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My famous duck-based rant

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


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Back in February 2001, noted ornithischiphile Pete Buchholz accused ducks of being boring. How dare he. I could only respond…

Portrait of a domestic Muscovy duck (Cairina moschata). Photo by Darren Naish.

“Errm… the evolution of carpal spurs and knobs, extreme pugnacity and territoriality, nest parasitism, creching behaviour, parental carrying of young both in the water and (!) in the air, monogamous pair-bonding, underwater copulation and the (?)reinvention of the penis, major sexual variation in tracheal structure, grass-eating and 20-minute gut carrying time, niche partitioning according to intestine size, carrion feeding on Subantarctic islands, the evolution of fern-eating, island giantism, island dwarfism, crepuscularity, serrated bill margins, filter feeding with buccal lamellae, deep-diving, species where males are flightless but females flighted, coevolution of browsing forms with spiky lobelioideaens, repeated increases and decreases in body size during phylogeny, the annual transportation of TONNES of sand… and, pant pant pant, quacking.

How *ON EARTH* can ducks be boring?????”

Assorted waterfowl I have known. Clockwise from top left: domestic Swan goose (Anser cygnoides), weirdly pale female Mallard (Anas platyrhynchos), Madagascan or Bernier’s teal (Anas bernieri), Black swan (Cygnus atratus), male Upland or Magellan goose (Chloephaga picta), and Mandarin duck (Aix galericulata). Photos by Darren Naish.

Ok, some of the claims made in the above (the one about penises, for example) are questionable and now seem incorrect, but I think you get the point. For Tet Zoo articles on ducks and other anseriforms, see…

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

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





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  1. 1. David Marjanović 6:42 am 07/18/2013

    I remember this one. I’ve always loved it. =8-)

    Link to this
  2. 2. SWestfall 6:49 am 07/18/2013

    What amazes me is how much intergeneric hybridization exists withi.n ducks. Those domestic Muscovies, which have a terrible name because they are from South America, are perching ducks that produce sterile hybrids when bred to domestic mallard ducks.

    I’ve seen photos of mallard/wood duck hybrids and wood duck hybrids with hooded mergansers.

    Hooded mergansers nest in the same tree cavities as wood ducks, and sometimes they engage in nest parasitism. It’s not unusual for a hooded merganser hen to lay her eggs in a wood duck nesting cavity, and the for the wood duck hen to hatch out the merganser egg.

    It turns out that hooded mergansers hatched out in wood duck nests have about the same survival rate as those hatched out in their own species’ nests. But it seems that there is still a real problem here for hooded mergansers don’t eat the same things wood ducks do. And there seems to be some issues with mergansers imprinting on wood ducks and mating with them.

    Link to this
  3. 3. pmurphy98 7:08 am 07/18/2013

    I must confess…I hadn’t seen this before today, and was under the impression that ducks were…well, not boring exactly, but not particularly interesting either. But I am happy to say that I have been converted. LONG LIVE ANATIDAE!!

    Link to this
  4. 4. BrianL 8:00 am 07/18/2013

    What I find particularly interesting, apart from that massive hybridisation taking place, is the massive amount of convergent evolution that has occurred in Anatidae. And then there’s the evolution into herbivorous pseudo-dromornithids when going flightless on isolated islands.

    Also note that, for such a diverse clade belonging to an ancient divergence of the neognath family tree, anatids do not seem to appear in the fossil record until the Oligocene and were apparently absent from at least the northern continents before that, weird though it might seem. Of course, pigeons and passeriforms follow the same pattern.

    Link to this
  5. 5. glynyoung 9:45 am 07/18/2013

    I can’t understand the fuss about ducks myself. I might have to ask my daughters Aythya and Mairi Netta.

    Link to this
  6. 6. John Harshman 11:03 am 07/18/2013

    For penis reinvention you could substitute penis size, of course. How about massive convergence? Feeding by diving invented at least 8 times, feeding by grazing at least 5 times. (With, by the way, at least one case of evolution of a pursuit diver from a filter feeder.) Lots of great sexual selection. One of the few instances of obligate brood parasitism in birds. Just about every possible sexual system, including stable threesomes. Two orders of magnitude in size variation. And my favorite, lots of colors and patterns in plumage and soft anatomy.

    Definitely my favorite order.

