The Cycle of Death: What Made The Dinosaurs Die?
Intriguingly, a similar mass extinction has ushered in the reign of the dinosaurs. Indeed, over the last 600 million years of life on earth, there seems to have been a cataclysmic change roughly every 60 to 70 million years, and smaller changes roughly every 30 million.
The Cycle of Death: What Made the Dinosaurs Die?
By Mr Ghaz, October 30, 2009
The Cycle of Death: What Made the Dinosaurs Die?
About 65 million years ago, three-quarters of all species alive on earth at the time died out within the space of a few hundred thousand years. The dead included every one of the mighty dinosaurs, which had dominated for some 60 million years. Their passing paved the way for the rise of the birds, mammals, and, ultimately, the emergence of humankind.
Intriguingly, a similar mass extinction has ushered in the reign of the dinosaurs. Indeed, over the last 600 million years of life on earth, there seems to have been a cataclysmic change roughly every 60 to 70 million years, and smaller changes roughly every 30 million.
As soon as scientists who study the early history of life – paleontologists – identified this pattern, they began to search for a cause. Many theories have been put forward, but in 1980 the geologist Walter Alvarez and his Nobel Prize-winning father, Luis, startled the scientific world with a new theory that, for a time, swept all others aside.
Heavenly Marauders?
Image via Wikipedia
In 1977 Walter Alvarez, working at Gabion in Italy, had discovered a puzzling layer of clay in rock strata that were around 65 million years old – puzzling because the clay was much too rich in the rare metal iridium to have come from the earth’s crust. The Alvarezes suggested that the clay might have come from outer space.
The theory was not as farfetched as it sounds. The debris of the solar system, which sometimes comes to earth as meteorites, is known to be rich in iridium. If a chunk of such debris 10 miles in diameter had hit the earth at around 100,000 miles per hour, it would have produced just such a layer.
First it would have unleashed more energy than all the nuclear warheads held in the world’s arsenals today – perhaps 10 times as much. That energy, mostly in the form of heat, would have swiftly vaporized part of the meteorite, as well as the surface of the earth, for miles around. Then as the vapor cooled it have again condensed into a fine dust that would have fallen to earth and settled as a layer of iridium rich clay.
However, before the dust fell, it would have been dense enough to blot out the sun, creating a decade-long “meteorite winter,” in which few plants could have survived. Fewer plants would have led to fewer herbivores and fewer carnivores.
Even the dust were not dense enough to have such an effect, hot debris from the meteorite would have traveled far beyond the point of impact and could have ignited fires on several continents. The resulting pall of smoke would certainly have wreaked havoc among prevailing life-forms.
Worldwide Search
Following the Alvarez announcement, geologists around the world searched local rock layers at the 65 million year level and found a layer of iridium-rich clay – a striking confirmation for the meteorite theory, even if no specific meteorite event could be pinned to that date.
But even the present surface of the earth, young as it is, bears the scars of dozens of such impacts. Some are hard to recognize, such as the Everglades swamp in Florida. Others, such as the crater near Winslow in Arizona, about 570 feet deep and 4,150 feet across, could hardly be explained in any other way. And the surface of the moon, where there is no weather to remove the evidence, is riddled with impact craters.
Image via Wikipedia
Still, paleontologists remain skeptical. They point out that the mass extinctions did not occur in the decade-long or century-long time scale of the meteorite winner, but over hundreds of thousands of years. And geologists have pointed out that there is a source of iridium much closer to home; it is not in the earth’s crust but deeper down, in the mantle. Research has shown that emissions from Kilauea volcano on Mauna Loa, Hawaii, match the composition of the iridium-clay layer much more closely than that known meteorite.
Winters of Discontent
Today there is a competing theory. Every 60 to 70 million years the earth goes through a period of intense volcanic activity. The resulting “volcanic winters,” although individually less catastrophic than those resulting from meteorites, have a cumulative effect that is equally drastic, and which may last more than a hundred thousand years.
However, some paleontologists remain unconvinced about both theories. In a recent poll, more than 10 percent maintained that even the mass extinctions themselves are an illusion. Say they: when a change in the world’s dominant life forms takes more than a hundred millennia to complete, no dramatic event in needed to explain it.
The scientific world has never been short of theories to explain the passing of the dinosaurs. But the search is still on, mostly for more facts to help us decide among them.
Liked it
38 Responses to “The Cycle of Death: What Made The Dinosaurs Die?”
On October 30, 2009 at 10:50 am
great write and interesting topic as usual!
