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The Prehistoric Croc Thread- Anything crocodilian related

24

Comments

  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    It appears that they had relatively huge heads and most of them did not exceed 7 meters long.

    http://palaeo-electronica.org/content/2016/1554-teleosaurid-size-estimation

    Machimosaurus_Stuttgart-Markus_Buehler.jpg


  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 91,434 Mod ✭✭✭✭ Capt'n Midnight


    It's hard to believe that the Amazon used to flow into the Pacific, before the Andes rose up. Or that the Congo used to be a tributary, before the Atlantic opened up.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    What was that about the Congo?


  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 91,434 Mod ✭✭✭✭ Capt'n Midnight


    Adam Khor wrote: »
    What was that about the Congo?
    Back in the days of Gondwanaland it used to flow into the Pacific Ocean.



    fosdis.gif


    a09fig03.gif


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    This animal has been known for a while now but only today it's been formally announced. At first it was believed it could've been a giant theropod in the same size class as Tyrannosaurus, but it turns out to be a notosuchian (a land crocodile). It would've been around 7 meters long, although its jaws and teeth are still comparable to those of T. rex. 
    http://www.newsweek.com/ancient-giant-crocodie-t-rex-teeth-madagascar-631590
    El-cocodrilo-gigante-Razana-fue-uno-de-los-mayores-predadores-del-Jurasico_image_380.jpg


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  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    Razanandrongobe. Scavenger or predator or both?


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Among big animals today, all predators are occassional scavengers. The exceptions are few- cheetahs for example rarely if ever scavenge, but that may have more to do with their need to avoid larger predators (lions, hyenas) than any actual dislike for carrion. If they only fed on prey killed by themselves, all captive cheetahs would starve. 
    Likewise, even the most dedicated scavengers- vultures- will kill live prey if pushed by hunger and presented with an opportunity. All things considered, I'd imagine Razanandrongobe was no different from modern meat eaters.


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    A link between crocodylomorphs and theropods?


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Convergent evolution. The crocodylomorph's answer to theropods, you could say.


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    Adam Khor wrote: »
    Convergent evolution. The crocodylomorph's answer to theropods, you could say.
    These organisms evolved? Did not suffer extinction as many species of dinosaurs?


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  • Moderators, Society & Culture Moderators Posts: 12,086 Mod ✭✭✭✭ riffmongous


    What an awful name, that will never catch on.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Did Razanandrongobe specifically evolve into something else? That I don´t know, since no remains of potential descendants have been found, at least to my knowledge. But its Notosuchian relatives continued to exist until the late Cretaceous, and another branch of land-crocs (Sebecosuchians) even made it to the Miocene, where some forms (Barinasuchus, for example) also reached pretty large sizes. 

    Barinasuchus_Arveloi.JPG

    And then after that, you had land crocs again, this time more closely related to modern crocodiles, such as the Australian Quinkana which was as large as today's saltwater crocodiles and like Razanandrongobe and Barinasuchus had serrated, blade like teeth to deal with land prey. Quinkana lasted until about 40.000 years ago, meaning it may have been seen the first humans to arrive to Australia (who knows, maybe ate a few too). 



    Quinkana_timara_skull.jpg

    But again, convergent evolution- same basic design, three different linneages.


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    If there had been a major dinosaur extinction event millions of years ago. One that ended many species. Razanandrongobe may have been lucky. Evolved.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Large animals in general tend to be the first to go with major extinction events, unfortunately.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Large animals in general tend to be the first to go with major extinction events, unfortunately.


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    Adam Khor wrote: »
    Large animals in general tend to be the first to go with major extinction events, unfortunately.
    Comparatively speaking. Read (somewhere) that primates were at first advantaged by their small size. Many later evolved into larger-sized species.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    That is my point; during times of ecological crisis in which food is scarce and competition fierce, small animals (say, small primates) are more likely to survive, especially if they're not very specialized, whereas the larger animals that need a lot more food, space etc tend to go extinct. Then later the smaller ones may evolve into larger species when and if the conditions go back to being favourable, but by doing so they risk extinction the next time there's a crisis.


