Dinosaurs - are they extinct and why?
Dinosaurs is a theme that continually fascinates the modern human being. What was the cause of the believed extinction at the end of the Cretaceous era some 65 million years ago and did they really leave the scene completely?
Sometimes we seem to wish that there were dinosaurs back on this planet. The film 'Jurassic Park' is just one such example, another is the many sightings of reptil-like 'things' in Loch Ness and other lakes. Not to mention the belief during the first half of the 20th century that dinosaurs really survived in som remote parts of Congo in Africa.
Well. The transition line from the Cretaceous era into the Tertiary era is defined by the extinction of dinosaurs. So even if we want it or not the dinosaurs are extinct by definition...
There is no other exact way to mark the end of the Cretaceous era. And it is believed to have been 65 million years ago. Plus/minus just a few million years.
Whether it was the result of predators (small mammals who eat the eggs of the dinosaurs), a cosmic crash (a big meteorite or name it asteroid is believed to have crashed into the Mexican Gulf somewhere near the Mexican coastline and it could possibly have wiped out the dinosaurs on earth by the following particle cloud that spread all over the earth and lowered the temperatures significantly and took away the sunlight and thus the basis for vegetation that fed the dinosaurs), global climatic change due to volcanoes or other, or something else (a 'bird flu' outbreak attacking the dinosaurs?).
All these theories seem to have some questions. If we take that of mammals consuming the eggs of dinosaurs that might be true for land-based dinosaurs. But those reptiles living in water were at least more protected, even if some species might go to the shore to lay eggs. The usual procedure by crocodiles and other 'descendants' of dinosaurs is to hide the eggs carefully in the sand making it difficult for predators to find them. Anyway, I don't believe that this theory was the reason of their extinction. Maybe just some dinosaur species living on land.
The other is the cosmic crash. No doubt that many cosmic crashes have occured including the one in the Mexican Gulf about 65 million years ago.
But even if there really was a particle cloud big enough to block the sunlight for many years in would not mean that all vegetation died out. The temperature might have dipped 10, maybe 20 degrees compared to before, but still the small amount of sunlight passing through the dark skies could have kept limited vegetation in the seas and in tropical areas. The giant tsunami associated with the crash that swept all over the Earth could have destroyed many habitats of the dinosaurs but still those in the sea at the time of the tsunami arrival would in many cases survive, also those in land areas above approx. 200 meters.
So the cosmic crash could not have wiped out all the dinosaurs. Maybe 50-70% of them, but not all.
Well, how about climatic change caused by volcanoes? No doubt that this can cause global climatic disruptions in the same way as the cosmic crash, but the same - not all dinosaurs would be extinct from that. What is interesting is the possibility of 'natural global warming' which can occur by releasing methane from the vast deposits of frozen methane on the sea bottom. Methane is a much more powerful 'global warming agent' than carbon dioxide, and the real threat to our planet now seem to be increased methane levels in the atmosphere. As a matter of fact, methane levels in the atmosphere have risen more than carbon dioxide levels during the past 50 years.
Methane emissions now come from garbage dump sites, agriculture, the use of natural gas (and 'biogas') in various applications, leaks from exploration of natural gas and pipelines/filling stations/gas tanks, gas powered vehicles, etc.
Methane release might have been the cause of high global temperatures about 55 million years ago (when the ice cover at the North Pole was suddenly depleted and temperatures rose to more the 20 degrees C at the Pole area). But that sharp rise did not mean the extinction of mammals so why should much smaller changes - as we know now - be the reason for the extinction of dinosaurs some 10 million years earlier?
Then what about the 'bird flu'? Well, that is my theory of the cause of the extinction of dinosaurs. A virus that swept over the planet and killed the survivors of the cosmic crash before that.
Nevertheless, most viruses would let some survive. But maybe this virus was more aggressive than other that we know of. And did not transfer to mammals, at least not at a significant rate.
Well, future research will show if I am right. Until then, this is just a theory.
