The following article is one of many contained in the book Dinosaurs and Creation by Dr. Donald DeYoung. He has given permission for us to reprint portions of his book, which is available on our book table at our monthly meetings.

How Does Evolution Explain Dinosaur Extinction?

By Dr. Donald DeYoung

Scientists have presented dozens of dinosaur extinction theories. Ideas range from humorous to the truly bizarre, including these:

• The earth's climate became either too warm, cold, dry, or wet for dinosaur health.
• A nearby supernova, an exploding star, flooded the earth with intense radiation, resulting in fatal mutations.
• A "death star" called Nemesis periodically approaches the solar system and wipes out living creatures by raining comets down upon the earth.
• A nearby collision between two neutron stars bombarded the earth with deadly muon particle radiation.
• There were deadly giant meteor showers or meteor storms.
• A passing comet poisoned the earth's atmosphere with chemicals, perhaps cyanide.
• Earth's oxygen levels decreased and the dinosaurs suffocated.
• The male dinosaurs grew too large to successfully reproduce.
• Too many offspring were born of one gender.
• Hormonal disorders arose in adult dinosaurs.
• Overpopulation.
• Extreme hay fever plagued the dinosaurs.
• Mass suicide was carried out by dinosaur herds.
• Dinosaurs were weakened by slipped vertebral discs.
• Dinosaurs slowly accumulated genetic disorders.
• A laxative plant in dinosaur diets disappeared, and they died of constipation.
• A ratlike mammal evolved that ate the dinosaur eggs.
• Weakened eggshells developed.
• New poisonous plants evolved and were eaten by dinosaurs, perhaps poisonous mushrooms.
• Dinosaurs ate plants containing drugs and died of an overdose.
• Viral infections swept the planet.
• Dinosaurs simply could not compete with evolving mammals.
• Either starvation or overeating occurred.
• Deadly insects evolved that carried parasites and disease.
• Monster storms called hypercanes temporarily destroyed the earth's protective ozone layer.

One particular extinction theory has gained wide acceptance since the 1980s. It involves the impact of a large meteorite, asteroid, or comet, about 10 kilometers (6 miles) ii diameter. The collision with earth is said to have occurred about 65 million years ago at the end of the Cretaceous period. The large object is estimated to have been traveling more than 50 times faster than a jet aircraft at the time of impact. This would have resulted in the dissipation of: tremendous amount of kinetic energy. There resulted worldwide firestorms, tsunami or tidal waves, and severe storms with acid rain. The scenario further pictures great cloud: of dust, soot, and smoke resulting from the impact explosion. This material was carried completely around the earth- by jet stream winds, and sunlight was thus blocked for many months or years. Plants could not grow in the semidarkness, including the vast numbers of sea plankton. The dinosaurs gradually starved from the resulting collapse of food chains worldwide. Altogether, 70-99 percent of the earth's living species are said to have gone extinct around the time of this catastrophe.

A possible collision site has been identified at the northern end of Mexico's Yucatan Peninsula. Called Chicxulub (pronounced as CHEEK-shoe-lube) after a nearby town, there is a craterlike circular formation 100-200 miles in diameter buried beneath a kilometer of water and rock. This geologic formation conveniently has been dated at 65 million years old. As further evidence of a collision, at various earth locations a clay layer at the Cretaceous-Tertiary (K-T) boundary appears to hold an unusual amount of the element iridium. The letter K is used for Cretaceous instead of C, from the German spelling of the word. Iridium atoms in the 2-inch-thick clay layer occur at only about 9 parts per billion, but this is still 30 times higher than in the surrounding rock. This particular element is known to be somewhat more abundant in meteorites, asteroids, and comets than on the earth. Thus the iridium atoms support the idea of dust fallout from an extraterrestrial impact. The collision idea was first popularized by physics Nobel laureate Luis Alvarez and his geologist son Walter who discovered iridium in the K-T clay layers of Italy in 1980. Since then, iridium has also been found at K-T boundaries in Denmark, New Zealand, and elsewhere.

In evaluating the popular impact extinction theory, several points need consideration. First, the Chicxulub structure is not known with certainty to be an actual crater. These large, unusual "cryptocrater" formations are numerous across the surface of the earth. Many of them may result from past geologic activity instead of impacts. Second, the observed iridium layer at the K-T boundary could be a dust deposit from volcanoes instead of from a space collision. Volcanic material generally includes trace amounts of the element iridium. In fact, a large region in western India called the Deccan Traps experienced massive volcanism at a similar relative time in history. This igneous event resulted in multiple layers of basaltic lava covering more than 500,000 square kilometers (180,000 square miles), to depths of a mile or more. Third, why did the alleged impact kill off the dinosaurs while many other forms of life remained healthy? Some of the least mobile creatures (tortoises, crocodiles) and also the most sensitive to climatic change (birds, fish) are still with us today. Fourth, the fossil record does not show an instantaneous demise of the dinosaurs. Some dinosaurs seemed to have died out within the Cretaceous period while others survived well into the Tertiary period, millions of years later in evolutionary thinking. Scientists have been unable to determine whether the K-T boundary layer itself was deposited in less than a year, or over tens of thousands of years. In view of these many problems, the impact view of dinosaur extinction remains uncertain, if not doubtful.

The possibility of a worldwide impact catastrophe is a popular topic today. For example, the collision of a Mars- sized object with the earth has been proposed to explain the moon's formation. Also, several dramatic movies have portrayed deadly asteroids or comets hitting the earth and endangering all life. In the evolution view there have been at least five major extinctions of life during earth history. These are called the Ordovician extinction (438 million years ago), Devonian (360 million), Permian (245 million), Triassic (208 million), and the "great dying" of the Cretaceous extinction (65 million years ago). The Permian event, as an example, is claimed to have eliminated 95 percent of all animal species living at that time. Some biologists believe we are now living during a sixth great extinction, this time brought on by man's domination of the earth. Creationists challenge the timescale that widely separates these extinction events. In the creation view there was one single major earth catastrophe of judgment that caused the near extinction of life, the Genesis flood of Noah's day. There also is a second, final judgment in the future when the heavens and earth will be cleansed by fire (2 Peter 3:10-12). Meanwhile, there is a definite future plan for mankind. We are not the result of chance, nor do we or the earth's animal and plant life face imminent extermination from a random asteroid collision.