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Wednesday, 6 July 2016

And drepanosaurs might fly... wait, really?

Minor update (06/07/16): Thanks to Andrea Cau, a few additional citations and points of discussion have been made below - the thrust and arguments of the post are the same, but the context is improved. Thanks Andrea!

Hypuronector limnaios restored as a glider. Have palaeontologists been smoking something of variable legality, or is there some basis to this?
Assuming you've reached level 5 of palaeontological geekdom you can't fail to know of the exceptionally weird Triassic clade Drepanosauromorpha. These generally small, long-bodied reptiles are largely, but not incontrovertibly, thought to nest at the base of Archosauromorpha (so between lizards and crocs in the landscape of modern animals) and are famous for their highly aberrant anatomy. Gracile, bird-like heads and necks sit atop long, robust and tubular bodies with deepened tails and stout limbs. The hands and feet are highly modified in each species, some bearing powerful claws, others having chameleon-like opposable digits. The end of their tails are modified into either grasping, prehensile organs or sharp hooks, these being interpreted as adaptions for anchoring the tail to vegetation or substrata. Exactly what drepanosaurs did for a living has long been a subject of discussion among academics, and they are nowadays generally considered arboreal or fossorial - or a blend of both. They're pretty awesome animals.

Because the Triassic was evolution's drug-fuelled, rebellious college days, it can't be considered shocking to learn that there's a drepanosaur species which is to drepanosaurs what they are to everything else. This distinctive, strange, and controversial species is Hypuronector limnaios (above). Reasonably good fossils of this small (c. 12 cm long) animal have been known for decades from upper Triassic deposits of New Jersey, but it received its name only relatively recently (Colbert and Olsen 2001). Hypuronector is often regarded as a swimming creature because of its dorsoventrally expanded, 'leaf-shaped' tail which lacks a hooked or prehensile termination (Colbert and Olsen 2001). Its tail is remarkable for the enormous chevrons (prongs of bone projecting downwards from the underside of tail vertebrae) which extend far below and behind their vertebra of origin to create the majority of the tail depth and its 'leaf-like' profile. Some authors have likened the outline of the tail skeleton to the body shapes of gymntoid or gymnarchid fish and suggested that it propelled Hypuronector through the deep, freshwater lakes its fossils were buried in, perhaps in a newt- or crocodile-like fashion (Colbert and Olsen 2001). Although possessing unusually long legs relative to other drepanosaurs and swimming animals, it's been argued that these were also related to an aquatic lifestyle. Specifically, it's suggested that they held the long, deep tail off the ground during terrestrial bouts, the tail apparently being incapable of elevation at its base (Colbert and Olsen 2001). This aquatic Hypuronector hypothesis has been around for some time. The animal was informally known as the 'deep tailed swimmer' in the 1980s (Fraser and Renesto 2005) and this moniker was transferred more or less entirely to its scientific name in 2001: loosely translated, Hypuronector means 'deep-tailed lake swimmer'.

Hypuronector limnaios skeletal reconstruction, from Renesto et al. 2010. Scale represents 10 mm.
At first glance at least, none of this sounds too outlandish: the tail of Hypuronector certainly has an oar-like shape, and we all know that lateral undulation of a tail is the commonest means of water propulsion for vertebrates. But there are other interpretations of Hypuronector which suggest it may not have been a swimmer at all. These alternative views suggest it was more like other drepanosaurs in being suited to climbing but, more remarkably, possibly a glider (Renesto et al. 2010). Sharing early versions of my gliding drepanosaur art (above) suggests that the latter hypothesis is not well known, even among experts. However, I want to stress from the outset that this is not All Yesterdays-style artistic speculation or the bizarre opinion of a 'fringe' worker. Challenges to the aquatic Hypuronector concept and suggestions that Hypurnoector was a more 'typical' arboreal form have been made by several authors (e.g. Senter 2004; Spielmann et al. 2006; Renesto et al. 2010; Castielloa et al. 2015), and the notion that it may have been a glider has been raised on reasonable (if perhaps not yet conclusive) evidence (Renesto et al. 2010). It follows older suggestions that some drepanosaurids - Megalancosaurus specifically - were gliders (see below; Ruben 1998; Renesto 2000) and, though this all might seem bizarre, there is some genuine scientific basis to it.

The aquatic Hypuronector hypothesis under scrutiny

Aquatic drepanosaurs are were first proposed in the early 90s (Berman and Reisz 1992) and quickly received criticism from drepanosaur workers (see Renesto 2010 for history). Hypuronector perhaps remains the best candidate for an aquatic, or at least amphibious species because of its unusual tail, but somewhat ironically, it's actually this paddle-shaped organ which seems to be the main problem for this hypothesis.

Holotype of Hypuronector limnaios, a partial skeleton with the 'paddle tail' (left), disarticulated torso and bits of limb and limb girdle. From Colbert and Olsen (2001).
One thing we should address straight out is that the resemblance of the Hypuronector tail to the body of certain fishes is not a the best endorsement for swimming habits. Fish do not swim using their whole bodies (the front end of any undulating swimmers needs to be stiff), and the gymntoid or gymnarchid fish likened to the Hypuronector tail don't really move their bodies at all when swimming. Rather, they propel themselves with oscillations of long, low fins along the top of bottom of their bodies. Thus, they may be a poor shape analogue for a sculling organ, and we're better off looking at the fins and paddles of swimming animals, not their entire bodies, for clues about the aquatic potential of the Hypuronector tail.

