The extinction of the dinosaur extinction problem is a problem. It just won't go extinct. Just a few weeks ago the asteroid that foul-tipped off Yucatan was upgraded in size and firepower when the crater was found to be bigger than first thought. In conclusion, the bigger the asteroid, the deader the dinosaurs?
Now, at the 1993 Geological Society of America meeting in Boston, comes word from USGS's Gary Landis (That's Landis not Larson. Larson is another dinosaur extinction speculator.) Landis concluded that the dinosaurs were respiratory system challenged. When the oxygen in the atmosphere fell from 35% to 28% they had no Jurassic Park sanatorium to retreat to. I think oxygen in the movie was only an air passage suffocating 20%. The 28% was curtains for them. Landis contends that 2/3 of the dinosaurs were gone before the foul tip off Yucatan. The fall in oxygen from 35 to 28% took some 300,000 to 500,000 years and was completed by 65 million years ago.
Richard Hengst, Purdue physiologist, says, "There were some serious problems with trying to get air into [a brontosaurus]." His choice of words suggests a mouth-to-mouth respiration. Not so. I think Richard means that the small, horse-sized nostrils of the brontosaurus and others just were not up to the job. There must have been a big sucking-sound as each dino inhalation and exhalation. At 35% oxygen, I am not so sure that any but the most agile dinosaurs would last long at all.
Lovelock in Gaia states that the probability of a lightning flash started fire increase 70% for each 1% rise in oxygen concentration above 21%. Above 25% most terrestrial areas would be like LA with brush fires with Santa Ana winds. A colleague, Andrew Watson of Reading University, bases Lovelock’s numbers on lab work. LTER forest-pyro types might brief CED readers regarding oxygen climate and fires. Anyway, it would look like the dinos would have to hang around 50% fuel moisture habitats or become roast dinosaur.
Like the DNA in Jurassic Park, Landis' oxygen data comes from gas trapped in amber, Minnesota amber. Landis notes that for the dinosaurs, the drop from 35% to 28% is like going from sea level to 7,000 feet. I am from a sea level LTER and the oxygen quality of the air at Estes Park provides me with great sympathy for the brontosaurus with horse-sized nostrils. I was thinking back to the residents of Estes Park, the ones that I remember, and the cafeteria staff. Did they have unusually flared nostrils? Even if they had had obviously large nostrils I would probably have attributed it to the aromas from the roasting dinosaurs. I think that is what Tom Callahan said we were eating; something about Aunt Erma's Saturday night special. As you know I was rather busy with the cranium and had not paid much attention to nostrils. Looking back on it, it would have been possible to use the conical earplugs that John VandeCastle provided as a measuring device. I could have put a scale on them with a ballpoint pen and surveyed nostril diameters. It is my good fortune that we will not hold the next All Scientists Meeting at Estes Park. So I thought.
Bruce Sellwood, Greg Price and Paul Valdes at the University of Reading (Nature Vol. 453:453-) have new temperature calculations on Cretaceous (144 million to 65 million years ago). The Cretaceous is thought to have had around 2000 ppm of XO2 (8x current levels). This research team works on oxygen isotope ratios in fossil Foraminifera shells of the period. They find the Cretaceous temperatures at 5 to 10 C warmer than today. They also conclude that putting more carbon dioxide into the air is redundant. Being redundant in England means unemployed. In the USA redundant means un-needed, already accomplished.
In 8xCO2 concentration, the brontosaurus would have to have tissue CO2 higher still. In addition, the high oxygen concentration in the Cretaceous air would require still lower levels of tissue oxygen. Based our experience with these concentrations, we need to consider toxicity of these gases.