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The Prehistoric Croc Thread- Anything crocodilian related

2

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  • 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: 90,508 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: 90,508 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


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


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


  • Moderators, Society & Culture Moderators Posts: 12,577 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, 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.


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  • 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


    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, 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, 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, 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




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  • 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


  • 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


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


    Pebas was the megawetland (sometimes called a lake, sometimes called a freshwater/brackish sea) that covered what is today the Amazon basin during the Miocene.

    https://phys.org/news/2019-02-giant-animals-amazonian-mega-wetland.html

    giantanimals.jpg

    It was the home of the notorious giant caiman Purussaurus, one of the largest crocodilians ever:

    latest?cb=20120626114659

    Purussaurus_7.jpg

    Purussaurus_4.jpg

    150227011710_sp_cocodrilo_624x351_titoaureliano.jpg


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


    Phytosaurs were superficially crocodile-like reptiles and occupied a similar niche during the Triassic. Most of the known species were freshwater-based but like crocodiles, it seems they did venture to sea- this new species being an example.

    https://www.livescience.com/65460-ancient-crocodile-like-animal-discovered.html

    aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwNS82MDgvb3JpZ2luYWwvTXlzdHJpb3N1Y2h1cy1pbGx1c3RyYXRpb24uanBnPzE1NTc1MjQwMjk=
    Researchers excavated the remains of four of these now-extinct sea monsters from the rocky slopes of the Austrian Alps. But even at 13 feet long (4 meters), these creatures — known as phytosaurs — weren't fully grown.
    The phytosaurs were only about 8 years old when they died, and they were "still actively growing," according to a bone analysis

    It should be noted that the largest phytosaurs, such as Rutiodon, Redondasaurus and Smilosuchus, could be as long as 8-12 m, making them comparable to the largest crocodilians and among the largest predatory reptiles of prehistory.

    C4TmVqCWEAY8956.jpg

    53006258_123088582162561_4817165406418416529_n.jpg?_nc_ht=scontent-ort2-1.cdninstagram.com


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


    It is but a tooth, but is interesting because until now, no juvenile Deinosuchus fossils had been described. The tooth came from an individual maybe less than one meter long.

    https://bioone.org/journals/Bulletin-of-the-Peabody-Museum-of-Natural-History/volume-60/issue-1/014.060.0104/First-Record-of-a-Small-Juvenile-Giant-Crocodyliform-and-its/10.3374/014.060.0104.short

    Deinosuchus (formerly known as Phobosuchus) was one of the largest most formidable crocodilians known from the fossil record; it lived during the late Cretaceous in coastal waters of North America (specifically, the coasts of the shallow sea that split the subcontinent in two), and apparently could travel long distances by sea, as do some crocodiles today.
    Despite its crocodile-like appearance and tolerance for salinity, it was more related to caiman and alligators than to crocodiles proper.

    There's actual, solid evidence in the form of bite marks that Deinosuchus fed on large dinosaurs, among other things.

    restos-deinosuchus-formacion-kaiparowits.jpg

    Deinosuchus.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




  • Moderators, Social & Fun Moderators, Society & Culture Moderators Posts: 30,827 Mod ✭✭✭✭Insect Overlord


    I can't add anything to this discussion, but I just wanted to comment that your thread title is wonderful. :D


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


    Fathom wrote: »
    Why prehistoric larger than today?

    The more I think about this, the more difficult I find it to answer.

    It is not as easy as saying they started out big and shrank over time; in fact, the fossil record does not support this at all. The first crocodilians (I'm using crocodilian in the broad sense here) were small, and even when, eventually, you start getting giant forms (starting in the Jurassic period), the smaller forms are still more abundant and more diverse. This does not change at any moment in their history; gigantic crocs were the exception, not the rule.

    Of course if you separate crocodilians into two categories, one being modern ones and the other extinct ones, you'll find more giants in the latter, but only because it spans millions and millions of years. Some giant crocodilians did coexist, but not all; most are separated from one another by millions of years.

    That being said, it is true that some of the extinct giants grew considerably larger than today's crocodiles. IIRC the largest reliably measured saltwater crocodile (Crocodylus porosus, usually considered the largest reptile in the world), was Lolong, who died in 2013 in captivity and was 6.17 m, and weighed over 1000 kg. There is some skeletal and anecdotal evidence of larger saltwater crocodiles in the wild; the very largest may plausibly grow to around 7 m.

    Compare this to some of the largest prehistoric crocodilians, such as Deinosuchus, Sarcosuchus, Purussaurus, Rhamphosuchus or Machimosaurus, which are estimated at 9-10 m (maybe 12 m for the very largest). Some of these giants have been estimated at 3, 5, even 10 tons. But they represent only a tiny fraction of the total of extinct crocodilian genera/species, which are often within the range of our living ones or smaller.

    Now there's something interesting I've noticed, which is that many of the prehistoric giants lived in conditions different from those of modern day crocodiles. For example, many of the giants were partially or fully marine (Deinosuchus, Machimosaurus, Piscogavialis, Toyotamaphimeia). Large size allows a marine animal to travel longer distances across the sea, with extra protection against other predators (sharks, etc) and the ability to spend long periods without feeding; insane weight is not an issue if you spend most of your life at sea.
    Many kinds of marine reptiles (ichthyosaurs, mosasaurs, plesiosaurs) tended towards gigantism. Even the saltwater crocodile, the largest of our days, is the one most likely to venture out to sea, and to travel long distances between islands, etc, although it can´t be considered a truly marine animal.

    As for the prehistoric giants known to have lived in freshwater, they are often associated with huge river or lake systems that do not exist today. For example, Sarcosuchus and Stomatosuchus lived in a huge delta where the Sahara desert is now. Purussaurus, Gryposuchus and Mourasuchus lived in what is today the Amazon basin but back then was a gigantic wetland or inland sea, at times connected to the ocean, and rich in huge aquatic prey. You only get these super giant crocodilians for as long as these huge water bodies exist- when they dry out or become reduced, the giant crocs dissappear.

    May as well mention that at least in the case of Sarcosuchus, there's been suggestion that it grew to a much faster pace than modern day crocodilians, possibly as a strategy to reduce its vulnerability to other predators (remember there were dinosaurs and other crocodile-like reptiles around), and so they reached larger sizes earlier than modern crocs, and kept growing afterwards for many, many years. Without humans to shoot them on sight, the big ones would've been practically safe from predation and may have lived for over a hundred years unmolested, unlike what happens with crocodiles today.


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