It stands to reason that Hypuronector would have swum like a crocodylian, newt or swimming lizard, where waves of lateral undulation in the tail generate forward thrust (Colbert and Olsen 2001). This requires tail anatomy which can accommodate a lot of lateral motion, and it's here that Renesto et al. (2010) suggest we hit a major issue. The caudal vertebrae of Hypuronector seem to permit some movement at the base and tip of the tail, but the mid-tail was pretty stiff. This is because the zygaopophyeses - processes of bone that overlap neighbouring vertebrae to guide their motion - are very long and have steep articular surfaces (below). In simple terms, they seem to have 'clamped' their adjacent vertebrae rather than - as expected for an undulatory tail swimmer - provided flat, horizontal surfaces for the vertebrae to slide over.

Further rigidity is provided by those amazing chevrons (Renesto et al. 2010). These rearward-projecting bones underlie the articulations of the adjacent 7-8 vertebrae, meaning any lateral motion at the vertebral joints had to overcome the stiffness of the 7-8 bony rods hanging beneath them. Although thin bones are somewhat compliant and the Hypuronector chevrons may have been flexible to a degree, it's difficult to see their arrangement as optimised for sculling habits: they may made the tail more paddle shaped, but to obvious detriment of tail flexibility and sculling potential. Indeed, we have to note that this configuration is very similar to biological structures adapted to resist bending. Tetrapod wings are a good example: the arrangement of bat fingers, pterosaur structural fibres and bird feather shafts with respect to the wing bones echoes the chevron distribution in Hypuronector. By contrast, deep-tailed swimmers, like crocodylians and newts, have chevrons which are short, robust, and do not significantly underlie neighbouring vertebrae. They are ideal structures for anchoring tail musculature, increasing tail depth and not interfering with tail motion. I have to agree with Renesto et al. (2010) that the potential of the Hypuronector tail as a swimming organ seems limited.

Hypuronector limnaios posterior trunk (left) and tail base (right) - note elevation of the latter with respect to the former, and the significant overlap of the zygapophyses. From Renesto et al. 2010, scale represents 10 mm.
Of further relevance here are the limbs of Hypuronector, which do not have obvious aquatic signatures. Aquatic, or even semi-aquatic animals tend to have proportionally short, squat limbs, often with expanded, paddle-like bones. But the limbs of Hypuronector are elongate, gracile and hollow (Renesto et al. 2010). Its hands and feet are not well known and variably interpreted, but the elements we have suggest that they were not paddle-like. Colbert and Olsen (2001) proposed that the limbs of Hypuronector were long to lift the tail from the ground when it left the water, their work suggesting that the vertebral column was too stiff to lift the tail on its own. But this can be seen as problematic for three reasons. Firstly, as pointed out by Renesto et al. (2010), articulated fossils of Hypuronector show the tail arcing upwards with respect to the trunk vertebrae (above): this is not thought to be taphonomic or diagenetic distortion. Secondly, the forelimbs of Hypuronector are somewhat longer than the hindlimbs, which is perhaps the opposite of what we would expect if dragging the tail was a concern - surely the body would tilt backwards with this arrangement? Thirdly, since when did reptiles, aquatic or otherwise, care about dragging tails? We need to be careful that we're not providing 'empty support' for hypotheses by inventing problems for our fossil animals to solve.

Maybe Hyperonector isn't 'the weirdo drepanosaur 'after all?

Taken collectively, these points about tail shape, tail arthrology and limb size must be viewed as problematic for the aquatic Hypuronector hypothesis, and maybe we should see if there are other interpretations of Hypuronector lifestyle which are more in tune with its anatomy. A good strategy for understanding strange fossil animals is putting the controversial, weird bits of anatomy to the side and first focusing on the more reliably interpreted components. With that said, let's ignore the controversial tail of Hypuronector for a moment and look at its limbs, limb girdles and trunk anatomy. As with all drepanosaurs, the shoulder and hip bones of Hypuronector are very tall and somewhat reminiscent of the limb girdles of chameleons (Renesto et al. 2010). It is thought both limb sets were highly mobile, although the drepanosauromorph fusion of the pectoral girdle into one solid structure, as opposed to having two separate halves like chameleons, would limit forelimb reach somewhat. The limbs were likely held in a sprawling pose and, because the femora and humeri are greatly elongated, Hypuronector likely had a wide, stable base to walk and stand on.

Bits and pieces of AMNH Hypuronctor specimens, including the only known cranial material (mandible, A-C) and the ventral view of a trunk and pectoral skeleton. Note the huge, curving ribs. From Renesto et al. 2010.
Hypuronector lacks the large, fused vertebrae over the pectoral region that we see in other drepanosauromorphs, but given that these likely reflect increased forelimb muscle mass and a reinforced pectoral region for digging and prey-capture (Castielloa et al. 2015), this may not impact locomotor mechanics too much. The trunk of Hypuronector was evidently powerfully muscled all the same, the tall neural spines of the dorsal vertebrae and the presence of large, curving ribs along the entire torso suggesting large muscles enveloped most of the body.

