Pterosaurs: Could they fly as soon as they hatched?

June 13, 2019 • 9:45 am

Pterosaurs were the first vertebrates to attain powered flight, and lived between 228 and 66 million years ago. They aren’t on the line to modern birds, which evolved well after pterosaurs appeared, and they appear to have gone extinct without leaving descendants. Often called “pterodactyls” or “flying dinosaurs”, they weren’t really in the group that included dinosaurs.

As you almost certainly know, they looked like this: (from Wikipedia):

While learning about these creatures this morning, I found that some of them were huge—as big as giraffes when they stood upright! One of them, Quetzalcoatlus northropihad a wingspan of up to 16 meters, or 52 feet!  Here’s some diagrams of that creature (the first two are from Wikipedia):

It was a big as a small plane! Here’s a comparison of Q. northropi with a Cessna 172 light aircraft:

Ambling about on four limbs, they are estimated to have been about 3 meters (10 feet) high at the shoulder, and as big as a giraffe from top to bottom:

Source: Mark Witton


Source: Wired

Members of this species were also heavy, of course: they weighed about 200–250 kg, or 440–550 pounds. No flying bird even gets close to that.

Now could these big puppies fly? Mark Witton, a paleontologist and artist, thinks they could have, and sets out the evidence at this post, which I’ll leave you to read since I want to emphasize a new paper instead. But can you imagine a giraffe-sized reptile flying? That would be something we’d all love to see.

On to the new results. It’s generally accepted that young pterosaurs (unlike most birds, including my ducks) came out of the egg fully ready to fly, even though they still could have hung around the nest and received parental care (there’s no evidence for such care). But not everyone agrees. A two-year-old story in the the Daily Beast describes research that suggested that, because their wing bones weren’t full ossified (turned into hard bone) when they hatched, they couldn’t fly until later:

If pterosaur parents stuck around, perhaps there wasn’t so much of an imperative for the little guys to take to skies immediately after hatching. And there’s evidence from one of the embryos, the authors argue, that they couldn’t if they tried. In a single individual, the researchers found that the thigh bone had mature features and shape (that is to say that it looked like an adult thigh bone, only smaller) while the wing bone had some features still missing or underdeveloped.

“We have made an important progress by showing that the same embryo had the humerus [one of the main bones of the wing] not well ossified, but had the femur very well developed,” Alexander Kellner of the Universidade Federal do Rio de Janeiro, one of the study authors, told The Daily Beast by email. He said the most likely explanation for this mismatched development is that hatchlings could run but not fly.

Well, a new paper in the Proceedings of the Royal Society B (click on screenshot below, reference at bottom), though it’s paywalled, suggests that newly hatched pterosaurs could fly after all, and were as precocious as their modern relatives, the crocodilians, which are born pretty much ready to go, looking like tiny adults but still requiring parental care. Judicious inquiry might yield you a pdf of the paper below:


Unwin and Deemng did extensive analysis of 37 eggs of one pterosaur, Hamipterus tiashanensis, ranging from very small eggs to eggs containing embryos and even a new hatchling. They also looked at 3 other pterosaur species, comprising 19 embryos in total. The analysis is complex, aging eggs by both their size and roundness (eggs get rounder as they develop, and absorb water through the semipermeable “shell”), and examining embryos and newly hatched pterosaurs.

What they concluded is that the flying parts of the pterosaur: the fore- and hindlimb leg bones (remember, the leg bones were part of the airfoil) were sufficiently ossified in very late embryos to be able to fly. Second, earlier studies claiming that the muscle attachments for flight couldn’t have been sufficient to power the wings, aren’t all that convincing. Here’s what the authors say. You can get the point through the jargon (I’ve omitted the references and put the key points in bold.)

Terminal stages of embryonic development, represented by MIC V246, IVPP V 13758, JZMP 03–03-2, and the humeri of a near-term embryo (no. 7) and a hatchling of Hamipterus , have multiple features that point towards flight ability in hatchlings. First, extensive ossification of all elongate structures contributing to the flight apparatus that are likely to have experienced significant loads in bending during flight. These include dorsal and sacral vertebrae, the limb girdles and diaphyses of long bones that form the wing spars. This stiffening of the skeletal components of the flight module is analogous to ossification sequences in Al. mississippiensis, the hatchlings of which are also highly precocial locomotors, but is in sharp contrast to most extant birds where, prior to hatching, only the central region of the diaphysis of long bones is ossified.

