Pterosaurs - the charismatic flying archosaurs of the Mesozoic Era - fall fairly nearly into two great assemblages: the primitive, mostly long-tailed basal forms (or 'rhamphorhynchoids') and the more strongly modified, consistently short-tailed pterodactyloids. Pterodactyloids emerged in the Middle Jurassic and persisted to the very end of the Late Cretaceous, and fossils show that they did an awful lot more in their evolution than did non-pterodactyloid pterosaurs. Several lineages evolved giant size, and bizarrely specialised skulls and dentitions show that they took to filter-feeding, mollusc cracking, and perhaps to frugivory, carrion feeding and terrestrial stalking (Wellnhofer 1991, Wellnhofer & Kellner 1991, Unwin 2003, Witton & Naish 2008). A list of anatomical characters show that pterodactyloids are most closely related to the rhamphorhynchids (Kellner 2003, Unwin 2003) - a group of Jurassic non-pterodactyloid pterosaurs that have a relatively low number of needle-like teeth and are best known for Rhamphorhynchus from the German Solnhofen Limestone. While intermediates between rhamphorhynchids and pterodactyloids are hypothesised to have existed, they have remained unknown. Until now [image above shows Darwinopterus predating on small maniraptoran theropod: image by Mark Witton].
Today see the publication of a remarkable new kind of pterosaur that bridges the gap between non-pterodactyloids and pterodactyloids, and it exhibits a surprising melange of characters. Named Darwinopterus modularis LÃ¼ et al., 2009, it's from the Tiaojishan Formation of Liaoning Province, China. The age of the Tiaojishan Formation has been controversial, and until recently many workers regarded it as Lower Cretaceous. However, the most recent work indicates a Middle Jurassic age (see supplementary data in LÃ¼ et al. (2009)). This is significant for reasons not related to pterosaurs, as the Tiaojishan has yielded small feathered maniraptoran theropods, most notably the troodontid Anchiornis (Hu et al. 2009: originally identified as a basal bird, and discussed as such here on Tet Zoo. Shown here, as restored by Hu et al. (2009). Wow, those feathered dinosaurs sure did look stupid). Anyway, the new taxon's name of course commemorates the 200th anniversary of Darwin's birth and 150th anniversary of the publication of Origin: a very fitting name, given the fact that - as we'll see - Darwinopterus represents a transitional fossil of the sort that Darwin predicted.
Like rhamphorhynchids and unlike pterodactyloids, Darwinopterus has a long fifth toe composed of two elongate phalanges, a proportionally short metacarpus, and a long tail with 27 vertebrae. These features are absent throughout pterodactyloids and are characteristic 'basal pterosaur' features. When alive, Darwinopterus would have superficially resembled a rhamphorhynchid, with a broad and obvious cruropatagium (the membrane that stretched between the fifth toes of both feet and incorporated the tail base), relatively short wings, and probably a diamond-shaped structure at the tip of its long tail.
Yet the great paradox about Darwinopterus is that it combines this archaic body plan with a neck and skull that look like that of a fully-fledged pterodactyloid. In short, Darwinopterus looks like a weird hybrid: a pterodactyloid head on a 'rhamphorhynchoid' body.
It seems reasonable to wonder whether this association is genuine. Happily, we can reject any possibility of fakery or chance association: the type specimen is - while not preserved in complete articulation [it's shown above; image courtesy of D. M. Unwin] - convincingly associated (that is: it's obvious that the skull and neck really do belong together with the rest of the skeleton). Even better, more than one specimen is known (like, about 20!), and at least one of these does have the head-neck ensemble articulated with the rest of the skeleton.
Interestingly, Darwinopterus's skull [shown above; image courtesy of D. M. Unwin] doesn't just recall that of a generic pterodactyloid, but specifically resembles such pterodactyloid taxa as the dsungaripteroid Germanodactylus. This at least suggests the possibility that the skull morphology seen in some basal pterodactyloids is a plesiomorphic hangover, and we may have to change some of our views on character polarity. A low, bony crest with a fibrous surface texture extends along much of the length of Darwinopterus's forehead and snout, and the nostril and antorbital openings are combined to form the nasoantorbital opening typical of pterodactyloids. The neck is proportionally long (even for a pterodactyloid).
Darwinopterus the modular pterosaur
So it's almost as if the head and neck were evolving at different rates from the rest of the body: in other words, Darwinopterus looks like a classic case of 'mosaic evolution' or modularity (hence the species name). This much-discussed evolutionary phenomenon has been considered controversial, in part due to a lack of good examples: Darwinopterus looks like one of the best yet discovered, and this isn't lost on LÃ¼ et al. (2009).
Darwinopterus lends support to the hypothesis that different segments of anatomy - the modules - can become disassociated, and then evolve at separate rates relative to one another. The linkage of pterosaur fore- and hindlimbs by way of the wing membranes has long led to suggestions that they formed part of the same module. The fact that Darwinopterus has a pterodactyloid-style skull and neck suggests that the head-neck module was decoupled from the rest of the body, and hence that members of the Darwinopterus + pterodactyloid clade first evolved a specialised head-neck module while still retaining a 'primitive' body. How is this sort of thing even possible? As LÃ¼ et al. (2009) state: 'the phenotypic modules identified here match closely to the expression domains of Hox genes ... This raises the possibility of a link between module selection and genetics and suggests a promising avenue for further exploration' (p. 7). Unfortunately, fossils aren't too amenable to genetic investigation [possible sequence of modular evolution in pterosaurs shown here, from LÃ¼ et al. (2009)].
Phylogenetic analysis confirms that, as strongly suggested by its apparent transitional nature, Darwinopterus is the sister-taxon to Pterodactyloidea (it has to be outside of this major clade, as published definitions are node-based*). LÃ¼ et al. (2009) found the Darwinopterus + pterodactyloid clade to be well supported in their analysis, and named it Monofenestrata. This is a reference to the evolution of the combined nasoantorbital fenestra, an autapomorphy of the clade, and previously thought unique to Pterodactyloidea [adjacent 'family tree', from Unwin (2003), shows simplified relationships between the pterosaur groups. Basal pterosaurs, aka 'rhamphorhynchoids', are down at the bottom in blue; pterodactyloids are in purple].
* Kellner (2003, p. 117) defined Pterodactyloidea as 'the most recent common ancestor of Pterodactylus and Quetzalcoatlus and all their descendants', and Unwin (2003, p. 158) defined it as 'Pteranodon longiceps, Quetzalcoatlus northropi, their most recent common ancestor, and all its descendants'. Both definitions are unsatisfactory. Kellner's would exclude ornithocheiroids if Unwin's topology is correct. Unwin's rests heavily on the hypothesis that ornithocheiroids (including pteranodontids) are the most basal clade within Pterodactyloidea: if ctenochasmatoids, or dsungaripteroids, are more basal than pteranodontids (as they are in many phylogenies) then they're excluded from Pterodactyloidea under his definition!
Aerial predation at the root of a radiation?
What, then, was Darwinopterus doing? We don't know, but we can make some good guesses. The rhamphorhynchid-like post-cervical skeleton of Darwinopterus was not well suited for terrestrial locomotion: its hindlimbs were short and weak, hindlimb movement would have been somewhat restricted by the large cruropatagium, the wrist region was short, and the wings were poorly suited for quadrupedal support. This description applies to non-pterodactyloids in general, and it seems that basal pterosaurs were all poor terrestrial locomotors, at least compared to pterodactyloids. And, in contrast to some other non-pterodactyloid pterosaurs, there are no indications that Darwinopterus was a proficient climber. Nor does it have any features that might be associated with swimming or diving. So, we can hypothesise that Darwinopterus was an aerial predator, doing whatever it did while on the wing.