    Link to this
  7. 7. AlexanderBerg 12:12 pm 07/18/2013

    Made me think; Darren, what would you consider to be the most boring group of tetrapods? I have a sneaking suspicion that all groups are more or less wierd, some more than others, but the baseline wierdness is still quite high – or? Are there any truly “simple” tetrapods (or animals/organisms for that matter)that just eat, procreate and die all in glorious insipidity?

    And as always, great post.
    Ducks seem to be some of the most foul, cruel and bad tempered birds I’ve set eyes on! (I wrote that in an Scottish accent… )

    Link to this
  8. 8. M Tucker 12:17 pm 07/18/2013

    Ducks ARE fascinating and I think simply saying, monogamous pair-bonding and reinvention of the penis, skips over a major point in duck behavior and evolution. Did you mention forced copulation? It is the amazing evolution of the female duck genitalia as a defense against insemination from forced copulation that seems to be driving the evolution of the penis. Sure, the penis might provide a better photo opp, and everyone seems to be more interested in talking about it, but it is what is happening with the female that is much more interesting, at least to me.

    Link to this
  9. 9. vdinets 12:52 pm 07/18/2013

    To me one of the most interesting aspects is the intelligence, for which geese are particularly famous since Lorenz’ work.

    Link to this
  10. 10. John Harshman 2:52 pm 07/18/2013

    And need one point out that they’re delicious?

    Link to this
  11. 11. CS Shelton 4:25 pm 07/18/2013

    I’d have disagreed with “delicious” having had roast duck at a chinese place once, but since then I had a duck soup with a duck egg in it (perverse, I know) that was tres awesome.

    Hey is it just me, or are some of those links dead?

    Link to this
  12. 12. shallyv 5:10 pm 07/18/2013

    Quack! Quack! You’re all quacks!

    Link to this
  13. 13. John Harshman 6:17 pm 07/18/2013

    In what universe is roast duck in a Chinese place not delicious?

    Link to this
  14. 14. Halbred 6:50 pm 07/18/2013

    Ducks (Anatidae) are certainly more interesting than duckbills (hadrosaurs).

    Link to this
  15. 15. Heteromeles 6:52 pm 07/18/2013

    What I want to know is, why didn’t the ancestors of today’s ducks take over the world during the Paleogene?

    Link to this
  16. 16. vdinets 8:19 pm 07/18/2013

    Halbred: duckbills are in a disadvantaged position for such a comparison. Note that of the interesting duck features listed by Darren, most wouldn’t be preserved in fossils.

    Link to this
  17. 17. Yodelling Cyclist 9:07 pm 07/18/2013

    @Halbred: Yes, I’ve wondered at why birds didn’t become even more dominant than they did in the paleogene. The best guess I have is that the herbivore niche is more effectively held by quadrupeds: walking on four feet makes it easier to balance with a large gut, and even if you insist on being a biped, having two fore limbs capable of grasping branches/dig for tubers etc. is an advantage. This is a guess!

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  18. 18. John Harshman 11:07 pm 07/18/2013

    Heteromeles: Well of course ducks did take over the world in the Paleogene. At least they (talking about gastornithids here) were top predators. OK, they might have been coconut-crackers instead, but that’s cool too. And they might not actually have been ducks but stem-Galloanserae, but that’s cool too.

    YC: So why didn’t birds maintain the top predator niches? What do you have for that? Why are there no more gastornithids (possibly) or phorusrhacids?

    Link to this
  19. 19. glynyoung 5:27 am 07/19/2013

    And who says they aren’t in charge now anyway?

    Link to this
  20. 20. JAHeadden 6:07 am 07/19/2013

    Eh, I’m not seeing the fascination. SURE, ducks are “cool” and all, and maybe most of what you said is TRUE, but … not all that show up there are DUCKS so quite clearly your argument is TOTALLY WRONG. (I hasten to add in seriousness that expanding the field of concern to Anseriformes would be acceptable.) Clearly, you left out feather variation, and for that you must be utterly ASHAMED.

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  21. 21. Gigantala 7:04 am 07/19/2013

    I think the issue is mastication. Mammals can chew on grass, ducks can’t; since anatids in general have such poor digestive capacities that a lot of their crap is still undigested grass, it’s obvious why herbivorous mammals took over.

    Link to this
  22. 22. glynyoung 7:26 am 07/19/2013

    In places herbivorous mammals eat the droppings of Anatids because the grass is already partially digested. Another service provided by wildfowl!

    Link to this
  23. 23. David Marjanović 9:52 am 07/19/2013

    What amazes me is how much intergeneric hybridization exists withi.n ducks.

    Remember that genera don’t exist outside of our heads.

