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Post by Horridus on May 21, 2011 23:16:52 GMT
They scavenged dead animals like vultures. Thanks Jack! |
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Post by dinoguy2 on May 22, 2011 17:28:38 GMT
You are implying Allosaurus took sauropods on. Ummm ... yeah .... I don't believe that is a new concept.... ;D True, but it's extremely unlikely any large theropod would have targeted adult sauropods, or adult anything. There were hundreds of easy to kill juvenile sauropods running around for every hard to kill adult. archosaurmusings.wordpress.com/2009/08/04/baby-killers-hunting-and-feeding-behaviours-of-large-theropods/It's highly illogical to think any theropod would have passed up this buffet of juveniles and risk its life to take on adults, and the presence of so many juveniles in the environment implies there would be no reason for coordinated pack hunting to ever need to evolve in those species. |
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Post by sid on May 22, 2011 17:46:14 GMT
It's highly illogical to think any theropod would have passed up this buffet of juveniles and risk its life to take on adults, and the presence of so many juveniles in the environment implies there would be no reason for coordinated pack hunting to ever need to evolve in those species. I agree, except for the last part... We don't know if ALL the herbivore dinosaurs which existed troughout the Mesozoic age in every corner of the planet bred multiples juveniles each and every time; i mean, this was surely true for some species, but applying this model to EVERY dinosaur is a bit preposterous, and the same can be applied to meat-eater dinos... They probably used different strategies to get their daily chow, as in modern animals: hunting alone, in pair, in mobs, packs, etc...  |
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Post by dinoguy2 on May 22, 2011 20:23:15 GMT
It's highly illogical to think any theropod would have passed up this buffet of juveniles and risk its life to take on adults, and the presence of so many juveniles in the environment implies there would be no reason for coordinated pack hunting to ever need to evolve in those species. I agree, except for the last part... We don't know if ALL the herbivore dinosaurs which existed troughout the Mesozoic age in every corner of the planet bred multiples juveniles each and every time; i mean, this was surely true for some species, but applying this model to EVERY dinosaur is a bit preposterous, and the same can be applied to meat-eater dinos... They probably used different strategies to get their daily chow, as in modern animals: hunting alone, in pair, in mobs, packs, etc... Certainly plausible, but keep in mind that so far there is no evidence that any dinosaurs laid eggs in anything other than huge clutches of dozens of eggs multiple times per year. Any large dinosaur that switched from being r-selected to k-selected would have had to develop some very unique specializations compared to its relatives, with small clutch size translating to extremely stringent parental care. Everything we know about them says they employed the sea turtle strategy, bombing the environment with as many offspring as possible, minimal parental care. anything else would have resulted in dozens of new enormous animals reaching maturity each year and decimating the ecosystem. Not impossible that some switched to an elephant-like, raise one baby at a time directly, strategy. But that's pure speculation until we find a sauropod nest containing only a few eggs. Which makes any speculation based on *that*, like pack hunting theropods specializing on adult sauropods because babies are rare, some kind of extra meta speculation  |
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Post by Horridus on May 22, 2011 20:49:20 GMT
What about hadrosaurs eg. the infamous Maiasaura? Large clutch sizes of course, but evidence of extensive parental care, with juveniles remaining nestbound for an extended period. That and certain theropods of course, but that feels like cheating... |
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Post by arioch on May 22, 2011 21:40:05 GMT
Also I´m not sure that stealing an offspring from those big sauropods/ceratopsians/wathever plant eater was so blatantly easy compared to directly try to kill the big ones (who in most of the cases had either enormous tails, spikes, horns, big claws or just an enormous mass to keep predators at bay and far from the young ones)... it would be definitely preferable, but neither option would be an easy job.
On the other hand, most of modern mammal prey can´t even defend themselves properly from lions/tigers/etc. Big theropods were much more vulnerable whichever prey they choose, so I suspect they had quite a flexible strategies when it come to target priority.
About the parental care, I doubt big duckibills or hadrosaurs could focus in more than 2 or 3 babies...They initially put a lot of eggs, but as a rule probably only a very few babies would survive the first weeks because of parental negligence, and not because those didn´t try, its just the adults were too big -and dumb- to keep an eye on all or even most of them. So a mixture of luck, incompetence and natural selection would decide which ones will reach puberty. I´m speculating though...
