Dinosaur Breath - Cretaceous Atmosphere Sample obtained and Studied.

The largest flying creature alive today is the Andean condor Vultur gryphus. At maximum size it weighs about 22 pounds and has a wingspread of about 10 feet. But 65 million years ago in the late cretaceous period, the last age of dinosaurs, there was another larger flying animal, the giant pterosaur Quetzalcotalus. It had a wingspread of over 40 feet, the size of a small airplane. Other pterosaurs were also quite large. The pteranodons of the late jurassic period, the classic flying dinosaurs of magazine illustrations, had a maximum wingspan of about 33 feet.

This presents a puzzle: how is it that the largest flying animals of the cretaceous were able to attain so much greater size than modern birds? There are severe physical limits associated with flight. It is difficult for large birds to generate enough lift to take off. Consider the well-known square-cube law: if you double the size of a bird by simple scaling, its wing area and associated lift go up by 22, or a factor of 4, while the body weight that must be lifted goes up by a factor of 23, or a factor of 8. When an evolving flying animal species increases in size the basic design must be altered to accommodate the reduced lift-to-payload ratio. But if anything, the pterosaurs were less well designed than modern birds. They lacked the birds' efficient keelbone muscle structure and the aerodynamic advantages of feathers. How, then, could pterosaurs have grown so large?

A missing piece of this puzzle may have been discovered. There are indications that the cretaceous atmosphere may have been much richer in oxygen. Today, Earth's atmosphere contains about 77% nitrogen, 21% oxygen, 1% water vapor, 0.9% argon, and 0.03% carbon dioxide, with traces of about a dozen other gases. It's been commonly assumed that earth-air stabilized at about this composition a few million years after life evolved on our planet when the early plants photosynthesized most of the primordial carbon dioxide into free oxygen, and the early bacteria converted most of the primordial ammonia to free nitrogen and water.

But now there is evidence that the cretaceous atmosphere may have been very different. Samples of 80 million year old air have been analyzed. You well might ask how there could be samples of air trapped and preserved for 80 million years. One might say that nature has provided the sample bottle.

Great forests of the extinct pine species Pinus succinifer once covered large areas of the world. Like modern pine trees the Pinus succinifer when injured by storms or boring insects had a tendency to drip pitch. This sticky resin would fall to the ground, accumulate, and eventually be buried. Over a multi-million year time span solidified pitch is fossilized into the hard resin amber. Amber in jewelry-grade specimens is almost clear, with a characteristic pale yellow color. Sometimes one finds ancient insects encased in amber. These were originally trapped in the sticky pitch and fossilized along with it, and they now provide an important base of knowledge about the insect life of past geologic eras.

As lumps of pine pitch fall to the ground and aggregate, pockets of air are sometimes enclosed, becoming tiny bubbles of air trapped in amber. The amber thus forms a natural "sample bottle", trapping air samples from millions of years in the past and preserving it for present analysis. Moreover, the sample bottles are labelled with a date of collection. Geological analysis of the rock strata in which the amber samples are found and evidence provided by organisms trapped in the amber along with the bubbles can be used to establish the age of the sample. In many cases the pressure inside such bubbles has become as high as 10 atmospheres from compression by the geological forces that converted the pitch to amber.

The bubbles are typically small, some only 0.01 millimeters in diameter. The quantity of air in such amber bubbles is minute. Even when a sizable sample of amber is crushed to release the trapped gases, the volume of air obtained is very small. Normal chemical analysis techniques would be utterly useless for such almost infinitesimal air volumes. But there is a better way.