Bo Persson
for comments: email at bossep_360@yahoo.com
Sometimes we seem to wish that there were dinosaurs back on this planet. The film 'Jurassic Park' is just one such example, another is the many sightings of reptil-like 'things' in Loch Ness and other lakes. Not to mention the belief during the first half of the 20th century that dinosaurs really survived in som remote parts of Congo in Africa.
Well. The transition line from the Cretaceous era into the Tertiary era is defined by the extinction of dinosaurs. So even if we want it or not the dinosaurs are extinct by definition...
There is no other exact way to mark the end of the Cretaceous era. And it is believed to have been 65 million years ago. Plus/minus just a few million years.
Whether it was the result of predators (small mammals who eat the eggs of the dinosaurs), a cosmic crash (a big meteorite or name it asteroid is believed to have crashed into the Mexican Gulf somewhere near the Mexican coastline and it could possibly have wiped out the dinosaurs on earth by the following particle cloud that spread all over the earth and lowered the temperatures significantly and took away the sunlight and thus the basis for vegetation that fed the dinosaurs), global climatic change due to volcanoes or other, or something else (a 'bird flu' outbreak attacking the dinosaurs?).
All these theories seem to have some questions. If we take that of mammals consuming the eggs of dinosaurs that might be true for land-based dinosaurs. But those reptiles living in water were at least more protected, even if some species might go to the shore to lay eggs. The usual procedure by crocodiles and other 'descendants' of dinosaurs is to hide the eggs carefully in the sand making it difficult for predators to find them. Anyway, I don't believe that this theory was the reason of their extinction. Maybe just some dinosaur species living on land.
The other is the cosmic crash. No doubt that many cosmic crashes have occured including the one in the Mexican Gulf about 65 million years ago.
But even if there really was a particle cloud big enough to block the sunlight for many years in would not mean that all vegetation died out. The temperature might have dipped 10, maybe 20 degrees compared to before, but still the small amount of sunlight passing through the dark skies could have kept limited vegetation in the seas and in tropical areas. The giant tsunami associated with the crash that swept all over the Earth could have destroyed many habitats of the dinosaurs but still those in the sea at the time of the tsunami arrival would in many cases survive, also those in land areas above approx. 200 meters.
So the cosmic crash could not have wiped out all the dinosaurs. Maybe 50-70% of them, but not all.
Well, how about climatic change caused by volcanoes? No doubt that this can cause global climatic disruptions in the same way as the cosmic crash, but the same - not all dinosaurs would be extinct from that. What is interesting is the possibility of 'natural global warming' which can occur by releasing methane from the vast deposits of frozen methane on the sea bottom. Methane is a much more powerful 'global warming agent' than carbon dioxide, and the real threat to our planet now seem to be increased methane levels in the atmosphere. As a matter of fact, methane levels in the atmosphere have risen more than carbon dioxide levels during the past 50 years.
Methane emissions now come from garbage dump sites, agriculture, the use of natural gas (and 'biogas') in various applications, leaks from exploration of natural gas and pipelines/filling stations/gas tanks, gas powered vehicles, etc.
Methane release might have been the cause of high global temperatures about 55 million years ago (when the ice cover at the North Pole was suddenly depleted and temperatures rose to more the 20 degrees C at the Pole area). But that sharp rise did not mean the extinction of mammals so why should much smaller changes - as we know now - be the reason for the extinction of dinosaurs some 10 million years earlier?
Then what about the 'bird flu'? Well, that is my theory of the cause of the extinction of dinosaurs. A virus that swept over the planet and killed the survivors of the cosmic crash before that.
Nevertheless, most viruses would let some survive. But maybe this virus was more aggressive than other that we know of. And did not transfer to mammals, at least not at a significant rate.
Well, future research will show if I am right. Until then, this is just a theory.
Bo Persson
for comments: email at bossep_360@yahoo.com
posted by LH at 7:23 PM
0 comments