It can be seen that Hypuronector trunk and limb anatomy matches pretty well with what we see in other drepanosaurs: powerful torsos and mobile limbs that seem well suited to walking and climbing. We might view its limb elongation as an adaptation to climbing, the increased length of the upper limb segments simultaneously increasing stability and enhancing reach while also keeping the centre of mass close to the substrate. Perhaps more surprisingly, Hypuronector is also similar to other drepanosaurs in certain aspects of tail anatomy. Although its tail has a different overall shape and lacks the derived tail-tips of true drepanosaurids, it shares the specifics of drepanosaur tail motion - flexible base and tip, rigid mid-length - with the rest of the group (Renesto et al. 2010). So perhaps the tail of Hypuronector was just a simpler, oddly-shaped variant on the drepanosauromorph tail and used for similar purposes: stability when climbing (a simple prop can aid traction, balance and recovery from accident), a brace when rearing to dig and feed, or simply for showing off (Renesto et al. 2010).

Putting these lines of evidence together, several authors have started to interpret Hypuronector as a more 'typical' drepanosaur, albeit a less-specialised species that lived like a modern arboreal lizard rather than a reptilian tree pangolin or pygmy anteater (Spielmann et al. 2006; Renesto et al. 2010). If this is true, we might view the shape of its tail as a mechanical red-herring, something which seems more important to Hypuronector behaviour than it actually was. Perhaps it had no more significance to locomotion and behaviour than do the cranial ornaments of dinosaurs and pterosaurs, structures which most now agree were more to do with communication and display than the mechanics of day-to-day life.

Yes yes yes, but we're here for the gliding stuff

Taking this idea of a climbing, generalist Hypuronector a step further, Renesto et al. (2010) note that there are several features of Hypuronector which might indicate it was a patagial glider - that is, an animal with membranes extending between its limbs to facilitate slower falls from elevated positions or glide between perches. The chief features of interest here are the the elongate limbs and, in particular, the forelimbs being as long, if not slightly longer, than the hindlimbs. This configuration is uncommon among reptiles. Well known reptiles with disproportionately long arms include canopy-browsing herbivorous dinosaurs, completely aquatic lineages like ichthyosaurs, derived sauropterygians and turtles, and flying animals like pterosaurs. It's clear that the former animals are playing an entirely different game to drepanosaurs, but the basic similarity between pterosaurs - small, gracile boned creatures which probably had climbing and gliding ancestors - and Hypuronector might be a little more intriguing. Forelimb elongation occurs again and again in patagially gliding tetrapods - pterosaurs, cologus, scaly tailed gliders etc. - and it's not unreasonable to wonder if the same phenomenon in Hypuronector betrays the presence of gliding membranes. The limb proportions of this species are not so extreme as to think it was an exemplar glider and able to travel long distances from vertical starts, but they may have housed membranes of sufficient size to cushion the fall of these small animals if they jumped or fell from high places. The deep, rounded shape of the tail becomes something to pay attention to here as well, it perhaps being well-shaped to help 'correct' a tumbling Hypuronector into the right posture for a steady glide.

Which might have been handy if the initial glide trajectory was what glider pilots call 'less than ideal'
As noted above, at least Megalancosaurus has been also posited as a potential glider in the past (Ruben 1998; Renesto 2000). These conversations were inspired (at least in part) by long-defunct (if you could ever really consider them credible!) ideas that birds may have had shared, close ancestry drepanosaurs or drepanosaur-like animals - let's quickly duck aqay further discussion of that. But why has the idea of gliding Megalancosaurus not caught on? Although not ruled out entirely (Renesto 2000), gliding doesn't seem to have stuck with this species because it its spiked tail, highly mobile wrists and ankles, and grasping appendages suggest it was quite highly adapted to climbing. While climbing and gliding are not incompatible, it also lacks features like the long, gracile limbs we would expect from flighted animals. The anatomy of Hypuronector, by contrast, is a little more generalised and ticks enough boxes in the glider column to think it could be possible.

Of course, it's worth stressing that any gliding drepanosaur is hypothetical at this stage, but we should not take this as reason to dismiss the idea out of hand. In addition to the evidence mentioned above, consider that many, perhaps all drepanosauromorphs seem to have been climbers of one kind or another, and we know from extant faunas that the step from climbing to gliding is often a short one (Renesto 2000). It's really not crazy to think extinct lineages were any less able to develop gliding forms than our modern ones, and drepanosaurs were exapted for gliding flight in many ways. Their skulls had large brains and overlapping visual fields (Renesto and Dalla Vecchia 2005) (ideal for judging distance and processing flight data); they were generally small animals with hollow limb bones (lightweight); their torsos were stiffened and reinforced (aids stability); their limbs were powerfully muscled and highly mobile (control of aerofoils) and their deep, strong tails might be ideal rudders and stabilisers. And as bizarre as it may seem to be discussing the possibility of gliding in an animal only known from bones, recall that pterosaurs were identified as flying animals in the early 1800s long before we discovered fossil remains of their wing membranes: we can identify flying animals if we look carefully enough at their bones. The challenge now is to see if we can test these ideas, perhaps carefully comparing the limb anatomy and myological signatures of Hypuronector with other drepanosaurs, modelling the effects that crazy tail has on a falling animal and so on. We can also look for Renesto et al.'s membranes on Hypuronector fossils, examining them with UV light and being extra-careful when preparing future Hypuronector specimens: experience with other delicate reptile specimens shows that it helps to know where to expect soft tissue when removing matrix.

So there we go, then: the Triassic, and drepanosaurs, might have just got even weirder/cooler/complicateder/more frustratinger than we all knew. I'm thinking we need to hang out in the Triassic even more in future blog posts - check out this label for previous conversations on Triassic topics. And note that my new art book, Recreating an Age of Reptiles, has several pages dedicated to Triassic animals - including Drepanosaurus.

