Deddly Posted January 25, 2018 Share Posted January 25, 2018 6 minutes ago, sh1pman said: (not yet crazy...) 6 minutes ago, sh1pman said: lock a group of... *volunteers* in a cage with T-Rex Link to comment Share on other sites More sharing options...
Green Baron Posted January 25, 2018 Share Posted January 25, 2018 This is one of the rare cases that i (hobby palaeontologist) actually recommend a wikipedia article, namely that of Tyrannosaurs. Read it with the usual grain of salt and follow the links, especially those with a real scientific background, like studies on functional morphology and palaeoecology. tl,dr: clearly a hunter, but probably didn't leave a body found lying by the side of the road if it wasn't too smelly yet. The ability of digesting carrion is extremely rare, for most organisms it is toxic to deadly. Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2018 Share Posted January 25, 2018 @tater said: Taphonomy limits what we can know. A shed tooth tells little, unless it is embedded in a healed wound, for example, since even a scavenger would also shed teeth (theropods had deciduous teeth). A healed wound means it was bit while alive. Current ideas tend to lean heavily towards predation as their principal form of food gathering, however (which is where I stand on the issue). None the less, it's still conjectural since we have relatively small numbers of examples, and their relative abundance is entirely determined on the particular situation of the particular deaths that resulted in fossils being left. The bones scattered everywhere in East Africa will never be fossilized. Only the few that happen to fall into the mud near a watering hole, for example will have a chance at mineralization. "Conjectural" is about as good as it gets for some things, there is nothing wrong with it, it's part of what makes paleontology interesting. I should add that there was a Calvin and Hobbes where Calvin observes that the color scheme of the dinosaur he drew in school was "a bit conjectural." My comment was a sideways reference to that (I looked for a jpg of the comic online, and couldn't find it). Here is a photo of a T. rex tooth fragment embedded in the healed tail vertebra of a hadrosaur: This is the smoking gun in the case for predatory behavior by T. rex. While we're at it, the case for T. rex being an obligate scavenger is not a good one. You hear things like, "Being huge is good if you're a scavenger, because you can chase everything else away from the carcass." But this doesn't actually work. Gigantism, as seen with T. rex, only evolves when there is specific selection pressure pushing for it. In the case of gigantic herbivores like the titanosaurs and other really large sauropods, the selection pressure for gigantism is obvious: extended periods of good climate and lots of lush vegetation, for many millions of years. But for obligate carnivores, the only way to have selection pressure for gigantism is to have a LOT of prey around. Scavengers do not have selection pressure to become very large, because there are no environmental situations where you would have lots and lots of dead carcasses laying around every day for millions of years. And even if there was a uniquely long period of increased scavengeable meat, this would benefit smaller, r-strategist scavengers who can reproduce quickly and take advantage of the food availability. Obligate scavengers are not known for fighting off other animals. Vultures, which are obligate scavengers, compete over animal carcasses with coyotes, which are not, but we don't see selection pressure pushing vultures to become gigantic and fight off coyotes. The larger the obligate carnivore, the more likely that it was a predator, not a scavenger. Link to comment Share on other sites More sharing options...
tater Posted January 25, 2018 Share Posted January 25, 2018 Like hyenas. They scavenge, but often by driving off lesser predators---which they can do, because they are also powerful predators. Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2018 Share Posted January 25, 2018 7 hours ago, tater said: I should add that there was a Calvin and Hobbes where Calvin observes that the color scheme of the dinosaur he drew in school was "a bit conjectural." My comment was a sideways reference to that (I looked for a jpg of the comic online, and couldn't find it). May have been at the time, but now we are able to extract pigmentation traces from small feathered dinosaurs and identify not only patterns, but the specific chemical signatures of specific pigments. I get excited about this stuff because I grew up creationist, so the fact we CAN use science to KNOW things about the past its just so cool to me. Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 32 minutes ago, Green Baron said: clearly a hunter, but probably didn't leave a body found lying by the side of the road if it wasn't too smelly yet When hungry, eats anything. Sometimes digs in trash cans. 23 minutes ago, sevenperforce said: Here is a photo of a T. rex tooth fragment embedded in the healed tail vertebra of a hadrosaur: Spoiler 23 minutes ago, sevenperforce said: I don't want to scare somebody, but... Spoiler Link to comment Share on other sites More sharing options...