Second, inferences regarding the implied lack of development of key flight muscles, based on the absence or poor development of osteological features, are insecure for two reasons: (i) muscle attachment sites do not need to be ossified in order to function effectively. In tension, cartilage can accommodate loads comparable to those for bone ; consequently, it cannot be assumed, a priori, that an incomplete deltopectoral crest directly implies a relatively small mpectoralis, the principal wing depressor; and (ii) the relative size and shape of the deltopectoral crest of embryos 7, 11–13 and the hatchling  is smaller than that of adult Hamipterus, but it is directly comparable in terms of shape and relative size to the deltopectoral crest of other pterosaurs including individuals of Anurognathus and Aurorazhdarcho that are widely considered to have been flight capable

Third, the relative elongation of long bones contributing to the wing spars, their relative proportions to each other and the relative elongation of the fore limb of mid and late term embryos compare closely to the same indices for mature, flight capable individuals of ornithocheirids [JAC: this is a well-represented pterosaur]. This is in sharp contrast to most birds and all bats where fore limb proportions comparable to those of adults, and flight ability, are only achieved at a relatively late stage of postnatal development.

And here’s a diagram showing that late-stage embryos had well developed “flight bones”: similar to those of hatchlings and immature pterosaurs:


Figure 4. Fossil record of prenatal and early postnatal development in pterosaurs. Darwinopterus modularis (a) ZMNH M8802. Hamipterus tianshanensis (b1–3) outlines of egg shape illustrating changes in size and shape; (c) IVPP V18942 embryo 5; (d) IVPP V18941 embryo 11; (e) IVPP V18942 embryo 12; (f) IVPP V18943 humerus of embryo 13; (j) IVPP V18942 hatched? egg; (k) IVPP V18942 humerus. Ornithocheiridae genus et sp. indet. (g) IVPP V13758 embryo. Pterodaustro guinazui (h) MIC V246, embryo; (l) MIC V241 hatchling. Pterodactylus kochi (m) BSP 1967 I 276. Not to scale. (c–f,j,k) redrawn from [8], (g) redrawn from [2], (h) redrawn from [22], (l) redrawn from [28]; (m) redrawn from [21].

One last question: Did they have parental care, even if hatchlings could fly? The answer is simply, “we don’t know, as there’s a lack of evidence”. As the authors say, “such a behavior is difficult to demonstrate.” Indeed, I’m not sure what would count as evidence for parental care except for hatchlings that were unable to fly and thus unable to feed themselves. But these hatchlings may well have been able to fly.

At any rate, it’s interesting to contemplate a hatching nest of baby pterosaurs, with all of them taking off soon after leaving the egg.


Unwin David, M. and D. C. Deeming. 2019. Prenatal development in pterosaurs and its implications for their postnatal locomotory ability. Proceedings of the Royal Society B: Biological Sciences 286:20190409.

97 thoughts on “Pterosaurs: Could they fly as soon as they hatched?

  1. Do we have any idea of what this initial flight might have looked like, i.e. struggling to get into the air from a standing start, or throwing themselves off a cliff and hoping the wings are up to the job?

    1. The post by paleontologist Mark Witton that Jerry linked to above (just below the first set of pictures) goes over this issue. He argues, convincingly in my opinion, that they could take off quite well rather than the awkward, bumbling, having to fall off a cliff scenario commonly supposed. It’s a very interesting article that I highly recommend, for what that’s worth.

      1. Yes, Great article.
        Why is it that we humans always assume that previous life forms were so much more inferior? Ostrom and Bakker (among others) debunked the slow and dull dino’s, why are so many still assuming this for pterosaurs?
        The animation of the technique of pterosaurs taking off referred to in the article is also highly interesting -and convincing.