A modern analytical instrument, the quadrupole mass spectrometer (QMS), is capable of analyzing very small gas samples into their constituent chemical elements. The gas sample is ionized, and an electrical discharge removes an electron from the gas atoms. These charged atoms are accelerated by a high voltage and passed between four charged bars. These bars run parallel through the instrument to form a "quadrupole" electric field. Adjacent bars have opposite voltages and are driven with a rapidly oscillating electric field. For ions of just the right mass, that varying electric field focuses and collects the atoms and delivers them very efficiently to the collection electrode at the end of the apparatus. For atoms of the wrong mass the field values are inappropriate, and they collide with the bar electrodes and are lost. The sensitivity and mass discrimination of this instrument are very good. It is relatively easy for the QMS to determine chemical abundances and even isotope ratios in a very small gas sample. That is what was done.

At a meeting of the Geological Society of America held last Fall in Phoenix, Robert Brenner of Yale University and Gary Landis of the U. S. Geological Survey reported the results of a QMS analysis of ancient air bubbles trapped in amber. They obtained a remarkable result. The atmosphere of the Earth 80 million years ago was discovered to have 50% more oxygen than modern air. Brenner and Landis found that for all gas samples taken from amber 80 million years old the oxygen content ranged between 25% to 35% and averaged about 30% oxygen.

Cretaceous air was supercharged with oxygen.

On the other hand, 40 million year old samples similarly analyzed showed about the same oxygen content as modern air, and 25 million year old samples showed slightly less oxygen than modern air. The composition of air has been shifting with time over a far broader range than geologists had thought possible. The cause of these excursions is not understood. Perhaps they are caused by a shift in the delicate balance between oxygen production by photosynthesis and oxygen trapping by exposed iron, sulfur, and organic reducing materials.

There is, of course, concern about whether these bubble samples accurately reflect the true atmospheric content. Is it possible that they have changed with time, leading to a false result? Atmospheric gases might have diffused in or out through the amber at different diffusion rates, changing the net composition of the trapped gas. Internal evidence of the samples themselves, however, argues against this. Most of the processes that are of concern, for example oxidation of the amber, would tend to reduce the oxygen content of the bubbles. Moreover, traces of hydrogen, a gas that diffuses far more readily than oxygen, are found in the bubbles with approximately modern concentrations. Analysis of bubble samples taken from modern tree resins also agrees with present atmospheric composition. The case for high oxygen in the cretaceous atmosphere seems, in a manner of speaking, air tight.

This result has very interesting implications about the era of the dinosaurs.

The dinosaurs apparently breathed air that was much richer in oxygen than our air and lived in forests and grasslands that were far more combustible than ours. The metabolisms evolved to live is such an atmosphere might be radically different from ours. This new information may be relevant to many puzzles of the cretaceous and jurassic periods.

The problem of how the giant pterosaurs were able to generate enough energy to become airborne has troubled many paleontologists. For example, the Encyclopedia Britannica makes the unlikely suggestion that the pteranodon may have launched itself by "running downhill" on its stubby legs. The discovery of the oxygen enriched atmosphere of the cretaceous period sheds new light on this problem. In such an atmosphere many of the constraints of metabolism are relaxed. The creatures of the cretaceous may have been literally turbo-charged like race cars by the oxygen enriched atmosphere. It becomes plausible that a flying creature that evolved during that period could reach size limits that are impossible in today's anemic atmosphere.

Another puzzle from the era of the dinosaurs is the carbon layer at the cretaceous-tertiary boundary. The Alvarez hypothesis attributes the end of the cretaceous period to the collision of the Earth with a large chondritic meteor. The disintegrating meteor dumped vast quantities of fine iridium-rich dust into the atmosphere, bringing on a sort of "nuclear winter" that was connected with the extinction of the dinosaurs. A curious feature of this event, the "cretaceous catastrophe", is that a world-wide layer of finely divided carbon has been found at the cretaceous-tertiary boundary stratum beside the iridium rich dust from the Alvarez meteor. If this carbon is soot from a fire then the quantity of soot involved is truly enormous. Its quantity would require the simultaneous burning of a large fraction of the plant life on the Earth's surface, a sort of world-wide fire storm.

