are crows black, or are they bright shiny ultraviolet?

    Link to this
  42. 42. Jerzy v. 3.0. 1:58 pm 11/23/2013

    @41
    Crows are shiny black. Ultraviolet enhances coloration of some birds (mainly plumage parts which are already shiny blue for our eyes) but does not change plumage very dramatically – at least in cases I know.

    Actually I am slightly confused what is known about the plumage of Microraptor. Are melanosomes similar to glossy black feathers, or just dark, glossy feathers? Later the authors compare plumage to a blackbird – do they mean male European Blackbird, Turdus merula, which is actually dull black and hardly glossy? At the same time, other people noticed suggestions of dark and pale bands on feathers.

    (Yes, actually it is amazing that we can say anything about dinosaurian plumage at all).

    Link to this
  43. 43. llewelly 2:48 pm 11/24/2013

    “As for the color, for all I know, black feathers are stronger, and the color may be a side effect of a need to have longer-lasting feathers for some reason.”

    If we’re talking about a forest floor bird, a reason could be to withstand abrasion from heavy brush.

    Abrasion from intra-specific combat comes to mind as well.

    Link to this
  44. 44. Tayo Bethel 2:59 pm 11/24/2013

    I cant think of any forest floor birds that are black—or at least none the size of Microraptor. Most forest floor birds are dull and cryptic.

    Link to this
  45. 45. Dartian 2:32 am 11/25/2013

    Tayo:
    I cant think of any forest floor birds that are black—or at least none the size of Microraptor.

    There is, at least, the black guineafowl Agelastes niger. The male satin bowerbird Ptilonorhynchus violaceus is also black(ish).

    Link to this
  46. 46. Yodelling Cyclist 3:31 am 11/25/2013

    Black curassow.

    Link to this
  47. 47. Gigantala 12:03 pm 11/25/2013

    Still, all are tropical birds that presumably are also camouflaging themselves.

    Link to this
  48. 48. JoseD 12:12 am 11/26/2013

    @EWilloughby & Jerzy v. 3.0

    Don’t forget about Luis Rey (See “The New Chinese Revolution Part 2″: http://www.luisrey.ndtilda.co.uk/html/chin1to4.htm ).

    Link to this
  49. 49. Dartian 2:14 am 11/26/2013

    Yodelling Cyclist:
    Black curassow

    It’s not wholly black, however; its plumage has fairly large white parts too. If we also consider birds that are mostly (as opposed to wholly) black, then the list of ‘black’ forest-floor birds obviously gets longer – it includes then, for example, trumpeters and various galliforms.

    Gigantala:
    all are tropical birds that presumably are also camouflaging themselves

    That’s definitely not the case with the male satin bowerbird – to the contrary, it goes out of its way to be conspicuous (to its conspecifics, especially females).

    The satin bowerbird isn’t exclusively tropical, by the way; it is found quite far south in eastern Australia. If you want wholly non-tropical examples of (mostly) black birds living on the forest floor, there are the males of black grouse and capercaillies (which, like the male satin bowerbird, obviously don’t use their plumage for the purpose of crypsis).

    Link to this
  50. 50. Jerzy v. 3.0. 9:07 am 11/26/2013

    There are quite a lot of glossy black birds in the tropical forest floor: some Lophura pheasants, guans and curassows, brush turkey, trumpeters, some tapaculos, melampittas etc. And cassowaries, naturally. There are also black small carnivores like mongoose and melanistic morphs of cats and civets.

    There is also even more birds with dull glossy plumage – like many other pheasants.

    In temperate forests, there are also males of some thrushes and South American tapaculos. However, not many birds in modern temperate forests live on the forest floor: snow.

    Link to this
  51. 51. rrockman 6:22 pm 12/2/2013

    A very comprehensive study, the like of which I can’t seem to find for pterosaurs.

    I have had many discussions recently with people from physics and engineering backgrounds that contest the fight ability of pterosaurs, mainly on the basis of lack of lift compared to birds due to lack of feathers, and a very forward positioned center of mass due to lack of tail.

    I still haven’t found papers studying the aerodynamics of pterosaurs in these terms, and models “surviving” flight tests or wind tunnels without additional stabilizers or similar artifacts. Can somebody point me in the right direction to find works like these? As a junior paleontologist, I hate not being able to reply sensibly to their claims, especially since they claim that 160 million years of wings don’t prove flight..!

    Link to this
  52. 52. David Marjanović 6:17 pm 12/14/2013

    “lack of lift compared to birds due to lack of feathers”

    Seriously?

    “a very forward positioned center of mass due to lack of tail”

    Same for birds, then. Also, what about the long-tailed pterosaurs?

    Link to this

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