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extinction
Dear List Members!
Hear is a translation of my 3 years old article pair. Let us discuss that!
- . -
I. THE UNLIKELY THEORY OF THE END OF THE LATE CRETACEOUS
What is the most fashionable theory for what happened about 65 million
years ago when "the late Cretaceous extinctions not only caused the demise
of the dinosaurs but also accounted for the huge losses of the
Foraminifers, the unicellular animals that serve as the basis of the sea
food chain", as Jozsef Palfy wrote in his book, The Extinct and Survivors
(Palfy Jozsef: Kihaltak es tulelok, Vince Kiado, Budapest, 2000)?
That theory is, "the extinctions at the end of the Cretaceous period were
triggered by a giant meteorite that had collided with the Earth. The
supposed chain of events leading to mass extinction is as follows: A cloud
of dust formed after the impact covering the whole Earth and causing
darkness for months or even for years, the collapse of photosynthesis,
drastic climatic change, and the breakdown of food chains." (Quotation is
from the same above mentioned book but we can read the same in many other
sources, hear it in radio programs, see spectacular fires with dinosaurs
howling and collapsing on television.)
Is this indeed what happened? The following will attempt to give an answer.
INTRODUCTION
There is a well known story:
The scientist takes a flea. He puts it on the table and says, "Jump, you
flea!", and the flea jumps. He grabs it again and tears out its jumping
legs and orders it to jump again. The flea does not jump this time.
Therefore the scientist states that fleas hear with their jumping legs.
The same thing, namely drawing a wrong conclusion from a fact, occurred
when scientists drew the inference between the so called iridium anomaly
and the collision of a meteor (asteroid) with the Earth, thus explaining a
mass extinction in the late Cretaceous.
(Iridium anomaly means that while this precious metal of the platinum group
is rare in the earth's crust, it can be a hundred times higher than the
average value in the late Cretaceous layers. The solid materials found in
the cosmos may also have higher iridium concentration than the crust.)
WHY IMPACT THEORY IS NOT AN ADEQUATE EXPLANATION?
Certainly there are other facts that we could bring up against this
hypothesis but it is unnecessary to introduce all of them for the
confutation. Let us take a look then at just some of those that would be
sufficient for disproving this theory.
1. On page 132 of the above mentioned book we find "according to the
estimates, 200 gigatons (billion tons) of vapor and the same amount of
sulfur dioxide penetrated into the atmosphere." And all this happened
suddenly, resembling an explosion due to the impact. Sulfur dioxide kills
virtually all living creatures. Therefore:
- In a vast land area all living things should have died, producing large
amounts of fossils since decomposers of dead bodies would have
perished as well.
- The high concentration levels of sulfur dioxide dispersed in the Earth's
atmosphere should have devastated all land creatures at higher evolutionary
stages.
Then where is this huge amount of fossils?
(With seas the situation is different since here solution and dispersion
take place much slower than in the atmosphere and binding processes may
also reduce the sulfur dioxide concentration. Therefore the effect here is
not so evident.)
2. The hypothetical location is the Mexican Gulf. The tsunami had not got
beyond the gulf according to the referred book. Opposed to this, the
Krakatau-explosion at the end of the 19th century - fortunately - causing
only a fragment of such a large-scale disaster, caused a tsunami on the
whole earth. A powerful tsunami would have devastated the eggs in the
seashore sand, the living creatures and ovules on the coast and in the
shallow water, etc.
Where are the huge amount of fossil records of such drifted and buried
living things?
3. As a result of the heat effect, all the living creatures nearby
disappeared (not only died but evaporated), further away, all living
creatures died but remained in destroyed forms and partly charred, further
still the devastation is selective. All this happened over such a vast area
that (along with the effect of the sulfur dioxide) it should have produced
fossils in large quantities.
Where are all these likewise particular fossils?
4. Within a very short period of time (minutes, hours, days, weeks based
on the distance) a large amount of fossils should have been produced in
high density.
Where are these?
5. The referred book wittily calls the effect 'volley firing'. That is, the
devastation would have depended neither on the age of the living thing nor
on any other factor modifying the frequency of the death. In such a case,
young individuals would have died in the same way as the old ones, the
healthy ones, or the sick ones, etc.
Have they found such unusual 'cemeteries'?
6. Iridium anomalies have been found all over the world but:
- Iridium has such a high melting and boiling points that as a result of
the impact it could only partly become vapor.
Due to its chemical characteristics in the atmosphere, it formed compounds
neither before nor after the collision. Therefore its characteristics have
not changed either.
- Due to its heavy weight it would have settled back very quickly onto the
surface of the earth.
So as the distance from the impact increases the iridium concentration
quickly decreases. (This is only true above a minimal distance since the
mechanical effect of the impact blows the pieces away.)
Do the iridium concentration values found show any corresponding
dispersion? (The value in Gubbio, Italy showed a value ninety times higher
than the average, while in Stevns Klint, Denmark, it was one hundred and
sixty times higher. The difference between the distances between the two
locations and the Mexican Gulf is relatively small, and Stevns Klint is the
one further. More contradictory to the expectations is that in the vicinity
of the presumed location of the impact scientists found a value as low as
one hundred and thirty.)
They also had determined the direction of the impact and according to their
estimates the strongest effect should have been northwestwards. Do the
concentration values found correspond to this? (Anyhow, the previous
paragraph is contrary to this as well.)