What produced this carbon layer and how? Was a fire ignited by the cretaceous meteor strike, or did the fire come later? How could such a world wide conflagration have occurred? Was it the meteor dust and its effects on climate and vegetation or the fire that killed the dinosaurs? The new information of oxygen content may provide important clues to these questions. The atmospheric oxygen data described above imply that the drop in atmospheric oxygen corresponded at least roughly to the cretaceous catastrophe.

One can imagine a scenario in which the Alvarez meteor dust blocks sunlight for several years, causing a large fraction of the surface plant life to wither and die. The brown dead vegetable matter would then provide excellent fuel in the oxygen rich atmosphere. Spontaneous combustion or lightning might trigger a fire that would spread over the brown landscape, producing the worldwide fire storm. A fire of this magnitude might well consume enough oxygen to account for the observed composition drop. In any case, the combination of dust, decimated vegetation, colder climate, a world-wide fire, and a 1/3 drop in atmospheric oxygen could certainly have combined to bring about the extinction of the dinosaurs.

From the viewpoint of the follower of science fiction there are important lessons here. Time travellers must be aware that the cretaceous period is not the same as the 20th century. Oxygen is present in incendiary quantities. Use cigarettes and matches only with great caution. Do not wear flammable clothing during your cretaceous travels. Do not leave camp fires unattended. Smokey the Tyrannosaur says, "Only you can prevent forest fires!"

REFERENCES:
Bubbles in Amber:
Richard A. Kerr, Science 238 #4829, 890 (13 November, 1987).

Talking about vultures: something is killing them off, natural or man-made. They may soon be history.


VULTURE DIE-OFF - INDIA, PAKISTAN, NEPAL
*****************************************
A ProMED-mail post

ProMED-mail is a program of the
International Society for Infectious Diseases


Date: Wed, 12 Feb 2003
From: ProMED-mail 
Source: New Scientist, 11 Feb 2003 [edited]



Lab to tackle mystery of vanishing vultures
--------------------------------------------
A new laboratory has opened in India dedicated to identifying the 
mystery disease that is exterminating South Asia's vultures. But the 
die-off is now so bad that scientists fear they will have to try 
breeding at least one species in captivity to save it from 
extinction, even before they diagnose the killer infection.

The big griffon vultures that used to be ubiquitous in India started 
dying off in the 1990s. In 2000 New Scientist reported that 95 
percent of Indian vultures of the genus Gyps had disappeared. Since 
then, the remaining population has halved, and the die-off has spread 
to Nepal and Pakistan.

Scientists fear the disease could spread to griffon vultures across 
Eurasia and Africa. "The ecological impacts could be horrendous," 
says Deborah Pain at the UK's Royal Society for the Protection of 
Birds.

It is already horrendous in India. Griffon vultures were the main way 
in which dead animals were disposed off. Now, says Andrew Cunningham 
of the Zoological Society of London, "the superabundance of uneaten 
animal carcasses poses a direct health threat and has led to an 
explosion in the stray dog population." These dogs carry diseases 
including rabies.

The cause of the deadly disease is still unknown, though suspicion 
centres on a virus. But it has been impossible to investigate fully. 
This is partly because collecting sick or dead birds is extremely 
difficult, and partly because Indian law prevents the export of 
tissue samples for study in foreign laboratories, although some 
samples have been allowed to go to Australia.

New hope has come with the opening of the Vulture Care Centre near 
Chandigarh, north of New Delhi, on 7 Feb 2003. It is funded by a 
grant from the UK's Darwin Initiative to scientists from the 
Zoological Society of London, the The Royal Society for the 
Protection of Birds, and the Bombay Natural History Society.

"The main purpose of the centre is to find out what is killing the 
vultures and whether anything can be done to make affected birds 
recover," says Cunningham. The UK division of Synermed, a diagnostics 
company, has donated an automated blood analyser to help track the 
disease process, determine which organs it damages, and gauge the 
effect of treatments.

