0 Members and 1 Guest are viewing this topic.
They were on holiday with the tortoises and turtles.
Quote from: Don_1 on 10/11/2009 15:30:17They were on holiday with the tortoises and turtles.Then why no postcard ?
I think there can be little doubt that a great number of insects, crocodilians and chelonians perished in the mass extinction which proved to be the nemesis of the dinosaurs rule. But sufficient numbers survived to leave a viable breeding stock. How they survived, I doubt we can ever know for certain, but it is very possible that their size and adaptability played a significant role.The giant dinosaurs would have required giant sized portions on their plate. With much vegetation suffering as a consequence of the big rocky thing buggering up the system, those which survived the initial consequences would have had trouble obtaining enough food to survive in the ensuing years. The smallest herbivores would have found competition from their big cousins too much to compete with. A contributing factor may well have been that many dinosaurs may have evolved to specialise in their eating habits. So a shortage of a particular plant type would also have had devastating effects on those which depended on them.Obviously, if there is a shortage of herbivores, the surviving carnivores would suffer. With ever fewer herbivores to predate, they would have to take whatever they could. This might well mean having to tackle an equally strong and well armed carnivore. With such a shortage of food, only the most adaptable would be able to survive.It has to be borne in mind that the mass extinction did not happen over night, nor over a few weeks, months or years. It was a slow process, with species dying out over a great many years. Although that big rocky thing may have been the instigator of the extinction, it was the subsequent consequences which finished off the job.One of the reasons the crocodilians survived may have been their watery habitat. Not only might the water have proved a shelter from the initial catastrophic event, it would also have been a draw to surviving animals. Thus the crocs could be almost assured of food. And then, there is the fact that crocs aren't particular about what they eat. A vital factor in survival at such a time.The turtles would have had similar advantages to the crocs, while the tortoises, which may have already been around for 200+ million years had probably evolved to be nonspecialist. Their shell protected them against predation, to a degree, and against dehydration. It could also be that the tortoises slow pace became a distinct advantage. Using little energy to move around, the tortoise can go long periods without food or water and being so low, they would have the advantage of being able to find and eat new shoots as they broke the grounds surface. Again, it is a fact that tortoises eat a wide variety of plants.The tortoises and turtles may have had one other advantage. They had come through quite a few previous minor mass extinctions and their earliest cousins, the anapsids, survived the greatest mass extinction of them all during the Permian period. Perhaps survival of such natural disasters has been somehow imprinted into their genetic code. I only hope they will survive the unnatural threat posed by man.There were other creatures around at this time. The earliest mammals were already on the scene, just waiting for their opportunity to become the new rulers of planet Earth, and this was it!
Didn't some of the dinos hang around and evolve into birds?Next time you tell your budgie he's a pretty boy, consider that he's waiting for an opportunity to evolve into Tyrannosaurus Budgie so he can bite your head off.[diagram=539_0]
Bifurcated wedding takle could be problematic.
Komodo dragons have only been around for 40 million years.The closest living relatives of dinosaurs are Archosaurs. http://en.wikipedia.org/wiki/Archosaur
No, I think Stefan is about right at 40m years.
Perhaps David Attenborough was referring to these reptiles, rather than dinosaurs? http://en.wikipedia.org/wiki/Mosasaur