7. There are some facts that are contradictory to the worldwide biological
extinctions. For example, although in North-America a change had taken
place in the flora, it has not occurred either in the Antarctica or in
New-Zealand.
8. If the explanation proposed to account for this theory was adequate in
the case of the survival of crocodiles, distant relatives of dinosaurs
(i.e. they are fresh-water animals), then why did birds (as opposed to all
the flying reptiles) survive the catastrophe, among of which there were
plenty of marine ones and ones dwelling far off the waters at these times?
Or turtles (while the ancient marine reptiles all disappeared)? And why did
arthropods survive once sulfur dioxide, being much heavier than the air,
may have even been enriched nearby the surface of the earth? And what about
the mammals living on the surface and in pits? Where were these intact or
slightly damaged groups of animals during the huge fires and smoke?
9. The "evidence" proposed to account for the theory's adequacy (just as I
have already proven it above in certain cases) is only useful to confirm
the fact of an impact and to demonstrate the location of it. But they do
not sate whether the impact indeed was as powerful as previously assumed?
Was it large enough to trigger such an effect?
Based on these findings we can substantiate that the impact theory does not
correspond to the facts.
Although for its popularity and widespread use it is important to prove the
inadequacy of this theory, what is there instead of it?
"A better explanation for the late Cretaceous events" attempts to give an
answer to this.
- . -
II. A BETTER EXPLANATION FOR THE LATE CRETACEOUS EVENTS
It is not yet known how long it took for the dinosaurs, ammonites, etc. to
die out, for we still have no means or method for determining so.
Under normal circumstances surface waters are more rich in the C13 isotope
than water in layers below. Therefore, lime skeletons of creatures living
on the earth's surface contain more of this isotope than those living
lower, but as the Cretaceous period ended, so did this significant
difference. Not until much later did this phenomenon reappear. Scientists
can determine only that this difference was formed within a 10,000 year
time period. Iridium anomalies also fail to give a more precise figure.
I have discussed in the previous material why impact theory does not
explain the late Cretaceous extinctions.
It is possible, that as a result of a cosmic effect around this time
iridium levels may have fallen suddenly and drastically. This could be a
result of the earth having traversed one or more clouds of dust or meteoric
material. Iridium falling off, possibly other materials accompanying it,
radiation, or a change in other environmental factors gradually
accumulating may have caused the extinction.
(Such death caused by accumulation was triggered, for example, by rising
DDT-levels in the case of carnivorous bird eggs. There was a possibly
similar case, namely the frequent occurrence of the egg in the egg
phenomenon at one of the French dinosaur provenances in the Late
Cretaceous. The small animals could not break through the shells of the
eggs laid with double walls and therefore died.)
Accumulation may also have had a selective effect. (In the DDT example, the
DDT did not destroy insectivorous birds or ticks.)
This process, having lasted for a long period of time, may have enabled
certain species to become resistant. (For example, DDT made many insects
resistant though not all of them. Another well known example is that of
certain, but not all, groups of bacteria having become resistant to
antibiotics.)
This theory is not 'disturbed' by the fact that there may also have been a
(possibly giant) meteor impact around this time, the effects of which would
have, at the most, only added.
This theory explains why iridium anomaly has been found all over, since due
to iridium's very low reactivity and its high melting and boiling point
even the tiny iridium particles could penetrate through the atmosphere.
(Even pure oxygen does not react to iridium when the latter is either
heated while dropping quickly or cooler when falling slowly. Iridium does
not react to nitrogen either under similar circumstances.)
How large might have been the amount of the additional material reaching
the earth?
According to page 132 of the book that I referred to in the previous
material the celestial body colliding with the Earth had a diameter of 10
km. The book also stated that its maximum speed reached 5km/s. Therefore it
penetrated the atmosphere in about 10 seconds. If this amount of material
only had been arriving for one year out of 10,000 years, then the figure is
about three ten millionth part per second of it. When converted into the
entire surface of the earth, we get a figure of one ten trillionth per
second per surface unit. Therefore, this would not have produced any giant
dust, heat, fire and smoke as a result of sulfur-dioxide, or tsunami
effect. For this reason we do not have to attempt to find an explanation to
the controversies discussed in the previous material.
So how large might have been the amount of this material?
The body with an assumed diameter of 10 km had a volume of about 500 km3.
Such amount would form about one mm thick layer on the entire surface of
the earth. If this amount had fallen down in one year, then it is not large
enough to cause unusual effects. This amount equals, for example, the
precipitation that would fall in half a day in Hungary.
How could iridium trigger extinctions?
As I wrote before, it was not necessarily the iridium itself, but rather
the effect of other materials, radiation, environmental effects all
together with the iridium. Iridium itself may have played a significant
role though, since while it is hardly oxidizable, it still does form
compounds in other ways. (Materials in the sea, especially when taking the
long period of time into consideration, might have dissolved iridium and as
a result it became much more active). We can not prove iridium's damaging
effect directly in the case of those animals that became extinct 65 million
years ago (not even the possible indifference or resistance of certain
animals). We only can make assumptions. Such is iridium's catalytic
activity, similarly to other elements of the platinum group, which might
have disturbed the vital processes. (That is iridium does participate in
the natural vital processes.)
We can see, therefore, that this theory does not have inconsistencies like
the ones of the impact theory. It does not assume nearly impossible events.
Therefore, it is undoubtedly better. In fact, it may even be true!
Endre Simonyi