Were Dinosaurs Gasping for Air?
A news story on CNN claims that “the air contained only about 10 percent oxygen at the time of the dinosaurs.” It climbed to 23% by 40 million years ago, then dropped to its current level at 21%, said the researchers. They feel that the rise of oxygen “almost certainly contributed to evolution of large animals.” Mammals and birds need three to six times the oxygen, they claim. They arrived at the oxygen levels by measuring carbon isotopes in sedimentary rocks at the bottom of the Atlantic Ocean. Their results were published in Science.1 News@Nature, Science Now, MSNBC, and LiveScience all carried the story.
1Falkowski et al., “The Rise of Oxygen over the Past 205 Million Years and the Evolution of Large Placental Mammals,” Science, Vol 309, Issue 5744, 2202-2204 , 30 September 2005, [DOI: 10.1126/science.1116047].
Let’s think this through. If this theory were correct, 80-ton dinosaurs, fast-running velociraptors, and pterosaurs as large as fighter jets (09/09/2005) were able to live on 10% oxygen, yet mammals could only survive as small rats, and as time went on oxygen levels increased. So the already big dinosaurs died off and the miniscule mammals grew in size due to the more oxygenated environment?
According to prior evidence, some mammals were at least medium sized during the time of the dinosaurs (see “This badger ate dinosaurs for breakfast,” 01/12/2005). The authors note this but simply dismiss it: “Data show a rapid increase from small to medium-sized mammals in the first few million years after the K-T event (Fig. 2). This size contrast is blurred slightly with the recent discovery of larger Cretaceous mammals, but this trend does not appear to be driven by oxygen.” Blurred slightly? It falsifies their basic idea that oxygen drove the development of large placental mammals. Whatever data they dislike are thus simply discarded as irrelevant. Many other life forms, such as plants, insects, shellfish and crustaceans, grew to enormous sizes during the supposedly low-oxygen periods.
Notice how they also placed their trust in the K-T meteor hypothesis: “Whereas a bolide impact at the Cretaceous-Tertiary (K-T) boundary and the ensuing extinction of dinosaurs provided ecological opportunity for the radiation of placental mammals,” la te dah, dum de dum dum, etc. This is more of the opportunistic theory of evolution: if you clear the ground of big dumb dinosaurs, large mammals will evolve, as if by magic, to fill in the space. Opportunity is thus the necessary and sufficient cause for the emergence of complete revolutions in body organs, body shapes, decorations, behaviors and capabilities, from bat flight to whale sonar, in hundreds of new kinds of animals. The Darwinian Density: “Well, they’re here, aren’t they? Since evolution is a fact, they must have evolved.”
The researchers didn’t seem to notice that the carbon-isotope measurements contradict direct measurements of oxygen from amber. According to an article on the USGS website, air trapped in prehistoric amber was claimed to have 30% oxygen in it – not 10%. Were the “300 analyses by USGS scientists of Cretaceous, Tertiary, and recent-age amber from 16 world sites” wrong? Or did these researchers forget to cross-check their measurements with the amber data? How about a little classic lab experimentation? They could grow mice in different amounts of oxygen and see if that affects body size. Once they find the magic oxygen formula, they could breed elephant shrews into elephants.
The hypothesis is based on circumstantial evidence, comparing oxygen with the geologic column, which is itself based on evolutionary assumptions. One would think that a few more requirements beyond oxygen would be necessary for the “success story” of the mammals. Why the news sources all repeated this wild idea uncritically is a study in itself.
Footnote: It turns out that National Geographic, bless its evolved heart, did consider other requirements for mammals to flourish. After indulging in the myth of “mammalian opportunism,” they quoted Robert Asher of the Berlin Museum of Natural History who, though impressed by the “fascinating correlation” of oxygen levels with mammal size and diversification, thought more had to be involved. Of all the other “causative factors” he could have listed, he mentioned only the one that Darwinists love most, because it intuitively explains the rise of specified complexity without a Designer. Listen carefully:
But is global oxygen is the magic bullet that explains the evolution of mammals 50 to 40 million years ago? “My guess,” Asher said, “would be no. … Like most other issues, there are a number of causative factors involved, including chance.”