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A new azhdarchid pterosaur: the view from Europe becomes ever more interesting


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Speculative reconstruction of Eurazhdarcho langendorfensis (in quad launching pose), by Mark Witton. From Vremir et al. (2013).

Another day, another new paper out in PLOS ONE. Today sees the publication of the new azhdarchid pterosaur Eurazhdarcho langendorfensis Vremir et al., 2013, a new species from the Upper Cretaceous Sebeş Formation of the Transylvanian Basin in Romania (Vremir et al. 2013). ‘Vremir’ is my good friend Mátyás Vremir; he worked together with Alex Kellner of the Museu Nacional in Rio de Janeiro, and with myself and Gareth Dyke (both of the University of Southampton) in the description of this new species.

Azhdarchids will already be familiar to a great many Tet Zoo readers; indeed, in recent years they’ve become more familiar to interested people in general thanks to appearances in books, TV documentaries and films. These are the often gigantic, long-necked, long-skulled pterosaurs of the Cretaceous (and especially of the Late Cretaceous), best known for Quetzalcoatlus from Texas, a giant form in which the wingspan was about 10 metres and the total weight was somewhere round about 200-250 kg (Witton 2008, Witton & Habib 2010).

Eurazhdarcho is not a giant: it had a wingspan somewhere round about 3 m (Vremir et al. 2013), making it one of the smallest known azhdarchids. But it’s significant for several reasons, one of them being that it’s known from a comparatively large amount of material. Most azhdarchid fossils consist of isolated vertebrae and other fragmentary remains, with associated or articulated skeletons being very rare. Our description of Eurazhdarcho is based on 15 bones, all discovered together at Sebeş-Glod in Transylvania, and most of which were collected by Mátyás in 2009. We know that other bones from the same specimen were collected later on, but they’re currently inaccessible to our research group.

Just in case you've forgotten how big the biggest azhdarchids were, here's a Hatzegopteryx to scale with a human and a big bull giraffe. Image by Mark Witton.

This all makes Eurazhdarcho Europe’s most complete azhdarchid yet reported… as you can see from the reconstruction shown at the top, however, that doesn’t exactly make the specimen all that outstanding. Eurazhdarcho is known from part of the neck skeleton as well as part of the right wing (Vremir et al. 2013). That’s enough for us to gauge the approximate size of the animal and to work out what its proportions were like. The silhouette shown here – showing Eurazhdarcho reconstructed in quadrupedal launch pose – was kindly produced by Mark Witton.

Azhdarchid cervical vertebrae are highly distinctive and there’s nothing else quite like them. Because they’re often found in isolation, and because they’re so distinctive, we probably understand them better than we do the rest of the azhdarchid skeleton. Indeed, it’s been possible to show that azhdarchid species can frequently be distinguished on the basis of differences and key features present on these bones. Eurazhdarcho has unique cervical vertebrae where the third one is especially long compared to the fourth one (these pterosaurs have nine cervical vertebrae in total) and where the prezygapophyses (the forward-pointing articular ‘prongs’ on the front surfaces of the vertebrae) are longer, and directly dorsally more strongly, than is normally the case in azhdarchids (Vremir et al. 2013). Other unique features are present in its cervical vertebrae as well.

One of the best preserved of the Eurazhdarcho cervical vertebrae (from Vremir et al. 2013). This is the 4th cervical. Scale bars = 10 mm.

Based on these assorted anatomical features, we are confident that Eurazhdarcho langendorfensis represents a new taxon. Azhdarchids as a whole are named for Azhdarcho, a Central Asian form named by Lev Nesov in 1984 for the Uzbek word azhdarkho, meaning dragon* (Nesov 1984). Eurazhdarcho essentially means, therefore, just ‘azhdarchid from Europe’, or ‘dragon from Europe’. The species name refers to the old Transylvanian-German name for Lancrăm, the village in the Sebeş-Glod area closest to the discovery site (Vremir et al. 2013). We abandoned early plans to name the species after our favourite local alcoholic beverage, the fruit brandy known as Pálinka.

* I have never known whether azhdarkho refers to dragons in the generic sense, or a specific dragon from a specific story or mythology. Do say if you know.

Our description of Eurazhdarcho is just the latest of several projects that involves both my own research group (led by Gareth) at the University of Southampton, and Mátyás (associated with the Transylvanian Museum Society at Cluj-Napoca) and our other colleagues in Romania. Mátyás has been discovering, preparing and describing Romanian pterosaur bones (and other tetrapod fossils) for years now. Gareth and I previously worked with him on the Romanian enantiornithine eggshell assemblage we published last year (Dyke et al. 2012).

More results of our collaborative efforts will be appearing in future – the Upper Cretaceous rocks of Romania are a fertile area for the discovery of dinosaurs, pterosaurs and other Mesozoic animals and numerous exciting discoveries have been made. Anyway, as always for a PLOS paper, the Eurazhdarcho research is fully open-access and available free to all.

Romania: where the gigantic azhdarchids are

Mátyás Vremir collecting fossils in the spectacular badlands of Râpa Roşie, Sebeş-Glod, Romania. Photo by Darren Naish.

Pterosaurs have been known from the Upper Cretaceous rocks of Romania for a while, with most of the fossils concerned being isolated teeth and collections of vertebrae and limb bones. None of these fossils are that impressive, but things changed in 2002 when Eric Buffetaut and colleagues named Hatzegopteryx thambema. This new species was named for a partial skull, an incomplete humerus and assorted bone fragments (all from the Maastrichtian Ciula-Densuş Formation of the Haţeg Basin). The bones are enormous: in fact the deep, robust section of the skull known for Hatzegopteryx had earlier been identified as that of a large theropod (Weishampel et al. 1991). Buffetaut et al. (2002) estimated the wingspan of the live animal to be more than 12 m. A lower estimate of 10-11 m has been published more recently (Witton & Habib 2010), putting this animal on the same footing as Quetzalcoatlus northropi.

Some additional Romanian azhdarchid bones that also come from large to gigantic animals (and are probably referable to H. thambema) have been found since the Hatzegopteryx holotype was described, including a femur, an enormous cervical vertebra and a section of lower jaw tip (Buffetaut et al. 2003, Vremir et al. 2013). Some of these are from the Sebeş Formation, the same unit that produced Eurazhdarcho, and from localities in the Sebeş-Glod region close to the one that yielded Eurazhdarcho.

We don’t know as much as we might like to about Hatzegopteryx, but there’s no doubt that it was enormous, and overall much like Quetzalcoatlus. These azhdarchids were so large that some workers have seriously proposed that they might have been flightless (Henderson 2010: see Witton & Habib 2010). We desperately want to test this hypothesis but it’s difficult to know what to do when their forelimb bones remain so poorly known. We’re working on it though.

Things to do in Romania when you’re an azhdarchid

The 'vulture azhdarchid' hypothesis, as depicted by Jan Sovak (this is from Philip Currie's poorly known 1991 book The Flying Dinosaurs). Ouch, featherless maniraptorans...

Eurazhdarcho doesn’t just provide new anatomical information on azhdarchids. It also augments the debate we’ve been having on azhdarchid lifestyle and ecology. As Tet Zoo regulars will know, there was a time when azhdarchids were consistently portrayed as ‘vulture pterosaurs’, specialised for a life of picking at dinosaur carcasses. It was later argued by some authors that some, most or all azhdarchids were aquatic ‘skim-feeders’, strongly tied to aquatic or even marine environments and specialised for hunting while on the wing. Other authors have interpreted azhdarchids as animals that frequented mudflats and either probed into the sediment or pulled invertebrates from burrows; others have suggested that azhdarchids were stork- or heron-like in ecology and, again, tied to watercourses.

Back in 2008, Mark Witton and I put forward the case that azhdarchids were well suited for terrestrial locomotion, and that there was a strong continental, terrestrial signal in the azhdarchid fossil record (Witton & Naish 2008). Data from azhdarchid posture, limb proportions, body shape and trackways all shows, we think, that these animals were swift, competent terrestrial striders, able to walk rapidly (and perhaps even to trot or run) with their wings folded up and their limbs held directly beneath their bodies (Witton & Naish 2008).

Azhdarchids were well suited for competent, quadrupedal terrestrial walking (and running?) and were well proportioned for this lifestyle, as shown by this diagram of the Chinese azhdarchid Zhejiangopterus. Image by Mark Witton, from Witton & Naish (2008).

Incidentally, claims that azhdarchids were not as tall as we said they were (Paul 2011) are based on the incorrect assumption that azhdarchids walked with sprawling forelimbs. Trackways and the degree of motion present in pterosaur shoulder joints show that they didn’t (ironic that Greg Paul – of all people – should use this line of argumentation!).

The data was always against the idea that azhdarchids have a strong marine or coastal association: as shown in this graph (from Witton & Naish 2008), their fossils are most strongly associated with terrestrial, continental settings. Eurazhdarcho is another member of the group from that sort of environment.

Ideas that azhdarchids were habitual denizens of wet places where the sediment was soft and waterlogged are contradicted by the proportionally small, compact feet of these animals (Witton & Naish 2008). Meanwhile, the notion that any large, long-headed, ultra-long-necked flying animal might be able to make a living by grabbing things while in flight – especially from the water – is, in my opinion at least, an absurd concept best left to the world of sci-fi. Remember that animals that feed habitually on the wing possess numerous specialisations for this way of life. Azhdarchids emphatically lack such specialisations, and look absurdly ill-suited for it. This has all been covered on Tet Zoo before: visit the links below for more.

