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Bathornithidae

April 25, 2016

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Paracrax gigantea/antiqua by Ornito Frenia

Bathornithidae was a lineage of flightless birds closely related to the more famous terror birds and modern seriemas that lived in North America from the Eocene to Miocene.

Basal forms like Paracatharthes probably could still fly, but as early as the late Eocene we see flightless forms, culminating in Oligocene forms like these, tur titans by bird standards.

Bathornithid diet is still somewhat uncertain, but based on their close relations, both alive and extinct, it can be assertained that they were carnivores.

So there you have it, North America’s most obscure theropod lineage.

17 Comments leave one →
  1. May 7, 2016 9:01 am

    Isn’t the idea that terror birds themselves were carnivores disputed nowadays?
    Also, why it seems that in the first half of the Cenozoic, large flightless birds were so successful? Why today just one or two generalist species remain in each landmass, if they remain, and why they have slowly but surely contracting distributions? Why did more forms evolve only in isolated islands, where they were ultimately vulnerable to extinction? And why most live in tropical or at least warmer climates? Is it due to mammalian pressure, or climate cooling? Are modern-type mammals so competitive?

    • May 7, 2016 11:21 pm

      No, you’re probably refering to Gastornis. Terror birds – as in, phorusrhacids – are still very much seen as macropredators.

      Also, flightless birds were successful in the late Cenozoic as well. Eogruidae was a lineage of ostrich-like flightless crane relatives that lived in Eurasia as recently as the Pliocene, for example, while ratites still frolick around in many mammal-dominated biomes.

  2. May 8, 2016 5:44 pm

    I knew about the gastornis, now I was searching about the terror bird diet revision, but I cannot find that. Perhapse either it was a fringe opinion or I am confusing it with gastornis indeed.
    Regardless, the Miocene isn’t too long ago, but it isn’t quite recent either. And it was still only one family. From the modern ratites, only the ostrich, which has a contracting distribution, lives with modern competitive mammals. Rheas live in South America, which has less large mammals, most of which arrived recently, and these birds also are smaller compared to the other ratites. And of course australian ratites are out of that comparison, because australia had traditionally other types of mammals, and like Pre-unification South America, the large animal nitches were more or less equally shared between mammals, flightless birds and non-avian reptiles. When I am talking about modern type mammals, I am refering mostly to the triad of ungulates, rodents and carnivorans, which seem to outcompete everything else. Perhapse the much feared reconstructed dinosaurs could not fare a chance if these mammals were present in the ecosystem. I don’t know why flightless birds cannot be successful. Their smaller brain size is popularly considered as a weak point, but it seems to simplistic to me. There could be other causes. Could it be their more cumbersome reproduction for example?

    • May 9, 2016 12:24 am

      Well, ungulates rodents lived in South America for most of the Cenozoic. I also think it’s unfair to dismiss other endemic megafaunal mammals like sparassodonts, meridigunulates or sloths, since they did fare well against “northern invaders” (carnivorans only appeared in South America during the Pleistocene, some two million years after sparassodonts became extinct, for example).

      In Australia, it’s still a predominantly mammalian fauna. Three clades of predatory mammals at the very least, plus a menagerie of megafaunal herbivores until fairly recently. And yet two lineage sof flightless birds, emus + cassowaries and the dromornithids, amanged to fare fairly well there as well.

      I say it’s more a combination of obscurity (groups like eogruiids and bathornithids being almost unknown to even several researchers) + unfortunate incidents (the extinction of eogruids does concide with the Pliocene climatic turnovers) rather than birds being unable to compete.

  3. May 16, 2016 4:11 pm

    “Isn’t the idea that terror birds themselves were carnivores disputed nowadays?”

    Not really, their skulls are even more robust than the ones seen in birds of prey, the second digits are “sickle claw-like” and at least andalgalornis had a neck similar to the seen in raptorial birds.

    “Also, why it seems that in the first half of the Cenozoic, large flightless birds were so successful?”

    Didnt we have fewer lineages of megafauna sized birds compared to mammals? And those lineages were fairly specialized, so once change happens and they go extinct the niches are taken by mammal groups.

    “Why did more forms evolve only in isolated islands, where they were ultimately vulnerable to extinction?”