    Definitely my favorite order.

    Remember that orders, too, don’t exist outside of our heads.

    Ducks (Anatidae) are certainly more interesting than duckbills (hadrosaurs).

    Dude, have you ever, like, looked at their teeth, man? Like, really looked at them, man. Whoa. Blows your mind, like.

    Well of course ducks did take over the world in the Paleogene. At least they (talking about gastornithids here) were top predators. OK, they might have been coconut-crackers instead, but that’s cool too.

    Viciously ripping the heart out of a… palm tree.

    (Same for dromornithids, aka Demon Ducks of Doom.)

    And they might not actually have been ducks but stem-Galloanserae, but that’s cool too.

    That’s even cooler!

    So why didn’t birds maintain the top predator niches? What do you have for that? Why are there no more gastornithids (possibly) or phorusrhacids?

    Shit happens, mass extinctions in particular. *shrug*

    Link to this
  24. 24. Heteromeles 10:54 am 07/19/2013

    Small reminder: grasses didn’t start taking over the world until well into the Cenozoic. Prior to that, analogous ecosystems would have been dominated by herbs and ferns of various sorts.

    As for why birds didn’t get into the business of being two-legged fermentation vats, I’m not sure either. Certainly a number of dinosaurs managed the trick (although to be fair, even more quadrupedal dinosaurs went for it).

    YA may have it right, although it could be birds’ lack of heavy tails that made it awkward for them to develop large guts. Flying makes it even trickier, because center of gravity kind of matters when you’re airborne.

    One thing that hasn’t been mentioned: most ducks and geese are pretty good flyers (e.g. http://www.deltawaterfowl.org/media/magazine/archive/2006-04/flight.php).

    Link to this
  25. 25. John Harshman 1:32 pm 07/19/2013

    Birds did get into the business of being two-legged fermentation vats. Well, one living species did. We don’t really know about the extinct ones.

    Link to this
  26. 26. Yodelling Cyclist 1:33 pm 07/19/2013

    @John Harshman:
    YC: So why didn’t birds maintain the top predator niches? What do you have for that? Why are there no more gastornithids (possibly) or phorusrhacids?

    I quite like David Marjanović “shit happens” response, but if I’m allowed to speculate freely….

    Big, flightless birds have two sorts of weapons, foot claws (which are constrained by the fact that the bird needs something to balance on during an attack), and beaks. If you want a big, powerful attack from the head, you want to reach out to bite with a big, powerful set of jaws in a robust skull, but birds then have a balance problem without the tail. Similarly if you want to be a fast bipedal runner, leaning forwards for high speed is difficult with a big head and no tail (seriously, humans don’t have high top speeds compared to, say, emus), so you have to bring the head back towards the centre of mass, bending the throat, making long runs hard, or bend the knees a lot shortening stride:leg length. Basically, I think mammals with teeth, claws and four feet have a slight edge over a terror bird. Mesozoic therapods could have more powerful heads (with teeth!) and efficient high speeds thanks to their tails.

    Link to this
  27. 27. Yodelling Cyclist 1:43 pm 07/19/2013

    Thinking logically(ish) from the last: really BIG predatory birds would be ambush predators in forests, plains runners would have to be smaller, and take smaller prey. Does this fit the observed pattern?

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  28. 28. BrianL 3:44 pm 07/19/2013

    Do we know if the droppings of ratites, moa nalo, dromornithids or *Cnemiornis* are/were as full of undigested food as those of flying geese? Surely, being large and flightless would allow for bigger guts and more efficient digestion?

    Link to this
  29. 29. Gigantala 4:07 pm 07/19/2013

    @Heteromeles: Still, herbivorous dinosaurs probably weren’t as limited as modern birds. Some people keep telling me that therizinosaurs probably were already becoming masticators, leaving only oviraptors and ornithomimosaurs as the only bird-like herbivorous animals that were significantly common in the Cretaceous (troodontids probably did what pachycephalosaurs did, and that was probably masticatin’)

    @YC: To be fair, large flightless birds have co-existed in mammal rich environments with their limitations for a long time. Ostriches were very speciose until the Pleistocene, and terror birds not only managed to co-exist with sebecids and sparassodonts as top predators, they might have also survived longer than previously thought, if the Uruguay remains are of any help.