Eurazhdarcho is yet another azhdarchid from a terrestrial, continental environment. Like most fossil animals, its remains were preserved within sediments laid down by a giant, braided river system, but the sediments and other fossils found in the same geological unit show that forested swamps, dry floodplains and riverside habitats all occurred in the region at one time or another. The layers of the Sebeş Formation that preserved Eurazhdarcho reveal evidence of topsoil. It seems that this was an inland, forested environment when Eurazhdarcho was alive. Turtles and small crocodyliforms are known from here, but so are hadrosaurs, rhabdodontids, the dromaeosaurid Balaur, and birds (Vremir et al. 2013).

Carving out niches in the Cretaceous

Big-bodied and small-bodied members of a given animal group are frequently found in sympatry, as here, where Great egrets (Ardea alba) and Snowy egrets (Egretta thula) are obviously found in close association. Photo by Emily Willoughby, used with permission. Wigeon included for good measure.

What makes Eurazhdarcho further interesting, I think, is the fact that its remains are about contemporaneous with, and discovered in close geographical proximity to, gigantic azhdarchid remains that probably belong to Hatzegopteryx. We assume that both were inhabitants of the same fauna and that their living spaces quite probably overlapped (Vremir et al. 2013).

So far as we can tell at the moment, the two are distinct in many details of their anatomy, meaning that we can’t seriously consider the idea that they might be growth phases of the same species. During Maastrichtian times, the Transylvanian Basin was therefore home to both a gigantic azhdarchid – one of the largest known – and a far smaller one; one of the smallest known, in fact. I think we can logically assume that these animals were doing different things ecologically, and living very different sorts of lives. In other words, we’re seeing clear evidence for niche partitioning in azhdarchids here.

This is one of those discoveries that doesn’t really represent any sort of surprise. We know from the modern world that ecosystems are often packed with closely related but differently sized members of a group: there is often or sometimes a bit of overlap in ecology and behaviour, but big-bodied species typically do ‘big animal things’ that small-bodied species typically don’t. We certainly assume that things were like this in the Mesozoic, but we can’t always know that they were. And, in some cases, they weren’t like this: you can have a fauna where a member of a group is a singleton, there on its own and without close relatives.

Some geological units reveal evidence of two or even three sympatric azhdarchid species. Diagram produced by Mark Witton and map used with kind permission of Ron Blakey, Colorado Plateau Geosystems, Inc; from Vremir et al. (2013).

This new information on the sympatry of small and large azhdarchid species led us to look anew at other geological horizons that yield azhdarchid fossils. Azhdarchids were widely distributed, their fossils being known from numerous Upper Cretaceous sites in North and South America, Europe, Asia, Africa and probably Australia (Barrett et al. 2008, Novas et al. 2012). Of these sites, several show the same pattern: small-bodied azhdarchid species co-existing with giant ones. Quetzalcoatlus northropi – the most famous member of the group – is from the Maastrichtian Javelina Formation of Texas. It’s well known that a smaller azhdarchid is known from the Javelina as well: known only as Quetzalcoatlus sp. (and still unnamed despite being known since the 1970s), it has frequently been discussed and illustrated, typically whenever Q. northropi is mentioned. Even better, there’s a third species in the Javelina. Pterosaur workers mostly know it thanks to the photo of its snout and lower jaw included in Peter Wellnhofer’s Illustrated Encyclopedia of Pterosaurs (Wellnhofer 1991) where it’s labelled as the partial skull of Quetzalcoatlus sp. (p. 144).

TMM 42489-2, as illustrated by Mark Witton. Scale bar = 100 mm.

Thalassodromid specimens compared with TMM 42489-2 (second down from top): I hope you can see why Martill & Naish (2006) interpreted it as a possible thalassodromid. From Martill & Naish (2006).

This specimen (technically, TMM 42489-2) is superficially thalassodromid-like in some respects (Thalassodromidae is the azhdarchoid clade that includes the Brazilian taxa Tupuxuara and Thalassodromeus. Thalassodromids were somewhat azhdarchid-like, but their neck vertebrae weren’t as long and they possessed giant, sail-like bony head crests). In view of this, Dave Martill and I wrote in 2006 that TMM 42489-2 should be regarded as a species of Tupuxuara (Martill & Naish 2006); Alex Kellner had done likewise somewhat earlier (Kellner 2004). I now think that we were wrong on this: in TMM 42489-2, the dorsal and ventral margins to that part of the rostrum dorsal to the nasoantorbital fenestra aren’t sub-parallel as they are in Tupuxuara and Thalassodromeus. Rather, the specimen seems to represent a relatively short-snouted azhdarchid, as Mark Witton explained in this 2010 Pterosaur.net Blog article.

Both Quetzalcoatlus sp. and TMM 42489-2 were in the 5-m-wingspan size range. That’s big, but it’s substantially less big than Q. northropi. The point here is that three sympatric azhdarchids were sharing the same point in time and space (well, near enough. You know what I mean). And we know that two of those animals at least (Quetzalcoatlus sp. and TMM 42489-2) differed in jaw shape.

The Campanian Upper Two Medicine Formation (famous for such dinosaurs as the duckbill Maiasaura and the horned dinosaurs Einiosaurus and Achelousaurus) also yields a very large azhdarchid (an unnamed form with an 8 m wingspan) as well as the small (2.5 m wingspan) Montanazhdarcho minor. And the Dinosaur Park Formation in Alberta (famous for its many, many dinosaurs) preserves evidence of, again, a giant with a 10 m wingspan as well as a far smaller azhdarchid half this size. The assumption is that one of these Canadian animals is a species of Quetzalcoatlus, but we need more information before we can commit to that possibility.

Wing and pectoral bones of the Upper Two Medicine Formation azhdarchid Montanazhdarcho minor, from McGowen et al. (2002). Montanazhdarcho lived alongside giant, Q. northropi-sized animals, but (as you can see from the scale bar) was small (for an azhdarchid).

So there’s something like a pattern here. Several – certainly not all –azhdarchid-bearing localities preserve evidence of two or even three sympatric species. Based on differences in body size and jaw shape, it’s reasonable to assume that these animals were doing different things. In other words, they were almost certainly practising niche partitioning, with the smaller species using different resources from the bigger ones.

Imagine yourself as a time-tourist, walking about any one of these Late Cretaceous environments. If azhdarchids were the terrestrial stalkers that Witton & Naish (2008) envisioned, you might turn a corner and encounter a gigantic, striding azhdarchid, as tall as an adult giraffe and reaching down to grab little dinosaurs, mammals and lizards from the undergrowth. Some short distance away, foraging together in a small family group, are members of a second species, less than half as big and ‘only’ 2.5 m tall. There are dinosaurs here – big ones, in the distance, as well as chicken-sized theropods lurking in the undergrowth – but here’s another reminder that the Mesozoic wasn’t a ‘Dinosaurs Only Theme Park’: there was room for big, terrestrial, ground-striding pterosaurs as well, and also room for lepidosaurs, crocodyliforms and so on.

Terrestrial stalking azhdarchids, by Mark Witton (from Witton & Naish 2008). This scene isn't set in Late Cretaceous Romania, but this sort of thing could have been seen there... If you could travel back in time and go see it, that is.

Island Romania, land of azhdarchids… and nary a big theropod?

Actually, one interesting thing to remember when discussing the Maastrichtian animals of Romania is that they were living on a large island, known as Haţeg Island. The exact size of this island has been debated, with projected sizes ranging from about 7500 sq km (similar to the combined land area of the Galapagos Islands) to over 200,000 sq km (similar to Ellesmere Island) (Benton et al. 2010).

Hypothetical flightless azhdarchid (as seen before on Tet Zoo). Ah... but >is< it hypothetical? Well, yes, it is. But we can dream. Image by Darren Naish.

It seems that some of the animals here were island-dwelling pecularities: the titanosaurian sauropods are dwarfs, the theropod Balaur and the ornithopod Zalmoxes are both highly peculiar members of their groups, and the hadrosaur Telmatosaurus is both a dwarf and an evolutionary relict that looks decidedly anachronistic for its time, for example. Intriguingly, big theropods are (so far) absent from the fossil record of the region. It might be tempting to suggest that the presence on Haţeg Island of these different azhdarchid species is linked in some way to this absence of large theropods. However, as is obvious from the discussion above, we already know that azhdarchids large and small were quite capable of inhabiting ecosystems where diverse theropods (including even giant tyrannosaurids) were present, so this idea may be moot. But, here’s an idea – could Haţeg Island be the perfect place for a flightless azhdarchid to evolve? Watch this space…

Azhdarchids (and their relatives within Pterosauria) have been covered on Tet Zoo a few times before. See…

Refs – -

Barrett, P. M., Butler, R. J., Edwards, N. P. & Milner, A. R. 2008. Pterosaur distribution in time and space: an atlas. Zitteliana B28, 61-107.

Benton, M. J., Csiki, Z., Grigorescu, D., Redelstorff, R., Sander, P. M., Stein, K. & Weishampel, D. B. 2010. Dinosaurs and the island rule: the dwarfed dinosaurs from Haţeg Island. Palaeogeography, Palaeoclimatology, Palaeoecology 293, 438-454.

Buffetaut, E., Grigorescu, D. & Csiki, Z. 2002. A new giant pterosaur with a robust skull from the latest Cretaceous of Romania. Naturwissenschaften 89, 180-184.