This blog glides on the gentle, supportive updrafts of Patreon

The paintings and words featured here are sponsored by the organisms almost as awesome as Hypuronector: my Patreon backers. Supporting my blog from $1 a month helps me produce researched and detailed articles with paintings to accompany them, and in return you get access to bonus blog content: additional commentary, in-progress sneak-previews of paintings, high-resolution artwork, and even free prints. For this post, we'll be taking a look at a (currently unpublished) painting of a more familiar drepanosaurid.

References

  • Berman, D. S., & Reisz, R. R. (1992). Dolabrosaurus aquatilis, a small lepidosauromorph reptile from the Upper Triassic Chinle Formation of north-central New Mexico. Journal of Paleontology, 66(06), 1001-1009.
  • Castiello, M., Renesto, S., & Bennett, S. C. (2015). The role of the forelimb in prey capture in the Late Triassic reptile Megalancosaurus (Diapsida, Drepanosauromorpha). Historical Biology, 1-11.
  • Colbert, E. H., & Olsen, P. E. (2001). A new and unusual aquatic reptile from the Lockatong Formation of New Jersey (Late Triassic, Newark Supergroup). American Museum Novitates, 1-24.
  • Fraser, Nicholas C., and Silvio Renesto. Additional drepanosaur elements from the Triassic fissure infills of Cromhall Quarry, England. Virginia Museum of Natural History, 2005.
  • Renesto, S. (2000). Bird-like head on a chameleon body: new specimens of the enigmatic diapsid reptile Megalancosaurus from the Late Triassic of Northern Italy. Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy), 106(2).
  • Renesto, S., & Dalla Vecchia, F. M. (2005). The skull and lower jaw of the holotype of Megalancosaurus preonensis (Diapsida, Drepanosauridae) from the Upper Triassic of Northern Italy. Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy), 111(2).
  • Renesto, S., Spielmann, J. A., Lucas, S. G., & Spagnoli, G. T. (2010). The taxonomy and paleobiology of the Late Triassic (Carnian-Norian: Adamanian-Apachean) drepnosaurs (Diapsida: Archosauromorpha: Drepanosauromorpha): Bulletin 46 (Vol. 46). New Mexico Museum of Natural History and Science.
  • Ruben, R. R. (1998). Gliding adaptations in the Triassic archosaur Megalancosaurus. Journal of Vertebrate Paleontology, 18 (3), 73A.
  • Senter, P. (2004). Phylogeny of Drepanosauridae (Reptilia: Diapsida). Journal of Systematic Palaeontology, 2(3), 257-268.
  • Spielmann J. A., Renesto S. and Lucas S. G. (2006). The utility of claw curvature in assessing the arboreality of fossil reptiles.Bulletin of the New Mexico Museum of Natural History and Science 37: 365-368.

31 comments:

  1. Mike from Ottawa6 July 2016 at 13:06

    Is the base of the tail mobile enough to make single-oared sculling a possibility? That would not require mobility within the central part of the tail (might require rigidity). No idea whether the tail shape would rule it out.

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    1. I believe the base of the tail is somewhat mobile (or more flexible than the middle, anyway), yes. But the issue here is that the tail is so big and long: the power required to move that through water would be tremendous, and it would make for very laboured, cumbersome swimming. This is why a lot of aquatic vertebrates have small caudal fins - they do the job just fine, and big fins have consequences.

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  2. I knew that Megalancosaurus had been proposed as a glider, but I had no idea that such a hypothesis was in vogue for Hypuronector! Wow, that's neat.

    If the Avicephala hypothesis is correct, and drepanosaurs are in fact related to weigeltisaurs, I wonder what implications this has for the functional anatomy of early avicephalans.

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  3. Hmmm…. Isn't the tail an additional flight surface in some mammalian patagial gliders (flying squirrels, maybe, but feather-tailed gliders at least)? As such they are expanded laterally (like the tails of such mammalian users of denser fluids, whales and beavers). But Hypuronectes's tail, being expanded by neural and hemal arches, is expanded vertically. I don't think this is conclusive bit of evidence against their having been patagial gliders, but it seems to complicate the picture...

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    1. I wouldn't impair gliding at least, since it was laterally flattened and it would have been unlikely to cause drag. Most likely it was a display device unrelated to aerodynamics, like Rhamphorhynchus' tail "diamonds"

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  4. Silvio Renesto7 July 2016 at 02:27

    Great overview,
    I agree that the vertically expanded tail is indeed a problem for a gliding interpretation, in fact, as written in 2010 and 2015 papers the tail was most probably a clinging device, at least for those genera with a spine at the end (Drepanosaurus Megalancosaurus Dolabrosaurus), or with a chameleon-like curled end (Vallesaurus). These taxa very probably weren't gliders, just arboreal. Hypuronector maybe different, I would love to find evidences of gliding.
    Anyway, all drepanosaurid tails (especially that of Hypuronector),may also have been effective for display.

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    1. I wouldn't impair gliding at least, since it was laterally flattened and it would have been unlikely to cause drag. Most likely it was a display device unrelated to aerodynamics, much like Rhamphorhynchus' tail "diamonds"

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    2. Thanks for comments, everyone. Silvio, glad you approve of the post - thanks for stopping by.

      Allen: "Isn't the tail an additional flight surface in some mammalian patagial gliders (flying squirrels, maybe, but feather-tailed gliders at least)?"