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  30. 30. Zoovolunteer 6:15 pm 07/19/2013

    How speciose were Ostriches? I know they spread as far as China – I think the Chinese form died out in historic times- but did they get down into India as well? And if so, why aren’t they there now (assuming they weren’t wiped out by humas)

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  31. 31. naishd 6:41 pm 07/19/2013

    Thanks for excellent (and amusing) comments. M Tucker – comment # 8 – says “Did you mention forced copulation?”. I didn’t in the rant given above (it was a spur of the moment, off the cuff kinda thing), but did you see this in the links (and, indeed, the other links referring to anseriform mating strategies)?

    Darren

    Link to this
  32. 32. LeeB 1 6:48 pm 07/19/2013

    Zoovolunteer, A search on Siwalik and Struthio turned up as the first hit a paper by Sahni et. al. in the Journal of the Palaeontological Society of India about Struthio eggshell in the palaeolithic of peninsula India.
    Apparently such eggshell occurs at over forty sites, so yes Ostriches did occur in India.
    Ostrich taxonomy, especially of pleistocene forms is still messy; S. asiaticus and S. andersoni are both used for asian forms in the pleistocene, but their difference from S. camelus is not clear.
    I suspect hunting and egg predation by humans is responsible for their extinction; after all people were responsible for much mammalian extinction in the same area at the same time.

    LeeB.

    Link to this
  33. 33. Yodelling Cyclist 6:59 pm 07/19/2013

    @Gigantala: Yeah, sure, ostriches, emus, rheas, mihirungs and especially Aepyornis all managed to survive as herbivores in mammal dominated environments. The trouble is, that’s about it for large (for the sake of argument, >10kg) flightless herbivorous birds with mammalian competition. Even with this list I would observe that ostriches, emus and to a degree aepyornis may have had a helping hand in the form of reduced water requirement (birds being able to excrete ureic acid rather than urea means that they require less water per mole of nitrogenous waste). Compare that to the list of mammal herbivores and it’s pretty clear win for mammals. Further I would point out that with the exception of mihirungs, all of the above (particularly the known cursorial species) have fairly small heads, and I don’t think any manage hind gut fermentation (please correct me if wrong). As for the terror birds, sure, there are niches out there for them, as I describe, but I think the quadrupedal mammalian bauplan may have been more easily adapted to changing circumstance.

    Looking over this I’m reminded of how downright odd mihirungs were. How the hell did they evolve? Did their ancestors develop in the semi desert until large enough to slug it out with mammals?

    Link to this
  34. 34. keesey@gmail.com 7:08 pm 07/19/2013

    “Ok, some of the claims made in the above (the one about penises, for example) are questionable and now seem incorrect…”

    Why was that thought, anyway? Was there an idea that they were nested in Neoaves or something?

    “species where males are flightless but females flighted”

    Gelflings?

    Link to this
  35. 35. Heteromeles 7:23 pm 07/19/2013

    Well, the real oddity among birds is…us. Seriously, humans have taken the flightless bird bauplan and done it one better.

    The key thing birds have that mammals don’t is that, at high speed, they don’t have to couple their breathing to their gallop. This doesn’t make for a tremendously fast animal, but it does potentially make for one with a lot of endurance. It is kind of interesting that the birds didn’t get into the “run them into the ground” hunting game the same way hominids apparently did.

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  36. 36. Yodelling Cyclist 8:19 pm 07/19/2013

    @Heteromeles: a.) insufficiently beweaponed to threaten an animal into flight or so beweaponed long distance pursuit becomes difficult for the above reasons. Humans have teamwork (not an avian strong point) and spears we can carry near our centre of mass when running. Sort of literally our strong point. B.) Too dumb to track an out-of-sight animal that has managed sprint out of sight (around a rock/tree/whatever). Just speculating. I’m surprised so few mammals are bipedal.

    I wonder how long it would take to selectively breed bipedal dogs…

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  37. 37. 4u1e13 11:40 pm 07/19/2013

    “I wonder how long it would take to selectively breed bipedal dogs”

    Ask Dr Moreau…

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  38. 38. BrianL 5:22 am 07/20/2013

    @Heteromeles: Realise that the ‘humans evolved as endurance runners’ hypothesis has been discussed in the comments of a TetZoo3 thread before and has not been looked upon favorably.

    To the list of large flightless birds in mammal-dominated environments we can probably add Eurasian eogruids, which were ostrich lookalikes (livealikes?) that existed from the Eocene to the Pliocene, until apparently replaced by true ostriches. Extinct or not, these creatures coexisted with a hoste of mammalian predators and competitors including such noteworthy ones as indricotheres, entelodonts and giant hyaenodonts.*Eremopezus* and *Remiornis* may be worth mentioning too.