    Maybe because they can reach the islands easier in first place? Either way, we have plenty of forms in many continents, Bathornithids themselves lived in north america until the miocene.

    “Are modern-type mammals so competitive?”

    Id say its hard to take a niche already taken.

    “From the modern ratites, only the ostrich, which has a contracting distribution, lives with modern competitive mammals. Rheas live in South America, which has less large mammals, most of which arrived recently, and these birds also are smaller compared to the other ratites.”

    Hmmm i disagree… SA had many diverse lineages of large mammals, both endemic and invasive, you cant really argue rheas didnt live with “competitive” mammals.

    “and like Pre-unification South America, the large animal nitches were more or less equally shared between mammals, flightless birds and non-avian reptiles.”

    I disagree again, most terrestrial large bodied niches were taken by mammals in SA, there were some lineages of large terrestrial diapsids, but most of the large diapsids were aquatic.

    “When I am talking about modern type mammals, I am refering mostly to the triad of ungulates, rodents and carnivorans, which seem to outcompete everything else.”

    While this might be the case in most islands, id like to remind one of the main examples people use, which is australia, is a heavily damaged ecosystem, with most of the megafauna extinct its easy to see how invasive species had so much success.

    “I don’t know why flightless birds cannot be successful.”

    They can be, its just that we dont have as many lineages of large flightless birds compared to large mammals, but many of their groups existed for millions of years. Maybe it has to do with birds being fairly specialized, while mammals have a larger range of generalist forms that can specialize more easily?

    • May 16, 2016 4:37 pm

      I wouldn’t say more specialised. If anything most flightless birds tend to be fairly generalist animals, megafaunal herbivores like dromornithids and elephant birds and predators like these Cariamiformes aside.

  4. May 30, 2016 5:54 pm

    I don’t find the reference, perhapse I confused terror birds with gastornis. But whatever they were, they went the way of sparassodonts. In a modern ecosystem, only carnivorans hold the terrestrial carnivore nitch in nearly all sizes, from weasels to lions.
    That Australia is overrun by invasives today is the effect of what I exactly wanted to say. That effect exposes the inherent competitive inferiority of the resident animals. Most were adapted to a place effectively like a big island, whith few and known predators and had low reproductive outputs and small brains. The first large species were killed off by the Aboriginals, and the remaining species now face problems due to human development and placental mammals. There might be some species that are not affected, but many of them are endangered. I wander what will happen when Australia will colide with India, providing that some natives have managed to survive up to then.
    If large flightless birds were so successful, we would have them in our countries all over the world, and probably we might be eating ratite or whatever other species steak now. The fact that most lineages went extinct now means something.

    • May 30, 2016 6:50 pm

      “I don’t find the reference, perhapse I confused terror birds with gastornis. “

      Likely, if you search for the andalgalornis neck flexibility paper you will see that it converges with predatory birds(buteo and owls at least). The skull being well adapted to pullback stress also doesn’t make sense from an herbivore perspective. Nor do the very pronounced tip of the bills or the raised second digit, which also hints for a predatory ecology.

      “But whatever they were, they went the way of sparassodonts.”

      We don’t even know if those were extinct due to competition, I recommend you check out this:

      https://www.academia.edu/5347506/The_Evolution_of_the_Cenozoic_Terrestrial_Mammalian_Predator_Guild_in_South_America_Competition_or_Replacement

      “That Australia is overrun by invasives today is the effect of what I exactly wanted to say. That effect exposes the inherent competitive inferiority of the resident animals. Most were adapted to a place effectively like a big island, whith few and known predators and had low reproductive outputs and small brains. The first large species were killed off by the Aboriginals, and the remaining species now face problems due to human development and placental mammals. There might be some species that are not affected, but many of them are endangered. I wander what will happen when Australia will colide with India, providing that some natives have managed to survive up to then.”

      I disagree strongly. The way I see it is, humans and climate change acted as the main drivers for megafauna extinctions in Australia. Once megafauna goes extinct it’s much easier for invasive megaherbivores(for example camels) or invasive mesopredators(for instance cats) to take over. Australia used to have an important guild of endemic megaherbivores like giant kangaroos and diprotodonts, while the carnivore niche was filled by hypercarnivorous marsupials and predatory diapsids.