      It is, but not in others (e.g. Draco). We also face the old issue of soft-tissue and osteology not always aligning: gliding geckos have soft-tissue lateral lobes which we might not predict from their skeletons - who's to say drepanosaurs might not have had the same sort of thing? So yes, I agree with your point, but there seem to be so many exceptions and caveats that it's hard to say tails have to be laterally expanded in gliding animals. This would all be a lot easier if our modern animals weren't so varied in their approaches to gliding...

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  5. I'm sure it's been said before, but: Go home, Triassic, you're drunk! Compared to their morphology, the various ideas about drepanosaur lifestyles are possibly just not weird _enough_. Keep pushing the envelope, guys!

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  6. Yeah... only I covered this in my book published 4 years ago: "The Secret Dinobird Story". I notice my name doesn't appear in this blog page so you've managed to find a reason to airbrush the person who has made the greatest contribution to the understanding of Drepanosaurs.

    I wonder if you can even be bothered to make an excuse for this blatant transgression. Don't give me that crap about peer review. You've shown that you disapprove of publishing anomalies yourself, when it suits you. In fact peer review is only there so that people can stick their noses up in the air and hide behind their poncy cravats when they can't do the science as well as others but want to pretend they can.

    THIS DREPANOSAUR ISSUE HAS BEEN SOLVED. It wasn't by you and it never will have been.

    You'll regret this.

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    1. When your book is an amateur pile of dog turd full of nonsense, don't get stroppy because it fell under the radar of a world respected and actually qualified palaeontologist. He wrote THE book on Pterosaurs, and you wrote a waste of a tree that is less scientifically accurate than the kids show 'Primeval.' The reviews on Amazon say it all.

      Also "you'll regret this" is the sort of language that can get a visit from the police, though I guess its easy to say from your keyboard. Mind you I imagine your threat has as much weight as your batshit crazy theories!

      Delete
  7. Silvio may have mentioned gliding for drepanosaurs in 2010 but I'd already covered the idea pretty expansively on either the vertpaleo list or the palaeo list over five years earlier, both of which Silvio subscribed and posted to, and, on the one I'm referring to, actually on the subject of drepanosaurs and at the time of my posting.

    Anyway, he doesn't seem himself to believe in gliding for drepanosaurs other than Hypuronector, so he can't claim credit for understanding Megalancosaurus.

    Palaeontology again revealed as an area seen to be not a science but a minor decoration on flawed social activity by groupists with pretences but no expertise in technical or difficult but vital abstract areas. Time I got on to Portsmouth University's funding procedures.

    John Jackson.
    http://sciencepolice2010.wordpress.com

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    1. Thanks for the comments, John. I was not aware of your book and my research for this post - including talking to several people who know drepanosaur science and specimens well - did not uncover it.

      As for the rest of your comments, I'm not going to dignify your accusations against myself or others with a response. But if you care for some advice from someone you obviously have little regard for, I would suggest that emailing any University about this blog post will be a waste of your time: this blog is not affiliated with or funded by any academic institution.

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  8. Was it ever suggested that these gliding Drepanosaurs could have begotten the first Pterosaurs? Just an idea

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    1. One study recovered drepanosaurs and pterosaurs as sister taxa, but its the minority against countless studies supporting a relationship between pterosaurs and avemetatarsalians like Scleromochlus.

      Considering early pterosaurs probably evolved from hopping, terrestrial ancestors, I'm inclined to agree that pterosaurs are scleromochlids, not drepanosaurs.

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    2. Unless you're a David peters fan this makes no sense.

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  9. As a side note, some of the material referred to Protoavis (the alleged Late Triassic bird from Texas) might actually pertain to drepanosaurs.

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  10. P.S. I bought a copy of 'Pterosaurs: Natural History, Evolution, Anatomy' and I thoroughly enjoy(ed) it. Not just a great read but also a great scientific reference.

    P.P.S. It's a shame that JohnVJackson is polluting this site with his brand of vitriolic pseudoscience.

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  11. It's great that Hypuronector is getting some attention. I have to say, the Triassic and Jurassic fossils of the east coast are really incredible (especially some specimens from Connecticut and New Jersey), and I believe that the Newark Group (which is sorta the granddaddy of all Connecticut Valley/ Triassic-Jurassic NJ geological units) may hold the key to better understanding the crazy reptile diversity at the end of the Triassic. I'm lucky enough to work at a museum where we have a couple large plates of tracks from the CT valley, and it would certainly be interesting to find those of drepanosaurs. If any tracks from these odd reptiles are to be discovered, my bet is they'll be found on the east coast first.

    Regards,

    Chase B.
    Paleontology Research Associate
    Stamford Museum, Stamford, CT.

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  12. David Marjanović14 July 2016 at 10:37

    I'm missing the idea that the tail of Hypuronector mimicked a cycad leaf. It was first mentioned in Senter (2004) and developed a bit more in Sébastien Steyer's popular book La Terre avant les dinosaures (Belin/Pour la Science 2009; translated as Earth before the dinosaurs, Indiana University Press 2012) on p. 170, beautifully illustrated by Alain Bénéteau in fig. 38 (on p. 169). I even dimly remember having read more recently that the cycad had been identified, but Google can't find it. Unfortunately Seb's book says on both occasions that cycads are tree ferns.

    BTW, you wrote "gymntoid" twice; that can't be right.

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  13. If the Triassic was evolution's "drug-fuelled, rebellious college days", then I suppose evolution must have gone to college twice *cough*Cambrian*cough*.