    @Yodelling Cyclist: Note that some accipittrids do hunt cooperatively and that we don’t know what phorusrhacids were capable of so I don’t think we should rule such behaviour out a priori.

    My personal guess is that laying large eggs and having to nest on the ground are problems for large flightless birds in mammal-dominated environments. However, having large clutches and many offspring on a regular basis would probably be an asset if your competitors are much slower breeders (as large mammals are) with enormous parental investment in offspring. In that case, the nesting phase might be a critical problem.

    I’d also like to point out that in the urbanised and rural settings in western Europe that I’m most familar with, I actually see ‘large’ herbivorous birds (in the shape of geese and swans) being more succesful then ‘large’ herbivorous mammals. Being particularly fecund, capable of safely flying over man-made barriers and being able to exploit both land and water seem to be their advantages over, say, deer, at least at first glance. At least swans also seem to be far less wary of humans.

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  39. 39. David Marjanović 8:01 am 07/20/2013

    Basically, I think mammals with teeth, claws and four feet have a slight edge over a terror bird.

    But a drawn-out global competition is exactly what we don’t see in the fossil record. They’re there, they stay there, and then suddenly they’re gone.

    Looking over this I’m reminded of how downright odd mihirungs were. How the hell did they evolve? Did their ancestors develop in the semi desert until large enough to slug it out with mammals?

    Australia was covered in rainforest from sea to shining sea into the Miocene, AFAIK.

    It is kind of interesting that the birds didn’t get into the “run them into the ground” hunting game the same way hominids apparently did.

    Oh no, not that again. X-) We discussed this hypothesis at excruciating length in two threads in April 2012 or so; hunting by endurance running is rare today because it only works under very special conditions and requires the ability to carry water – it clearly has not been a factor in our evolution.

    On the endurance of phorusrhacids we can only speculate, but I bet it was very impressive.

    I’m surprised so few mammals are bipedal.

    Why? What would the selective advantage be of the process of becoming bipedal?

    Our bipedality is an exaptation from brachiation. We didn’t become bipedal on the ground.

    *Eremopezus* and *Remiornis* may be worth mentioning too.

    *E.* has a peculiar grasping foot and may have been yet another predator…

    My personal guess is that laying large eggs and having to nest on the ground are problems for large flightless birds in mammal-dominated environments.

    Ostriches cope well, though.

    Link to this
  40. 40. BrianL 9:34 am 07/20/2013

    @David Marjanovic: According to Murray and Vickers-Rich in ‘Magnificent Mihirungs’, the idea that Australia was largely covered in rainforest during any time in the Cenozoic is a misconception. Instead, they say, we should imagine the forests of Australia during this period to have generally been drier than what we now see in the Cape York Peninsula. Seeing that I haven’t come across this argument elsewhere (though I haven’t actively looked for it either), I don’t know how accurate it is, though. The authors also claim that dromornithids most likely evolved from screamer-like ancestors (not implausible, I think) in coastal environments as these are the source of many arid-adapted plants in Australia and that they subsequently spread into the interior of Australia. There, large size and reach allowed them to succesfully compete with generally small marsupial herbivores. Sounds plausible to me, but I’d still consider the hypothesis rather shaky.

    They also claim that dromornithids had the upper hand over herbivorous marsupials as long as their stature and bauplan allowed them to reach higher to feed. By the time giant kangaroos and diprotodontids evolved, this would have been undone. They further claim that dromornithids couldn’t grow even larger than they did because of limits on egg size. I don’t know how convincing I find that argument as theoretically you could probably grow a larger bird from an egg the same size (sauropods, giant ornithischians and most relevantly giant theropods appear to have managed far more and from smaller eggs, I should add). As far as I know, we also don’t know if large dromornithids laid eggs the size of those of *Aepyornis* or if that egg size is even the maximum possible size.

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  41. 41. Heteromeles 11:13 am 07/20/2013

    @BrianL: Would you believe I actually participated in that conversation? And if you go back, you’ll find that most of the scorn was heaped by David M (our resident fount of negativity), so it’s scarcely a settled issue.

    Having owned a pet pigeon (brain roughly peanut sized), I’m pretty sure of one thing: birds are surprisingly smart. That bird learned some things faster than the undergrads I taught at the time, and retained them better. The idea that birds are innately too stupid to chase over an extended course doesn’t pass the sniff test.