    2. Relying on a cliff for a convenient take off point isn’t a strategy which I would associate with a long and successful life. Just one wrong landing – out of reach of a cliff – would leave a pretty vulnerable beast on the ground. We’ve all seen broken-winged birds unable to take off. They don’t have a good survival record either, absent altruistic humans.
      But there’s a different datum in PCCE’s article that plays on the brooding habitat at least. At least 56 pterosaur eggs and embryos in four species are discussed by their measurements. That really strongly implies that these pterosaur species used brooding sites that were in areas of net sediment deposition. Cliffs are erosive features. Therefore, at least the brooding sites of these species pterosaurs were not in cliffs.
      Did pterosaurs jump out of trees? Possible. But a tree that can brood a 200kg adult plus a considerable amount of nest, lining and possibly rotting vegetation for warmth … that’s a pretty chunky tree, with very widely spaced branches that the wings could steer through. The roots would leave traces in the soil, with good preservation potential.
      I can’t envisage a good way to brood pterosaurs except on more-or-less open ground. Maybe in long ground vegetation (this is long before the spread of current grasses), but basically open. Maybe somewhat isolated on river banks, lakeside islands. Maybe isolated, maybe in colonies. There’s a range of possibilities covered by extant birds.

    1. Isn’t J. Coyne giving aid and comfort to the creationists by printing a picture of a human standing around looking at a pterosaur? How long do you think it will be until they print the picture, attribute it to Jerry and claim: “See, we were right all along!”

    2. Yes, they could have swallowed us in one gulp. ‘Awesome’ really is the operative term.

  2. Thank you for all of the research you do. I liked seeing you on Lloyd Evans’ “John Cedar’s Channel” yesterday. (I don’t know what you would normally wear for a video interview, but the Hawaiian shirt was great!)

    You make very clear and easy-to-understand explanations of dogma that we have never been allowed to question.

    For those of us who heard the “explanations” of young-earth creationism along with doomsday-isms all our lives, which had to be taken on really bad faith, it is refreshing to hear and see solid evidence and decide for myself what I believe.

    I wish I could have been a scientist, although I would have focused on neurobiology I think. Or maybe I’m too impatient. Either way, I’m here now and glad to learn about your work.

    Thanks again! Lori

    1. Seconded! I too could/should/might have become a scientist, but at a vulnerable age I got sidetracked helping others by doing stuff I was good at, hence my career as an audio engineer. But I eagerly read all your science posts!

  3. … and lived between 228 and 66 million years ago.

    Damn, that’s a pretty good run Pterosaurs had. Wonder how long man’ll last on this planet. All depends whether AI keeps us around as pets, I suppose. 🙂

    1. Well, not to argue against that amazing run, there were many species of Pterosaurs over those millenia. We are but one.

      1. Eeep. Apologies for the “eats shoots and leaves” quality of that comment. A giggling nephew distracted me.

      2. More than 150 million years, mammal’s great radiation only took off about 65 million years ago.

    2. I recommend the Hyperion series of Sci Fi books that Michael Fisher recommended to me years ago if you want to read about AI and human interactions.

  4. Very interesting. It greatly impresses me the amount of training, knowledge and sheer determination it must take for paleontologists to deduce so many interesting things from such fragmentary evidence.

    A question for you from my nephew (warning…he’s 11);

    Why can’t you hear a Pterosaur going to the bathroom?

      1. Or a slightly more morbid version:

        Why can’t you hear a pterodactyl using the bathroom?
        Because the P is si-
        Because they’re all dead.

      2. Stolen from FB:

        “Do you think I reference dinosaurs too much when I write?” I asked

        She was silent, like the p in pterodactyl, but it said everything.

        — this is funny but the pedant in me noticed that pterodactyls aren’t dinosaurs.

          1. I hope pterosaurs pooped before flying (like some birds) and didn’t poop while flying (like some other birds).

      1. Yes the letter ‘π’ is only silent at the beginning of a word, we say helicopter, not helicotter and apoptosis, nor apothosis (although some do).