tater Posted January 25, 2018 Share Posted January 25, 2018 I worked with paleontologists for 10 years, mostly on theropods. Like I said, I'm in the predator camp, though I'm confident that they'd steal a carcass should they come across a lesser predator. Colors vary so much that unless you have evidence of pigments on the species in question, it's conjectural. Even then, pigments vary markedly by specific eco system. Take tigers and lions for example. Panthera tigris and Panthera leo have slightly different skeletal morphology, but if all we knew of them was bones (or fossilized bone), telling coloration would be impossible. Finding pigment for one would tell you nothing about the other. You'd not get the mane on male lions, either. I'm sure there are lizard and bird examples separated by just a few km with entirely different pigmentation (particularly birds) on species that are nearly identical from a skeletal standpoint. Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 (edited) Pussies Cats Felines are clever. They can distinguish fresh meat from a rotten one. Are the currently living reptiles enough clever for this, too? Or are they eating any piece of meat (or former meat)? Edited January 25, 2018 by kerbiloid Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2018 Share Posted January 25, 2018 8 minutes ago, kerbiloid said: Pussies Cats Felines are clever. They can distinguish fresh meat from a rotten one. Are the currently living reptiles enough clever for this, too? Or are they eating any piece of meat (or former meat)? Birds certainly can, and predatory theropods were more similar to birds than they are to living reptiles. Link to comment Share on other sites More sharing options...
Green Baron Posted January 25, 2018 Share Posted January 25, 2018 (edited) This has nothing to do with cleverness. Organisms only need a rudimentary signaling device to tell the good from the bad. Insects signal a path but haven't even a brain. Wild living hyenas actually hunt most of their prey themselves. Edited January 25, 2018 by Green Baron Link to comment Share on other sites More sharing options...
Scotius Posted January 25, 2018 Share Posted January 25, 2018 I'm a simple man. If i see a towering animal with rows of big, pointy teeth i do not assume it is a harmless scavenger. I run away. After all, even if it is a scavenger, it needs only to kill me to be able to scavenge meat off my carcass Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 (edited) 4 minutes ago, Green Baron said: This has nothing to do with cleverness. Organisms only need a rudimentary signaling device to tell the good from the bad. Insects signal a path but haven't even a brain. Hyenas actually hunt most of their prey themselves. So, do the the current reptiles distinguish fresh and rotten meat (regardless of their intellect), or they don't care? (Birds - I see, but a bird vs lizard is like a human vs monkey) Edited January 25, 2018 by kerbiloid Link to comment Share on other sites More sharing options...
tater Posted January 25, 2018 Share Posted January 25, 2018 The teeth adaptations of hyenas for bone-crushing (this is from memory) is frequently used to paint them as scavengers, but given their environment, where they might be driven off by a pack of lions (or humans), the ability to get at the nutrient-rich marrow easily is adaptive for them regardless. 1 minute ago, kerbiloid said: So, do the the current reptiles distinguish fresh and rotten meat (regardless of their intellect), or they don't care? Unsure, though some (alligators, crocs, or both, can't recall) stuff meat away until it is a bit ripe to ease consuming it (their teeth don't function well for slicing bites off). Link to comment Share on other sites More sharing options...
Just Jim Posted January 25, 2018 Share Posted January 25, 2018 (edited) 7 minutes ago, kerbiloid said: So, do the the current reptiles distinguish fresh and rotten meat (regardless of their intellect), or they don't care? 11 minutes ago, sevenperforce said: Birds certainly can, and predatory theropods were more similar to birds than they are to living reptiles. One thing you have to bear in mind, concerning birds and rotten carcasses, is buzzards... which we have plenty of in Florida. They're huge, and can eat nearly anything... and I mean anything! In fact, I think they prefer their armadillo road-kills to be a little on the rotten side... My point is, if some theropods had even 1/10th the insane immune system a buzzard has, then I see no reason they wouldn't go after something most other dinosaurs take one sniff of and run the other direction. Oh, as for modern lizards... the little ones around here prefer live insects... including cockroaches... which aren't quite rotten, but still NASTY!!! Edited January 25, 2018 by Just Jim Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2018 Share Posted January 25, 2018 (edited) 13 minutes ago, Just Jim said: One thing you have to bear in mind, concerning birds and rotten carcasses, is buzzards... which we have plenty of in Florida. They're huge, and can eat nearly anything... and I mean anything! In fact, I think they prefer their armadillo road-kills to be a little on the rotten side... My point is, if some theropods had even 1/10th the insane immune system a buzzard has, then I see no reason they wouldn't go after something most other dinosaurs take one sniff of and run the other direction. Turkey vultures have specific adaptations to allow them to consume meat that other scavengers leave behind. IIRC they have something like fifty times more strains of bacteria on their faces and in their guts than similar birds. Edited January 25, 2018 by sevenperforce Link to comment Share on other sites More sharing options...