    Birds as chasers may well fail on the prey handling level (e.g. a bird couldn’t kill something big enough to pay off the cost of running it down), but again, it’s not clear why that would be the case. T-Rex managed quite well with two feet and a mouth, after all, and that’s what birds have.

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  42. 42. BrianL 11:56 am 07/20/2013

    @Heteromeles: If you had a dog in that discussion, so did I. I remember being the first in that thread to question the hypothesis. I’m not sure I’d agree with you if the subject was ‘scarcely settled’ as I think the arguments against it were pretty strong, but hey that’s personal opinion (or perhaps even bias) for you. Regardless, I don’t think it’s neccessary to personally attack David Marjanovic over it. The man may be precise to the point of being pedantic (I hope I don’t insult him myself now!) but I don’t think his remarks are ever meant to be negative for the sake of negativity.

    I’d also like to mention out that I enjoy reading your own blog. I also agree with you that neither their intelligence nor having to kill their prey with only a beak and two feet would seem a feasible reason for large carnivorous birds to be ‘inferior’ to large carnivorous mammals. There would seem to be advantage to towering over your quadrupedal prey too. This certainly seems the case in, say, secretary birds, seriemas or even storks. Perhaps birds have simply never grown to the size where they would be the most powerful predator around? Granted, something like *Brontornis* may well come close to that. Also, I have little doubt that an adult tyrannosaurine would be lethal to any terrestrial potential prey or competitor the modern day (or even the entire Cenozoic) could offer.

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  43. 43. Yodelling Cyclist 1:32 pm 07/20/2013

    Let’s go right back to the original question: why didn’t birds radiate in the palaeocene rather mammals, and occupy the megafaunal niches? Without wishing to rehash the entire palaeocene extinction event discussion we had recently, it’s a good question. I stand by saying that mammals could outcompete the birds, because they did. I stand by the observation that it’s marginal because large birds DID manage to evolve in that environment: but never really dominated. The scholarly minds around here have produced less than twenty lineages of mega faunal birds from their collective memories. Mega mammals win, I would say. In no environment are the mammals in second place. Now let’s consider Squamata. If you consider the ratio of large birds:mammals:squamates in terms of species (or almost any other parameter). Mammals win, birds seem to be coming in second. Given that competitive advantage leads to significant feedback in this scenario, a small advantage for mammals would be become a huge disparity in the above ratio. Once a large bird has managed to get to a point where they can take on the mammals, there’s no reason for them to go anywhere. So we do see what I describe: a few large bird lineages arise in the palaeogene in the face of mammals evolving towards the same niches they survive. A very few more manage to evolve against mammalian pressure, but nowhere do we really see New Zealand type environment on continents with mammals. Sure, rheas must have run from terror birds, but nowhere are the grasslands filled with vast herds of diverse ratites being run down by a profusion of predatory birds of great variety. Instead we have ecosystems with a few large birds, rarely more than one ecospecies per environment. Even if a few come to mind, make a mental list of the mammals in the same environment.

    I tend to view evolution like a Monte Carlo simulation of a chemical reaction on a given potential surface – so random attempts are occurring with merry abandon, but only those attempts that yield a better form survive, and crucially those lineages starting with a steeper descent to a high efficiency form for a given niche will dominate that niche. It’s more complex than that because an ecospace can accept more than one species in a given niche and the complexity of the environment over time and place makes this very tricky. In short, yes there are bird lineages that succeed in becoming large in spite of the mammals, but I can name lottery millionaires – many play, some win, few do.

    What’s all this about ducks needing threesomes?!

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  44. 44. Yodelling Cyclist 1:38 pm 07/20/2013

    @BrianL: Carnivorous birds don’t start out giant carnivorous birds – if we return to original palaeocene discussion, it’s a game of small volant bird against small mammal, and whoever can become a giant predator and dominate that niche first is who we crown the winner. Brontornis is scary. Something the size of a Trumpeter, however, versus, say, a large mongoose? Now run that experiment separately on multiple continents with slightly different faunal mixes, and you see our mammals win more often than the birds in the contest of being more efficient predators.

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  45. 45. Yodelling Cyclist 1:50 pm 07/20/2013

    @Heteromeles and BrianL: yep, tyrannosaurids are bloody terrifying, granted, but they rely in big heads with sharp teeth, decent bite force and skeletal strength, counterbalanced by a tail. The birds that get through the KT have no tail for balance, so my above post kicks in.