Darwinopterus combines a proportionally huge, long-snouted skull with slender, widely spaced, spike-like teeth and a proportionally long, relatively flexible neck. One interesting possibility suggested by this combination of features is that it was an aerial predator of other flying vertebrates. Indeed, we know that Darwinopterus was contemporary with smaller pterosaurs, small gliding maniraptorans and gliding mammals. In fact, is it coincidental that this possible aerial predator appears in the fossil record at the same time as the earliest aerial maniraptorans? As regular readers of Tet Zoo will know, bats have become dedicated predators of other flying vertebrates (birds in particular) on several occasions, and it's always been surprising that pterosaurs didn't. Perhaps they did, though we need more analysis and better data before we can be at all confident about this [adjacent image shows the predatory phyllostomid bat Chrotopterus auritus eating a smaller bat. It was previously featured in this article on the evolution of vampires, and originally came from a website called Tropical Bats, now unfortunately defunct and unfindable].
Given that Darwinopterus was at the base of the largest and most diverse pterosaur clade, its anatomical and behavioural specialisations may well have set the stage for what was to come. How neat if aerial predation of little theropods 'drove' the early stages of the pterodactyloid radiation.
For previous articles on pterosaurs see...
- Dsungaripterid pterosaurs and the proliferation of Wittoniana
- The Wellnhofer pterosaur meeting, part I
- The Wellnhofer pterosaur meeting, part II
- The Wellnhofer pterosaur meeting, part III
- Crato Formation fossils and the new tapejarids
- Terrestrial stalking azhdarchids, the paper
- Pterosaurs breathed in bird-like fashion and had inflatable air sacs in their wings
- A month in dinosaurs (and pterosaurs): 4, flaplings and head-sails anew
- A month in dinosaurs (and pterosaurs): 5, pterosaurs vs birds, or not... or is it?
Refs - -
Hu, D., Hou, L., Zhang, L. & Xu, X. 2009. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus. Nature 461 640-643.
Kellner, A. W. A. 2003. Pterosaur phylogeny and comments on the evolutionary history of the group. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 105-137.
LÃ¼, J., Unwin, D. M., Jin, X., Liu, Y. & Ji, Q. 2009. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society B doi:10.1098/rspb.2009.1603
Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 139-190.
- . 2006. The Pterosaurs From Deep Time. Pi Press (New York).
Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books Ltd (London).
- . & Kellner, A. W. A. 1991. The skull of Tapejara wellnhoferi Kellner (Reptilia, Pterosauria) from the Lower Cretaceous Santana Formation of the Araripe Basin, northeastern Brazil. Mitteilungen der Bayerischen Staatssammlung fÃ¼r PalÃ¤ontologie und Historische Geologie 31, 89-106.
Nice post, Darren: thanks for using my image (see the story behind it here). Just a few points:
- In the Darwinopterus paper, LÃ¼ et al. (2009) do make some effort to move away from a node-based definition for Pterodactyloidea, stating that they now diagnose pterodactyloids through postcervical characters only. They don't go any further than this, but it may be an indication that at least one next Big Pterosaur Phylogeny Paper will use characters, instead of nodes, to define clades.
- "probably a diamond-shaped structure at the tip of its long tail"
At SVP, Dave Unwin mentioned that LÃ¼ Junchang was unhappy with the tail vane in the PR image, suggesting that Darwinopterus lacked one. I'm not clear, though, whether this reflects a conservative viewpoint (there is no direct evidence that this structure existed on Darwinopterus , after all) or a genuine reason to think that it lacked a tail vane (like other soft tissues presevered on the distal tail).
Hi Mark - thanks for the link to your article and congrats on the art. On definition of Pterodactyloidea, LÃ¼ et al. (2009, p. 5) say that 'we retain the phylogenetic definition and content of Pterodactyloidea used by other recent studies': it's their diagnosis that's based on post-cervical autapomorphies. In other words, we're no better off, unless there's a newer definition out there (don't have time to check).
As for tail vanes... we assume a widespread presence, but they're only definitely known for Rhamphorhynchus, Sordes and Pterorhynchus. If these are all really rhamphorhynchids (as they are in Unwin's phylogenies, but not necessarily in everyone else's), I suppose an argument might be made that they were unique to this clade. However, soft tissue data from other specimens is thin on the ground and it would be nice to know if they were present in, say dimorphodontids or campylognathoidids. Judging from reconstructions (both in the technical and popular literature), it seems that most pterosaur workers do indeed consider them widespread. I too would like to know if LÃ¼ is basing his opinion on evidence, or preference.
Yes, I had similar thoughts on the phylogenetic bracketing of tail vanes: all the taxa I could think of were rhamphorhynchids. The absence of tail vanes - and indeed tails - in pterodactyloids and anurognathids indicates that they weren't essential for pterosaur flight, an obnservation borne out by the drastic the variation in known vane morphology - long, lobbed structure in scapognathines, triangular or diamond shaped in rhamphorhynchines. It may not be entirely unreasonable to suspect that not all long-tailed pterosaurs had tail vanes, but, in most cases, the absence of such structures in fossil specimens will be difficult to distinguish from preservational effects. While we could, I suppose, find soft tissue from the distal tail, I'm not going to hold my breath: although wing membranes and soft-tissue crests preserve with some (not much, but some) regularity, pterosaur skin is represented by only a handful of finds.
Incidentally, the only long-tailed pterosaur restoration I can think of that lacks a tail vane is Owen's 1870 Dimorphodon (plus a few copycat images): have tail-vaned pterosaurs really been so prevalent for so long?
Good to see it out! Unfortunately it's in Proc. B, so I don't have access >:-( .
Re tail vanes: my guess is that long tails were there precisely because of the tail vanes--to have something with a long moment arm for stability. Lose the vane, lose the long tail.
the only long-tailed pterosaur restoration I can think of that lacks a tail vane is Owen's 1870 Dimorphodon (plus a few copycat images)
Do you consider Burian a copycat artist? He did a fairly well-known restoration of a vane-less Dimorphodon.
As for other long-tailed but vane-less pterosaur restorations, here's one of Eudimorphodon. So yes, such restorations do exist.
Cool, cool. I somehow managed to miss the SVP talk (probably it was at the same time as two other interesting talks); will have to find out later today if I have access to Proc. R. Soc. B in the lab. 20 specimens... incredible... I'm especially interested in why they consider it Middle Jurassic, when the new Anchiornis paper says Oxfordian.
Incidentally... is there any evidence yet that any nonavian maniraptoran was capable of sprawling? AFAIK not.
Dartian: Must've missed the Burian one or, at very least, not paid much attention to it: do you know of anywhere it's posted online?
Mark: The only online version of it that I've managed to find is this (those with poor eyesight, be warned).
Oh, I found another and better version here (scroll down to the Mesozoic stuff and click on the image to enlarge).
Padian and Rayner (1993) have a table of soft tissues that are preserved in various pterosaurs, and they say that one is present in Dimorphodon. I've not found any mention of this anywhere else, but Owen (1870) describes bony tendons lying alongside the tail, so I wonder if that's what they were thinking of.