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  14. If you have an interesting point of view or a topic that you want to read more about, NoZombo can fulfill your wish. Our goal is to inform you, inspire you, to arm you with suitable weapons, to give you information that you can use daily and in that way fight against the unknown and unforeseen. Just visit NoZombo . Milestones of Success

    ReplyDelete
  15. I'm surprised the internet hasn't turned this into a massive meme yet.

    ReplyDelete
  16. Hello Tim Williams. You're another who's never lost a scientific argument with me... because you're scared to follow one through to the end. You must have typed half a million words into the internet on dinobirds. Which do you think is most likely to have inspired anyone to say: "It's thanks to Tim Williams that we understand this"?

    Can you tell me of anything you've done in science that matched my solving of the drepanosaur riddles? Or my solving of the way the rear wings of Microraptor worked? Or or how dromaeosaur tail worked, etc etc.

    I didn't chase you up much because it was obvious to me you would never be anything but a poisonous person pretentiously playing with words. I left it to others to say:

    "In other words, you have >no< model or scenario for the evolution of flight.
    In which case, why are you posting about this mythological subject?"

    And you learned so quickly that a decade and a half later, someone else was able to say:

    "What scenario do you prefer, then, logically, for the origin of flapping flight? At one point or another you have discounted all of the transitional states that have been proposed, saying all of them can only happen after the acquisition of the full powered flight apparatus...

    "In some cases you seem to venture up to the brink of logic (as in noting that ANY downward motion of the wing would add lift), but then you retreat to a strange, ex post facto position (arguing that only things that have advanced flying capabilities can be models for the incipient stages of flight). In fact,
    reading back, it appears that you must dispute that paravians are the ancestors of the birds, is that correct? Because you do not seem to see wings, asymmetrical feathers, hugely long arms, or tiny body size, as even remotely indicative of aerodynamic behaviors."


    You're like a Martian who came down to Earth, having only studied the superficial word patterns of scientists, but not realising they need to represent something meaningful underneath. Sokal (not the pheneticist) used augmented transition networks to write an underlyingly meaningless spoof philosophy paper which got published. It had a lot in common with your writings. It's amazing you can be like that and still have a science PhD. Was it in beans or cows? I can't remember. You call me a pseudoscientist, but I know of no better example of that than you - and in such a competitive field.

    And it's a long shot perhaps, but that "Williams" in Australia who was involved in some kind of famous scientific scandal - he wasn't your father, was he? It might perhaps explain the meaningless but obsessive sneering at other's attempts at science.

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  17. "...However, I want to stress from the outset that this is not All Yesterdays-style artistic speculation or the bizarre opinion of a 'fringe' worker."

    Didn't take long for weasel-words to reveal your sub-culture's characteristic hatred of outsiders: "...the bizarre opinion of a 'fringe' worker."

    As if scientific advance ever happened at the centre. You, with your total lack of interest in the nature of science - the philosophy of science - or the sociology or psychology of anything (certainly not of science), are never going to be the arbiter of who should and shouldn't be impugned for their scientific worth. And then of course to have all their subsequent offerings pre-judged.

    It is those at the cutting edge who do the real science of course - not the lumpenproletariat posers pretending to lead from the middle where the uninspired flock for mob safety. Science is not just a standard social activity with science-like decorations. It has its own distinctive character, since novelty is its business. Its criterion is the correct use of the central principle to guide innovation, not adherence to backward group beliefs. Mistakes may happen at the front but nothing happens at all anywhere else.

    "Hypuronector lacks the large, fused vertebrae over the pectoral region that we see in other drepanosauromorphs, but given that these likely reflect increased forelimb muscle mass and a reinforced pectoral region for digging and prey-capture (Castielloa et al. 2015), this may not impact locomotor mechanics too much."

    Yeah - right :-( . Maybe a bit of shoulder for powering the arm but not even as much of that as you'd think. But you don't think mechanically. There hasn't been ANY theorising over the mechanics of the drepanosaurs except by me. Great! You've left the field to me. Pace Sylvio but the mechanics of jointed bones isn't difficult enough to just say 'probably had something to do with flicking the head forward' and leave it at that. (Also wrong is: "...the vertically expanded tail is indeed a problem for a gliding interpretation...".) I have claimed and will again that a theory doesn't have to have "a mechanism"; but a mechanism is just a level of modelling, modelling can be done in cascading levels, and the point is you don't have to go all the way down to the subatomic particles... and yet if you (all of you now) can't come up with SOMETHING to explain how the dorsal stuff does what you say it does, you should get out of the field - or at least you should get out of the way of someone who can.

    And you haven't remarked on the significance of Hypuronector having no dorsal stuff but has gliding membrane-suitable limbs, whereas the ones with different limbs have the dorsal stuff. Though you have noticed it, haven't you :-> . But you can't allow yourself to use it because if you tried you would be seen to be violating your group creed, and then what would happen to you?!

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  18. "As noted above, at least Megalancosaurus has been also posited as a potential glider in the past (Ruben 1998; Renesto 2000). These conversations were inspired (at least in part) by long-defunct (if you could ever really consider them credible!) ideas that birds may have had shared, close ancestry drepanosaurs or drepanosaur-like animals - let's quickly duck aqay[?] further discussion of that."