- ., Grigorescu, D. & Csiki, Z. 2003. Giant azhdarchid pterosaurs from the terminal Cretaceous of Translyvania (western Romania). In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 91-104.

Dyke, G. Vremir, M. Kaiser, G. & Naish, D. 2012. A drowned Mesozoic bird breeding colony from the Late Cretaceous of Transylvania. Naturwissenschaften 99, 435-442.

Henderson, D. M. 2010. Pterosaur body mass estimates from three-dimensional mathematical slicing. Journal of Vertebrate Paleontology 30, 768-785.

Kellner, A. W. A. 2004. New information on the Tapejaridae (Pterosauria, Pterodactyloidea) and discussion of the relationships of this clade. Ameghiniana 41, 521-534.

Martill, D. M. & Naish, D. 2006. Cranial crest development in the azhdarchoid pterosaur Tupuxuara, with a review of the genus and tapejarid monophyly. Palaeontology 49, 925-941.

McGowen, M. R., Padian, K., de Sosa, M. A. & Harmon, R. J. 2002. Description of Montanazhdarcho minor, an azhdarchid pterosaur from the Two Medicine Formation (Campanian) of Montana. PaleoBios 22, 1-9.

Nesov, L. A. 1984. Upper Cretaceous pterosaurs and birds from central Asia. Paleontology Journal 1984 (1), 38-49.

Novas, F. E., Kundrat, M., Agnolín, F. L., Ezcurra, M. N. D., Ahlberg, P. E., Isasi, M. P.,  Arriagada, A. & Chafrat, P. 2012. A new large pterosaur from the Late Cretaceous of Patagonia. Journal of Vertebrate Paleontology 32, 1447-1452.

Paul, G. S. 2011. Azhdarchids were NOT as big as giraffes! Prehistoric Times 97, 22.

Vremir, M., Kellner, A. W. A., Naish. D. & Dyke, G. J. 2013. A new azhdarchid pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: implications for azhdarchid diversity and distribution. PLoS ONE 8(1): e54268. doi:10.1371/journal.pone.0054268

Weishampel, D. B., Grigorescu, D. & Norman, D. B. 1991. The dinosaurs of Transylvania. National Geographic Research & Exploration 7 (2), 196-215.

Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books Ltd., London.

Witton, M. P. 2008. A new approach to determining pterosaur body mass and its implications for pterosaur flight. Zitteliana B28, 143-158.

- . & Habib, M. B. 2010. On the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues and comments on pterosaur flightlessness. PLoS ONE 5(11): e13982. doi:10.1371/journal.pone.0013982

- . & Naish, D. 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS ONE 3 (5): e2271. doi:10.1371/journal.pone.0002271

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!

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





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  1. 1. Halbred 8:27 pm 01/30/2013

    I have a question that’s probably stupid.

    Why are the skeletons of LARGE dinosaurs so often fragmentary? Look at sauropods: sauropods are often known from bits and pieces, especially guys like titanosaurs and diplodocids. But even smaller sauropods, like Brachytrachelopan, are articulated but largely incomplete.

    Here’s the thing, though: these animals were HUGE. Sauropods were HUGE, yet so often the only surviving bones are verts (right?) or some limb material. Aren’t these bones incredibly heavy? Where do they go? Does the skeleton just break apart like a Crash-Test Dummy once the meat is gone?

    Same with ceratopsids. Lots of skulls, not much skeletal material. Same with ankylosaurs–lots of pelvises, spines, and armor, but not a lot of skeletal material (right?). Same with azhdarchids. They’re known from wing bits and pieces of skull. Smaller dinosaurs (and pterosaurs) are seemingly more complete more often. Maybe I’ve been making incorrect assumptions. But it’s frustrating sometimes, probably for the reader as well as the researcher, to have something like “the most complete European azharchid” and it’s some snout and wing bones, but it’s the same for a lot of dinosaurs. What is happening to these enormous, heavy sauropod skeletons that makes them…vaporize?

    Link to this
  2. 2. kmkohler 8:41 pm 01/30/2013

    This article seems to confirm (or at least make plausible) that Azhdarkho is indeed a specific dragon.

    http://en.wikipedia.org/wiki/Zahhak

    Link to this
  3. 3. RaptorX 8:51 pm 01/30/2013

    Very cool to see another Mesozoic azhdarchids described, although I must say I haven’t heard much info concerning the Two Medicine and Dinosaur Park giants until now. Thanks!

    “It might be tempting to suggest that the presence on Haţeg Island of these different azhdarchid species is linked in some way to this absence of large theropods. However, as is obvious from the discussion above, we already know that azhdarchids large and small were quite capable of inhabiting ecosystems where diverse theropods (including even giant tyrannosaurids) were present, so this idea may be moot.”

    Interesting you say that. A while back I recall someone (appologies for not remembering exactly who) suggest that azhdarchids were filling the same niches as theropods, which explains the absence of many mid-sized theropods in some formations where they would normally make up the middle part of the food chain.

    For example, in Two Medicine you have large theropods (Daspletosaurus, Gorgosaurus) and small theropods (Saurornitholestes, Troodon, ect) but no theropods providing the mid-sized range, and hypothetically that’s where these giant azhdarchids fall. Holtz did suggest an alternative where perhaps the mid-sized range was filled by juvenile tyrannosaurids due to their prolonged childhood and teenage years. I personally find the latter more likely, since its easier to imagine than a 400 pound “broken umbrella” killing something like a 20ft, one ton hadrosaur. Still I’m not sure, but it’s good to know that theropods and azhdarchids were able to co-existed so well.

    Link to this
  4. 4. John Harshman 9:08 pm 01/30/2013

    Azhdarchids are very puzzling as always. If only we had time travel, paleontology would be so much easier. Of course someone would probably step on a butterfly and eliminate human civilization, but there’s a downside to everything.

    Link to this
  5. 5. JoseD 11:18 pm 01/30/2013

    Naishd: “The ‘vulture azhdarchid’ hypothesis, as depicted by Jan Sovak (this is from Philip Currie’s poorly known 1991 book The Flying Dinosaurs).”

    That book’s on my Want list. Why is it so poorly known, though?

    Link to this
  6. 6. Christopher Taylor 12:08 am 01/31/2013

    Halbred (#1): Others more knowledgeable about fossilisation processes than me will doubtless have more to say, but one factor working against the preservation of large animals is the problem of burial. To be fossilised intact, a dead animal usually needs to be quickly sealed away from all the processes that would normally break them apart. The actions of scavengers, the sun, wind and water, etc. can quickly render a corpse unrecognisable. Small animals are much more likely to be buried in landslides, anoxic mud or whatever, but it would take a lot of mud to bury something the size of a sauropod. So most fossilised sauropods will have probably been subject to some degree of post-mortem interference: a couple of hungry theropods gnawing on limb bones, for instance.

    Same with ceratopsids. Lots of skulls, not much skeletal material.

    Is this actually the case? Or does the general assumption that ceratopsid postcrania are dull and samey mean that they tend to go under-reported?

    Link to this
  7. 7. vdinets 1:27 am 01/31/2013

    Azhdarkho (spelling very variable) is a winged demon in many Turkish and East Iranian mythologies, from Turks to Siberian Tatars and Tajiks. There are many local versions, some aquatic, multi-headed and/or fire-breathing. It can be remarkably similar to more western versions, for example, it often threatens a city and demands virgin sacrifices. The Russian-language page I am translating from (http://myths.kulichki.ru/enc/item/f00/s00/a000089.shtml) says that it is of Indo-Iranian origin; that might explain its similarities to European myths. It has been incorporated into Balkan Slavic mythologies (as azhdaya) and Russian fairy tales (as Zmei Gorynych, the fiery serpent).

    As for sympatric Azhdarchids of different size, there are actually two possibilities. They could do different things, or they could do the same thing in slightly different ways, just like the two egrets on the photo. If the remains of two different-sized species are found together more often than they would be by chance, the latter possibility is more likely. Are they?

    Link to this
  8. 8. Mark Robinson 1:46 am 01/31/2013

    I’ve always understood Azhdarkho to be a singular specific entity but don’t have a credible reference.

    @John Harshman – ah, the other “butterfly effect”. Any time-travelling device would also need to be a space-travelling one, able to accurately determine where Earth would have been at your chosen destination time, and exactly where a surface suitable for standing upon would be.

    On second thoughts… you go and I’ll stay back at the lab to make sure that there’s no problem this end.

    Link to this
  9. 9. amdurso 2:34 am 01/31/2013

    Really excellent article, very thorough. Good to read some paleoecology.

    Link to this
  10. 10. Pristichampsus 2:43 am 01/31/2013

    I am rather tempted to suggest that the short-snouted big-bend azdharchid could be eating something tougher. The idea of a crab eater was proposed for Quetzalcoatlus, but maybe this other creature could be durophagous in this manner, if not for crushing things, then simply to have a more forceful peck, or less delicate jaws.

    Link to this
  11. 11. Finback 4:36 am 01/31/2013

    One thing that feels a bit odd to me – the comparison image with the giraffe; the head of the giraffe looks HUGE compared to a human. I know giraffe heads aren’t tiny little things, but what’s the upper size on one?

    Link to this
  12. 12. Jerzy v. 3.0. 5:12 am 01/31/2013

    Cool article! I would expect a pterosaur which was theropod analogue (predator of things similar size to themselves) to look more like a hawk or a cat. That is have short, massive skull with teeth or hook to tear flesh, flexible, strong neck, and maybe powerful arms with large curved claws.