"Even doing the basic veterinary work is quite a step forward," 
Cunningham told New Scientist. If the disease is identified and birds 
can be tested to ensure they are healthy, the centre will be 
converted to a captive breeding facility to help the population 
recover.

But Cunningham warns that the Darwin funding runs out in 2004. 
Furthermore, one of the 3 species at risk, _Gyps tenuirostris_, which 
is unique to the Indian subcontinent, is now down to a few hundred 
birds, and faces extinction.

[Byline: Debora MacKenzie]

Yeah, I found it very interesting too. I also found it very garbagy. What is necessary to support flight is not oxygen. The present day concentrations of oxygen -about 20% are more than enough to support the metabolism of a flying creature. The difference between inspired and exspired air is only about 1-2%. We don't use but a tiny fraction of the oxygen we breath in. What is required to support any metabolic activity is the utilization of carbohydrates. These metabolic processes have been fixed and static since the inception of life. Further, modern birds, when they face long term energy requirements do not even use oxygen. They metabolize glucose via anaerobic pathways, building up a lactic acid deficit. In no way is a lack of oxygen a rate limiting step in the metabolism of flighted birds.

What explains this ridiculous article. The answer is the by-line. See where it comes from? Analog Science Fiction and Fact. This magazine was the finest science fiction magazine ever edited. I remember Isaac Azimov show casing his robot/detective novels here. I remember Hal Clement's "Mission of Gravity" here and the first publication of the Dune series. And then the editor, John Campbell went off the deep end with his Dean Drive "Reactionless space drive", his quasi- mystical Hieronymous machine [draw the circuit of the device on paper, think happy thoughts and away you go, etc, etc, etc. The magazine fell into disrepute, Campbell was marginalized and the rest is history. Sad.

Bubble in amber, 1987. I thought I had read about this a long time ago.

The problem of how the giant pterosaurs were able to generate enough energy to become airborne has troubled many paleontologists. For example, the Encyclopedia Britannica makes the unlikely suggestion that the pteranodon may have launched itself by "running downhill" on its stubby legs. The discovery of the oxygen enriched atmosphere of the cretaceous period sheds new light on this problem. In such an atmosphere many of the constraints of metabolism are relaxed. The creatures of the cretaceous may have been literally turbo-charged like race cars by the oxygen enriched atmosphere. It becomes plausible that a flying creature that evolved during that period could reach size limits that are impossible in today's anemic atmosphere.

I think this is missing another point that is just as important: were these animals built such that, given more oxygen, they could madly flap their wings at a rate fast enough to get airborne? Was the atmosphere more dense as well? Also, just having a higher level of oxygen doesn't mean that more energy is available since that's a function of available nutrition and metabolic rate. That is, with more oxygen a faster rate of aerobic metabolism could be supported, but it would continue only as long as there was substrate for it. Regardless of how much oxygen was available, it would still take as much energy to get a pound of flesh airborne then as now.

Also, almost double the oxygen would result in huge amounts of oxygen free radicals, a source of mutation and damage of DNA. I imagine that this will be postulated as a means in addition to radiation of introducing genetic variety.

I do not doubt that the analysis of the bubbles was carried out properly. The conclusion is a bit brash and bold though, and needs to be worked on.

At what rate do gasses diffuse through amber? If O2 is slower than N2 then after a while there will be more O2 than N2 in the sample. Same is true for diffusion in, O2 could possibly diffuse in if the osmotic pressure is correct. The researchers need to answer these questions.

The theory that the earth's atmospheric concentratin is stable is one based on equilibrium. Plants eat what animals exhale and vice versa. Plus, the more O2, the more fires, lowering the amount of O2 over time. The CO2 level over the very long term is dictated by seafloor subduction and volcanism. Lots of CO2 means lots of eachells, which become limestone and is subducted, to return as CO2 in volcanic gas after a delay. lower CO2, less seashells. This takes millions of years, though.

