ChatterBank1 min ago
extinction of dinosaurs
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I watched a film the other week and they were talking about dinosaur extinction and the big meteor wiping them out etc... anyway in response this person said, well how come it didnt wipe out birds and insects and fish etc? surely birds feed on shrubs and insects, but if shrubs were wiped out then most insects would fail and birds - then theres the whole fish thing.... withouht oxygen and atmosphere etc.... how come?
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Actually, there were at least two such mass extinctions (perhaps as many as 5 or 6).. . The Permian-Triassic extinction of roughly 250 million years ago and the better known, more studied Cretaceous-Tertiary extinction that ended the age of the dinosaurs about 65 million years ago. The Permian-Triassic destruction was far more severe as applicable to all life on the planet. No class of life was spared from the devastation. Trees, plants, lizards, proto-mammals, insects, fish, mollusks, and microbes -- all were nearly wiped out. Roughly 9 in 10 marine species and 7 in 10 land species vanished. Life on our planet almost came to an end.
Determing the actual cause is quite difficult. One of the primary reasons is the continental construct of the planet was significantly different 250 million years ago. An almost singular land mass commonly termed Pangea was surrounded by a nearly single ocean called Panthalassa dominated the landscape. Only much later did continental drift form the landmasses we are familiar with today.
Suffice it to say that almost 95% of the planet's marine species were lost as well as 70 percent of the land's reptile, amphibian, insect, and plants species went extinct.
The later Cretaceous-Tertiary extinction occurred with a more modern continental distribution enabling scientists to generally agree that the cause was probably a meteor strike. Although the event was catastrophic, compared to the earlier event, it only destroyed about half of all marine species and about 15% of all marine families were lost, making it about half as severe as the earlier event. In fact, many large groups were left relatively unscathed, including the gastropods and brachiopods....
Determing the actual cause is quite difficult. One of the primary reasons is the continental construct of the planet was significantly different 250 million years ago. An almost singular land mass commonly termed Pangea was surrounded by a nearly single ocean called Panthalassa dominated the landscape. Only much later did continental drift form the landmasses we are familiar with today.
Suffice it to say that almost 95% of the planet's marine species were lost as well as 70 percent of the land's reptile, amphibian, insect, and plants species went extinct.
The later Cretaceous-Tertiary extinction occurred with a more modern continental distribution enabling scientists to generally agree that the cause was probably a meteor strike. Although the event was catastrophic, compared to the earlier event, it only destroyed about half of all marine species and about 15% of all marine families were lost, making it about half as severe as the earlier event. In fact, many large groups were left relatively unscathed, including the gastropods and brachiopods....
A lot of scientists believe that an asteroid strike on the Yucatan peninsular wiped out the dinosaurs but am I the only one who disagrees?
If the asteroid killed the dinosaurs. then surely there would be loads of dino fossils intermingled with and also above the C-T layer, yet all the fossils found so far are from the period which preceded the asteroid strike. To me, the dinosaurs died out, for whatever reason before the asteroid came.
If the asteroid killed the dinosaurs. then surely there would be loads of dino fossils intermingled with and also above the C-T layer, yet all the fossils found so far are from the period which preceded the asteroid strike. To me, the dinosaurs died out, for whatever reason before the asteroid came.
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