    BTW, is there any such clearly predatory pterosaur?

    Link to this
  13. 13. naishd 5:38 am 01/31/2013

    Great comments, thanks everyone.

    Halbred (comment 1): yeah, as Chris said (comment 6), small animals occasionally get buried whole, hence nice, articulated skeletons. Big animals – and giant ones in particular – virtually never do. Think about elephants and such. Their remains are sitting around on the ground for years, even decades, meaning that their skeletons become substantially disarticulated. It takes pretty exceptional circumstances (burial by ash, sinking into mud, incorporation into a lava flow, mud slide or massive flood event) to get the whole animal preserved intact. Furthermore, big land animals tend to live in open, continental environments (on plains, in forests etc.) where the chances of preservation are low anyway. No wonder good remains are rare.

    Something else to think about: you mentioned sauropods. Were the bones of sauropods more susceptible to transportation and disintegration than those of big mammals or ornithischians due to their substantial pneumaticity? Just a thought.

    There is a whole book on the broader subject here, by the way…

    Behrensmeyer, A. K. & Hill, A. P. 1980. Fossils in the Making. Vertebrate Taphonomy and Paleoecology. The University of Chicago Press, Chicago & London.

    Darren

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  14. 14. naishd 5:55 am 01/31/2013

    Azhdarchids and theropods (comment 3): I don’t think we should necessarily imagine azhdarchids filling a ‘theropod niche’. Remember that azhdarchids seem to be like ground hornbills or marabou storks in behaviour – they were almost certainly eating small animals, but I don’t think they were arch predators, overlapping in ‘ecospace’ with maniraptorans or tyrannosauroids or whatever. Azhdarchids perhaps (I think) ate anything small enough to be picked up and thrown into the back of the mouth, plus they can (so far as we know) fly to new areas as and when they feel like it; they’re most likely ecological generalists. What I’m saying is that they can probably ‘fit’ into any contemporary ecosystem without competing with predatory theropods.

    As for the whole issue of predatory behaviour in pterosaurs in general (comment 12): we don’t know of any pterosaurs that look like they could have been arch-predators like hawks or falcons. Sure, some were almost certainly aerial predators of insects and even of birds and other pterosaurs (recall that Darwinopterus has features suggesting the possibility of maniraptoran-eating), but no ‘true’ predators as yet. They might not have existed.

    Darren

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  15. 15. naishd 6:12 am 01/31/2013

    re: Giraffe in Mark’s illustration (Finback, comment 11)… It’s not too difficult to find giraffe skulls that are 70 cm long. On an adult person, 70 cm is the approximate distance between the top of the head and the hip. In the illustration, the giraffe’s (approximate) skull length would extend from the top of Mark’s head to somewhere round about the side of his hip. When we imagine that it’s meant to be world-record giraffe (5.8 m tall or so), it’s possible that the skull is, say, more than 80 cm long… in which case the head of that giraffe is not unreasonably big. I think Mark was careful to get the scaling right – he may want to say more on this.

    Darren

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  16. 16. Gigantala 7:16 am 01/31/2013

    @naishd: Acthelly, Thalassodromeus has been suggested as something of a pterosaurian “eagle”, having more adaptations for predating on larger prey than other azhdarchoids.

    Then there’s Dimorphodon, Campylognathoides and several rhamphorhynchids that have been suggested as being raptorial carnivores.

    Link to this
  17. 17. Gigantala 7:17 am 01/31/2013

    And if you ant to get technical on it, istiodactylids fill the bill too, although they were more likely scavengers than genuine specialised predators.

    Link to this
  18. 18. naishd 7:27 am 01/31/2013

    Gigantala (comments 16 and 17): I’m totally happy with the idea that thalassodromids and maybe other pterosaur taxa were routinely foraging on the ground, feeding on small vertebrates and, furthermore, that istiodactylids were (possibly) scavengers.

    However, in the comment above I was responding to the idea that some pterosaurs were raptorial, hawk-like predators – ok, many raptors routinely eat insects, lizards, snakes etc., but the inference here is that we’re talking about the sort of behaviour whereby the animals are capable of tackling prey their own size, were routinely pursuing and subduing other flying animals etc. I don’t think any (known) pterosaurs were doing this.

    Darren

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  19. 19. Gigantala 8:48 am 01/31/2013

    Which is more or less what I was adressing. I was merely stating that it has been posited that Thalassodromeus and several “rhamphorhynchoids” were possibly tackling prey substantially large in proportion to their body size.

    Surely the bulk of their diet was probably smaller prey, but according to researchers like Mark Witton, there were at least some specialisations not seen in azhdarchid like taxa.

    Link to this
  20. 20. RaptorX 10:04 am 01/31/2013

    @Naishd

    Thanks for the clairification on that Darren. I understand that they were mostly stork-like in ecological niche, but I still can’t help but wonder how this might overlap with the local theropod species. I guess its just an interesting concept I was attracted to, like how the Sebecosuchia seemed to have competed with theropods in some places, but yes it doesn’t seem like competition between pterosaurs and theropods is suggested by the current evidence.

    As for this proposed “raptorial pterosaur”, didn’t we find out that Raeticodactylus has a foot anatomy similar to that of eagles? Or did Dave disprove that? I haven’t been all that up-to-date with pterosaur discoveries so I don’t know…

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  21. 21. Heteromeles 11:46 am 01/31/2013

    Aren’t things like gulls, skuas, frigatebirds, cranes, storks, and herons better analogs for pterosaurs than raptors are? Not to focus too much on the obvious, but I don’t recall seeing any pterosaur having legs suitable for capturing prey. They see to be stuck using their bills instead.

    I’m trying to recall if any skua has managed to kill a bird on the wing. Certainly they kill many birds on the ground. Any help out there?

    There’s another fun question, actually: any evidence of a vegetarian or omnivorous pterosaur?

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  22. 22. Gigantala 12:36 pm 01/31/2013

    Tapejarids.

    In addition, I think some of the supposed predatory rhamphorhynchids might actually had been “frugivorous”, feeding on gingko and podocarp fruits.

    If fruit bats have sharp teeth are are furgivorous, why not some pterosaurs?

    Link to this
  23. 23. David Marjanović 1:05 pm 01/31/2013

    Why the German name? (I mean, why not, but…)

    Philip Currie’s poorly known 1991 book The Flying Dinosaurs

    An awesome book it is, just short on text.

    Of course someone would probably step on a butterfly and eliminate human civilization, but there’s a downside to everything.

    That’s the right attitude!

    Is this actually the case? Or does the general assumption that ceratopsid postcrania are dull and samey mean that they tend to go under-reported?

    I do wonder.

    With Permian therapsids from South Africa, it used to be the case that only the skulls were collected and the rest of the skeleton was left in the field!

    On second thoughts… you go and I’ll stay back at the lab to make sure that there’s no problem this end.

    How? If there’s a problem at the other end, you have never existed.

    (OK, that might depend on the kind of time travel.)

    didn’t we find out that Raeticodactylus has a foot anatomy similar to that of eagles? Or did Dave disprove that?

    No idea; details, please!

    Link to this
  24. 24. JAHeadden 2:16 pm 01/31/2013

    Chiming in on two points:

    1. It seemed odd in the original paper that, while the question of synonymy with Hatzegopteryx thambema was raised, a method for discriminating distinction between differently-aged azhdarchids was not. Pterosaurs do not seem to be the subject of the same types of osteological correlates for ages that birds and many other sauropsidans may bem as they develop epiphyseal ossification of cartilages or neurocentral sutures, or limb proportions much in keeping with “adult” status rather early. How DO you determine whether the holotype of Eurazhdarcho langendorfensis was mature enough to hurdle the possible “juvenile of a larger taxon” barrier it might represent? (I understand that there are smaller and larger azhdarchids in various formations, the Javelina being a good example).

    2. Ecologically speaking, “maniraptorans” are nowhere near “top predator” in most ecosystems, with the Djadokhta interdune environments being one possible exception, or various small islands which would not support a macro-macropredator the size of a carnosaur or whatnot. It is easy to imagine that, in a decent-sized landmass like the latest Cretaceous Haţeg Island, without something the size of Hatzegopteryx thambema to compete with it on the ground, it is likely then that it was the apex predator, and that it may have suppressed other predators from attainign larger size. Meaning … it was eating ornithopods?

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  25. 25. Heteromeles 2:50 pm 01/31/2013

    Since I wrote a (mediocre) time travel novel, my firm belief is that, if time travel’s possible, every fossiliferous or evolutionarily important area is set off as a red zone with rangers patrolling it to keep idiots from messing up the continuity. Time travelers would confined to the areas that don’t matter to the future. If you think about the fossil record for a second, you’ll realize that most of Earth, for most of history, really didn’t matter in the scheme of things. You could have enormous, long-lived empires in that blankness, and it would have all been ground to dust a long time ago.

    So, if you want to travel in time, just make sure you’re totally irrelevant to the past or future. That’s all.

    Link to this
  26. 26. naishd 4:05 pm 01/31/2013

    Thanks for comments. I, too, haven’t heard anything about Raeticodactylus having an eagle-like foot and assume that this is a mistaken misremembering.

    Jaime (comment 25) – you say that “a method for discriminating distinction between differently-aged azhdarchids” wasn’t provided… well, I dunno – there is the differential diagnosis where we specifically say that “there are currently no overlapping elements between EME VP 312 and specimens referred to the giant-sized Haţeg azhdarchid Hatzegopteryx thambema“. Note also that the latter material “is currently under study by our team”. So, more to come. Don’t forget that histology can be used to gauge the ontogenetic stage of an individual.