    I’m also not sure I completely buy the idea that Mesozoic era therapods would totally dominate a modern ecosystem. Sure – T-Rex is going to overmatch anything in a straight fight, but it’s so specialised to its own environment and prey, I can’t help but suspect that a population would not thrive in the modern world. Maybe because the only prey big enough to be worth their while are elephants and rhinos…. And they may not breed fast enough to support a T-Rex population. Just speculating again….

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  46. 46. Yodelling Cyclist 1:57 pm 07/20/2013

    @Davd Marjanovic: fair point about the dubious advantages if bipedal life. I was really wondering why there’s never really been a mammalian ‘theropod’. Other than, say, kangaroos and a variety of rodents. Clearly, not something mammals are very good at. Why that is I have no idea.

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  47. 47. Gigantala 5:04 pm 07/20/2013

    Because most placental mammals don’t have thick and rigid enough tails, and tend to have too flexible spines. Xenarthrans and pangolins, with their bizarre skeletical features, did manage to produce theropodian walkers.

    Quadrupedally in general may also benefit mammals better than other tetrapods, as we have vertically flexible backbones and other amniotes don’t. The only sauropsid clade to have equally vertically flexible backbones, the crocodylomorphs, are also among the few endothermic sauropsids to never experiment with bipedality (pterosaurs being the other, presumably due to their small torsos, massive forelimbs and being able to fly anyways).

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  48. 48. John Harshman 6:46 pm 07/20/2013

    What’s all this about ducks needing threesomes?!

    Dunno about “needing”, but Anseranas is famous for having a majority of “pair bonds” consisting of one male and exactly two females, with the females often close relatives of each other. I don’t know of any similar case in any other species of animal. Do you?

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  49. 49. David Marjanović 9:49 am 07/21/2013

    Instead, they say, we should imagine the forests of Australia during this period to have generally been drier than what we now see in the Cape York Peninsula.

    Interesting. It would surprise me for at least the early Eocene, but I don’t know more than that!

    Anyway, there is a maximum possible egg size, because at some point the shell has to either break or become too thick for diffusion through the pores. I guess the connection between egg and adult size is that breaking it would require evolving hyperprecocial chicks (though the megapodes have done it…) that keep growing for a long time and have a different ecological niche than their parents for years. This is the plesiomorphic state of affairs, and the sauropods started close to it, but birds are far away from that.

    And if you go back, you’ll find that most of the scorn was heaped by David M (our resident fount of negativity),

    :-D :-D :-D :-D :-D

    Did you notice you just committed a textbook example of an ad-hominem argument? “It was said by [person], so it’s wrong!” :-D

    so it’s scarcely a settled issue.

    Those discussions were by no means all about me. I just write detailed comments (look what I’m doing right here, I’m responding to two parts of a sentence separately) with lots of paragraph breaks, each of which is doubled by the stupid software here. For these reasons, I am overrepresented in comment length. Most of the actual arguments were furnished by Dartian, who is usually much calmer than I am; maybe that makes him invisible to you. Several other people were also crucially involved.

    Birds as chasers may well fail on the prey handling level (e.g. a bird couldn’t kill something big enough to pay off the cost of running it down), but again, it’s not clear why that would be the case. T-Rex managed quite well with two feet and a mouth, after all, and that’s what birds have.

    I agree and add eagles.

    I don’t think his remarks are ever meant to be negative for the sake of negativity

    Indeed not. I don’t discuss topics for social ends (toadying, trolling, anything), I discuss them for their own sake. I simply have SIWOTI syndrome.

    I’d also like to mention out that I enjoy reading your own blog.

    Oh, I didn’t know Heteromeles has one. Where is it?

    nowhere do we really see New Zealand type environment on continents with mammals

    This makes New Zealand itself all the more intriguing: up to the Miocene, it had at least one species of flightless terrestrial mammal.

    The only sauropsid clade to have equally vertically flexible backbones, the crocodylomorphs, are also among the few endothermic sauropsids to never experiment with bipedality

    …Well, I don’t think Pristichampsus was endothermic, but according to the one biomechanical study I know of it (Rossmann 2000, N. Jb. Geol. Paläont., Abh.) it was probably capable of running bipedally once it had reached high enough speeds (which wasn’t a problem).

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  50. 50. Yodelling Cyclist 5:37 pm 07/21/2013

    David Marjanović may or may not be a chirpy chap (I’ve never met him), but regardless of this his personal levels of optimism do not make him wrong.