        1. It is when speaking English but not in the original Ancient Greek or in other modern languages.

    1. Agreed. Extinct, ancient animals are fascinating in themselves, and in my imagination even more so – a 200kg monster flies over drying washing and defecates – but the sheer knowledge required to make informed inferences is the most impressive of all.

      1. Oh shit. That never occurred to me before and now I can’t get it out of my mind. I need brainwashing (literally) 🙂


    1. If a freakish alien shows up and says, “Take me to your leader” ,we should do what we can to make it happen.

  5. It is wonderful how much detail is available from these fossils, and it is so much fun to imagine seeing these things.

    1. Hear hear! I have no useful comment on this post whatsoever; but, bearing in mind some of Jerry’s recent concerns about whether people read his science posts, I’d just like to say that I do – every one – and I find them all both fascinating and leaving me wanting to know more. Please keep them coming, Jerry, together with your own personal and inimitable gloss on them all!

  6. I first came across that Mark Witton article last year some time and can only 2nd Jerry’s recommendation that it is worth reading. Fascinating and convincing.

    It seems funny to me that there was, still is, such doubt that these creatures could take off, fly and do both things well. I wonder just what people suppose such creatures did do to get around? I can’t think of any creatures off hand that are innately clumsy at whatever form of locomotion they’ve evolved to use. And pterosaurs are so evidently highly specialized for flight and their lineage existed for so long it seems that people doubting their ability to fly competently bear the larger burden of proof.

    1. I don’t think pterosaurs are “so highly specialised for flight” – the Wiki on pterosaurs says that there were nimble species capable of running well on the ground for example. The pterosaurs are a vast, diverse clade [or order] presumably with a variety matching or exceeding “the mammals” say. I would expect non-flying pterosaurs for example, rather like penguins.

        1. You are being specific – I am speaking of the entire clade & I did say there was a lot of variety!

          1. Which ones do you propose could not fly? Are there any known with reduced wings? (I do not know of any, but then these books might be biased).

          2. Hi Nicolaas. I’ve given my best answer to your good question at comment #31 below. I did it as a new thread because I wanted the full column width because it’s a lot of words. Can’t shorten despite Da Roolz!

      1. I don’t disagree that they were much more nimble even on the ground than many suppose(d). But I do think they are highly specialized for flight. I’m not sure if you’ve read the Mark Witton article (?) but it goes over many of those specializations.

        Many birds are also very nimble on the ground and also very highly specialized for flight. It does seem likely, or at the least highly plausible, that there were flightless pterosaurs like ostriches, emus and so on, but the highly specialized features necessary for flight would almost certainly still be clearly evident in them just as they are in flightless birds.

        I agree that pterosaurs were a diverse group but they were all adapted for flight. That’s one of the key features that leads to us grouping them together.

        1. Yes. And all I’m saying is that despite being specialised for breathing air without gills there are plenty of animals who nevertheless changed jobs & became masters of the sea – including the biggest ever sea going animal.

          By the same virtue we can be absolutely sure that pterosaurs all being “specialised for flight” is on a sliding scale. It would not shock me to hear of pterosaurs with tough old legs galloping about on the plains of old like a modern 30 mph cassowary.

          Loads of bird species have given up on flight & many of them, you couldn’t tell they’re flightless from the fossils. Burrowing owls come to mind as an example & they’re “specialised for flight” right?

          Yes I’ve read a lot of Witton including the link you mention.

          1. For a moment I had an urge to reply. Too tired. Be testy if you like, I don’t want to play.

          2. It isn’t a game that I’m playing – we are at cross purposes in our use of words I think & that’s not a problem.

    2. I’d recommend all of Witton’s site, not just that article. His blog is one of the ones I check regularly. So much fascinating information.

      1. And both Witton and Unwin have written books on pterosaurs that are well worth picking up. Great art AND great information.

    3. Most modern birds can’t fly when they hatch. This shows that agile fliers can often have babies that can’t fly. The question has to be answered by evidence.

      1. I wasn’t attempting to address the main issue of the post at all. My comment was somewhat off topic, about the large degree of skepticism even among experts that pterosaurs could not have been competent fliers. It seems these days most experts have come around to agree that the evidence does support that they were competent fliers. Evidence that I briefly described in my answer as specialized adaptions for flying. I also gave a reference to more information regarding the evidence from an expert.