Owen, R. (1870) Monograph of the fossil Reptilia of the Liassic Formations. Part II. Dimorphodon macronyx. Paleontographical Society, London, pp. 41â81.
Padian, K. and Rayner, J. M. V. (1993) The wings of pterosaurs. American Journal of Science, 293-A: 91-166.
While I'm at it... Here's a quite, er, interesting rendition of a flat-tailed Dimorphodon. (I don't know who the artist is, but the image is pretty old; from the 1950ies, I think. Interestingly enough, the Pteranodon restoration looks almost modern.)
Are you sure it's from the 50s? It looks like three well-known restorations copied by hand (in a remarkably incapable way) into the same picture, with a new background that features grass.
The homepage doesn't tell as far as I can see.
Are you sure it's from the 50s?
It may also be from the early 60ies, but not later than that. Unless I'm much mistaken, the illustration was originally made for the French GlobÃ©rama encyclopedia series (the volume called L'aventure de la Terre). There were several editions of this book series throughout the sixties; I don't know for sure when the first edition was published. (Here is the site where I found the image.)
That the image is a crude copycat job can't be doubted...
So...Darwinopterus may have been the pterosaurian equivalent of a spectral bat? Maybe that's why we don't find any falconiform-esque pterosaurs; all of the aerial predator pterosaurs filling said raptorial niche were acting like big killer bats as opposed to big killer hawks.
Maybe a similar reason is why many pterosaur clades evolved long snouts. Rather than extend their feet like hawks and screw up their various patagia (not to mention bringing them that much closer to the ground and crashing), they used their heads to snag prey.
Pterorhynchus does not have a tail vane of the same type as Rhamphorhynchus. I was very kindly passed a potograph of the tail of Pterorhynchus by John Nudds taken after additional preparation to that figured in Czerkas's book. This appears to show a series of small flanges, with squarish outline along both sides of the length of the tail, but no large vane at the end. Have not seen the specimen myself, so can only comment on the basis of the piucture, but if accurate, then this specimen demonstrates that a broad terminal vane is not a requirement for flight. There are some younger Rhamphorhynchus specimens with long tails that have smaller vanes. I suggest the vane has little to do with flight and much more to do with sex and an indication of adulthood/maturity.
Am I the only one who thinks Darwinopterus is the closest living thing to those awfull "monster pterodactyls" in old movies? You know, with rhamphorhynchid/dimoprhodontid/campylognathid tails and pterodactyloid heads
Darwinopterus is a good name, honoring the great man in his becentennial year, and on top of that, one of those "non-existent" transitional forms the creationists are always talking about!
Yes, Pterorhynchus has a long tail vane--I think it runs along something like a third of the tail. I've been very excited about Frank since the SVP talk, thanks for the article, Darren!
Could one of you kind souls forward me a copy of the paper? Proc. Roy. Soc. B still hasn't figured out open-access yet...
Also, wonderful picture, Mark! I LOVE that it's going after a theropod!
"Hu et al. 2009: originally identified as a basal bird, and discussed as such here on Tet Zoo. Shown here, as restored by Hu et al. (2009). Wow, those feathered dinosaurs sure did look stupid)"
Says the one who likes Slow Worms!
Seriously though, Darwinopterous rules.
Speaking of Pterorhynchus, I was curious whether these taxa were not in fact synonymous? Are they distinguished in the paper? They do appear to share much the same cranial form and details of the pterodactyloid head/neck and rhamphorhynchoid shouldsers/body/tail aspects. I do note that in the tree figure (4a) Pterorhynchus is merely one node down and in a polytomy with other "transitional" pterosaurus, like Sordes. However, the provenance of the material (slightly questionable for Czerkas' taxon) suggests a link, and the morphology is concordant between the two at least somewhat closer than, say, Sordes is:
1) short metacarpus, 2) long tail, 3) inclined quadrate, 4) confluent nasal and antorbital fenestrae.
Whereas details of the humerus and shoulder are obscured (and in this partly obscure the base of the neck, and may be disarticulated), and I do not think the preservation of the tail is clear enough to infer elongation of the zygapophyses, the teeth seem less numerous although of the same shape and proportions. The postcrania is certainly "non-pterodactyloid" in form, while the cranium and potentially the neck are pterodactyloid in form.
Half of the 'weirdness' of feathered maniraptors for me comes from the error.
Impressions of neck intergument show that that at least sometimes, the thin neck was masked by dense proto-feathers. So they resembled 'neck-less' modern birds, more like Bluetit than a snake-necked Jurassic Park monsters.
In real life, it would not be so different from some modern bird with more developed leg feathers, eg. Goshawk or some race of domestic chicken.
Is the size proportion accurate?
Pterorhynchus is probably from beds that are more or less contemporaneous with the Tiaojishan Formation (yes, there is a big debate about this in China, but its not all that pertinent here). So, we were particularly careful to determine whether the holotype and only known specimen of Pterorhynchus wellnhoferi might, or might not, be an early find of Darwinopterus. We concluded that it wasn't because, for example, it has a relatively small skull, and neck that place it well inside the pink 'rhamphorhynchoid' clouds in Figures 3a and 3b of our PRSSB paper. In addition, the skull construction (e.g. shape of the cranial crest, separate nasal and antorbital openings) appears to be quite different from that of Darwinopterus. In the published tree these taxa may appear to be quite closely positioned with respect to one another, but they are separated by a substantial number of character state changes. That all said, a detailed description of Pterorhynchus is sorely needed, but then again, that's true for many pterosaurs.
Thanks for clearing that up, Dave. Jaime had me wondering about that, too, though to be honest I haven't cracked open Pterorhynchus' description in forever (I have very little reason to crack that particular book open anyway).
I will discuss this in my upcoming post about Darwinopterus, though, if only to compare the skulls.
Cool post. You mention the possibility of aerial predation driving pterodactyloid evolution. Might this have driven maniraptorans to become better flyers as well?
I used to be a big fan of phylogenetic definitions, but I've come to believe that they're fine only as long as we are confident of the topology behind them. Their major purpose is to tell us what to call fossils that are attached to a tree anchored by extant taxa. Otherwise, they tend to clutter the nomenclature with junior synonyms (that weren't realized as such when defined).
The definitions just have to be made with minimal care. Many published before 2000 or something were created in complete carelessness...
Care is effective when the topology you're assuming is merely unresolved. It doesn't help when that topology is actively wrong.
Uncle Bob included a restoration of a flock of tail-vane-less dimorphodontids in The Dinosaur Herises. Do you folks not even have copies of that landmark text? Shame on you! :)
Thanks for the reply. My comment derives largely from the reprepared skull -- I have also seen a post-re-preparation photo of the material, and it shows a very short antorbital fenestra, a very short nasal with a long descending ramus, and a massive huge naris, but no trace of an ascending ramus of the maxilla that isn't adjacent to the premaxilla; which suggests, much like it does in Pterodactylus and even more so in Germanodactylus, that the external bony naris and the antorbital fenestra are confluent. Even if the remainder of the skull appears more or less rhamphorhynch-like, the elongated and tapered jaws and pronounced romus of the jaws anterior to the bony external nares are more pterodactyloid like than they are even like those of Dorygnathus, Sordes, et al.
