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How did the diplodocoid sauropod become extinct at the end of the jurassic?
Topic Started: Jul 26 2012, 12:00 AM (4,187 Views)
SpinoInWonderland
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What do you think is the reason for the complete annihilation of the diplodocoid sauropods at the end of the jurassic?
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theropod
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Probably changes in climate and vegetation favoring macronarian teeth design.
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SpinoInWonderland
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I thought that it was some kind of undiscovered lesser mass extinction event, like an ice age or something
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theropod
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There was a lesser mass extinction at the end of the jurassic, probably caused by the exact factors I mentioned. That´s why ornithopods got so dominant during the cretaceous
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Rashido
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I would assume they were outcompeted. Perhaps by hadrosaurs and ceratopsians, as well as the more advanced titanosaurs.
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SpinoInWonderland
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theropod
Jul 26 2012, 12:41 AM
There was a lesser mass extinction at the end of the jurassic, probably caused by the exact factors I mentioned. That´s why ornithopods got so dominant during the cretaceous
Whatever caused that mass extinction, it destroyed the stegosaurians and the non-spinosaurid megalosauroids also, so there are likely more factors than the ones you listed
Edited by SpinoInWonderland, Jul 26 2012, 12:46 AM.
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Agentjaguar
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Climate change -> vegetation changes -> large herbivores do not adapt quickly -> extinction -> followed by extinction of large predators (i.e. Allosaurus)
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theropod
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brolyeuphyfusion
Jul 26 2012, 12:45 AM
theropod
Jul 26 2012, 12:41 AM
There was a lesser mass extinction at the end of the jurassic, probably caused by the exact factors I mentioned. That´s why ornithopods got so dominant during the cretaceous
Whatever caused that mass extinction, it destroyed the stegosaurians and the non-spinosaurid megalosauroids also, so there are likely more factors than the ones you listed
Stegosaurids made it to the cretaceous (eg. Paranthodon, Wuerhosaurus), although they got rare, and so did non spinosaurid megalosaurs (eg. Afrovenator).

I think that stegosaurs got repressed and finally went extinct is BECAUSE of ornithopods great success, which was caused by the extinction of diplodocids. Megalosaurs might have been specialised on stegosaurs.

diplodocids likely fed on the same kind of vegetation as ornithopods during the jurassic, because they usually didn´t reach that far up with their necks. When this vegetation changed, Ornithopods, that were able to chew, had an advantage, while diplodocids couldn´t sustain themselves. Stegosaurs could survive becuase they were smaller, but finally ornithopods outcompeted them. Imo it could be that megalosaurs were specialised in hunting stegosaurs, because:

We can see, that animals specialised in hunting sauropod have a weak bite and wide gape, not the case in megalosaurs. The sauropod hunters were Allosaurs.
They actually rather resemble Tyrannosaurs, thus I think they were specialised in small, but well defended herbivores.
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Godzillasaurus
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As other species continued to evolve, they ran into much competition. Remember that titanosaurs replaced diplodocids and brachiosaurs and became even larger.
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Superpredator
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brolyeuphyfusion
Jul 26 2012, 12:35 AM
I thought that it was some kind of undiscovered lesser mass extinction event, like an ice age or something
Why am I not surprised you believe Diplodocoid got extinct by a lesser extinction and not by getting out-competed??
Anyway, I believe climate change+new species of plant+new herbivores+ requirement of huge amounts of food every day=dead Sauropod.
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Cat
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Some titanosaurids were also huge. Perhaps their dentition was more suitable to to changing vegetation. Maybe the longer necks of diplodocids weren't longer necessary for the kind of vegetation that existed at the beginning of the Cretaceous. Probably long necks give some disadvantage in term of circulation system and energy expenditure, so when no longer required for feeding purpose they were replaced by shorter ones. Very long tails weren't longer necessary either to counterbalance the shorter necks. Still, I think long whip-like tails would have been a better defensive weapon. It was probably a trade-off involving several factors. Some titanosaurids evolved also armor, so that could have compensated for the lack of whip-like tails.
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Admantus
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Weren't diplidocids around during the early cretaceous? I think amargasaurus was a diplodicid.
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Godzillasaurus
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Admantus
Jul 26 2012, 11:21 PM
Weren't diplidocids around during the early cretaceous? I think amargasaurus was a diplodicid.
No, amargasaurus was a titanosaur. Diplodocids, unlike brachiosaurs, dies out at the end of the Jurassic. Brachiosaurs died out in the Early Cretaceous I believe.
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Godzillasaurus
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Agentjaguar
Jul 26 2012, 02:18 AM
Climate change -> vegetation changes -> large herbivores do not adapt quickly -> extinction -> followed by extinction of large predators (i.e. Allosaurus)
But remember, even larger predators evolved in the Cretaceous. Tyrannosaurus (though more of a scavenger), carcharodontosaurus, giganotosauruds, and spinosaurus. Diplodocids were replaced by even larger saurpods.
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Admantus
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Godzillaman
Jul 27 2012, 08:30 AM
Admantus
Jul 26 2012, 11:21 PM
Weren't diplidocids around during the early cretaceous? I think amargasaurus was a diplodicid.
No, amargasaurus was a titanosaur. Diplodocids, unlike brachiosaurs, dies out at the end of the Jurassic. Brachiosaurs died out in the Early Cretaceous I believe.
Amargasaurus is a dicraeosaur, a group of dinosaurs related to diplidocus and kin.
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