    4. I wonder how much take off room they needed which makes me wonder about their environment.

      1. Well yes. There are birds – mostly with long wingspans – that are definitely not good at taking off. They need a long takeoff run and lots of flapping to get liftoff.

        Swans for instance. Or albatross.


    1. That struck me instantly too. I wonder how big q. antonovii would turn out to be? 😉


  7. These days it’s thought the many pterosaur species covered the spectrum of diets: piscivores, terrestrial carnivores, omnivores or insectivores. Do we know the diet of the particular beasts in the paper? What would the newly minted flying pter eat? It’s difficult to imagine an animal fresh from the egg having the wing, beak, eye coordination to catch anything on the wing so perhaps they run about hunting worms using their wings for short distance escapes from predators.

    Anyway here’s a cat-sized Pter from Hornby Island:

    1. Maybe they hung around eating things in water and such like herons do today. I always think of pterosaurs when I see herons flying.

  8. I wonder if their heads are so big to balance with the body for flight. I’ve heard that body size is limited by what bone and muscle can support but I guess pterosaurs were so big because their prey was. And I suppose a big head is needed to swallow a big animal, too.

    1. I’ve never understood why the dinosaurs were so big anyway. And why, after their extinction, didn’t dinosaurs re-evolve – because mammals, given a chance, kept that from happening?

      1. Dinosaur herbivores became so large IMO because they existed in a succulent, hot rain forest type environment. And I mean really hot & really wet. Plant food was extraordinarily plentiful & there was a lot of CO2 about which is what plants are made of [CO2 + water is practically all there is to making plants].

        Under such conditions plants grew tall & tough competing with other plants for sunlight & underground water resources, while also evolving defences against plant eaters.

        Herbivores grew bigger to better exploit the plant food & carnivores grew bigger to exploit the herbivores. We end up with a ever cycling arms race of plants vs plants vs herbivores vs carnivores

        That’s my guess.

        The extinction of the dinosaurs was also a permanent change of climate & a stripped back, generally less complex ecology that took 10s of millions of years to grow complex again. The reboot had a cooler climate where there wasn’t the ‘drives’ for gigantism on dinosaur scales to be an option. The dinosaurs were wiped out except birds – because less able to cope with a ‘nuclear winter’ situation for many months whereas mammals are tiny & can hibernate.

        I have no clue how birds survived all this – the latest thinking is only ground-dwelling birds [such as pheasant type birds] under 5 kg survived & presumably got by on seeds & insects.

        1. Well that’s another reason for us to lower CO2 levels then (besides sea level rise and all the rest of it). Dinosaur infestations!

    2. “I guess pterosaurs were so big because their prey was”
      There is a huge variety in adult pterosaur size – pterosaurs are of many, many different sizes.
      The size of predators mapped to the size of their prey isn’t that simple, there are many advantages to being large besides taking on larger prey.

  9. I’m not sure what would count as evidence for parental care

    How about fossilized hatchlings with bone fragments in their gut from prey larger than they are? That would be pretty strong evidence that the parents did the catching and dismembering before feeding it to the hatchlings.

    1. Based on the bill shape, I would think they swallowed their prey whole. I think the hooked bill of today’s birds of prey is evolved to tear prey apart.

  10. The Pterodactyl name was borrowed in the 70s by the Ultalight aircraft firm and made fairly successful models for some time. It also lacked a tail just like the orignal. The idea that they could have come out of the egg ready to fly is something. I do not know of anything today that does that unless it is at the fly or bee level.

  11. I have to say, PCC(E)’s title would’ve been so much better for the original paper than the stilted version the authors chose.

    If the conciseness of the term “postnatal locomotion” is desired for searchability, then surely the article’s keyword list is the appropriate place.

  12. That giraffe sized Pterosaur must have been a horror. I didn’t know they grew so large. I can’t imagine something that big and heavy flying. What kind of noise would those giant wings have made?

    Are there any animals that can fly right after birth? I don’t think bat pups can. Google just told me they can’t.