I do appreciate you guys looking deeply into the issue with Czerkas' taxon, and hope that it does receive the detailed investigation it deserves, at least as a Liaoning (nonJehol) rhamphorhynch-like grade pterosaur.
"Also, wonderful picture, Mark! I LOVE that it's going after a theropod!"
Funnily enough I always thought that before Darwinopterus the rise of the birds was linked to their ancestors ability to hunt down pterosaurs. The pterosaurs had no competition so they would have been weak against the dromaesaurids.
As Darwinopterus show however, pterosaurs became powerful aerial predators at the time when dinosars were learning to fly.
I wonder how birds were able to carve out their own niche amongst the pterosaurs with such predators around.
"Might this have driven maniraptorans to become better flyers as well?"
Makes sense to me.
Eric brings a fascinating question: "how birds were able to carve out their own niche amongst the pterosaurs".
Birds diversity didn't prevent bats from finding their own way up to the skies, but in their beginning, proto-bats have probably found some peculiar niche to unleash their "rising".
Pterosaurs originated in Late Triassic, and birds in Late Jurassic (or maybe, Upper Middle Jurassic). Late Jurassic Proto- or near-birds were present in East Asia and Europe (Solnhofen), but not in Tendaguru or Morrison Fms (until now, at least). It'd lead us to point an origin for proto-birds in the shallow sea islands between Asia and Europe? Later Asian linneages became more diverse, reaching the phantastic diversity observed in Daohugou and Yixian sites.
When I first heard that Darwinopterus probably fed on small, feathered dinosaurs, it made me wonder if the selection pressure on them led to their ultimate development or further refinement of flight as an escape strategy? These interactions are what drives evolution! This is probable fodder for a Doctoral thesis.
How big was Darwinopterus? Basing on the scale bar, it was 70-cm-long.
And finally! a picture of a bat-eating bat. I always wondered whether those existed, but nobody I asked knew!
FYI: Wayback cache of Tropical Bats site at - http://web.archive.org/web/20080413071102/www.biologie.uni-ulm.de/bio3/… -
Contact info shown as: Dr. Marco Tschapka, Department of Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11
Care is effective when the topology you're assuming is merely unresolved. It doesn't help when that topology is actively wrong.
Even then it helps, unlike nobody has ever had the slightest inkling of doubt that it might possibly be wrong in favor of another topology. Take all topologies that have ever been proposed and all that you think are likely to ever be proposed into account when crafting a definition.
There is a weird and little known group called falcons Falconidae (little known apparently among paleontologists). They show that Darwinopterus could be just as likely a hunter of terrestrial organisms - either from soaring flight or from perch.
But there is nothing falcon-like about Darwinopterus: if it was an aerial predator as proposed, its anatomy indicates that it was grabbing reasonably large prey in flight, with its toothy jaws, and it lacks the predatory features seen in raptors. So, no, it was not just as likely a hunter of terrestrial organisms. I think that more likely analogues are big, predatory microbats, like ghost bats and some phyllostomids.
I'd like to point out something. This morning, out of morbid curiosity, I looked in my Czerkas book at Pterorhynchus. I don't think any sort of comparison with Darwinopterus is even possible. I'm not sure HOW the authors were able to restore the skull even tentatively. If it weren't for the fact that teeth are preserved near the tip of the snout, I'd have a hard time figuring out it was the skull. It is either encased in matrix, severely crushed, or bits and pieces of natural cast.
On the other hand, Darwinopterus' head looks a whole lot like Germanodactylus--I restored both skulls this morning based on the new paper and Wellnhofer's book. Even their crests are similar. How close is Germanodactylus to the base of Pterodactyloidea?
As Dave said earlier, there has been re-preparation of the material, and the entire skull is exposed with many details from the nasoantorbital region to the hyoid aparatus exposed, revealing a detailed (although still crushed) skull. The fracturing present is indicated in apparent absence of a portion of the braincase and occiput and of the material around the anterior end of the external body naris, which may or may not indicate the opening was smaller than is preserved, and obscures the dimensions of the region.
I just saw it over at Dinoforum, Jaime. Wonderful preparation! I still say the two are quite different, but I'll need to take a closer to look to be sure. Certainly the crest morphology is very different.
How close is Germanodactylus to the base of Pterodactyloidea?
There are three hypotheses on pterosaur phylogeny (by three groups of researchers) that contradict each other in major respects. Don't expect a consensus to emerge anytime soon.
Has Anchiornis actually been found to be a flyer as the artwork suggests. I haven't really heard anything to suggest this (although it may still be possible).
Comparing the skeletal drawing of Anchiornis with an image of Microraptor found on the internet I'm not sure that Anchiornis was that much of a glider, or a flyer. I still may be wrong though.
Actually I would like to retract that last statement.
But there is nothing falcon-like about Darwinopterus: if it was an aerial predator as proposed, its anatomy indicates that it was grabbing reasonably large prey in flight, with its toothy jaws, and it lacks the predatory features seen in raptors. So, no, it was not just as likely a hunter of terrestrial organisms. I think that more likely analogues are big, predatory microbats, like ghost bats and some phyllostomids.
I'm not so sure about the bat analogy. Most of the 'macropredatory' extant bats take plenty of non-flying prey; they catch such prey on the ground (pallid bat Antrozous pallidus with scorpion prey here), or on tree trunks and branches, or, in the case of fishing bats, at the water's surface. Aerial pursuit of birds or other bats* is not that common among extant chiropterans; false vampire bats et al. usually take such prey by surprise, preferentially from their victims' roosting places. It's true that the greater noctule bat Nyctalus lasiopterus is an apparent exception in this regard, but unlike those other carnivorous bats, which are mostly tropical, the greater noctule has seasonal (and predictable) access to large concentrations of nocturnally migrating passerines**.
* Under most circumstances, it's probably hard for a predatory bat to get close enough to another (microchiropteran) bat to be able to take it by surprise in mid-air. I'd expect that a small vespertilionid, molossid, or some other potential prey species would be able to hear the echolocation calls of an approaching megadermatid or large phyllostomid sufficiently well in advance to take evasive action.
** From a noctule's point of view (or rather, point of echolocation), a small passerine might be easier to catch at night in mid-air than a small bat - precisely for the reason that the passerine probably can't detect the approaching noctule in time.
I'm not so sure about the bat analogy.
I'm not sure either. It's a hypothesis. But you're right: I was imagining Darwinopterus to be an aerial hawker that grabs prey after pursuit; SOME predatory bats definitely do this (Greater noctules) but most are generally thought to grab prey while it's roosting. I say 'generally thought' because we don't seem to know much either way, and - since the discovery of Greater noctule predation on nocturnally migrating passerines - it's looking likely than pursuit predation of flying vertebrates occurs more widely among bats than hitherto realised. Note that bringing echolocation into the discussion is a bit of a red herring, as megadermatids at least will hunt predominantly by sight at times and not echolocate at all.
Bottom line is that there are no exact analogues for the inferred predatory behaviour of Darwinopterus, because there aren't volant predators that apprehend vertebrate prey, in flight, with the mouth alone. But I still think predatory bats come closest.
Note that bringing echolocation into the discussion is a bit of a red herring, as megadermatids at least will hunt predominantly by sight at times and not echolocate at all.