    Eagles have an advantage when they handle prey in that they tend to approach from above and have wings to help them steady and adjust position: they don’t walk up to animals of similar (or larger) size, lie on their backs and start grappling with both feet. This may well be why Haarst’s Eagle never became flightless, there’s too much advantage in a top attack, and there’s too muhc evolutionary dead ground whilst an animal is too large to fly and too small to take on the ancestral prey species. Any mutant eagle that was too big to fly would have to outcompete it’s fellow eagles for mate sand the adzebills for food… There’s a very good reason for there being no category in the paralympics for judoka with no arms.

    On the subject of New Zealand: yes one, rather bizarre and tiny mammal has been found. I would suggest that the development of the New Zealnad fauna prior to the Quaternary is so poorly understood that speculation on the subject is a bold proposition. Somehow sphenodonts survive but small mammals do not, and podacarps flourish. Weird. Possibly even weirder: only I think 12 species of native ants. Moa divergence at only 6m years before present, while the “drowning maximum” is at 22m years ago. No, New Zealand is odd, and the data (at least the freely available data to a complete amateur like myself) does not line up to a neat scenario.

    As a nod to the blog article: Finsch’s duck. Big flightless duck from NZ.

    Link to this
  51. 51. AndrewD 5:37 pm 07/21/2013

    David,
    Try this http://heteromeles.wordpress.com/

    NB No matter how long your Tet Zoo posts are I am sure I have seen longer ones in the lounge at another blog ;)

    Link to this
  52. 52. Heteromeles 9:25 pm 07/21/2013

    Thanks Andrew, beat me to it. I save that blog for the more goofy posts and crazy ideas. I’ll apologize to David M, since I didn’t check the thread before responding. Next time the argument comes up, I’ll blame Dartian.

    The general problem with the idea that mammals are better than birds is that this simply doesn’t appear to be true for the later half of the Mesozoic, nor for the Paleocene. It could indeed be that the K-T mass extinction basically reset the system with dinosaurs and mammals on the same footing and that mammals won by accident, because it took millions of years for mammals to get bigger than the biggest birds. That doesn’t suggest that mammals were massively better, at least at first.

    The other suggestion is that, after the K-T, conditions fundamentally changed in a way that somehow favored mammals. Two possibilities are angiosperms becoming dominant in plant communities worldwide, and ectomycorrhizae becoming dominant in more temperate forests. I have no idea why either of these would favor big mammals over big birds, but these roughly coincide with mammals coming to dominate many non-flying niches.

    Link to this
  53. 53. Andreas Johansson 5:48 am 07/22/2013

    The Mesozoic wasn’t exactly notable for big birds was it? It might be that the KT simply knocked out the dinosaurian lineages with a talent for size.

    Link to this
  54. 54. David Marjanović 6:47 am 07/22/2013

    Point taken on eagles.

    Possibly even weirder: only I think 12 species of native ants.

    what

    what is this I don’t even

    Wow. O_O

    Try this http://heteromeles.wordpress.com/

    :-o Awesome. I’ll need to become a regular.

    Link to this
  55. 55. LeeB 1 9:13 pm 07/22/2013

    We actually have only eleven species of ants and three species of termites native to New Zealand; also no social bees or social wasps.

    Of course we now have introduced and invasive species and are trying to get rid of some of the latter.

    LeeB.

    Link to this
  56. 56. Yodelling Cyclist 7:51 am 07/23/2013

    Now a really good question is why didn’t the crocodylomorpha take over in the paleogene. Answers on a postcard.

    Link to this
  57. 57. Heteromeles 12:19 pm 07/23/2013

    @55: “Now a really good question is why didn’t the crocodylomorpha take over in the paleogene. Answers on a postcard.

    How about: “because…”

    Link to this
  58. 58. David Marjanović 6:21 pm 07/23/2013

    Because those that could have taken over, the herbi- and omnivores, had just died out?

    The terrestrial carnivores and the marine forms fared pretty well; and pristichampsids aren’t even known from the Cretaceous.

    Link to this
  59. 59. Dartian 12:51 pm 07/24/2013

    John:
    at least one case of evolution of a pursuit diver from a filter feeder

    Oh? Which anatid would that be?

    David:
    Most of the actual arguments were furnished by Dartian, who is usually much calmer than I am

    What do you mean “usually”? I’m ALWAYS calm, goddammit!!!

    Heteromeles:
    Next time the argument comes up, I’ll blame Dartian.

    :) For the record, personally I rather enjoyed that discussion.

    Link to this

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