|Evolution in the News - July 2015|
|by Do-While Jones|
Why did all the dinosaurs die?
The big question when I was growing up was, “What killed the dinosaurs?” Over the years, the question has remained—but the answer keeps changing.
The answer I was taught in 1953 was, “The mammals killed them all off.”
Near the end of the Age of Reptiles, the warm-blooded mammals began to appear. These were tiny little furry fellows, no larger than a rat. At the Flaming Cliffs we found skulls and skeletons of eight of these little mammals. It is quite possible that they ate the dinosaur eggs. Thus many dinosaurs were never born. This must have happened in many parts of the world. 1
It was the politically correct answer at the time because it proved Darwin was right. It was proof that survival of the fittest caused mammals to drive dinosaurs to extinction.
Younger students have been taught this explanation:
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction. …
As originally proposed by a team of scientists led by Luis Alvarez, it is now generally believed that the K–Pg extinction was triggered by a massive comet/asteroid impact and its catastrophic effects on the global environment, including a lingering impact winter that made it impossible for plants and plankton to carry out photosynthesis. The impact hypothesis was bolstered by the discovery of the 180-kilometre-wide (112 mi) Chicxulub crater in the Gulf of Mexico in the early 1990s, which provided conclusive evidence that the K–Pg boundary clay represented debris from an asteroid impact. The fact that the extinctions occurred at the same time as the impact provides strong situational evidence that the K–Pg extinction was caused by the asteroid. 2
This explanation was even more politically correct because it blames climate change, and helped to explain how so much evolution could have happened so quickly.
Yet the devastation caused by the extinction also provided evolutionary opportunities. In the wake of the extinction, many groups underwent remarkable adaptive radiations — a sudden and prolific divergence into new forms and species within the disrupted and emptied ecological niches resulting from the event. 3
But now the political need is for the American public to be even more frightened by the terrible danger of climate change. Therefore, the dinosaur demise must be blamed primarily upon the climate change before the asteroid impact! (The asteroid just finished the job.)
Well before an asteroid struck the planet some 66 million years ago, Earth was already in turmoil, a record from an ancient lakebed in northeastern China suggests. Investigators knew from ocean floor sediments that the climate was unstable at the end of the Cretaceous period, when the dinosaurs were making their last stand. But findings from deep drilling in the Songliao Basin, presented at a conference here this spring, show that the climate swings on land were far more drastic, with average annual temperatures going up or down by as much as 20°C [68°F] over tens of thousands of years—a geological eyeblink. “It certainly wasn't a good time for the dinosaurs,” says Robert Spicer, a paleoclimatologist at the Open University in Milton Keynes, U.K.
The intense greenhouse effect drove average temperatures to about 22.3°C [72.14°F] —compared with 5°C [41°F] at Songliao today. Adding to the climate turmoil, the warming was interrupted just after the K-Pg boundary by a brief cooling episode, which the team attributes to dust, soot, and aerosols from the Yucatán impact.
Paleontologists suspect that dinosaurs were feeling the stress. In a review last August in The Geological Society of America Special Papers, paleontologist David Archibald of San Diego State University and colleagues noted that the number of nonavian dinosaur species shrank by half in the last 10 million years of the Cretaceous, with the biggest losses occurring in the Maastrichtian. The Chicxulub impact was, Wang says, “the straw that broke the camel's back.” Put another way, Spicer says, “if the asteroid came in on a less stressed system, the effects would not have been so severe.” 4
Not only did climate change cause the death of the dinosaurs—it almost prevented them from evolving in the first place!
Dinosaurs once dominated the world — but they spent their first 30 million years stranded on its geographic fringes. Large dinosaurs flourished near the poles, but only a few small ones, no larger than ostriches, managed to gain a foothold in the hotter low latitudes.
The latest research suggests that an unstable climate in these regions kept big dinosaurs at bay for millions of years, as conditions at lower latitudes swung violently between wet and dry periods.
The finding is based on a detailed climate history reconstructed from sedimentary rock in New Mexico that dates from about 215–205 million years ago, during the late Triassic period. Back then, the area sat just north of the equator, roughly where Costa Rica is today. The region was dominated by archaic reptiles (some related to crocodiles), with only a few small dinosaur species present. 5
Dinosaurs lived near the poles because the world was much hotter before man-made global warming.
Science Against Evolution takes no official position on climate change (even though I have privately 6).
We only mention climate change as an example, showing that politics drives “science.” Scientists have produced contradictory analyses that “prove” that human activity causes climate change, and “prove” the climate change was even greater before man existed. Human responsibility depends entirely upon political need.
We don’t claim that money causes honest scientists to change their minds—but funding is given to scientists who already believe what the sponsor wants to hear, and not to scientists who will produce evidence that contradicts the sponsor’s belief.
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Roy Chapman Andrews, All About Dinosaurs, 1953, Random House, page 140
4 Jane Qiu, Science, 12 June 2015, “Dinosaur climate probed” , p. 1185, http://www.sciencemag.org/content/348/6240/1185.full?sid=940b2687-402e-4cd8-bdff-9cf5a5dac524Vol. 348 no. 6240
5 Douglas Fox, Nature, 15 June 2015, “Extreme climate change slowed dinosaurs' rise”, http://www.nature.com/news/extreme-climate-change-slowed-dinosaurs-rise-1.17728
6 Do-While Jones, “Belief in Global Warming”, http://scienceagainstevolution.info/dwj/warming.htm