Yes, but don't megadermatids switch to using vision only when they are hunting non-flying prey? By the way, are you sure it's really vision that they mainly use? I thought 'gleaning' bats mainly rely on hearing. Do you have a reference?
there aren't volant predators that apprehend vertebrate prey, in flight, with the mouth alone.
But there are! Skuas and large gulls catch smaller birds in flight; great black-backed gulls, for example, catch prey the size of puffins that way. And frigatebirds catch flying-fish above the water's surface. (Aren't frigatebirds the classic living pterosaur analogies anyway?)
Finally, something off-topic but surely of general interest: David MarjanoviÄ finally has his own blog!
Yes, but don't megadermatids switch to using vision only when they are hunting non-flying prey?
Well, to date there isn't evidence that they hunt flying prey* (viz, all hunting is of non-flying prey), but it has indeed been shown and/or suggested (read on) that some gleaning bats (not necessarily just megadermatids) will rely on vision when light levels are good - though they obviously use hearing too, and rely on it more when light levels are lower. Bell (1985) found the phyllostomid Macrotus to _rely_ on vision when illumination was good enough, and when prey was silent, and suggested on the basis of this evidence that 'many other bats may use vision in some aspects of prey location' (p. 346). I was also influenced by John Altringham's statement: 'Although it has not been investigated, I suspect that the large eyes of many carnivorous bats are used in detecting prey - some individuals certainly use vision (e.g. Bell, 1985). The large, forward pointing eyes of the Australian ghost bat, Macroderma gigas, are almost owl-like' (Altringham 1999, p. 219). I may have inadvertently over-stated the case, as I'd forgotten that these were speculations rather than findings, sorry.
* By which I mean 'prey that are flying at the time of capture', not 'volant prey' (viz, birds, smaller bats).
As for oral apprehension of flying prey: I had completely forgotten about gulls and whatnot. Sigh, I really should have gone to bed earlier last night :)
As for David's blog: according to a comment he left on Pharyngula, it was created by mistake as a by-product of the login procedure that PZ has set up. I'm sure David can fill us in on all the details...
Refs - -
Altringham, J. D. 1999. Bats: Biology and Behaviour. Oxford University Press, Oxford.
Bell, G. P. 1985. The sensory basis of prey location by the California leaf-nosed bat Macrotus californicus (Chiroptera: Phyllostomidae). Behavioral Ecology and Sociobiology 16, 343-347.
I absolutely do not have my own blog. I had enough of being locked out of Pharyngula, so I signed up at the one identity provider that I had heard works (TypeKey/TypePad and Movable Type crash 2/3 of the time, OpenID displays the URL of the profile page instead of the username, and I already knew that LiveJournal, as its name suggests, is a blog-hosting site). I noticed rather late that vox.com is... wait for it... a blog-hosting site. During the registration process I actually deleted the stupid name and the deeply, deeply silly URL of the automatically created blog, but they must somehow have come back when I went on to the next page.
Right now I'm working on three papers at the same time, and I'm also supposed to do other things. Do not expect me to write any blog posts till my thesis is finished... and even then, assuming I actually have time, I'll try to find the best blog-hosting site, so I won't necessarily stick with Vox.
I'VE HAD IT WITH THE MOTHERFUCKING REGISTRATION ON THAT MOTHERFUCKING BLOG!!!
Darren, thanks for the Bell (1985) reference.
Registration at Pharyngula was turned off today. :-} Will be switched back on on Monday, though.
Concerning having a blog, I'll try to ask how much longer the "We want you" ad by ScienceBlogs will stay up. They seem to only want people who already have a blog, but... if the offer stays up till my thesis is finished...
you are confusing. Falcons show that adaptations for pursuing flying prey are identical as swooping on terrestrial prey (which is many times more numerous).
BTW - does any pterosaur have joint adaptations suggesting that it could hover?
Very useful for both aquatic (terns, kingfishers) and terrestrial (kestrels, kites) predators!
The first link goes straight to the pdf, the second to a page where you can download the Word file that is the supp. inf..
does any pterosaur have joint adaptations suggesting that it could hover?
No. That would require rotating the wing, or part of it, with respect to the body. Hummingbirds do it by rotating the shoulder joint; pterosaurs can't do that because their wings are attached to the body. Bats do it by rotating their forearms; pterosaurs can't do that because, well, they aren't mammals, forearm supination and pronation are just not possible without breaking bones.
Aerial predation on flying passerines is indeed more widespread in bats than previously recognised, it has also been confirmed in the great evening bat Ia io.
Why again are we comparing pterosaurs to bats? Since the mid 90s at least, the connection between models of pterosaurs as bat analogues has been on the decline, thanks to a long extensive effort on the parts of people like Chris Bennett and Kevin Padian. It's one of those "myths" of biology as extensive as the apparent distinction between "pterosaurs" and "pterodactyls" that blogger PZ Myers purports to educate on Pharyngula.
One major issue about aerial prey capture in birds is that many falconiforms do not use their jaws but their feet, so Darren is correct in asserting that there is nothing very "falcon-like" about ANY pterosaur when it comes to prey capture. However, aside from insectivorous birds and bats, few fliers aquire prey on the wing with just their jaws, and the exceptions are often adapted to a specific environment that corresponds to that prey capture (e.g., gulls and frigates).
To my knowledge, the teeth in Darwinopterus do not correspond to "fish-eaters" like rhamphorhynchids etc., which are anteriorly or extensively procumbent; nor are the jaws seemingly adapted to high-speed surface catching as has been proposed for some ornithocheiroids/anhanguerids; the feet are not adapted for prey-capture, but are very small. This leaves up with essentially vertical yet conical teeth in a long robust jaw, which seems primed for vertebrate, perhaps insectile prey, but hardly does it seem to be adapted for "insects-on-the-wing" (see anurognathids), which leaves us with the proposition of flying vertebrate or terrestrial vertebrate prey.
Is the flying vertebrate prey idea really that objective? What really forces the pterosaur OFF the group to hunt, rather than ground-based pursuit?
a specific environment that corresponds to that prey capture
What do you mean by "correspond"?
anteriorly or extensively procumbent
Do you mean "procumbent at the tip of the jaw or throughout"?
In the discussion about taking flying prey with the jaws alone, this may be of interest:
Zegula, T: (2006): EichelhÃ¤her Garrulus glandarius erbeutet juvenile Schwanzmeise Aegithalos caudatus im Flug. Charadrius 41:4, 223-224
I just saw this paper today. An Eurasian Jay was observed capturing a juvenile Long-tailed Tit that way. And other similar observations are also cited in the paper. So it's not just gulls/skuas/frigatebirds that do it, but also sometimes corvids.
Hi all, a few comments.
Hovering pterosaurs (comment 57): Chatterjee & Templin (2004) looked at the possility of hovering in pterosaurs, produced power curves (required power vs airspeed), and concluded that hovering was indeed possible in Eudimorphodon, Pterodactylus, Rhamphorhynchus and Dorygnathus (p. 46). I have no idea whether the maths works out here, but one conspicuous problem is that their estimates of airspeed are contingent on mass, and their mass estimates are insanely LOW (see Witton 2008). Some rotation (comment 58) might be possible in the pterosaur wing: Hazlehurst & Rayner (1992) made the case for humeral rotation in some taxa.
Comparing pterosaurs to bats (comment 60): Jaime, suggesting that some pterosaurs might have employed the same predatory tactics as some bats is not the same as saying 'pterosaurs looked and behaved like bats', so I don't see what your problem is. I agree that 'the case of the bat-winged pterosaur' (see Padian 1987) misled people in the past.