      Mordern Australia though is very lacking in the fauna part. What extant endemic predators of Australia will prey upon fully grown camels? What’s going to compete with feral cats and foxes? We know even mesopredators like the Tasmanian devils do affect invasive species (from what I recall research shows that in areas where Tasmanian devils are present, cats forage mostly during the day, when they’re gone cats start foraging in the night, that puts a risk juvenile quolls, which are other important endemic predators, to falling prey to cats. I also recall its hypothesized that they’re the reason foxes didn’t gain a foothold in tasmia). If even Tasmanian devils already have a significant impact in fauna, whats to say when you remove things like thylacoleo, V. priscus, diprotodonts, quinkana, short-faced kangaroos,etc.?

      The thing is most of Australia’s endemic keystone species are extinct or in decline, so thats why i imagine most invasive species have an easy time on a place where many niches are empty.

      Tl;dr I don’t see feral cats and foxes having that much of a good time with thylacoleo and V. priscus walking around, this is without taking into account other endemic mesopredators that would occupy similar niches but are extinct or gone from mainland Australia(thylacines and Tasmanian devils for example).

      About marsupials being less effective predators. I have no idea since ive never searched on it. But current research is showing that at least thylacoleo was a very effective apex predator.

      Also, Australian varanids got to asia and coexisted with placental predators so yeah.

      “If large flightless birds were so successful, we would have them in our countries all over the world, and probably we might be eating ratite or whatever other species steak now. The fact that most lineages went extinct now means something.”

      The group of large flightless predatory birds of this post coexisted with placentals for millions of years though. Granted they went extinct, but competition isn’t the only factor for extinction.

    • May 30, 2016 7:53 pm

      The reason carnivorans are success is mere luck. They co-existed with hyaenodonts, mesonychians, entelodonts and several other gorups for millions of years, for example, and only became sole mammalian carnivores AFTER these groups went extinct in the Miocene.

      Luck is more often responsible than inherent “superiority”. Mammals, after all, competed with rhynchocephalians and squamates, animals typically dismissed as “inferior” from the classical perspective.

      And, as I said, eogruiids and other groups survived until very recently, well AFTER carnivorans became dominant

  5. June 1, 2016 1:30 am

    There is another theory floating around stating that in fact camels are the ecological replacement of the diprotodon, and not a harmful invasive. I have also read about the tasmanian devil displacing foxes in Tasmania, and also I read in the same article for the hesitance of Australians to introduce it at the mainland. Generally, Australians hold the state of the ecosystem in 1788 as the ideal form, which was in fact already degraded, and so do not attempt great reintroductions. The Komodo dragon was initially native to Australia, but no one is keen on reintroducing it back again. Also I believe that introducing some New Zealand species in protected parts of Australia and introducing unique australian species, like monotremes, in other parts of the world wouldn’t be a bad idea, but who does it given the modern state of conservation thinking and laws?
    ps. Most people wrongly think that mesozoic mammals were like the triad (carnivorans, ungulates, rodents) of today, so they find it strange that they competed with rhyncocephalians and other reptiles. But in fact they were very different. Their brain was very small, and it is possible that some reptiles were more intelligent than them. I read in paper about australian mammal-reptile competition that monitors are more intelligent than quolls, but the information was just anecdotal, though not unreasonable. And also their temperature regulation might not be so precise as in modern cold-adapted or large species. Overall, these mammals were more like opossums and tenrecs, rather than modern-type mammals.

    • June 1, 2016 3:17 pm

      There was also some statements of quolls displacing cats in New Zealand. Unfortunately, I can’t find a proper source for this. Either way, it goes to show that australian mammals are capable competitors to placental mammals.

      I don’t think there any studies on Mesozoic mammal intelligence. Based on living non-therians (monotremes and marsupial moles*), they could be reasonably stupid. However, marsupials have been shown to be fairly intelligent, so I have doubts that quolls were outmsarted by monitors.

      *Marsupial moles may be living dryolestoids, according to Agnolin et all 2014

    • June 1, 2016 8:47 pm

      “There is another theory floating around stating that in fact camels are the ecological replacement of the diprotodon, and not a harmful invasive”

      I recall that being mentioned, but the problem i see is that diprotodonts had to deal with a bunch of large predators(quinkana, thylacoleo, V. priscus), so they didnt overpopulate the place. Im not aware of how is the situation for camels, but i do recall hearing dingoes have declined very badly. Overall, camels in australia remind me of the situation with deer in britain.

