21 Jan What Really Caused The Cretaceous Extinction Event
What Killed the Dinosaurs?
It is an indisputable fact that dinosaurs disappeared from the fossil record around 66 million years ago. On a geological scale, it happened very quickly, probably within 30,000 years. Although there are occasional claims of surviving species in the form of cryptozoological creatures such as Mokele Mbembe, Ogopogo, and the Loch Ness Monster, to date, none of these claims have any substantiating evidence. It is a very good bet that the entire family of saurischian dinosaurs ceased to exist around 66 million years ago. But why?
A little background is in order, so bear with the paleontology lesson for just a moment. There were actually 2 distinct orders of dinosaurs, identified by the type of hip joint they possessed. saurischian dinosaurs had hips that resemble reptile hips, however, they were not reptiles. Dinosaurs were a distinct genus from reptiles. Most saurischian dinosaurs walked on all fours, such as Triceratops, Apatosaurs, Ankylosaurs, and such. Another order of dinosaurs had hips more closely resembling modern birds, and in fact, are suspected of being the direct ancestors of modern birds. They were called ornithischian dinosaurs, and they walked on two legs, at least for part of the time. The most famous version of these dinosaurs are the Raptors, and Hadrosaurs. After the extinction event, all dinosaurs disappeared from the fossil record, but the ornithischian dinosaurs progeny seemed to have survived as birds.
Within 30,000 years of the assumed dinosaur extinction, geological strata show a layer of abnormally high levels of iridium (IR, atomic number 77). This strata level is known as the K-T (Cretaceous-Tertiary) Boundary, and marks the end of the Cretaceoous Era, and the beginning of the Tertiary Era, also known as The Age of Mammals. Iridium is rare in the Earth’s crust under normal circumstances, and is present in large amounts only as a result of extreme volcanic activity, and in asteroids. Iridium is a heavy metal, and, like lead, sank to the Earth’s core during the planet’s formation. The high levels of iridium are indicative of some serious geological and ecological changes in the planet within a relatively short period of time. However, at present, the evidence that the iridium levels have anything to do with the Cretaceous Extinction Event are only circumstantial. As of yet, there is no ‘smoking gun’. There are two popular theories on what caused the Cretaceous Extinctions.
The Cosmic Fender-Bender
Currently, the most popular theory is the Alvarez Asteroid Impact theory, postulated in 1980 by a team of scientists led by Luis Alvarez. The Alvarez team originally discovered the high levels of iridium in the strata of 66 million years ago, and determined that the unusually high levels (as high as 120 times normal) could only be accounted for by the impact of a large asteroid.
It was known that large asteroids had hit the earth in the past, and in the 1970s, Antonio Camargo and Glenn Penfield, while prospecting for oil on the seafloor, discovered a large impact crater at Chicxulub, off the coast of Mexico’s Yucatan Peninsula. It was later dated, and matched the correct time frame for the K-T Extinction. Another indicator of a cataclysmic event was the presence in the K-T layer of shocked quartz, indicating some serious seismic disturbances.
Random geological samples from different areas of the world seemed to indicate that this event was more or less a planet-wide disaster. Estimated effects would have been planet-wide firestorms from core ejecta thrown into the atmosphere, increased infrared and ultraviolet radiation coming through the disrupted atmosphere, killing plant life, huge tidal waves destroying coastlines as far as hundreds of miles inland, and a huge world-wide dust cloud that blocked sunlight for over a year, killing most of the plant life on the planet. Other effects may have included elevated CO2 levels, creating a Greenhouse effect, acid rain, etc…
When Planets Break Wind…
The other main theory is the Deccan Trap Theory. The Deccan Trap is a very large area of solidified flood basalt in India. It is 6000 feet deep and covers and area of a little less than 200,000 square miles. It is the largest volcanic feature on the planet.