And, on corvids (comment 62): I recall an account where a pair of Carrion crows had learnt to scare passerines (including thrushes) into flying over a nearby lake. The crows then grabbed the bird by the leg (escape options are limited when flying over a lake surface). So, we now have a list of flying tetrapods that catch other flying tetrapods on the wing: black-backed gulls, skuas, frigatebirds, some corvids, some vesper bats, possibly other microbats like ghost bats.
Refs - -
Chatterjee, S. & Templin, R. J. 2004. Posture, locomotion, and paleoecology of pterosaurs. Geological Society of America, Special Paper 376, 1-64.
Hazlehurst, G. A. & Rayner, J. M. V. 1992. An unusual flight mechanism in the Pterosauria. Palaeontology 35, 927-941.
Padian, K. 1987. The case of the bat-winged pterosaur: typological taxonomy and the influence of pictorial representation on scientific perception. In Czerkas, S. J. & Olson, E. C. (eds) Dinosaurs Past and Present Vol. II. Natural History Museum of Los Angeles County/University of Washington Press (Seattle and London), pp. 65-81.
Witton, M. P. 2008. A new approach to determining pterosaur body mass and its implications for pterosaur flight. Zitteliana B28, 143-158.
"Jaime, suggesting that some pterosaurs might have employed the same predatory tactics as some bats is not the same as saying 'pterosaurs looked and behaved like bats', so I don't see what your problem is."
Jaime ALWAYS has some sort of problem. Seriously. There's nothing you can do.
"Why again are we comparing pterosaurs to bats?"
Because like bats, the main "food grabber" of pterosaurs is the jaws, as opposed to the feet as seen in raptorial birds.
Anyway, what about Darwinopterus acting like a predatory bird, but at the same time hunting like a big bat, using its jaws.
Hi I'm doing some background research on pterosaurs for a sculpture I'm contemplating making since reading Wellnhofer and Unwin, spurred on again by Darwinopterous, and now reading through your fascinating comments.
The design that's evolving would hang on a ledge or similar. I've struggled with how to pose the head, I'd envisioned it looking over it's shoulder but I've come to realise that it would look much more 'natural' tilting it's head over backwards, enabling it to have an unrestricted view behind it, as if watching for prey or danger.
It's also occurred to me that upside down is a better way to fish, is there any reason why a pterosaur couldn't fly or glide on it's back?
When fishing it's eyes would then be nearer the water level with an unrestricted view, (perhaps a nasal crest is a fly by touch gauge?) then it would also make sense to grow a head crest so that the force of water and fish taken at speed doesn't break the neck by forming a backstop. This would also enable a bigger fish to be taken with less danger. Bigger fish means bigger bird. There's then the obvious evolutionary advantage.
Is this feasible?
[from Darren: sorry, delayed by spam filter]
Why again are we comparing pterosaurs to bats?
As others already have pointed out, we weren't. We were looking for examples of extant flying vertebrates that catch other flying (or at least airborne) vertebrates by using their jaws rather than their feet*.
* Incidentally, insectivorous bats do use their feet - sort of - when catching aerial prey; when closing in on the victim bats use the patagia uniting their fore- and hindlimbs as a surrounding "net". Whether bird-catching bats such as the greater noctule or the great evening bat Ia io (Thabah et al., 2007) do so too is not yet known, but it wouldn't surprise me if they did.
on corvids (comment 62): I recall an account where a pair of Carrion crows had learnt to scare passerines (including thrushes) into flying over a nearby lake. The crows then grabbed the bird by the leg (escape options are limited when flying over a lake surface).
Wasn't there some footage in the BBC's Blue Planet where a raven was capturing small alcids (crested auklets?) in flight? Anyway, many species of corvids are on record as occasional predators of flying birds and even of flying bats (e.g., HernÃ¡ndez et al., 2007).
we now have a list of flying tetrapods that catch other flying tetrapods on the wing: black-backed gulls, skuas, frigatebirds, some corvids, some vesper bats, possibly other microbats like ghost bats.
You can add tyrant flycatchers to that list; Gamboa (1977) observed a brown-crested flycatcher Myiarchus tyrannulus catch a rufous hummingbird Selasphorus rufus in flight.
You might also replace '(greater) black-backed gulls' with 'most large gulls'; aerial capture of small to middle-sized birds is fairly common behaviour by gulls. Herring gulls, for example, are notorious predators of land birds migrating over stretches of sea. And returning to Larus marinus; puffins are not the largest flying prey taken by greater black-backed gulls. Donehower (2006) suggests that they may even successfully take adult glossy ibis Plegadis falcinellus in flight.
Donehower, C.E. 2006. Likely predation of adult glossy ibis by great black-backed gulls. The Wilson Journal of Ornithology 118, 420-422.
Gamboa, G.J. 1977. Predation on rufous hummingbird by Wied's crested flycatcher. The Auk 94, 157-158.
HernÃ¡ndez, D.L., Mell, J.J. & Eaton, M.D. 2007. Aerial predation of a bat by an American crow. The Wilson Journal of Ornithology 119, 763-764.
Thabah, A., Li, G., Wang, Y., Liang, B., Hu, K., Zhang, S. & Jones, G. 2007. Diet, echolocation calls, and phylogenetic affinities of the great evening bat (Ia io; Vespertilionidae): another carnivorous bat. Journal of Mammalogy 88, 728-735.
sorry, delayed by spam filter
Do you know why that happened, Darren? There was no URL in my comment.
Anyway, one more comment on the subject of avian predation on flying vertebrates. Sometimes the predator doesn't even need to be flying itself; Spofford (1976) described a greater roadrunner Geococcyx californianus that leapt at flying hummingbirds and other small birds and occasionally succeeded in catching them.
Spofford, S.H. 1976. Roadrunner catches hummingbird in flight. The Condor 78, 142.
Do you know why that happened, Darren?
Sorry, no clue. It happened to me yesterday, and I also got a message saying that I'd submitted too many comments in too short a time. Huh, and this is MY blog! It is generally agreed that Movable Type's publishing platform is crappy, but ScienceBlogs is too far down the road to switch or turn back.
Anyway, many thanks for all those notes and references, very interesting stuff.
Oh, on the subject of birds catching others in flight, there are published accounts of storks catching sparrows and other passerines (e.g., Berthold 2004). I was saving this for my article on the feeding behaviour of big waterbirds... but it's not yet finished.
Berthold, P. 2004. Aerial "flycatching": non-predatory birds can catch small birds in flight. Journal of Ornithology 145, 271-272.
"* Incidentally, insectivorous bats do use their feet - sort of - when catching aerial prey; when closing in on the victim bats use the patagia uniting their fore- and hindlimbs as a surrounding "net". Whether bird-catching bats such as the greater noctule or the great evening bat Ia io (Thabah et al., 2007) do so too is not yet known, but it wouldn't surprise me if they did."
Bulldog bats of the genus Nocutilio also use their feet to catch prey, and in a much more literal manner than most of the insectivorous bats. But as far as I know they are basically the minority of bats who do this.