On October 30, 2009 at 10:51 am
great read
On October 30, 2009 at 10:51 am
Very interesting
On October 30, 2009 at 10:52 am
This was a wonderful article and well written, you had all the pictures to back up your facts and apparently did a lot of research. Thank you for sharing.
On October 30, 2009 at 11:03 am
Another wonderfully written and researched article. As long as we deal in theory and not fact there will competing theories to compound the issue. In the absence of any llikely fact coming to light regarding your article I expect another theory to emerge at any time.
On October 30, 2009 at 11:30 am
You’ve done it again Mr Gaz. A wonderful, interesting article that gives much for the mind to ponder.
On October 30, 2009 at 11:31 am
Interesting! It was like watching a movie!
On October 30, 2009 at 11:51 am
Most informative. Wonderful phots. Well presented. Thank you.
On October 30, 2009 at 11:55 am
I enjoyed your presentation but the evolution of AIDS may be a clue that the species may have been wiped out by a simuliar virus. And that would seem more likely.
On October 30, 2009 at 12:00 pm
I guess when our time is up, its up and there is nothing any of us can do about it… Great read my friend!!!
On October 30, 2009 at 12:04 pm
Interesting article and pics.
On October 30, 2009 at 12:33 pm
A great and interesting post..
On October 30, 2009 at 12:49 pm
Very interesting and well researched article as always.
On October 30, 2009 at 2:11 pm
You’re research is so good a well written article and a great read!
On October 30, 2009 at 2:14 pm
A well written and presented article that was a pleasure to read.I don’t know much about dinosaurs or what could have happened to wipe them out,but loved your article and the pictures along with it.
On October 30, 2009 at 2:17 pm
Really interesting theories, but I don’t expect these people will ever agree. Excellent work.
Christine
On October 30, 2009 at 2:35 pm
This is awsome! i never thought about dinosaurs much, other than wishing they were still around. Great article!
On October 30, 2009 at 6:45 pm
Good article and nicely written!
On October 30, 2009 at 7:11 pm
Your work always amazes me Mr Ghaz! Always brillaint in all sense and it is very pparent you spend a lot of time on your articles as they are always so well presented well reseached and well written!! Very interesting article, you have my like!
On October 30, 2009 at 7:46 pm
Wow…really interesting article you have here.
On October 30, 2009 at 8:34 pm
Excellent article and I was very impressed with your research and pictures. This was amazing work and look forward to reading more of your articles.
On October 30, 2009 at 8:47 pm
great pictures from you, they reckon dinosaurs are still here in the form of birds, they are all around us, so really they havent died out they just got smaller.
On October 30, 2009 at 9:04 pm
Fascinating article and excellently presented!
On October 30, 2009 at 9:29 pm
Great pictures, excellent article, nice work, sir it is a pleasure to see such great work.
On October 30, 2009 at 9:52 pm
Another great article, Mr.Ghaz. I enjoyed reading about the dinosaurs and loved the pictures. Thanks for sharing. Well done.
On October 30, 2009 at 9:56 pm
This was a great article, very interesting and well written.
On October 30, 2009 at 11:20 pm
a great and wonderful article..amazing post as usual..well done Mr Ghaz. Have my like it.
On October 31, 2009 at 12:02 am
Very interesting article. I’m always interested to read about dinosaurs!
On October 31, 2009 at 12:46 am
Fascinating article. The pictures are awesome. Well done.
On October 31, 2009 at 1:10 am
A great and interesting read.
On October 31, 2009 at 3:36 am
Very nice write up, to bad we can’t go back in time and really see what ended there reign. It could have been a whole host of things?
On October 31, 2009 at 6:10 am
A well researched post with lots of points for pondering. Well, done.
On October 31, 2009 at 8:48 am
Excellent, informative piece from the master! Great picture selection to support it too.
On November 1, 2009 at 8:06 am
Excellent, finely-written article about a subject that awes scientists and lay people alike.
On November 1, 2009 at 8:43 am
This was great Mr Ghaz..absolutely wonderful and well presented article..loved the pictures as well..I really liked this article..well done my friend. Thank you .. Stumbled!:)
On November 1, 2009 at 8:55 pm
Wow what an amazing story… the narration is superb.. The research was well done…
The pictures support the article…..
But who knows what exactly happened to the dinosaurs, some believe that they may be present even today, in some remote uninhabited places….
Hope they come back… for us to see and enjoy their majesty
On November 2, 2009 at 10:18 am
As always, great article, Mr Ghaz.
I always find it funny that the dinosaurs had to wait millions of years after their extinction before they were given a name.
On November 17, 2009 at 4:45 pm
that was really breathtaking and true to life. i really enjoyed this. excellent.
Post Comment