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The Allosauroidea thread (allosaurs, carcharodontosaurs and kin)

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    #2
    dlofnep
    Closed Accounts Posts: 20,759 ✭✭✭✭dlofnep


    http://upload.wikimedia.org/wikipedia/commons/f/f6/Allosaurus_size_comparison.svg - Size chart.


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    #3
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    Epanterias is no longer a valid genus. The specimen has been reassigned to Allosaurus amplexus. Another species of Allosaurus approaching 40feet in lenght was A. maximus (formerly Saurophaganax maximus)
    It's worth remembering that Allosaurus was fairly light weight for a large theropod. A 40 foot Allosaurus would weigh about half the weight of a 40 foot Tyrannosaurus.


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    #4
    dlofnep
    Closed Accounts Posts: 20,759 ✭✭✭✭dlofnep


    Yeah, which made them ideal for sprinting after some tasty dinos ;)


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    #5
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    The tooth is 9.83cm long, about half the size of T.rex's largest teeth. Precious little else is known about this dinosaur.
    The palaeontologists have concluded that this is the largest tooth of a carnivorous dinosaur to have been found to date in Spain.

    The features and size of the 9.83 cm tooth provide key information needed to identify its former owner. The researchers are in no doubt - it was a large, predatory, carnivorous dinosaur (theropod) belonging to the Allosauroidea clade, a group that contains large carnivorous dinosaurs measuring between six and 15 metres

    Full article here.

    allosauroidea_tooth_300_196.jpg


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    #6
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    Since the new spinosaur has gotten everybody in the mood for some giant carnivore discussion, I thought you might enjoy this piece by Dinosaur Tracking Blog which chronicles the family history of another high spined theropod, Acrocanthosaurus atokensis. Surprisingly, it's not closely related to the spinosaurs at all, but their 'rivals' the carcharodontosaurs (who also feature prominently in the aforementioned thread).

    dino-acrocanthosaurus.jpg&sa=X&ei=aEeJTeKcOM25hAe064THDQ&ved=0CAQQ8wc&usg=AFQjCNGDhu2vBzPKDT4zMUR673Fzuugdjw
    Image by L.D. Austin


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    #7
    Rubecula
    Registered Users Posts: 8,551 ✭✭✭Rubecula


    In that drawing it looks a lot like a T.Rex with a bad back condition. How would it compare size wise?


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    #8
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    The bigest one found was 38 feet (about 11 and a half metres) with a skull over four feet in lenght and an overall similar build to the giant carcharodontosaurs, but not quite as massive in build. It was roughly the same size as a T. rex, although the largest Tyrannosaurus specimens were marginally bigger.


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    #9
    Rubecula
    Registered Users Posts: 8,551 ✭✭✭Rubecula


    But it has a friendly smile:pac:


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    #10
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Rubecula wrote: »
    But it has a friendly smile:pac:

    The same friendly smile you see in crocodiles today... ;)


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    #11
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    In Arkansas, US.

    http://washingtonexaminer.com/news/2011/10/new-dinosaur-tracks-found-southwestern-arkansas

    acrocanthosaurus_jb.jpg


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    #12
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Another article on the same find. The journalists are calling Acrocanthosaurus "T-Rex cousin". o-O

    http://abcnews.go.com/Technology/dinosaur-tracks-found-arkansas-cover-football-fields-made/story?id=14690741


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    #13
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    The bastardization of every theropod as a 'T. rex cousin' continues....

    :(


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    #14
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Galvasean wrote: »
    The bastardization of every theropod as a 'T. rex cousin' continues....

    :(

    T-Rex must be tired of so many sudden relatives...


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    #15
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    It's like when you win the lotto... (I'm told)


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    #16
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Galvasean wrote: »
    It's like when you win the lotto... (I'm told)

    Indeed...


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    #17
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    It's two separate discoveries; one of them is a juvenile Acrocanthosaurus found in the Cloverly Formation. The study says that Acrocanthosaurus grew at rates similar to Allosaurus and tyrannosaurs, but also that it seemingly reached adulthood in 20 or 30 years (Tyrannosaurus rex at least grew faster then, as it is said that it reached adulthood at around age 18... or that's the last thing I read).

    http://www.sciencedirect.com/science/article/pii/S0031018212001435?v=s5

    There's also a baby Brachiosaurus measuring only 2 meters long, found in the Morrison formation:

    http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2012.01139.x/abstract

    Both are extremely interesting as we know very little about baby dinosaurs- we tend to imagine them as miniatures of their parents yet we know at this point that it wasn´t the case. I only wish they publish reconstructions of the creatures at one point...
    Acrocanthosaurus-249x352.jpg


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    #18
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    New theropod teeth from the latest Cretaceous (Maastritchian) of Brazil have been found and analyzed. Some of them seem to belong to abelisaurs, but the most interesting ones seem to be from carcharodontosaurs, which were supossed to have went extinct long before the late Cretaceous.
    Of course, being just teeth, we can´t be sure- they may belong to some other kind of theropod that developed similar diet habits/teeth, or even to crocodilians. When the blade-like, serrated teeth sebecids were found for the first time, scientists believed non-avian theropods had made it to the Eocene in South America, because the teeth were so similar.