I wonder if future pterodactyloid finds will reveal a whole family of "terror pterosaurs", who basically took the niche of aerial raptorial predators by hunting on the wing, and maybe got a big more talented at it (as in, using the features that made pterodactyloids so famous to improve their in-flight hunting). Or maybe predatory birds started appearing early in the Cretaceous. Or even non-avian maniraptorans took the place of raptorial birds until true flying avian predators started popping up.
Darren, and apparently MichaelErickson,
I was aware of at least Darrn once understanding this, but apparently it needs o be restated:
If I "have a problem" with something, it is't actually a problem. It's being a critic. And I really try not to be a jerk, or make issues personal with other people (being heavily adverse to ad hominem comms in scientific works). When some people ignore the data and turn to the people making the argument, I get the odd feeling that they aren't actually interested in the science, are bad at communication, or both. Personally, I like asking questions, and understand that there are people out there who make a lot of basic assumptions without must data backing them to support their arguments. And this is my biggest pet peeve in the sciences, because a lot of otherwise decent workers do this. Attempting comprehension in working the base data to avoid as many possible assumptions as I can has pevented me from actually publishing my own stuff, otherwise I might have more than abstracts to my name right now.
Currently, because I tend to post here or over at SV-POW! (given that I've known Darren a while and once tried to write a paper with him) I have been openly critical of the papers because of these assumptions (this being based on familiarity with the people), and it seems this gives me a bad name. I'm okay with that. I was openly critical of a few other papers by Lingham-Soliar ove on my own blog and on the inosaur Mailing List, yet I don't seem to have taken flak bout that, either -- who'da thunk? But when the reactions to an argument are less than data based (and I'm fine with being wrong) are personal (like Mike Erickson's above at #64 and Darren's initial response at #63) then I feel they are ignoring the points (or even the intent, as I was criticising something that Darren was also criticising, and was not criticisim HIM!) for the person. This, as I have found, is also common in the sciences, and I do not think it is correct. If you do, please, go make your own blog and complain about me there.
At least David's response to me (#61) was technical and dealt with the points, which follows from my tendency to confuse my writing with other people's ability to comprehend my meaning (often also obscure).
David: 1. Diet relative to environment can be correspondent: We assume for example that many of the pterosaurs in Solnhofen beds were piscivorous or horeline feders because of the environment, while others require specific adaptations (often diagnostic) to infer a different diet (as in the anurognathids). Diet can correspond to environment [to a degree] as such an environment is often the first indication of possible foods.
2. "Extensive" versus "anteriorly" procumbency in teeth means what you think it means. I am not sure my terms are incorrect. The distinction lies between Rhamphorhynchus versus Anhanguera, which is potentially size-based.
3. :) I was being brisk.
Regarding the exact method of capture of flying birds by bats: I suggested in an earlier comment that bats might, in fact, also to some extent use their feet (rather than their jaws only) when catching birds. A closer reading of the relevant papers suggests that this appears indeed to be the case.
IbÃ¡Ã±ez et al. (2001:9702) say that 'one greater noctule carried in its claws feathers identified as belonging to E[rithacus] rubecula', and Thabah et al. (2007:731), cited above, say that 'we caught an adult female I. io with feathers in its claws and blood stains on its mouth and claws'. This suggests that the hindfeet do play some active role in avian prey capture in both Nyctalus lasiopterus and Ia io.
IbÃ¡Ã±ez, C., Juste, J., GarcÃa-Mudarra, J.L. & Agirre-Mendi, P.T. 2001. Bat predation on nocturnally migrating birds. Proceedings of the National Academy of Sciences of the U.S.A. 98, 9700-9702.
Jaime (comment 72): I'm sorry if you took my comment (# 63) as any sort of personal attack. I really did not mean it that way.
Darren, I have a lot of respect for you, so don't take this the wrong way: I get VERY uppity when people bring an individual into an argument about a largely objective pursuit of inquiry, being science. It wasn't that you made anything personal about me, but that when I responded about the argument regarding Bats vs. Pterosaurs, it wasn't even pointed at you, so I am not sure how it would provoke a defensive posture.
Like I said, sorry for the misunderstanding. You are a valued member of the 'Tet Zoo community' :) When they unveil the statue, your name will be listed on one of the plaques.
Diet relative to environment can be correspondent:
Correspondent to what?
Diet can correspond to environment
Oh, that at least makes grammatical sense now. But I still don't quite understand it.
as such an environment is often the first indication of possible foods.
So you meant to write that "diet can depend on the environment"? As in: Solnhofen is not likely to contain terrestrial megaherbivores, but is likely to contain piscivores?
In the last few years, I've noticed that much of what you write takes a lot of effort and headache to understand. You seem to write "in real time" -- words pop up in your mind (almost in no particular order) and flow directly into the keyboard. Please do something against that, it's really exhausting. Maybe finish your argument, then mentally explain it to someone else, and then write that explanation down. And then maybe reread it before posting it.
Speaking of keyboards: take yours, turn it upside-down, and knock it gently. Tons of dust will come out. There are lots of letters in comment 72 that are just missing and have to be guessed from context.
"Anyway, one more comment on the subject of avian predation on flying vertebrates. Sometimes the predator doesn't even need to be flying itself; Spofford (1976) described a greater roadrunner Geococcyx californianus that leapt at flying hummingbirds and other small birds and occasionally succeeded in catching them." (Comment # 68)
---> Another example: I have seen a domestic cat stand up on its hind legs and use its forepaws to snatch a flying bird (it was a bird that had gotten into a house and so had flown over the cat several times-- but I think the cat managed to catch it on the first pass after it stood up.)
Actually, yours was an example of mammalian, not avian, predation of flying vertebrates... The point about making a distinction between the two is that cats and some other terrestrial flesh-eating mammals can, and do, use their forelimbs* to snatch prey from the air. Terrestrial birds (such as the roadrunner mentioned above) typically don't have this option.
* Dog-like mammalian predators, on the other hand, have less dexterous forelimbs than cats; on the relatively rare occasions when they try to snatch prey - or a frisbee - from the air, they'll do so with their jaws.
Dartian-- Sorry: I wasn't reading carefully enough and overlooked the "avian". ... As to the cat/dog difference, I take it the optimization of the canine skeleton for cursoriality is why they don't have the forelimb dexterity of cats?
Yes, they can't supinate their forearms. (Opposite situation of theropods.)
Not to toot my own horn (somewhere, Bender cries "Wooo!") but I've given many people a place to lambaste me in my own juices on this topic, here. I have attempted to be civil, as it were, although with the exception of one figure, every image link in the work is cribbed (which I will attempt to emend in the future). Also, forgive the spelling errors.
In fact, most dogs can supinate their forelimbs, but it's not by much, and certainly will be as limited as it is in cheetahs (Acionyx sp.) because of the constraint on the carpals and metacarpals that limits the motions the forelimb can act apart from the linear motions of locomotion. As dog forelimbs (along with cheetahs) are the primary pivot points in running, when such an animal is inacapble of supining the limb, rotating it about would dislocate the wrist and probably the elbow. An even more extreme analogy could be found in the horse, in which the forelimb is also capable of a degree of supination, and again for the same reason as the dog.
It is true, however, that a cat (to a grade of cat, anyway) is far more capable of supination than a dog is, but for the purpose of foot-first prey acquisition, while dogs are head-first acquirers and are free to develop their limbs for pursuit running (and an analogy exists in cheetahs where the limbs are extended, the skull is smaller and the dentition is reduced to the minimum for rendering meat and the choke that finished the prey). Small cats at least primarily use their limbs in locomotion and, like many early caniniforms, were partially if not wholly arboreal and would also have been foot-first or head/foot prey acquirers, reducing the specialization of one complex over another.