    Darren

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  27. 27. Eriorguez 4:24 pm 01/31/2013

    On the topic of flightless giant Azhdarchids, I’d say that, in my opinion, the lack of major differences between the Quetzalcoatlus and Hatzengopteryx (I recall reading there was no diagnosic differences, and the overlapping material was undistingable; recall being the key word) could mean they were the same taxon, or at least closely related sister taxa, who didn’t covergently evolve that large size. If that was the case, I’d argue agaist their dispersal being land-based, and in favor of giraffe-storks flying across the young Atlantic. Still, Q.northropii is, again IIRC, scrappy and a bit of a descriptional mess, while Hatzengopteryx is not so complete to begin with, so I guess the only thing this student can do is speculate and read more…

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  28. 28. Gigantala 4:49 pm 01/31/2013

    If they were flightless though, why bother retaining literally all adaptations for flight present in pterosaurs?

    Of course, it is possible that the juveniles could fly and that only the fully grown adults were flightless, in that case a global distribution would make sense since, much like megapodes, the youngesters would be exceptional flyers.

    Link to this
  29. 29. RaptorX 5:22 pm 01/31/2013

    @David Marjanović & naishd

    My mistake, I remembered something about it having an odd femur similar in shape to a theropod’s, and somehow my mind brought it back to me as having Eagle-like tallons. Don’t know how that happened, just ignore what I said.

    Still, looking over everything discussed here, I was wondering about the posibility of a pterosaur using its rear limbs in catching fish. Not in an eagle-like fashion, but how about something along the lines of raking like in fishing bats? I know that some rhamphorhynchids had large hook-like toes, but do we know if these could be used in a similar way?

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  30. 30. SRPlant 5:30 pm 01/31/2013

    “So, if you want to travel in time, just make sure you’re totally irrelevant to the past or future. That’s all.”

    Where do I sign?

    Link to this
  31. 31. Jerzy v. 3.0. 6:38 pm 01/31/2013

    I wonder if pterosaurs had ability to swallow relatively large prey whole? Herons, cormorants and spoonbills can swallow enormous fish whole. I remember a tame Grey Heron which eaten whole chicken leg sans meat (articulated tibia and femur) and then another femur, although later it couldn’t close its beak fully.

    Another idea – could azhdarchid pterosaurs be analogues of cranes, not just storks? That is feed also on plant items and maybe dig a little into ground with their bills.

    Link to this
  32. 32. Heteromeles 7:32 pm 01/31/2013

    @SRPlant: “So, if you want to travel in time, just make sure you’re totally irrelevant to the past or future. That’s all.” Where do I sign?

    Possibly at this Amazon link.

    Link to this
  33. 33. TimWil 9:53 pm 01/31/2013

    RaptorX: “A while back I recall someone (appologies for not remembering exactly who) suggest that azhdarchids were filling the same niches as theropods, which explains the absence of many mid-sized theropods in some formations where they would normally make up the middle part of the food chain.”

    I’ve wondered if eudromaeosaurs filled this niche. Although not mid-sized, smallish dromaeosaurines and velociraptorines might have “punched above their weight” in terms of predatory guilds. So they acted like mid-sized predators, targeting prey larger than themselves – including azhdarchids. We know that _Saurornitholestes_ and _Velociraptor_ both fed on azhdarchids, and I’m willing to bet the azhdarchids were caught live by the predators (rather than just scavenged).

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  34. 34. JoseD 10:55 pm 01/31/2013

    @Naishd

    Besides making sure my question in Comment 5 isn’t forgotten about, I wanted to let you that I recently posted “Good, semi-good, and bad dino sources” ( http://jd-man.deviantart.com/journal/SD-Good-semi-good-and-bad-dino-sources-351589315 ) & that Conway et al. are an important part of it (Besides being 1 of the good sources, I referenced your work when reviewing some of the other sources). I also wanted to make sure that I did your work justice. Many thanks again for being awesome.

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  35. 35. Dartian 3:51 am 02/1/2013

    Darren:
    the head of that giraffe is not unreasonably big. I think Mark was careful to get the scaling right

    I respectfully disagree. Even if the giraffe’s body height is right, the body proportions are definitely off compared to the human figure (Mark?), and the head in particular is indeed way too big. For example, that giraffe’s ear is now longer than the human’s entire head – in fact, the giraffe’s ear is longer than the human’s thigh! That just isn’t right!

    Did Mark use a much smaller giraffe as a model for this illustration, and then just isometrically re-size it to ‘world record’ height? That could explain the disproportionality.

    Regarding time-travel: Alas, if someone actually did invent a functional time machine I don’t think that palaeontologists would ever get a chance to use it. Perhaps I’m too cynical, but I fully expect politicians and the military to take exclusive control of it and use it to try and re-write history. They would send saboteurs or assassins back in time in order to prevent certain things from happening. (Killing Osama bin Laden before 9-11, or Hitler before the Second World War – that kind of stuff.) Which, presumably, would result in a butterfly effect of clusterfuck proportions.

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  36. 36. naishd 4:08 am 02/1/2013

    Thanks for comments. Fair enough, I screwed up on the giraffe (see comments 15 and 35) and Mark should be lynched.

    Could azhdarchids have been crane-like (comment 31)? Mark Witton and I did have omnivory in mind for these animals, as have other workers who agree with our model (see, e.g., Ősi et al.’s work on Bakonydraco), but we imagined ground hornbills as the best modern analogues. I would certainly agree that they could be imagined as somewhat crane-like as well: remember, however, that cranes are often associated with wetlands while azhdarchid feet indicate a preference for dry places. And, yes, I know that some cranes spend time on plains, steppes and other dry places.

    As for herons eating large objects, don’t forget this Tet Zoo article, and this one too.

    JoseD: sorry for missing your question (comment 5). I don’t know why Currie’s book The Flying Dinosaurs is so poorly known. Here in the UK, it’s ‘rare’ – I only ever saw it for sale once, and purchased it on that occasion (this was at the NHM in London, back when they had a really good bookshop).

    Darren

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  37. 37. Andreas Johansson 4:22 am 02/1/2013

    TimWil wrote:
    We know that _Saurornitholestes_ and _Velociraptor_ both fed on azhdarchids, and I’m willing to bet the azhdarchids were caught live by the predators (rather than just scavenged).

    Why? Offhand, scavenging seems extra likely when the eatee might just fly away if alive.

    Not saying they couldn’t target live azhdarchids, just curious why it should be the smart bet over scavenging dead ones.

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  38. 38. MarkWitton 4:30 am 02/1/2013

    Lots to comment on here, so apologies for the brief responses:

    Re. giraffe head size: As Darren has said, giraffe heads are a lot bigger than we think. Our perception of their size is distorted by them being a good 4-5 m above our heads. I had the opportunity to view a bull Rothchild’s giraffe at his head height last summer, and it was seriously huge. 70 cm seems a likely length. My illustration may be a little off, but I don’t think it’s that unreasonable.

    On pterosaur diets: I don’t think there are any pterosaurs adapted for subduing and eating prey larger than themselves. Attila Ősi’s work on the teeth of many early pterosaurs suggests a diet of fish, insects and small vertebrates in different groups, with perhaps some omnivory thrown in here and there. I especially doubt that Dimorphodon was an aerial predator, because several authors (including myself) have found it to be a rather heavyset animal, and thus a relative ineffective flier. I also don’t buy the Darwinopterus “maniraptoran predator” hypothesis – I discuss why at length in my book. Thalassodromeus may have been capable of subduing relatively larger prey than equivalently sized azhdarchoids because its skull is comparatively robust, but it probably wasn’t especially ‘raptor’-like.

    The azhdarchids vs. theropods thing. I have wondered if azhdarchids became very important animals in impoverished Maastrichtian dinosaur ecosystems, being the dominant ‘medium size’ predator (note ‘medium size’ is based on mass, not linear dimensions’). This may explain some of the discrepancies in theropod body size in some Maastrichtian faunas. I stress this is very much just an idea though: I don’t have any strong evidence to back it up – just one powerpoint slide, in fact.

    Finally, on (giant) azhdarchid taxonomy. The taxonomic situation with azhdarchids is a difficult one to assess because we are still waiting for descriptions and diagnoses of the Quetzalcoatlus northropi and Quetzalcoatlus sp. remains. I have commented several times that the current presentation of the taxonomy of these animals is wholly unsatisfactory and murky, and that the holotype wing of Quetzalcoatlus northropi will have to be particularly unusual to differentiate it from the wing bones of other giants. Some of the new giant azhdarchid material mention in Darren’s post may help to help untangle some of these problems, but we’re still working on it and cannot offer any particular insights at this stage.

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  39. 39. Dartian 5:08 am 02/1/2013

    Mark:
    giraffe heads are a lot bigger than we think. Our perception of their size is distorted by them being a good 4-5 m above our heads

    It turned out to be surprisingly difficult to find a good photograph on the web where the heads of an adult giraffe and an adult human are directly comparable by being in close proximity (and not distorted by perspective), but here is one. Look at the size/length of the giraffe’s ears and compare them with the head of the human. (Then imagine how the giraffe’s ears would compare in length with that man’s thighs.)

    Link to this
  40. 40. Jerzy v. 3.0. 7:02 am 02/1/2013

    Re: time travel. I heard interesting back-door explanation. If time travel was possible/invented, then the reality would indeed change in series of time paradoxes, however one would ultimately result in a timeline where time travel was never invented/impossible. At which point the reality would stay constant forever.