Since burning things combine O2 woth C, the isotopic ratios in the calcium carbonate of seashells fossilozed in marble can give clues about ancient atmospheric concentrations, and this work does not suggest much higher O2.

Plus, why should more O2 mean bigger flyers? Pterodons wer probably gliders like albatrosses, not flappers like chicadees.

Now, chicadees the size of pterosauers would be something!

You missed an essential part of the article. O2, the oxygen molecule, is much heavier than N, a nitrogen atom. Therefore, if the oxygen level was higher, the atmosphere was heavier. Imagine the difference between flying in modern air, and "flying" under water, which any scuba diver can do.
Now move 10% down the scale from air toward water. Ceatures could get airborne and fly in that, who could not fly today. That's the difference.

Congressman Billybob

Latest column, "Using the Old Noodle," now up on UPI and FR.

Was the atmosphere more dense as well?

Dunno. 65 MYA a 10 km wide bolide hit the earth. The impact was large enough to blast enough rock debris into the space to set essentially the entire planet ablaze as it fell back.

Question 1: How much air was blasted permanently off the planet by the strike itself?

Question 2: As luck would have it the strike was in shallow water on the continental shelf. How much hypersonic steam do you blast into space cooling off a 200 km wide crater gouged down to magma?

Question 2a: How much atmosphere gets entrained on the edge of a 200km wide hypersonic jet of steam?

Enough to drop sea level atmospheric density by, pick a number, 20%? 50%? 70%?

The likelihood that the heat of the impact would have burned most of the earth seems to have been too much for the imagination of the author. If the richer atmosphere made the huge dinosaurs and airborn creatures possible, and the oxygen was consumed by the vast burning as well as the other factors you mention, then that would account for their extinction, and the fact that the survivors were much smaller types of critters. I also suspect that the ozone layer would have been destroyed, which would explain why the survivors were nocturnal, feathered or hairy, or likely to hibernate in mud or hollows in embankments.

Note: this topic is from 2/17/2003. It's a re-ping. Thanks vannrox .

The atmosphere of the Earth 80 million years ago was discovered to have 50% more oxygen than modern air. Brenner and Landis found that for all gas samples taken from amber 80 million years old the oxygen content ranged between 25% to 35% and averaged about 30% oxygen. Cretaceous air was supercharged with oxygen. On the other hand, 40 million year old samples similarly analyzed showed about the same oxygen content as modern air, and 25 million year old samples showed slightly less oxygen than modern air. The composition of air has been shifting with time over a far broader range than geologists had thought possible. The cause of these excursions is not understood. Perhaps they are caused by a shift in the delicate balance between oxygen production by photosynthesis and oxygen trapping by exposed iron, sulfur, and organic reducing materials... This result has very interesting implications about the era of the dinosaurs. The dinosaurs apparently breathed air that was much richer in oxygen than our air and lived in forests and grasslands that were far more combustible than ours. The metabolisms evolved to live is such an atmosphere might be radically different from ours. This new information may be relevant to many puzzles of the cretaceous and jurassic periods.

Interesting article, but goes against what is already known.

During the Carboniferous period, oxygen content of the atmosphere was high (approximately 35%), hence all the large insects and such that have no active respiration (i.e. lungs and such). You don’t see these in the Mesozoic.

Also, dinosaurs initially evolved in a period of low atmospheric oxygen (i.e. portions of the Triassic, with an low estimated oxygen content of 10-12%), and some evolved air sacs and such to deal with this (i.e. these are still preserved in birds today). This allows them to thrive in a low oxygen content atmosphere, and to have a very efficient metabolism when atmospheric oxygen content is higher.

So, this hypothesis really doesn’t make any sense...

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.


GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach	join list or digest view topics view or post blog bookmark post a topic subscribe

Thanks Robert, wherever you are. Note: this topic is from 2/17/2003. Blast from the Past, but too interesting not to ping. To all -- please ping me to other topics which are appropriate for the GGG list.