Thanks for the cat versus dog review! Acinonyx seems to be a cat which has evolved into a partial dog-mimic. (Partial: I think the basic cat physiology keeps it from being a distance runner like wolves and coyotes.) ... Foxes seem to be ecologically similar to small cats: are they typically canine in being jaw-first prey acquirers, or do they mimic cats in greater paw use? And if the latter, are they capable of more forelimb supination than other canids?
Considering its "surprising melange of characters" can we classify Darwinopterous as a Hopeful Monster?
Considering its "surprising melange of characters" can we classify Darwinopterous [sic] as a Hopeful Monster?
No, because we don't know its parents... :-)
If all those pterodactyloid features it has appeared all at once, from one generation to another, then the first individual of Darwinopterus was a hopeful monster. But that is... not probable.
If Pterorhynchus is related to Darwinopterus as suggested then the hopefull monster thing can very likely be thrown into the trash, because Pterorhynchus is still quite "rhamphorhynchoid" in appearence and kinda of forms a bridge between Darwinopterus and whatever came first. At the very least it might resemble its ancestor.
Is it clear if Pterorhynchus does form a clade with Darwinopterus or if it is just one step beyond? Because I think it could be some interesting implications if Pterorhynchus was thrown into the picture, like questioning whereas Pterodactyloidea is paraphyletic or not...
Sorry, meant "polyphyletic"
I doubt it's paraphyletic or diphyletic, as you seem to be implying. Still, somebody needs to redescribe Pterorhynchus, and quick!
I'd like to note that I do not think that Pterorhynchus and Darwinopterus are synonyms. There do, as Dave Unwin attested to above, seem a substantial number of differences that makes it clear these are not even morphs of the same general taxon. The variability between the two is therefore likely phylogenetic. As such, the issue I brought up was to see how close a look at Pterorhynchus we got to have, given that (for a variety of reasons) the taxon has been somewhat obscure. The host of features it shares with Pterorhynchus suggests that the mosaic features seen in the new taxon were (partly) present in Czerkas' taxon. The poor preparation that preceeded its description has done nothing to help that taxon's reputation, so only now does it seem adequate description could take place.
Wow, look at all the juicy pterosaur discussion! A couple of (belated) thoughts:
1) Dedicated aerial hunting raptors are rather structurally distinct. They have significantly stronger limb bones than other raptors (and other birds). A similar, albeit weaker, trend seems to exist in carnivorous bats (I need to collect a larger sample here before I can conclude anything). Several posters have already noted that bats hunting birds/other bats on the wing use the wings and hind limbs to capture prey. Furthermore, Tuttle and others have noted that Megadermatids and spectral bats tend to take birds and bats that are resting/roosting or on the ground. They are not, furthermore, nearly so dedicated to aerial hunting as things like falcons or accipters. The upshot is that there appear to be very few (if any) aerial predators that ram large flying prey with their jaws, as it were (at least, this is my impression from the literature and observation). It is possible that some of the bats for which data are absent will turn out to do so, but I doubt it on structural grounds. In any case, I personally do not see much to imply aerial hunting of large vertebrate prey by any known pterosaurs, though if any did so, they too would likely have to use a patagial net (again, there are biomechanical reasons to expect this, though expectations aren't always met). I'd be happy to discuss more with any interested parties, should someone out there actually think my thoughts on this sort of thing matter...
2) Re: Hovering. Hummingbirds and nectar-feeding bats use sustained hovering stroke in which the wing is "flipped" and camber is reversed. This is a powerful way to hover (and is better developed in the hummers than the bats), but most birds hover by use of a full momentum reversal. The largest living bird to sustain FMR for long, repeated bursts is the osprey. Larger birds use the same dynamic to brake for landings - it is sometimes called a "flutter stroke" in the literature. There is nothing preventing pterosaurs from using a FMR approach, but only little ones would be able to really hover with it, and even then, they would be more constrained in this regard than birds. Anurognathids might have been better at it than some other taxa (more on this later).
Dedicated aerial hunting raptors are rather structurally distinct. They have significantly stronger limb bones than other raptors (and other birds).
Very interesting. Has that information been published? Do you have a reference?
Anurognathids might have been better at it than some other taxa (more on this later).
Now it gets really interesting.
Sheesh, Mike, way to drop a bomb and then just skitter away! :-D
"Anurognathids might have been better at it than some other taxa (more on this later)."
Considering that Anurognathus had a wingspan of 50 cm (which AFAIK is larger than that of the average aerial insectivorous bird), any likely of targetting aerial vertebrates? Flaplings of other pterosaurs perhaps?
Proportionate for their size, Batrachognathus and other anurognathids have very large wings, potentially (and proportionately, again) large than other pterosaurs (compared to mass). This may influence their flight dynamic ever so slightly. They also have well developed feet, relatively large pedal unguals compared to the manual unguals, and very large manual unguals at that. I am actually surprised no one has proposed any form of active substrate-based hunting in the technical literature yet, although I think it has been implied their ungual curvatures resemble some groups of birds. Robust limb structure, long limbs, and very long wings at size suggest that anuroganthids are anything but ordinary, and I think Mike is hinting at cool things to come.
With regards to anurognathid size: a 50 cm span is indeed much larger than seen in things like swifts and swallows. However, it is right in the average ballpark for the larger, nocturnal insectivorous birds - nighthawks, potoos, and other large caprimulgiform birds. They still hawk insects, not vertebrates. The only exception are frogmouths, but they largely eat terrestrial vertebrates (and still eat mostly insects, from what I'm led to understand).
Re: Raptor limb strength - no reference yet; I'm working on that manuscript now. The aquaflyer bone strength paper is now finally in press, so it's on to the raptor writeup. And there was much rejoicing...
Finally, with regards to Anurognathids: yes, they have some really interesting things going on. Hint: look not just at the total length of the wing, but *where* the length comes from (and doesn't). Also consider strength of the proximal long bones. The crests on the proximal humerus are intriguing, too. I'm afraid that's all the hints for now...
Happy paleo adventures everybody!
Re: Raptor limb strength - no reference yet; I'm working on that manuscript now.
I.e., 'Wait for the paper'? Dang!
there appear to be very few (if any) aerial predators that ram large flying prey with their jaws, as it were (at least, this is my impression from the literature and observation)
It does happen, though (at least occasionally). Fisk (1970) observed a common grackle Quiscalus quiscula kill a cedar waxwing Bombycilla cedorum in flight by hitting it with its beak. The grackle 'flew into the flock from above, hit one bird a blow, apparently on the nape, and followed its fall to the ground'. Clapp (1986) observed a great-tailed grackle Q. mexicanus kill a barn swallow Hirundo rustica in a similar manner. And I'm pretty sure that there are more such cases of killing/crippling prey by aerial beak ramming described in the ornithological literature, particularly in the journals' 'Short communications'/'General notes'/'whatever it happens to be called' -section.
Clapp, R.B. 1986. Great-tailed grackle kills barn swallow in flight. The Wilson Bulletin 98, 614-615.
Fisk, E.J. 1970. Common grackle kills cedar waxwing in air. The Wilson Bulletin 82, 465.