    Readers new to the subject may wonder about the warning away from "...further discussion of that." Of what? you might ask. What's "long-defunct"? Birds and drepanosaurs? We can now announce that drepanosaurs are dynamite. Many/most dinobird workers (Mark and most others here) have hard-wired the "Birds from dinosaurs" theory into their social identity. The alternative version that posits an archosaur tree with a trunk of small gliders, with repeated spurs offshooting large forms down from the trees to spawn all the grounded archosaurs (and proto-archosaurs - choose your own taxon names) and later, powered feathered fliers (and earlier, pterosaurs), WILL stop your career if you espouse it. The name of the game for Mark's group is: Loyalty To The Group First And Last, Right Or Wrong; Do Any Science We Can Manage IF It Doesn't Clash With Fanatical Devotion To The Group.

    I'd almost given up waiting for the inevitable piece of evidence that sunk the clique. Every discovery that threatened it was treated like the glass slipper that really only fitted Cinderella, but the Ugly Sisters forever insisting it was theirs. The "Fringe elements" predicted feathers on any dinosaurs decades ago and were poo-pooed before being vindicated. Then when feather-like plumes were even found on ornithiscians, it showed plumes (or feathers) went deep into the early history of dinosaurs. The Ugly Sisters claimed the plumes were for display and perhaps insulation and brooding. But very early plumes that were definitely aeronautical - and especially in a very basal group like drepanosaurs - are poison. Early gliding plumes are a nightmare on their own, but if they are relatively unrelated yet homologous with ornithiscian and theropod plumes/feathers, that means it brackets ALL of archosauria and more, and goes all the way down to the turtles... and beyond (i.e. the Permian).

    THAT is the reason "no-one" has been able to solve the drepanosaur riddle: it requires gliding plumes whose horrific earliness makes Birds From Dinosaurs impossible to support, and therefore strikes at the heart of The Empire. (Point of information: I solved it in about 2000-2001 on the SVP list and then wrote it up in my book The Secret Dinobird Story in 2012. This is why Mark pretends he hasn't heard of my book; and my mentioning of this kind of thing is why other commenters to this post are desperate to give the impression I'm a lunatic who eats grandmothers.)

    So the solution is just hanging in the air for anyone to pluck... but if Mark's gang took that one last step they'd fall over the cliff, taking their creed and their clique's credibility to their doom. They can't touch it. They say they want to solve drepanosaurs but they don't seem to be able to take the final logical step. The observations are: a group that starts as membrane gliders, then drops membranes whilst developing odd dorsal structures - sometimes including Paired Hinged structures Exactly in the right place for supporting sets of steerable gliding plumes. The brain seems to be as developed as in other aeronauts. And I could draw you a diagram of one possible way the plumes, plume roots, bones and muscles could have worked, which is more than could be done for a theory that said the dorsal structures were for flicking the head forwards.

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  19. Further details with implications beyond drepanosaurs are that though they are distant from dinosaurs, they DO carry aeronautic plumes, which, if homologous with dinofeathers, will have been predicted by the theory of the archosaur tree having a gliding and eventually flying central spine. We still have crocs, so if their cellular genetic biology says yes to their scales being homologous to feathers, which as far as I know it does, then you're going to have a hard time proving that the earliest feathers Weren't evolved for gliding... and that the epidendrosaurs/Yi qi etc Didn't come from gliding forms, and that Anchiornis/Achaeopteryx and kin Weren't from that broad lineage too. And as a special bonus, Protoavis, with its quill-bumps on its hands, its neck vertebrae that resemble those of drepanosaurs, and its legs which some say resemble those of a young coelophysid, fits in perfectly. Numerous groups of theropods can have come down from the trees and lost flight, just like numerous groups of palaeognaths did after the Cretaceous, to give rise to numerous grounded "ratites" on isolated continents. The coelophysids could have had their own gliding ancestor, distinct from the one that gave rise to Eoraptor, and maybe from the one or more that gave rise to the tetaneurans, and different from the ones that perhaps gave rise to different trodonts; and a similar story, but by now with powered-flying ancestry, to other troodonts, to grounded dromaeosaurs, and grounded oviraptors etc.

    By the way, all the other "evidence" for Birds From Dinos is also crocked. Morphological based-cladograms? Don't work - check mammals - but before arguing about cladograms, take five years off to learn some statistical algorithm nous. Or take a short cut and read my book. "Oh but all the feathered dinosaurs from China prove Dinos From Birds!" ?? All you prove by saying that is your charlattan statut because you're trying to draw an asymmetrical conclusion from a symmetrical premise: My theory: Animal type D from animal type B. Your theory: Animal type B from animal type D. Your evidence for your theory: Types B and D are closely related. Can you see why that piece of chop-logic is better evidence for its user being a shameless bullshitter than that his theory is better than mine?

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  20. "The challenge now is to see if we can test these ideas, "

    My advice to those who don't know anything about philosophy of science, is never to mention testing. Yes, testing is part of Popperism which is something I follow and you don't, but read my chapter 2, and the last few paragraphs of the Sciencepolice-14 rules.


    "So there we go, then: the Triassic, and drepanosaurs, might have just got even weirder/cooler/complicateder/more frustratinger than we all knew. I'm thinking we need to hang out in the Triassic even more in future blog posts..."

    Frustrating for you, clear to me. I'm thinking you ought to hang out where the answer has been waiting for your precious eyes to fall on it for the last five years:- My Book!


    "...the latter hypothesis [gliding drepanosaurs] is not well known, even among experts."

    I'm the expert. I'm the one who solved the problem, remember? And why weren't your "experts" reading the SVP list 16 years ago? (Actually, some were.)