    EDIT: A later study found that these teeth may belong to abelisaurids after all. :/

    I have to admit it's an exciting idea, tho- to have T. rex and carcharodontosaurs walking the Earth at the same time, albeit in different places.

    http://ojs.c3sl.ufpr.br/ojs2/index.php/rbg/article/view/21309
    images?q=tbn:ANd9GcQ0AVv6iS_RsDWWkIoiw5ELXIxC2ZObWST181MqC9wFVsGQ7l0U


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    #19
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    I guess we may soon be throwing out the conventional logic that carcharodontosaurs were outcompeted by smaller, 'more advanced' theropods. Perhaps another cases of 'lack of evidence =/= evidence of absence'.


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    #20
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Galvasean wrote: »
    I guess we may soon be throwing out the conventional logic that carcharodontosaurs were outcompeted by smaller, 'more advanced' theropods. Perhaps another cases of 'lack of evidence =/= evidence of absence'.

    I think it makes sense that if carcharodontosaurs were specialized sauropod-hunters, and sauropods made it to the very end, there is no reason to suposse that carcharodontosaurus wouldn´t make it along with them. Perhaps they simply became rarer/less diverse, but then, same happened with tyrannosaurs in North America it seems.


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    #21
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    I wouldn't pay too much heed to that idea. That recent study showed that sauropods were at their most diverse during the Maastrichtian (even more so than in the late Jurassic). I honestly think we'll find more and more Maastrichtian diversity. we just need to dig more!


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    #22
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    It seems there's also a maxilla of the late Cretaceous Brazilian carcharodontosaur, not only teeth. It was quite a bit smaller than its earlier relatives; its skull was only 80 cms long.
    1-s2.0-S0195667112001176-gr4.sml

    http://www.sciencedirect.com/science/article/pii/S0195667112001176


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    #23
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    So, considering the time ecological difference and smaller size we can assume this is a different genus to Carcharodontosaurus - any sign of a name yet?


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    #24
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Not yet, to my knowledge.


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    #25
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Unfortunately, the article calls Allosaurus "T-Rex's Smaller Cousin" despite the fact that T-Rex is more closely related to penguins or hummingbirds than to Allosaurus.
    It misguided me into believing it was about Albertosaurus... :(

    http://news.yahoo.com/t-rexs-smaller-cousin-ate-falcon-study-finds-183243842.html

    56694_web.jpg


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    #26
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    This culture of calling everything a cousin of T. rex is getting a little bit grating...

    But hey at least they follow up with:
    "Many people think of Allosaurus as a smaller and earlier version of T. rex, but our engineering analyses show that they were very different predators.""


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    #27
    Rubecula
    Registered Users Posts: 8,551 ✭✭✭Rubecula


    It is bloody annoying this "everything is related to T-rex" attitude. I think we are predators too so we must be related to T-Rex as well. "ROARRRRRRRRRR" :D


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    #28
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Rubecula wrote: »
    It is bloody annoying this "everything is related to T-rex" attitude. I think we are predators too so we must be related to T-Rex as well. "ROARRRRRRRRRR" :D

    Guess we are if we consider we are all descended from a same common ancestor... but then why not start calling potatoes T-Rex relatives while we're at it?

    PS- Regarding the "Many people think of Allosaurus as a smaller and earlier version of T. rex, but our engineering analyses show that they were very different predators.""part, I figured that out at age 3 and I didn´t need engineering analyses... or a phD :pac:


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    #29
    Galvasean
    Registered Users Posts: 30,746 ✭✭✭✭Galvasean


    I just counted the fingers. If it has three it was an allosaur. If it had two it was a tyrannosaur. Bear in mind back then the quality of theropod illustrations was at times dubious.


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    #30
    Kess73
    Registered Users Posts: 25,560 ✭✭✭✭Kess73


    Ties in nicely with my theory of how sparrowhawks are great to watch if one wants to form ideas about theropods. Much better example than a falcon as Sparrowhawks will hunt on foot as well as on the wing making them a much more rounded ambush predator :D

    Some on here may remember me rambling on about it a year or so ago. :)



    Sparrowhawk: The T-rex Allosaurus of back gardens. :P


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    #31
    Adam Khor
    Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Nothing beats Harris hawks or the Johnny Rook when it comes to pack hunting dinos, tho :D

    Then the crested caracara and the secretary bird hunt on land much more often than sparrowhawks.


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