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Post by Horridus on May 22, 2011 21:57:17 GMT
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Post by sid on May 22, 2011 22:04:17 GMT
To Dinoguy2: yeah, there's no evidence that they laid less eggs, but i don't think this completely rules out the "medium to extensive parental care hypotesis" as i call it... To Arioch: mmh... don't understimate dinosaurs intelligence; birds and crocs are quite intelligent afterall, and remember, don't judge the brain of a certain species in human terms; plus, if dinosaurs evolved 225 million of years ago and they are still here, well, i would not call 'em "incompetent"  ;D |
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Post by arioch on May 23, 2011 7:28:06 GMT
But most of non avian theropods couldn´t even fly to flee from Daddy´s wrath if things gone wrong! this is definitely a lot less risky job... ;D And sid, I´m not calling all of them dumb (in human terms) but it seems obvious to me that big sauropods or even adult duckbills couldn´t look after all their small newborn chickens at the same time...it seems unlikely to me that their senses and perception were developed enough. They probably did what they could though, but can´t avoid some collateral damage. |
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Post by gwangi on May 23, 2011 12:41:02 GMT
mmh... don't understimate dinosaurs intelligence; birds and crocs are quite intelligent afterall, and remember, don't judge the brain of a certain species in human terms; plus, if dinosaurs evolved 225 million of years ago and they are still here, well, i would not call 'em "incompetent" ;D Yeah, and crocodiles have lots of young and are very large in relation to them. They try to protect their young but keeping track of that many small babies is difficult so they loose a lot. That doesn't make crocodiles dumb but you can see how many dinosaurs may have been similar. |
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Post by dinoguy2 on May 23, 2011 13:21:37 GMT
What about hadrosaurs eg. the infamous Maiasaura? Large clutch sizes of course, but evidence of extensive parental care, with juveniles remaining nestbound for an extended period. That and certain theropods of course, but that feels like cheating... I was talking mainly about sauropods. There's some debate about exactly how much parental care was going on with Maiasaurua, but it seems obvious that the parents at least fed them until they were able to leave the nest at a few months old. What happened to the babies after that, nobody knows. But we should look to crocs and birds that have similar after hatching care for clues, not to mammals. |
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Post by Horridus on May 23, 2011 17:48:13 GMT
But we should look to crocs and birds that have similar after hatching care for clues, not to mammals. Absolutely. |
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Post by stoneage on May 23, 2011 21:21:30 GMT
But we should look to crocs and birds that have similar after hatching care for clues, not to mammals. Absolutely. What about Monotremes? |
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Post by Horridus on May 23, 2011 21:48:25 GMT
What about Monotremes? I know you're joking...but [falls for bait] their methods of parental care are different, so the point is still valid. |
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Post by Griffin on May 27, 2011 6:37:32 GMT
"I don't mean to be condescending. I'm just trying to inject some scientific thinking into the discussion. A monster fan would read this news and say, "Wow, that is cool! Now that's something I want to believe is true." A science fan will ask, "Where's the evidence?" then go read more or talk to others looking for some, If there is none, dismiss it as bogus until some turns up."
Words to live by. Anybody remember a while back that article about Sinornithosaurus being venomous? How about the kangaroo-jumping hadrosaurs? Anybody ever see a follow up article for those? Scientific papers? No? hmmmm Thats because they turned out to be bogus. But they never release articles about that do they?
"Secondly, most people consider Tarbosaurus to be little different from TRex. They were essentially thought of as the same animal until recently."
Not really. Bone-wise there are some noticeable differences to a somewhat savvy eye. Different genuses. Thats more differences between the two of them then there are between say a lion and tiger (same genus, still to really different animals.)
"Taken to its extreme by the elephant-hunting lions of one particular nature preserve in Africa .. I recall seeing the show where about two dozen lions were hanging all over a full-grown elephant in the middle of the night. The elephant eventually tired and fell, and then the feast began ..."
Yeah that happened in the ngorongoro crater. Its one (or at the most a few) isolated instance. Def not typical hunting behavior by any means. Animals do desperate and dangerous things in desperate situations. The lions just happened to be lucky that night (and weren't without casualties I'm pretty sure). I'm also willing to bet that elephant wasn't a healthy individual.
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Post by dinoguy2 on May 27, 2011 13:00:10 GMT
"Secondly, most people consider Tarbosaurus to be little different from TRex. They were essentially thought of as the same animal until recently." Not really. Not really indeed. Because of the way we talk about dinosaurs people start to assume genus=animal. But really, species = animal (even ignoring subspecies, population differences, etc., which we can't really know for prehistoric life). Tyrannosaurus is not a species, and Tarbosaurus was never thought to be T. rex by anyone. Whatever you want to say "T." stands for, it's always been T. bataar, and nobody has ever suggested that T. rex and T. bataar are the same animal, any more than they would P. leo and P. tigris. |
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Post by Horridus on May 27, 2011 16:17:08 GMT
People like Greg Paul (ie. lumpers - and sorry to single out Paul again, but being so famous and all one immediately thinks of him) have tended to consider Tarbosaurus bataar to be a Tyrannosaurus species ('Tyrannosaurus bataar'), but others have maintained that it belongs in a separate genus as part of a distinct Asian tyrannosaurid radiation. Apparently T. bataar has features that link it to Alioramus.
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Post by arioch on May 27, 2011 16:27:26 GMT
Doesn´t Mr Paul also considers Torosaurus and trikes to be the same? (Also some of the theropods in his book have pronated hands, but that´s beyond the point.) |
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Post by sbell on May 27, 2011 16:42:02 GMT
Doesn´t Mr Paul also considers Torosaurus and trikes to be the same? Perhaps, but that paper was from Horner and...someone else whose name I can't remember (not meant as a slight, I just can't remember, and don't feel inclined to go find it). |
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Post by Griffin on May 27, 2011 17:03:15 GMT
Doesn´t Mr Paul also considers Torosaurus and trikes to be the same? (Also some of the theropods in his book have pronated hands, but that´s beyond the point.) And pachycephalosaurus/Dracorex/Stigimoloch....probably others in there too I can't remember. lol I don't think I'd blame him for lumping considering he has to draw all those  Which ones have pronated hands? Give me a Pg number |
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;D