    Finally, your years studying at Portsmouth university had no influence on you, detectable in anything you might say or do palaeontologically, eh? Sounds like a waste of time and money, so I hope it was fun. Unless you expect us to believe you use a completely different set of brain circuits when the channel your words pass down isn't connected administratively or financially to the university. That is as unbelievable as your claim not to have heard of SDS, and as your claim that later drepanosaurs didn't glide on plumes.

    And as I touch on elsewhere, simply saying a critic's message is too awful to consider, is a cheating way of ignoring the message, and one which your group relies on far too often. Everything I've said in these comments is true; they may reflect badly on you but I'm just reporting the problems you cause and suggesting ways to fix them. Don't try and say it's all my fault.

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  21. Neil:
    “When your book is an amateur pile of dog turd full of nonsense, don't get stroppy because it fell under the radar of a world respected and actually qualified palaeontologist. He wrote THE book on Pterosaurs, and you wrote a waste of a tree that is less scientifically accurate than the kids show 'Primeval.' The reviews on Amazon say it all.”

    Also "you'll regret this" is the sort of language that can get a visit from the police, though I guess its easy to say from your keyboard. Mind you I imagine your threat has as much weight as your batshit crazy theories!


    Hello "Neil": I wonder who you might be - apart from yet another palaeo groupie who's yet to learn that a scientific criticism must contain science. Instead, you offer:

    1) Lying:

    So I'm "amateur", am I? Actually I'm formally professionally qualified in at least two different sciences: in the first, experimental psychology, I learned about how to design experiments - not just using stats but also the philosophical underpinnings of experimental theory, which can also be adapted to historical sciences. Both Keith Oatley and visiting lecturer Richard Gregory stressed the importance of Popperian principles. Of course no-one in archosaur palaeontology seems to have enough understanding of stats/IT to understand cladograms, so I'm way ahead of any of you there. I didn't even need my MSc in information systems: many years of designing and implementing algorithms to simulate natural/evolutionary systems would have put me ahead of any of you on its own. Under Dave Martill's tutelage, no palaeontologist ever emerges from Portsmouth University palaeo department with enough nous in stats/IT merely to understand your major phylogenetic tool, nor with an understanding of how to formulate and judge scientific theories and interpret evidence. He never got anywhere near explaining what to do when theorising fails and you have to simulate. And of course none of you has ever compiled a line of computer code so you can't do any simulations even if you want to. None of you has a definition of science, nor of evidence, to fall back on. I defined them: for sciences in general (in that book you insult but haven't read), and showed how historial sciences need a slightly different approach. Of course everything I say sounds odd in a forum like this since none of you gets beyond the standard guessing of the average bloke in a pub, plus some pretentious whitewashing. Mark guessed that Hypuronector's tail might be of aerodynamic significance but of course he has no physics, as none of you seem to have, so none of you can go beyond that. Can't even use any aerodynamic jargon. Even as an air cadet before I got my gliding wings I could have written a better aerodynamic analysis of the drepanosaurs than has ever been done. Mark has contributed to papers dealing with flight, but he didn't do the nitty gritty. Your claim that Mark is a "qualified palaeontologist" is amusingly true. Qualifying as a palaeontolgist even twice over, qualifies you for nothing beyond pub wisdom except pretentious groupist bullshit...

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    1. Hey John. While you're probably not going to see this (Given the year 'tween your first appearance and this one, which honestly I think I'm the first person to notice?), I'm just going to point out the phrase "YOU WILL REGRET THIS!" is a noted internet meme stemming from a character in SimCity

      So I'd highly recommend not using that phrase because I was tempted enough to do a drepanosaur themed "YOU WILL REGRET THIS" meme to begin with, but this sort of pushed that temptation further along the way

      Please consider a less overly aggressive tone. Thank you!

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  22. Neil again:
    2) Groupism.

    The name of your game is groupism. Which is why you never get anywhere, and why only outsiders can advance the science. Your comment is an example of joining a group, then strengthening it and your place within it by identifying, othering and insulting outsiders. So you're all blanks on moral philosophy too. As a psychologist I am at least sensitive to these issues of personal deception and group corruption, whereas all you have for sociology is the petty gang behaviour you learned in kindegarten or perhaps your youth clubs.

    3) Ignorance.

    We mentioned your group ignorance under Lying; but your attack, right or wrong, of anything you see as criticising the group you identify with, violates science because science is all about criticising theories. We can tell you intensely resent any outside contribution... even though science requires every possible theory to be considered. You hate the fact that I've reported your misdoings, but since you've never even considered let alone defeated any of my scientific arguments, it's clear your unfounded criticisms of them deserve to be attacked. You say "The reviews on Amazon say it all". Indeed they do. They were made by people like you, and are all groupism and no science. But I'm not surprised to hear you recommend basing scientific judgements on cheap churlish fatuous comments on the internet. At least my comments link to a 100,000 word book that resolved three areas of palaeontology, and addressed the field's underlying corruption.


    So you're a blatant liar, your strategy is ignorant groupism, and although Mark has made scientific statements in this blog post, and I've actually done and dusted the whole drepanosaur issue in the book, you, "Neil", say nothing scientific at all. It's one more filthy strategy your kind overuse: avoiding losing arguments by suggesting your opponent is too outrageous to engage with... without ever actually demonstrating it. Why not break the habit of a lifetime and try some real science, here? I can't say you talk a good game - saying "your batshit crazy theories!" wouldn't qualify you for that - but it does tempt us to invite you to refute, using genuine science, ANY SINGLE POINT I make in the book. And finally, what did you learn at university, and what contributions to science have you ever made? Do tell.

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