    Thanks for this fascinating post PCC(e); I love the science posts, especially when they’re about dinosaurs.

  13. It amazing enough to see such creatures as chickens start pecking seed right out of the egg, let alone flying immediately. Quit an amazing analysis. I watched blue heron young beginning to fledge. They got quite a bit of practice flapping while standing on a branch facing into the wind. Their first flights were to branches within 10 or 20 feet of the nest, where they would wait for the parents to return with noms. Then all the siblings would race each other back to the nest with a few wing flaps to get the regurgitated goodies. Such a gradual approach seems natural. I wonder why the Pterosaurs were so impatient.

  14. The dragons on Game of Thrones were brilliantly modeled and convincingly took to flight, showing how a large animal could do it.

  15. Just as there were many different pterosaurs, ecologies and over millions of years maybe they also had differing behaviours regarding flight birth. Then again this is of the cuff and i have no idea.

  16. Thanks, Jerry, for posting really informative and interesting paleontology of dinosaur-like flying birds- this is really amazing stuff.

  17. But can you imagine a giraffe-sized reptile flying? That would be something we’d all love to see.

    See, yes, but I’m not sure I’d want to be near one when it was hungry … 🙂

  18. Compare a pterosaur hatchling with a precocial vs. altrical bird hatchling. Precocial animals are comparatively advanced at birth or hatching.
    Altrical birds cannot begin to sustain themselves until after they fledge and leave the nest, which can take weeks. But even precocial birds, such as chickens and ducks, can’t immediately sustain themselves either, until the remains of the egg-sac is consumed, and their down dries out. They need a day or two to gather strength. Parental care is necessary to protect the vulnerable chicks at this time, too. Unless the chick is of a Megapode species, in which case it was hatched in a great pile of composting plant matter, which generated the heat required to incubate the egg.
    All reptiles seem to be precocial e.g. Snakes, tortoises, turtles, lizards, crocodilians, so I am guessing that mama pterosaur at least protected her hatchlings from predators until they were ready to move about on their own, and the hatchlings had gained enough wing-area/body-mass ratio to fly.

  19. Hey, I remember a long time ago Paul Topping suggesting here the book Pterosaurs – it is in fact by Mark Witten- it’s an interesting book, my library had it! Good pick!

  20. “muscle attachment sites do not need to be ossified in order to function effectively. In tension, cartilage can accommodate loads comparable to those for bone” is an essential and correct point, moreover, those little ones were of course much lighter than the adult ones.
    I think -after reading all these posts- that pterosausrs probably were rather precocious compared to many birds. We did not find any nests that would make us think otherwise, but here absence of evidence is indeed not evidence of absence.
    Whichever way we look at it, either these baby-pters were precocious fliers, or the older ones were committed parents feeding their young.


    The following quote is taken from WITTON/HABIB, 2010 [lightly edited by me to remove footnote numberings & the like distractions – the original is in the link above of course]

    “Could giant pterosaurs fly?

    There is virtually no indication from the anatomy, biomechanics, aerodynamic performance or depositional contexts of any giant pterosaurs that they had lost their ability to fly. This is particularly so for Pteranodon, an animal with anatomy so skewed towards a glide-efficient wing morphology that its terrestrial capabilities may have been lessened. The case is not so clear-cut for azhdarchids: as pterosaurs living within continental settings and apparently possessing good terrestrial abilities, they meet some criteria that may be expected of a flightless pterosaur. However, like Pteranodon, giant azhdarchids also possess skeletons that function well as flying apparatus and were almost certainly flighted as well.

    These observations do not preclude the existence of flightless pterosaurs, however: it is entirely conceivable that some forms may have abandoned flight given the right environments and selection pressures. In our view, however, the pterosaur lineage closest to abandoning flight may not be giant at all but, rather, the considerably smaller basal pterosaur clade Dimorphodontidae (wingspans of 0.6–1.3 m). Dimorphodon has been found to be a particularly heavyset pterosaur with relatively high wing loading, attributes found in modern fliers like rails and galliforms, that find flight particularly energetically expensive. Given that Dimorphodon also possesses an unusually robust skeleton – including long limbs and well-developed appendages – it was probably also a competent terrestrial (or, more likely, scansorial animal that spent much of its time grounded. Dimorphodontids therefore possessed characteristics quite conducive to developing flightless habits and there seems little reason to assume that more derived members of this group could not have abandoned flight in the right conditions.