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  41. 41. Jerzy v. 3.0. 7:07 am 02/1/2013

    @38
    Does it mean that somebody can write a paper with a redescription of Q. northropi basing on diagnostic material and first description of unnamed Q.? Sounds like an opportunity to make an extremely well cited paper in paleonthology, although perhaps a bit mean.

    Link to this
  42. 42. Jerzy v. 3.0. 7:10 am 02/1/2013

    Re: giraffe head is huge indeed – see eg this link:
    http://www.tripadvisor.com/LocationPhotos-g44926-Springfield_Missouri.html

    (I hope spam filter doesn’t block it).

    Link to this
  43. 43. MarkWitton 8:46 am 02/1/2013

    [from Darren: sorry, delayed by spam filter]

    Dartian: I’m very certain that your image represents a juvenile or otherwise very small giraffe. The animal in my picture represents a record breaking, 6 m tall individual. As Jerzy’s has noted, there are other images that show quite the opposite. I also found these:

    This image…

    Another (relies a bit on foreshortening, but still looks fairly large)

    A replica skull over two feet long

    Some giraffe heads are really big. That’s how it is.

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  44. 44. vdinets 8:55 am 02/1/2013

    Jerzy: apparently, that has already happened :-(

    There is, however, a possibility that when you travel in time, every time you arrive into some point in the past you create a time junction and an entirely new world with a slightly different trajectory. When you leave it to return to your point of origin in the old world, the new world either ceases to exist or continues to exist separately from yours, and is forever inacessible. So there are no paradoxes, and no matter what you do in that new “past”, your own world remains unchanged.

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  45. 45. Heteromeles 9:54 am 02/1/2013

    About time travel…

    I could be wrong, but I believe Larry Niven was the one who noted that, if time travel was possible, but there’s only one timeline, then eventually someone would screw up the timeline so much that time travel became impossible. That’s been around since the 1970s, and even Star Trek has thrown up “continuity police” on occasion to either stop this or use it for a reboot. This contrasts with the Dr. Who “timey-wimey” ball. In the Whoverse, they’ve come up with so many contradictions about what time travel is that it’s all rather murky.

    As for the infinitely splitting time stream (every time a machine goes back, you get a new time-line), that’s an offshoot of the multiple worlds quantum theory. In this one, you can go back in time whenever you want, but you can never come forward to the same world you left, so sorry. However, this machine would have real effects in the present, because every splinter sect,would-be world ruler, and survivalist who could afford a machine would take off, and we’d never hear from them again. It’s a great self-perpetuating franchise, in its own way, and a great (if expensive) way to get rid of malcontents. You do have to throw out the first law of thermodynamics to get this result, but minor quibbles…

    I had a little fun with the idea of limited timeline branching, and continuity police. The problem with such a political solution is that, when the time comes to bifurcate Earth’s timeline, the dispute over who gets what on which timeline inevitably results in a mass extinction, along with diverse and contradictory disasters recorded in the fossil record (like a simultaneous asteroid strike and trap vulcanism, whose effects don’t interact even though they should have). The continuity patrol comes along after the bifurcation and mitigates the mess to the point where it no longer interferes with continuity. They then carefully monitor the downtime paleontologists and geologists to make sure they didn’t leave any dangerous clues lying around. This explains all those paleontology students who got degrees and disappeared into the general populance, never to be heard from again, and the scarcity of paleontology jobs in general. Really.

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  46. 46. SRPlant 9:56 am 02/1/2013

    @vdinets

    So the chances of retroactive elimination of dictatorial monorchid tetrapods remain slim?

    (Had to get “tetrapod” in there somehow otherwise one could be accused of being off topic)

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  47. 47. SciaticPain 11:29 am 02/1/2013

    On theropod/azhdarchid cohabitation, I do find it curious that azhdarchid style pterosaurs do not become prevalent well into the Cretaceous. Why didn’t pterosaurs of this nature evolve earlier, surely there was lots of small prey/baby dinos throughout the Jurassic for them? Perhaps azhdarchid style pterosaurs evolved on small island ecosystems(more typical of Cretaceous than Jurassic), bereft of large theropods. Once they perfected this terrestrial hunting strategy they could have successfully exported it to larger landmasses in spite of large theropods?

    On specialist vs generalist feeding strategy. I believe the giant azhdarchid pterosaurs were fundamentally specialists of dinosaur nesting colonies, supplemented by opportunistic foraging/scavenging during the “off season”. Although the stork analogy is useful there is good reason we don’t see storks anywhere near the size of azhdarchids because the ecological space for such a forager does not exist today in slow reproducing mammal dominated habitats. Although not a perfect analogy, there are types of birds (sheathbills, caracaras, skuas) that are primarily dependent on seabird colonies. Dinosaur nesting colonies would have opened up such opportunities for azhdarchids to grow so large and the ability to fly allowed them to reach distant, seasonal colonies.

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  48. 48. JAHeadden 2:09 pm 02/1/2013

    Darren:

    The differential diagnosis notes that it cannot discriminate between Hatzegopteryx thambema and Eurazhdarcho langendorfensis, by which they lack comparable material. This is not to say that they should be synonymized, merely that it leads one to doubt without ontogenetic data the distinction of “small” versus “large” azhdarchids as distinct taxa. Witton’s worry about the lack of diagnostic quality in Quetzalcoatlus northropi is a valid one, though based on material that is clutched pretty close to the breast at the moment.

    I worry, though: The type humerus of Hatzegopteryx thambema is in pretty bad shape, which calls into question how much of it may be useful. Indeed, how intact is the surface around the distal end of the humerus? I will, of course, wait for the paper on this subject and the larger specimen also alluded to.

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  49. 49. Gigantala 4:15 pm 02/1/2013

    @JoseD: I wouldn’t accuse people of cyberbullying when you committed such yourself.

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  50. 50. Jerzy v. 3.0. 9:12 am 02/2/2013

    @45
    I realized that it is long before Niven. The first novel I recall about time travel changing the world into the one without time travel is The End of Eternity from 1955 by Isaac Asimov.

    In scifi, when I hear some new idea, usually there turns to be several stories or a whole sub-genre developing it. Unfortunately, stories with the well-developed ideas are often badly written and vice versa. So I don’t read much scifi, rather reviews, summaries etc.

    @47
    I think azhdarchids or any specialized morphotype needs time to evolve. The same, pteranodontids didn’t evolve earlier although there had been plenty of oceans with large fish etc.

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  51. 51. Jerzy v. 3.0. 9:15 am 02/2/2013

    @47
    Certainly there have been sauropod nesting colonies long before azhdarchids.

    Good point that pterosaurs (and birds) could disperse well, so could specialize in unusual food resources.

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  52. 52. Shuhray 10:29 am 02/2/2013

    Could they have wings with holes to catch fish?

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  53. 53. JoseD 11:28 am 02/2/2013

    @Naishd

    Sorry in advance for the following deviation from the topic at hand, but trolls/cyberbullies should be called out on their actions.

    @Comment 49

    Good to see you too Gigantala/Johnfaa, but not really. I see you’re still making unsupported claims. You’re also still on my Ignore list, so go waste someone else’s time. This is just a reminder (since you apparently forgot) b-4 I continue ignoring you.

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  54. 54. David Marjanović 12:30 pm 02/2/2013

    Time travel: follow the link I posted.

    If you think about the fossil record for a second, you’ll realize that most of Earth, for most of history, really didn’t matter in the scheme of things. You could have enormous, long-lived empires in that blankness, and it would have all been ground to dust a long time ago.

    I think you’ve massively underestimated the butterfly effect.

    Still, looking over everything discussed here, I was wondering about the posibility of a pterosaur using its rear limbs in catching fish. Not in an eagle-like fashion, but how about something along the lines of raking like in fishing bats? I know that some rhamphorhynchids had large hook-like toes, but do we know if these could be used in a similar way?

    Being so strongly adapted to hanging from trees, bats can supinate their lower legs by 180°. They can make the soles of their feet, and thus the points of the claws, point forward. That’s what fish-eating bats do. Pterosaurs? No way.

    For a very similar reason, hovering pterosaurs (comparable to hummingbirds or small bats) are impossible.

    We know that _Saurornitholestes_ and _Velociraptor_ both fed on azhdarchids

    V. is news to me, as is the existence of azhdarchids in Mongolia. Are you sure you aren’t talking about a source that lumped S. into V.? (That was fashionable for some time.)

    simultaneous asteroid strike and trap vulcanism

    They were not simultaneous! The volcanism started long before the impact + mass extinction and ended long after it, and the main episode of basalt outflows ended 300,000 years before it, along with the modest temperature increase it had caused! This has been known, and published in places like Science, for well over a decade now.

    This explains all those paleontology students who got degrees and disappeared into the general populance, never to be heard from again, and the scarcity of paleontology jobs in general. Really.

    You are a genius.

    Why didn’t pterosaurs of this nature evolve earlier, surely there was lots of small prey/baby dinos throughout the Jurassic for them?

    I guess suitable ancestors weren’t yet available.

    @JoseD: I wouldn’t accuse people of cyberbullying when you committed such yourself.

    Having read JoseD’s link and the 7 pages of forum that that link links to, I’m not sure if “cyberbullying” is the right term for what either of you have done. But why didn’t you comment over there instead of here?