Princeton geologist Gerta Keller theorizes that the massive volcanic activity that formed the Deccan Traps approximately 66 million years ago vented a large amount of sulphuric acid vapors, methane, and other poisonous chemicals into the atmosphere, covered millions of square miles in lava, started huge forest fires over thousands of acres of land, and other catastrophic events, that caused the massive K-T Extinction Event.
The Swiss Cheese Syndrome
The Swiss Cheese Syndrome is a term I have coined to describe the unreasonable adherence to a theory even after it has been shown to be full of holes. While both theories explain the elevated iridium levels, they account for nothing else. These theories are taught in our educational institutions without any hard evidence other than circumstantial.
Here is what we do know:
- Approximately 66 million years ago, almost 75% of all species of plants, animals, and microorganisms disappeared from the fossil record.
- Representatives of each genus of animal and plant did survive the K-T Extinction Event, except for saurischian dinosaurs. Of all life on the planet at the time, only saurischian dinosaurs apparently failed to survive.
- According to the fossil record, most, if not all animals larger than 2 or 3 feet did not survive, except for dinosaurs. Even the small species disappeared after the K-T event.
- Next to insects, dinosaurs were the most successful, adaptable, and prolific macroscopic life form on the planet at that time.
- The Earth was struck by a 6-mile diameter asteroid that hit in the ocean off the coast of Mexico approximately 66 million years ago.
- There was massive volcanic activity on the tectonic plate that contains modern day India, around 66 million years ago.
- There is a layer of geologic strata dating from around 66 million years ago that contains extremely high levels of iridium. It appears to be world-wide, although that has not yet been proven 100%. Iridium comes from 2 known sources: the Earths core, and asteroids.
Anything else is all speculation, including any relationships between these known facts. Here are some of the problems with current theories:
- Of all the orders of plants and animals alive at the time of the K-T Event, dinosaurs, and only dinosaurs became extinct. Cockroaches, mouse-like mammals, insects, flowers, trees, bushes, bacteria, fish, amphibians, etc… all managed to survive as orders. Why just dinosaurs? Any planet-wide disasters would’ve affected all species equally, unless some had advantages over the others that would give them a better chance. Dinosaurs were the most successful orders on the planet. It is unlikely that other orders would have any significant survival advantages over them.
- The Chicxulub meteor was only 6 miles in diameter. The Earth is 7918 miles in diameter, or over 1300 times as large. This impact would’ve been similar to shooting a grapefruit with a BB, except that a few thousand miles of rock are much harder than a grapefruit. The Chicxulub Crater is only 12 miles deep. It is unlikely that the meteor even penetrated beyond the crust, which is up to 20 miles deep, and certainly not the mantle, which is over 1600 miles deep. The effects from this meteor are most likely grossly over-estimated. They liken it to several thousand (million, or whatever) nuclear bombs, but this is incorrect. A meteor would not trigger a nuclear reaction, which has completely different effects from a simple collision. First, the only heat a meteor would generate upon impact are from friction with the atmosphere, and the impact itself, far less than a nuclear detonation would produce. The actual incident would be over much faster than a nuclear detonation, which can go on for quite some time, until the fissionable material has been used up. All the damage from a meteor would be concussive… Considerable: yes. Planet-wide: unlikely. The meteor did not penetrate deep enough to spew ‘flaming ejecta’ high enough into the atmosphere go cause massive world-wide forest fires. It might have generated a huge tidal wave, causing damage several hundreds of miles inland, but certainly not over the entire Earths landmass. As far as the dust cloud, where did all the dust go? It had to eventually come down somewhere. Why is there no geological layer of strata made up of dust and debris? Why have we not found any fossils showing evidence of charring or burning? Why are there no dinosaur fossils actually in the K-T layer? And, how did everything else manage to survive? Why did just the dinosaurs die-out?
- The Deccan Trap Theory has all of the holes as the Impact Theory. Why just the dinosaurs? Why not cockroaches? Why not flies? Why not viruses, bacteria, snakes, fish, etc…?