    We stress, however, that there is currently no evidence that any pterosaurs fully surrendered their flight abilities and, conversely, a wealth of evidence suggesting that all pterosaurs were flighted. Accordingly, this calls into question why some pterosaur flight models have predicted flightlessness in giant pterosaurs, and we suspect that such errors are results represent a priori assumptions over the mechanical similarities of birds and pterosaurs”


    The three vertebrate groups that have achieved powered flight:

    A. BATS [50 million years, 1,200 described species]

    There are around 5,450 species of mammals extant of which an amazing 20% are bats. There’s no evidence of even one flightless bat species in all of bat history.

    Why is this? For one thing the bones are fragile & fossils are rare so flightless exceptions might be lost to us for ever, but also there’s the problem of the evolutionary ratchet – bat hind limbs are fit for nothing but to hang from trees – it’s difficult to imagine many evolutionary paths that would take us from a tree-hanger to some monstrous open plains cassowary analogue ground runner. It hasn’t got the legs so to speak given the bones of the hind limbs are very thin and weak & consist of quite a range of fragile bones.

    But hang on… Vulcanops jennyworthyae is a bat that occurred during the Miocene in New Zealand, a large burrowing microchiropteran that probably ate arthropods & plant material around twenty million years before present. It could walk on its hind legs among the leaf litter hunting up food & it is thought that it roosted in trees/bushes, but fed terrestrially. Did it fly up & down to/from the roost or clamber up & down the trunk? I think the consensus is it flew short distances, but I think it could have one day been a contender for flightlessness. Unrealised I suppose. Here’s a picture – very much the artists impression on little evidence given only a few scraps of the beast are known for sure:

    Of the 1,200 species of bat known ONLY TWO of them can walk on ground – The vampire bat & the burrowing bat AKA the lesser short-tailed bat. The body of the modern burrowing bat is physically adapted for walking. It has claws at the base of its toes, grooves on its feet and also at the elbow joint. These physical features allow the bat to strengthen its wrists and to propel itself into moving forward. The modern burrowing bat takes advantage of this singular advantage to forage for food both on the ground and in the air.

    B. PTEROSAURS [150 million years, 120 described species]

    Evolved a vast array of shapes & sizes – the smallest pterosaur measured no bigger than a sparrow & the largest reached a wingspan of nearly 40 feet. They eventually occupied niches as diverse as the birds & lived alongside birds for say 60 million years. The number of pterosaur species alive at any one time, must have been on a similar scale to that of birds once pterosaurs moved into [almost?] as many niches as birds. There is no physiological evolutionary ratchet I can think of that would prevent an island-isolated pterosaur from going part-time terrestrial & eventually adopting full time walking. We know that some pterosaurs had good, powerful hind feet for walking.

    I put the chances of of there being no island-isolated flightless pterosaurs ever, in a window of 150,000,000 years… at zero.

    C. BIRDS [150 million years, 10,000 described species]

    There are many flightless bird species – all they needed was some kind of alternative locomotion to open that potential evolutionary door. The known or suspected flightless described species are below though lots of them are guesswork based on fossil evidence or merely that they’ve never been seen to fly. They are not all independent cases of flightless species as flightless birds further diversified into a few species that remained flightless.