    Link to this
  55. 55. David Marjanović 12:55 pm 02/2/2013

    Could they have wings with holes to catch fish?

    Uh, what? Like a net, so they couldn’t fly?

    Link to this
  56. 56. JoseD 1:13 pm 02/2/2013

    David Marjanović: “V. is news to me, as is the existence of azhdarchids in Mongolia. Are you sure you aren’t talking about a source that lumped S. into V.? (That was fashionable for some time.)”

    I think TimWil’s referring to Hone et al. 2012.

    David Marjanović: “Having read JoseD’s link and the 7 pages of forum that that link links to, I’m not sure if “cyberbullying” is the right term for what either of you have done. But why didn’t you comment over there instead of here?”

    He can’t b/c he’s been banned from DA several times for cyberbullying (E.g. here). 1 of those times, he spammed my inbox w/a flaming message.

    Link to this
  57. 57. RaptorX 1:26 pm 02/2/2013

    @David Marjanović

    “V. is news to me, as is the existence of azhdarchids in Mongolia. Are you sure you aren’t talking about a source that lumped S. into V.? (That was fashionable for some time.)”

    Nah, he’s right. Hone described a fossil of an azhdarchid within the body cavity of a Velociraptor early last year.

    Link to this
  58. 58. RaptorX 1:28 pm 02/2/2013

    Whoops, looks like Jose beat me to it… XD

    Link to this
  59. 59. Shuhray 9:23 pm 02/2/2013

    Yes, like a net. They couldn’t fly, they fished with wings.

    How to cite other people’s comments?

    Link to this
  60. 60. David Marjanović 9:22 am 02/3/2013

    Oops. Thanks for the reminders of that paper, now I remember it…

    Yes, like a net. They couldn’t fly, they fished with wings.

    – How could that ever evolve?
    – Wouldn’t that require movements that pterosaurs couldn’t do with their wings?
    – There’s no evidence from any known pterosaur that it couldn’t fly.

    How to cite other people’s comments?

    Copy and paste what you want to cite, and put <i> tags around it. Unfortunately, <blockquote> doesn’t work on scientificamerican.com.

    Link to this
  61. 61. Heteromeles 12:30 pm 02/3/2013

    Good grief, David, you think I was serious about time travel? I’m honored. Writing stories where causality is a feedback loop is a real pain, I can assure you. I’ll admit I did enjoy dreaming up the Institutes for Applied Phylogenetics and Biogeography, just to prevent those butterfly effects everyone is so worried about. I’m cynical enough to believe that time travel will breed bureaucracies, just to maintain continuity. After all, bureaucracies are better than almost any other type of organization at protecting their own existence, so who better to make sure that history stays more or less the way it happened?

    In any case, the real point (as with the Azhdarchid skeletons that started this) is that paleontologists work with fragments against a large background of emptiness. I suspect that most paleontologists stay sane by ignoring the extent of the emptiness, how much we can’t know.

    Still, every once in a very long while, it’s worth stepping back from the fragments and looking at the vast gulfs that surround them. There are so many places that didn’t and couldn’t leave fossils that there is room for a small sustainable civilization at just about any time in Earth’s history, up to the last 10,000 years or so. It may be cruel to point this out, but it’s also true. If there are time travelers up-time from us, we’re almost certainly never going to see a trace of them.

    Link to this
  62. 62. Jerzy v. 3.0. 3:30 pm 02/3/2013

    @61
    Those hidden civilizations would need to know future fossil sites in millions of years time and 100 percent keep away from them. A difficult job!

    We know at least that no planet-wide technical civilization existed on Earth since Paleozoic. Signs would be eg. fossilized trash in river and ocean deposits or exhaustion of surface metal deposits.

    Link to this
  63. 63. Jerzy v. 3.0. 3:34 pm 02/3/2013

    Just feeling silly:
    So, adult Hatzegopteryx could swallow a mature paleo-artist whole?

    Link to this
  64. 64. RaptorX 5:19 pm 02/3/2013

    @Jerzy v. 3.0.

    I don’t see why not. In fact if I was to somehow able to go back in time, I’d be more scared of azhdarchids than any theropod. Theropods would probably spend the majority of their time sleeping, like modern raptors and predatory animals. Meanwhile azhdarchids would probably be stalking prey for longer periods of time and foraging more frequently like storks. They’d be more of a common and active threat, plus they could just fly right into any fenced-off area I may be able to put up.

    Although, this also brings up the idea of vice-versa to TimWil’s statment; would azhdarchids also feed on deinonychosaurs? They certainly fall into the range Hatzegopteryx’s prey size.

    Link to this
  65. 65. Heteromeles 6:42 pm 02/3/2013

    @Jerzy, agreed. That’s why I specified “small” and “sustainable” for any time traveler civilization. It’s another small irony that perfect sustainability also hides a civilization from the paleontological record. As our civilization becomes more sustainable, we’re also going to leave behind a lot less junk for the archeologists to find.

    As for mistakes, remember that, for most of Earth’s history, there are millions of years downtime to catch and fix mistakes. Personally, I’d bet that many settlements would spring up to service the rangers who keep people out of critical fossiliferous and evolutionary areas, but that’s just me.

    Incidentally (and slightly more seriously), there’s a little book by Jan Zalasiewicz (The Earth After Us) that talks about the fossil evidence of our civilization that will be visible in the geological record 100 million years from now. It’s a lot less than one might think. For example, the people most likely to leave useful human fossils wore a pair of concrete galoshes to the bottom of the Hudson River a few decades ago.

    Link to this
  66. 66. Gigantala 8:10 pm 02/3/2013

    @JoseD: Again, very hypocrital on your part.

    But alas, pointing out flaws in your arguments is like talking to a particularly mute wall, so…

    Link to this
  67. 67. David Marjanović 8:38 am 02/4/2013

    Good grief, David, you think I was serious about time travel?

    ~:-| What do you mean?

    After all, bureaucracies are better than almost any other type of organization at protecting their own existence, so who better to make sure that history stays more or less the way it happened?

    Good point!

    That’s why I specified “small” and “sustainable” for any time traveler civilization. It’s another small irony that perfect sustainability also hides a civilization from the paleontological record.

    A perfectly sustainable civilization that uses, say, metals still has to mine them once, even if it recycles them happily ever after. And it has to stay away not just from the usual suspects of areas with sedimentation, but also from fissures (let alone caves) in limestone.

    And its presence will still exert a selection pressure on something.

    I’m not saying we’d necessarily have already detected such a civilization; but to keep it safely undiscoverable is not easy at all.

    Link to this
  68. 68. naishd 8:46 am 02/4/2013

    So many comments…

    Some quick responses. Jaime (comment 48): if you’re referring to overlap between Hatzegopteryx and Eurazhdarcho, all I’ll say is… overlapping material, stay tuned (some of what we say in the Eurazhdarcho paper is now out of date). As for ontogeny in pterosaurs, don’t forget that there is a thing called histology!

    Jerzy (comment 63): across the jaw joints, Hatzegopteryx was about 500 mm wide. Across my shoulders, I’m c. 520 mm wide. It is therefore conceivable, perhaps, that a giant azhdarchid could swallow a human, especially a juvenile or small adult one. Yes, palaeontologists have already thought about this issue.

    Darren

    Link to this
  69. 69. Jerzy v. 3.0. 10:05 am 02/4/2013

    I think any self-respecting pterosaur would throw food to the air to fit a human perpendicularly to the throat.

    Thanks for the link, it answers the question which is, of course, most important: could you fly on them? ;)

    Link to this
  70. 70. Cameron McCormick 11:14 am 02/4/2013

    RE: Giraffe Heads

    Markus Bühler directed me to this photograph of a 5.8 meter tall Rothschild Giraffe at a German zoo. The head looks pretty similar in size to what Mark illustrated, although perhaps just a tiny bit smaller.

    Link to this
  71. 71. Heteromeles 12:21 pm 02/4/2013

    My thanks for the link too, Darren. Next time we get time traveling shenanigans on TV (please with some semblance of character development next time!) it will be some luckless farmer trying to scare a pack of large azhdarchids away from prize herd of organic dairy goats. Give them the intelligence and general disposition of water monitors, and they could be truly serious nuisances, quite unlike the swarming nasties that have shown up on earlier TV shows.

    Link to this
  72. 72. JAHeadden 7:47 pm 02/4/2013

    Naish: Yes, I am in particular concerned with histology. My concern is that histology has to be backed up with multiple sections, and that broken, shattered specimens may not be useful because they do not capture the total circumference of the bone used, and LAGs may vary in expression around the circumference. Nonetheless, I look forward to new data as was suggested in the paper with the giant specimen.

    Link to this
  73. 73. naishd 4:44 am 02/5/2013

    Jaime – you’re doing that thing again (arguing simply for the sake of having an argument). Stop it. Nobody mentioned LAGS. More on azhdarchids soon…

    Darren

    Link to this
  74. 74. JoseD 11:32 am 02/5/2013

    Naishd: “Yes, palaeontologists have already thought about this issue.”

    I didn’t know about that article, so many thanks for sharing. That does remind me though: Everyone seems to agree that pterosaur diversity was declining in the Cretaceous; However, how likely is it that, based on the evidence, birds were outcompeting/replacing pterosaurs in the Cretaceous?

    Heteromeles: “Next time we get time traveling shenanigans on TV (please with some semblance of character development next time!) it will be some luckless farmer trying to scare a pack of large azhdarchids away from prize herd of organic dairy goats. Give them the intelligence and general disposition of water monitors, and they could be truly serious nuisances, quite unlike the swarming nasties that have shown up on earlier TV shows.”