Green Baron Posted January 25, 2018 Share Posted January 25, 2018 8 minutes ago, kerbiloid said: So, do the the current reptiles distinguish fresh and rotten meat (regardless of their intellect), or they don't care? That depends, those who have the ability to feed on carrion do so of course, those who don't, don't. Cleaning up carcasses is a niche, but it is rare, as is carrion. But that is not necessarily a parallel to Jurassic big lizards as their lifestyle and niches were different. Just take warm and cold-bloodedness for example. @Just Jim: really a buzzard or a vulture ? Just asking, as i have heard that there can be confusion ... Link to comment Share on other sites More sharing options...
Just Jim Posted January 25, 2018 Share Posted January 25, 2018 (edited) 7 minutes ago, Green Baron said: @Just Jim: really a buzzard or a vulture ? Just asking, as i have heard that there can be confusion ... Sorry. Everyone I know just calls them buzzards, but they're mostly Turkey Vultures and some Black Vultures... about 80/20 mix. We also have Bald Eagles and Osprey, which are just as large, but you can tell the difference if they're not too high up. 8 minutes ago, Green Baron said: But that is not necessarily a parallel to Jurassic big lizards as their lifestyle and niches were different. Just take warm and cold-bloodedness for example. Agreed, but given how large (and nasty) something like a T-Rex carcass must have been... and how much meat there is, it seems logical something would have adapted to take advantage and scavenge after the big predators left. Edited January 25, 2018 by Just Jim Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 (edited) Spoiler Regardless of the theme, just thought about taking cold/warm alligator Edited January 25, 2018 by kerbiloid Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2018 Share Posted January 25, 2018 6 minutes ago, kerbiloid said: Hide contents Regardless of the theme, just thought about taking cold/warm alligator Craziest adaptation I've ever seen. Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 1 minute ago, sevenperforce said: Craziest adaptation I've ever seen. They survived when an asteroid hit. Link to comment Share on other sites More sharing options...
Green Baron Posted January 25, 2018 Share Posted January 25, 2018 10 minutes ago, Just Jim said: Sorry. Everyone I know just calls them buzzards, but they're mostly Turkey Vultures and some Black Vultures... about 80/20 mix. We also have Bald Eagles and Osprey, which are just as large, but you can tell the difference if they're not too high up. Agreed, but given how large (and nasty) something like a T-Rex carcass must have been... and how much meat there is, it seems logical something would have adapted to take advantage and scavenge after the big predators left. In the end (and the beginning): bacteria. Never a mistake to mention them :-) Seriously, the circle will control itself if it works, and it did for many 10s of millions of years. You'll have a food pyramid with predators at the top, but there will never be more than can feed on the biomass below. A singe rotting top predator is a rare sight. We can imagine that once a trex was too weak to hunt or too old, it was killed and eaten. 6 minutes ago, kerbiloid said: They survived when an asteroid hit. Though probably meant as joke (i never know when you're joking :-)), this deserves a like ! Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 (edited) 5 minutes ago, Green Baron said: Though probably meant as joke (i never know when you're joking :-)), this deserves a like ! Of course I didn't mean exactly these ones, but this winter is nothing compared to a post-asteroid winter. Edited January 25, 2018 by kerbiloid Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2018 Share Posted January 25, 2018 10 minutes ago, kerbiloid said: They survived when an asteroid hit. I didn't realize that ghavials, crocodiles, and alligators actually diverged before the KT, but they did. Link to comment Share on other sites More sharing options...
Green Baron Posted January 25, 2018 Share Posted January 25, 2018 (edited) @kerbiloid, were you aware when you posted ? Say that you were ! Edited January 25, 2018 by Green Baron Link to comment Share on other sites More sharing options...
kerbiloid Posted January 25, 2018 Share Posted January 25, 2018 (edited) 6 minutes ago, Green Baron said: were you aware when you posted ? Say that you were ! I am. If there was no winter after the chicxulubing, it's OK, I didn't see it myself, I just read about it. (But I'm fond of the picture of myriads of croco jaws sticking out of ice around the continents) Edited January 25, 2018 by kerbiloid Link to comment Share on other sites More sharing options...
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