    North Island brown kiwi
    Common ostrich
    Somali ostrich
    Asian ostrich
    King Island emu
    Kangaroo Island emu
    Tasmanian emu
    Dwarf cassowary
    Southern cassowary
    Northern cassowary
    Elephant birds
    Southern brown kiwi
    Great spotted kiwi
    North Island brown kiwi
    Little spotted kiwi
    Okarito kiwi
    Greater rhea
    Darwin’s rhea
    Campbell teal
    Auckland Island teal
    Campbell teal
    Fuegian steamer duck
    Falkland steamer duck
    Chubut steamer duck
    Amsterdam wigeon
    Bermuda flightless duck
    Finsch’s duck
    New Zealand merganser
    Turtle-jawed moa-nalo
    Small-billed moa-nalo
    O’ahu moa-nalo
    Maui Nui large-billed moa-nalo
    California flightless sea-duck
    Kaua’i mole duck
    New Zealand geese
    New Caledonian giant scrubfowl
    Noble megapode
    Viti Levu scrubfowl
    Junin grebe
    Titicaca grebe
    Atitlán grebe
    Flightless cormorant
    Jamaican ibis
    King penguin
    Emperor penguin
    Adélie penguin
    Chinstrap penguin
    Gentoo penguin
    Little blue penguin
    White-flippered penguin
    Magellanic penguin
    Humboldt penguin
    Galapagos penguin
    African penguin
    Yellow-eyed penguin
    Waitaha penguin
    Fiordland penguin
    Snares penguin
    Erect-crested penguin
    Rockhopper penguin
    Royal penguin
    Macaroni penguin
    Chatham penguin
    Saint Helena hoopoe
    Ascension night heron
    Cuban flightless crane
    Red rail
    Rodrigues rail
    Woodford’s rail
    Bar-winged rail
    New Caledonian rail
    Lord Howe woodhen
    Calayan rail
    Pink-legged rail
    Guam rail
    Roviana rail
    Tahiti rail
    Dieffenbach’s rail
    Chatham rail
    Wake Island rail
    Snoring rail
    Inaccessible Island rail
    Laysan rail
    Hawaiian rail
    Kosrae crake
    Ascension crake
    Henderson crake
    Invisible rail
    New Guinea flightless rail
    Lord Howe swamphen
    North Island takahē
    Samoan woodhen
    Makira woodhen
    Tristan moorhen
    Gough Island moorhen
    Tasmanian native hen
    Giant coot
    Hawkins’ rail
    Brown mesite
    Great auk
    Jamaican caracara
    Rodrigues solitaire
    Viti Levu giant pigeon
    Saint Helena dove
    Henderson ground dove
    New Zealand owlet-nightjar
    Cuban giant owl
    Cretan owl
    Andros Island barn owl
    Lyall’s wren
    Long-billed wren
    North Island stout-legged wren
    South Island stout-legged wren
    Long-legged bunting

    1. Nice write up

      dumb ideas popped in my head after skimming it :

      could there be pterosaur fossils on the ocean floor? Maybe not because they would float- were their bones lower density than dinosaurs? Or were they already found in locations where oceans used to be?

      Just noting the questions for now… I’d have to read about it … later…

    2. Your UTTERLY AMATEUR INTUITION sounds pretty plausible to my utterly amateur intuition. Thanks for the analysis.

      1. Thank you rick! I was a bit shocked looking at some of the pterosaur fossils – a lot of conclusions are reached on a bit of jaw with teeth or a skull & spine [oversimplifying, but that kind of thing] & I can’t bring myself to go beyond 80% with what I’m reading – the data is so gappy. The vast menagerie of pterosaurs are going to surprise us – for example I am wondering if any sparse fossils lacking indicator features identified as birds are actually pterosaur bits given the amazing convergence in certain features:

        Pneumatic hollow bones
        Flow-through respiratory system
        Feather type insulation

        At the moment I’m looking up what limitations there might be on pterosaur smallness – is their a humming bird analogue? Nectar sipping pterosaurs perhaps?

        1. Flowering plants evolved just 125 million years ago so it’s not likely pterosaurs were nectar eaters. There might have been small flyers but I wouldn’t know what they’d eat. Maybe flying insects. Swallow analogues.

          1. African or European swallow analogue? And didn’t they have digital back then?

  22. We conclude that pterosaurs were volant due to our exposure other extant volant vertebrates – bats and birds.

    If birds had gone extinct millions of years ago and we now only had the evidence of their fossil skeletons we probably would never have imagined that they could actually fly. Let alone conceived of feathers and plumage. What other unknown typical behaviours and characteristics lurk undiscovered in the fossils of other extinct critters?


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