    Why monitors? Based on what I’ve read (the aforementioned Witton article & the papers cited therein), pterosaurs had a bird-like intelligence.

    Link to this
  75. 75. Heteromeles 11:52 am 02/5/2013

    I wasn’t thinking of monitors for their specific sensorium, but for their general ability to solve problems, willingness to go anywhere, and willingness to at least experiment with eating anything. The other things is that modern birds have (I believe) a higher encephalization quotient than do pterosaurs, so I’m not sure that pterosaurs would react quite as quickly as birds do. In other words, I’m thinking about attitude and reaction time. This contrasts with the flocks of pterodactyls treated basically as swarming bees in a couple of time travel SF TV shows that shall remain nameless.

    Actually, as a side thought, here’s a compare for someone to run: how does encephalization compare between birds, bats, and pterosaurs? Is there a correlation between higher encephalization and smaller body size? The things I’m thinking is that :
    a) there’s a tradeoff between brainpower and body size, in terms of resources and energy. Brains are proportionally energy hungry and resource intense, so if you’re flying with a big brain, you better have access to a lot of high-quality food to feed both brain and wing muscles (let alone guts).
    b) A big Azhdarchid may not have to think quite as fast as, say, a sparrow, simply because it’s physically going to take it longer to react. I’ll wait for the big rig drivers and big jet pilots to chime in on this, but I’m thinking that if your body will take a second to respond regardless, perhaps you can get away with slower reaction times and a proportionally smaller brain. Perhaps this is why bird have never reached the size of Azhdarchids? They’re too brainy to grow that big.

    Link to this
  76. 76. JoseD 7:38 pm 02/5/2013

    Heteromeles: “I wasn’t thinking of monitors for their specific sensorium, but for their general ability to solve problems, willingness to go anywhere, and willingness to at least experiment with eating anything. The other things is that modern birds have (I believe) a higher encephalization quotient than do pterosaurs, so I’m not sure that pterosaurs would react quite as quickly as birds do. In other words, I’m thinking about attitude and reaction time.”

    I get what you’re saying now & you’re right in that birds are a little more encephalized than pterosaurs. However, relative cerebrum size is more important to intelligence than relative brain size. W/that said, “the gross morphology and relative size of the forebrain, olfactory bulb, and optic lobe associated with modern birds may have first evolved in the prehistoric flying reptiles, the pterosaurs” (See “Pterosaurs – forebrain”: http://www.pigeon.psy.tufts.edu/avc/husband/avc5vpth.htm ).

    BTW, this reminds me: How do crocs & monitors compare to birds & mammals, intelligence-wise? I would think that at least monitors would overlap w/less endothermic mammals (E.g. Xenarthrans).

    Heteromeles: “Perhaps this is why bird have never reached the size of Azhdarchids? They’re too brainy to grow that big.”

    I thought it had more to do w/aerodynamics (E.g. Feathered wings vs. Membranous wings). I don’t know much about that though, so I could be wrong.

    Link to this
  77. 77. David Marjanović 8:53 am 02/6/2013

    The other things is that modern birds have (I believe) a higher encephalization quotient than do pterosaurs, so I’m not sure that pterosaurs would react quite as quickly as birds do. In other words, I’m thinking about attitude and reaction time.

    Why would reaction time be positively correlated with the ratio of brain to body mass? I’d even argue that the fewer nerve cells are involved in a reaction, the faster it’ll be – I’m thinking of reflexes.

    Perhaps this is why bird have never reached the size of Azhdarchids? They’re too brainy to grow that big.

    Judging from Argentavis, the limiting factor for birds seems to be the ability to take off. The hindlimbs of birds are useless in flight, yet that is what they use to jump off. Pterosaurs jumped off with their wings.

    How do crocs & monitors compare to birds & mammals, intelligence-wise?

    Crocs learn from the behavior of their prey.

    Link to this
  78. 78. Heteromeles 4:44 pm 02/6/2013

    Actually, I’d suggest that reaction time should correlate with encephalization. Here’s why, using the human brain as a model. According to Sleights of Mind, or optic nerves have a bandwidth of a couple of megapixels. It feels like we see more because our eyes are constantly moving (saccades), and because our brain stitches the rather low quality information it gets into a high resolution picture, effectively using predictive modeling to stitch the data together. Magic illusions work by hacking the model, basically.

    One good example for humans (and dogs) is the phantom ball illusion, where you pretend to throw a ball. Even though the ball doesn’t leave your hand, a dog (and most people) will instinctively follow the motion, to the point of even thinking they see the ball, when their eyes report nothing of the sort.

    All of this predictive modeling requires a lot of brain power. It’s vitally necessary (for example, by allowing flying animals to match trajectories), but brains aren’t cheap.

    If you don’t have the brain power, you’ve got a couple of choices: slower reaction times or fixed behaviors. Insects do the later, making their simple set of responses rather more sophisticated by adding randomness, especially as a defense.

    While one could suggest that pterosaurs were more simple flyers with a simpler set of responses, the bigger ones are large enough that they could have gotten away with slower reaction times than birds have.

    As I said, this is speculation, but the point is that there’s no reason to think they would have reacted as either birds or bats do.

    Link to this
  79. 79. Mike from Ottawa 10:20 pm 02/6/2013

    Two things, one is that Phil Currie’s poorly known 1991 book The Flying Dinosaurs is available cheap used at places like Abebooks.com (my copy is on its way).

    The other, speaking of books, is to say that Mark Witton is a man of many talents but shameless self-promotion is apparently not one of them. Fortunately, I’m shameless and as I have no pecuniary interest in the endeavour, it’s not self-promotion if I do it, so I’ll point out Mark’s upcoming (June 23, 2013) is entitled ‘Pterosaurs: Natural History, Evolution, Anatomy’ and it can be pre-ordered at Amazon UK and Amazon US [just search on the ISBN: 0691150613].

    Mike from Ottawa

    Link to this
  80. 80. David Marjanović 9:05 am 02/7/2013

    All of this predictive modeling requires a lot of brain power. It’s vitally necessary (for example, by allowing flying animals to match trajectories), but brains aren’t cheap.

    Do birds do that much modelling? Or does their higher temporal resolution make up for it? They have long been said to see lightbulbs go on and off 50 times per second.

    Link to this
  81. 81. Heteromeles 11:05 am 02/7/2013

    That’s a great question, David, and I mean that honestly.

    A few weeks ago, I tried the phantom ball trick with some rice, using the cowbirds and brewer blackbirds trying to mooch off my lunch as my experimental subjects. None of them even twitched when I pretended to throw some rice, but they were all over the individual grains I did throw. I’ve tried similar things with pigeons and had the same results. It would be great to replicate this under controlled conditions, but it appears they aren’t subject to the thrown ball illusion, even on small objects.

    The key question, as you point out, is whether they’ve achieved speed without increased brainpower, or whether they simply have a different set of models that generate their own illusions. I honestly don’t know. Going back to Konrad Lorenz, we’ve got some information about the illusions that birds respond to (suggesting that they model–think duck decoys). But at the same time, the linguistic abilities of African gray parrots, to pick one example, suggest they are more efficient.

    Someone could have a lot of fun determining which human visual illusions (if any) birds respond to. Probably a magician specializing in working with young children would be invaluable in setting up experiments, since young children don’t have the same set of illusions that adults do.

    Link to this
  82. 82. Christopher Taylor 5:41 pm 02/7/2013

    The key question, as you point out, is whether they’ve achieved speed without increased brainpower, or whether they simply have a different set of models that generate their own illusions.

    I agree that this would be an important complicating factor. You mentioned the ‘fake ball’ trick with dogs. But if you trick a dog in this way, then try to do it a second time, the dog’s a lot less likely to be gulled twice in a row because it’s cottoned onto the trick. Is it possible that birds aren’t gulled by a fake food throw because they don’t _expect_ you to throw food?

    Link to this
  83. 83. Heteromeles 12:17 am 02/8/2013

    @Christopher: it’s a good question. The weimeraners I’ve known will go with the phantom ball multiple times, because they’re enjoying running. One bearded collie refused to go for the phantom at all.

    With the birds, though, I’m pretty sure they’re tracking the trajectory of the particles and saw that it didn’t leave my hand. I had a pet pigeon and tried stuff like that, and he was very good at tracking the trajectories of things that left my hand, and as I recall, he never fell for a phantom throw. Again, this is an experiment anyone can try, although you might have to wait for the snow to melt. Get takeout rice, find a flock of beggars, and do as many reps as you want. You could even run it as a class exercise, if you are so inclined.

    Link to this
  84. 84. llewelly 8:31 pm 02/8/2013

    Heteromeles , the “faster seeing” of pigeons is probably due to their higher flicker-fusion threshold:
    http://web.archive.org/web/20101205102051/http://pages.cthome.net/rwinkler/fff.htm

    or here for Lea and Dittrich’s paper:
    http://books.google.com/books?id=m9MP1NSRSe8C&pg=PA143

    What I would like to know, is do nocturnal birds have as high a flicker fusion threshold as pigeons do? How do nocturnal mammals compare to diurnal mammals?

    Link to this
  85. 85. Gigantala 12:54 pm 02/9/2013

    Speaking of which, will anyone adress Piksi barbarulna and “Ornithocheirus”?

    Maastrichtian pterosaur diversity seems to have been higher than previously thought.

    Link to this

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