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    65 million years ago. All animals with 25 kg body weights become extinct. Suggests Chandra Wickramasinghe in Where Did We Come From: Life of an Astrobiologist.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Not really true- some animals larger than that survived, including the 2-3 meter crocodile Borealosuchus and the 4-5 meter long Thoracosaurus (a sea crocodile), as well as Champsosaurus (which actually grew bigger after the end of the Cretaceous). The crocodiles can be explained because they're capable of surviving a long time without feeding, but the seemingly warm-blooded champsosaurs are more difficult to explain.


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    Adam Khor wrote: »
    Not really true- some animals larger than that survived, including the 2-3 meter crocodile Borealosuchus and the 4-5 meter long Thoracosaurus (a sea crocodile), as well as Champsosaurus (which actually grew bigger after the end of the Cretaceous). The crocodiles can be explained because they're capable of surviving a long time without feeding
    Borealosuchus and Thoracosaurus exceeded Chandra Wickramasinghe's body weight claims. Both aquatic. Champsosaurus was mostly aquatic too?


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  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Champsosaurus was most certainly aquatic- more so than crocodiles, even. It has even been suggested, at least for one of the species, that only the female was able to walk on land, whereas the male had weaker limbs and was unable to do so, being restricted to water his entire life.(Females would have retained the ability to walk on land because of egg laying).


  • Moderators, Category Moderators, Science, Health & Environment Moderators, Society & Culture Moderators, Regional Abroad Moderators Posts: 8,301 CMod ✭✭✭✭ Fathom


    Adam Khor wrote: »
    Champsosaurus was most certainly aquatic- more so than crocodiles, even. It has even been suggested, at least for one of the species, that only the female was able to walk on land, whereas the male had weaker limbs and was unable to do so, being restricted to water his entire life.(Females would have retained the ability to walk on land because of egg laying).
    Cool Khor! All 3 aquatic. Survival advantage? For heavy weights.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    The article has a HUGE error- it says Deltasuchus lived at the same time as T. rex, when in reality it lived about 95 million years ago, and T. rex 68-66 million years ago.
    Deltasuchus was about six meters long, the size of our largest Nile and saltwater crocodiles- bite marks indicate it fed on dinosaurs among other things. It is the first broad snouted, big game hunting crocodile known from that time and place (the others were long and narrow snouted, like gharials).
    http://www.foxnews.com/science/2017/09/15/giant-dinosaur-eating-crocodile-discovered-in-texas.html
    Deltasuchus_motherali-novataxa_2017-Adams-Noto-Drumheller.jpg


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    This is very interesting. I remember reading many years ago about how caiman could do this, but apparently it's more widespread among crocodylians than we thought. This is not paleontology but has possible implications for dinosaurs and their thermorregulation abilities.
    https://www.nature.com/articles/s41598-018-24579-6.pdf
    4979133206_cfee336c39_b.jpg


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    The finds show that Cuban crocodiles, although very restricted nowadays, were much more widespread during the Pleistocene.

    http://digitallibrary.amnh.org/handle/2246/6920

    Cuban crocodiles are notorious for their aggressive temper and for being the most agile crocodile species on dry land.

    Cuban-Crocodile.jpg?fit=745%2C483&ssl=1

    Here's a painting of a Cuban crocodile attacking a ground sloth (also a flightless Grus cubensis crane).

    MF-3327-1-756x540.jpg


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  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭ Adam Khor


    Had a couple distinctive "horns":

    02724634.2018.1528450?journalCode=ujvp20

    DyKrZWYX0AESaW_.jpg

    It lived in Brazil during the Miocene, and was related to the gigantic Purussaurus, which was one of the largest crocodilians known from the fossil record:

    cs7_vnor.jpg

    150227011710_sp_cocodrilo_624x351_titoaureliano.jpg

    Today, most caimans are relatively small crocodilians- except for the black caiman (Melanosuchus niger) which is the largest member of the family and the largest Amazonian predator nowadays. Acresuchus is believed to have been ecologically similar.

    13230151_1049382801806351_4231595413498432164_n.jpg?_nc_cat=108&_nc_ht=scontent.fssa7-1.fna&oh=98457da1e8886c96e592b2e77e3d8c91&oe=5C937614

    418198_269431843134788_1764811767_n.jpg?_nc_cat=102&_nc_ht=scontent.fssa7-1.fna&oh=0eb402caec645a68607eab18ed56b9f6&oe=5CA1E124

    21092013184645_N6KA57UZRW.jpg


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