On Monday, April 26, 1999 9:15 PM, veselinka.stanisavac [SMTP:veselinka.stanisavac@siol.net] wrote: > << File: Header.TXT >> > > However, I still have trouble in figuring out how meat eaters moved on > leaving behind their (conservative - "immobile") herbivorous prey, just to > find eventual new prey "on the other side of the hill , across the desert, > across the river", etc. It could have happened just as an accidental event > (many times in a long history, of course) - a sole predator or a group - > crossing the "secret barrier" herbivorous dinosaurs didn't care crossing. A > sort of "osmotic" barrier: transparent for predators but not for herbivorous > dinosaurs (odd). One possible scenario that crossed my mind is based some rather localised catastrophe (this touches some of the KT-speculations, actually). Maybe a local epidemic, flood, draught, bushfire, vulcanic eruption, whatever... Of course (relatively) many herbivores often need to browse some sort of vegetation, meaning they have to eat many many relatively small mouthfuls for very long periods of time, while (relatively) many carnivores catch or find something to eat, eat as much as they can and then go about essentially without food until they are both hungry again and the next fooditem "comes along" (either caught or found). This means relatively speaking, carnivores can "hop" much more easily from one group of potential prey to the next, which can be quite some distance away, while herbivores need more of a "green trail" to follow while migrating. I can imagine one of the mentioned local catastrophe killing parts of both (edible) vegetation and the animal in a certain small local area. After that the left-over herbivores in the area continue feeding on the left-over vegetation, maybe doing a relatively slow migration away from the affected area towards unaffected area's. The remaining carnivores however could first feast on the victims from the event (not always possible of course, depending on the catastrophe). Perhaps they could even catch/eat the remaining herbivores and then have a full belly both nothing more to eat. Especially if the local event is a draught and the vegetation suffers severely and thus also the herbivores. What would such a small group of carnivorous animals do that is the area they alwasy lived in but that no longer contains enough food for them or even food at all? They search for food. Such a group could very easily venture quite a long way into territory previously unknown to them; they really have no choice. Even if the group wanders around and finds nothing after all, in the course of millions of years I'm sure something like this must have happened at least regularly I guess, so even if say a percentage of such groups actually finds "a new home" succesfully before starving you would have an example of the kind of "osmotic barrier" mentioned. Just some speculation by a computer programmer interested in the Mesozoic. Go ahead, fire at will.. (Oh no, sorry. Leave Will out of this. Just fire answer at me please. <grin>) Met vriendelijke groeten, Jarno Peschier
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