      “Generally, Australians hold the state of the ecosystem in 1788 as the ideal form, which was in fact already degraded, and so do not attempt great reintroductions. ”

      Kinda like going to an africa safari without a single zebra, elephant or lion in sight.

      “Most people wrongly think that mesozoic mammals were like the triad (carnivorans, ungulates, rodents)”

      Well, two of these groups are quite specialized, so im not surprised small generalist forms didnt resemble them at all.

      “so they find it strange that they competed with rhyncocephalians and other reptiles.”

      Hm, while the large size niche is dominated by mammals, monitors are important mesopredators in africa and asia, constrictors are also pretty widespread and crocodylomorphs attain some of the largest size ranges for predatory animals in the ecosystems they live in.

      Btw, mentioning australian keystone species again, Dr David Peacock has some papers on how a healthy population of quolls could have been one of the main factors rabbits had dificulties estabilishing a foothold in mainland australia in the first introduction attempts. If his hypothesis is true, its another example of how important keystone species are to enviorments, with quolls and other native predators being essential to stopping invasive animals, viewed as pests on modern australia, from having sucess colonizing the place.

      Another interesting paper is Prowse et al. (2014), that argues humans were the main cause for the extinction of keystone species in australia, including the holocene extinctions of the thylacines and tasmanian devils in mainland australia(even more than competition with dingoes).

  6. June 4, 2016 1:28 am

    I didn’t say that all marsupial mammals are competitively inferior to placental mammals. Modern australian large cangaroos seem to have benefitted from human expansion, and due to their unique reproductive cycle, they might be competitive in resource-limited environments outside Australia. Other diprotodontids might be competitive as well in small animal nitches, like some arboreal possums. Like the post-interchange America, I believe it is certain that some marsupials will survive, or even flourish, but the proportion of successful clades will be smaller than that of placental mammals.
    I don’t think modern monotremes are a good analog for mesozoic mammals. In many respects, they are very specialized. They are quite competitive in their nitches, primarily for not having any serious competition. I don’t think it improbable that they would establish successfully outside Australia. Regarding their intelligence, the short-beaked echidna at least has an impressive prefrontal cortex and anecdotally it seems very intelligent. Perhapse better analogs for mesozoic mammals are opossums, hedgehogs, tenrecs, golden moles, marsupial moles, tree shrews, possibly dasyurides, etc. Shrews are too tachymetabolic and specialized. Could rabbits be a borderline example as well?
    But not only marsupials suffered in Australia, many rodents have suffered contracting distributions and extinctions as well. The most striking feature of many rodents though in Australia is that they have been “marsupialized”, for example, they have smaller reproductive output, longer lactation and in some species even the young attach to a teat while the mother is foraging. Could it be the harsh environment which makes mammals more energy-conserving, but less competitive, the primary factor for their failure rather than taxonomic position?
    I never stumbled on such a paper suggesting such a radical taxonomic revision. Is the new placement of marsupial moles supported by any serious scientists, or is that like the placement of rabbits besides marsupials etc? I will go and check.

    • June 4, 2016 2:09 am

      https://peerj.com/preprints/755/

      It’s still not peer-reviewed, but no one seems to have problems with its suggestions.

    • June 4, 2016 5:50 pm

      “Like the post-interchange America, I believe it is certain that some marsupials will survive, or even flourish, but the proportion of successful clades will be smaller than that of placental mammals.”

      The problem for me is using the GABI as an example. First reason why id be careful with that is because the invasive species in Australia are arriving in an enviorment where many keystone species have gone extinct. The second is because id wait for more research into the GABI itself, the papers showing panama closed millions of years earlier, the meteor in argentina that coincides with the faunal turnover there and the early immigrant taxa all sound kinda fishy for the typical “blitzkrieg” picture where the main factor for extinctions was northern taxa being superior.

      One thing im curious though, is if evidence is pointing out more towards the “overkill” theory for australian megafauna extinction or climate change. If anyone has looked into this do tell.

  7. June 4, 2016 2:17 pm

    From what I searched, a later paper showed again affinity with australidelphian marsupials. Fossoriality or any other extreme adaptation shapes animals of distant clades alike, so it might be more a result of convergent evolution. We will see.

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