The Most Likely Suspects…
In science and mathematics, there is a principle known as Occam’s Razor. It says, very basically, that the simplest explanation that accounts for all the known facts with the least amount of assumptions has the greatest chance of being the correct one.
We know that both a meteor strike, and massive volcanic activity occurred around the time of the dinosaur extinction, but there is no direct causal relationship established by physical evidence. It is all circumstantial, with a lot of assumptions being made which may, or may not be correct. Several alternate hypotheses are possible. For instance, could the dinosaurs have already been in decline well before the K-T event?
Dating methods for things that far back in time are nowhere near precise. They are accurate to within 10,000 years or so, but that’s about as good as it gets with fossils. On a non-geological scale, that’s a really long time….almost as long as Homo sapiens has been around. Fossils are dated subjectively, meaning we date them according to the strata they are found in. We know how old the strata they are found in is, roughly. Strata is dated in 2 ways. We know how long it takes for a thin layer of strata to form, so by measuring the thickness of a layer of strata, we can calculate how long it took it to form. Counting the layers back to the one the fossil was found in, we can tell how long ago the animal lived, within maybe 10,000-30,000 years. Radiocarbon dating cannot be used because it only works on organic materials. Fossils are bones where the calcium had been replaced by rock, making them inorganic. Another way to date rocks is by measuring the amount of radioactive decay. We know the half-life of radioactive isotopes contained in rocks and minerals. By measuring how much remains in them, we can tell how old the rock is, within a certain range of say 30,000 to 50, 000 years (or maybe more). It’s not precise, but it’s the best we have right now.
So, the time frame for dinosaur extinction could be off as much as 60,000 years either way…maybe more. And we’re also stuck with that pesky question: Why only the dinosaurs? There is fossil evidence that dinosaur species may have been experiencing a general decline, however, this could also be due to the nature of fossils. A fossil is only formed under a certain set of circumstances, and only 1 in several thousand animals wound up as a fossil. It is possible that climactic changes made the incidence of fossilization even more rare in the later part of the Cretaceous Era. But, what is they were actually in decline before the cataclysms? It seems that mass extinctions are actually a normal part of the planet’s evolution. In Earth’s history, there have been several mass-extinctions, spelling the end of dominance for invertebrates, fish, amphibians, and lastly, the dinosaurs, in turn. But only the K-T event led to a complete disappearance of all species of a single order of life. And all of the other mass extinctions did not coincide with meteor strikes or volcanic activity.
So logically, we have to ask, “What do we know of that only kills specific types of animals and plants?” The first obvious answer is Us. Throughout our history we have hunting specific species to extinction, and deprived certain animals and plants of habitat, and poisoned them with our pollution. But the dinosaurs were gone a long time before we arrived on the scene. What else? The next answer is: Disease. Other than predation, disease is the only thing we know of that can single out specific species or orders of organisms to prey upon. And without medical intervention, diseases can absolutely be devastating on a world-wide basis. There are viruses and bacteria that effect potatoes, trees, people, dogs, mammals, birds, etc…. The Black Plague and Smallpox did a fair job of drastically reducing the human population, and might have completely wiped us out were it not for the advent of medical care, however primitive at the time. Could the dinosaurs have been on the edge of being wiped out by Dino-AIDS, or Dino-plague? Perhaps the meteor and the volcanos were simply the coup de grace, finishing off the few survivors with immunities. With their hosts gone, the pathogens would simply disappear, or maybe they evolved into the micro-terrors that we are familiar with today, like anthrax, HIV, Bird-Flu, Ebola, Lhasa Fever, etc….
The Disease Theory (my term) is the only explanation (even though it’s not even a theory, yet…) that explains all the known facts without making any assumptions. We know diseases existed 66 million years ago. At present, I know of no method to test this theory, unless the effects of disease can show up in fossils, and it is unlikely to be tested anytime soon, since the scientific world seems to be happy with the other theories, holes and all. At present, the reasons for the dinosaurs extinction is just a matter of speculation. But in my humble opinion, it warrants further study…