Lessons from the dinosaurs have been unlearned over time

We’ll probably never live down our little April Fools’ Day joke about coal and casinos coming to Huntington Beach.

It was inspired by a trip that we took recently to Arizona. On the first night, we stayed at the Avi Resort, an Indian casino on the Colorado River just south of Laughlin. At the time, we were more interested in the common goldeneyes and nesting Inca doves than in slot machines or jokes.

The main purpose of the trip, however, was not birding for Vic, but rocks and fossils for me. I wanted to see the Petrified Forest National Park in eastern Arizona. Also, I was looking for some good illustrations to use in my presentations on evolution at the Orange County Conservation Corps.

The museum at the Petrified Forest National Park and the Museum of Northern Arizona in Flagstaff both had wonderful murals that depicted different aspects of the Mesozoic Era, also known as the age of dinosaurs.

This era spans from the beginning of the Triassic Period (250 million years ago) through the Jurassic to the end of the Cretaceous Period (65 million years ago).

The petrified forest is about 225 million years old, and that is the era that mainly was being interpreted there. We learned about many strange, long-extinct animals from the Triassic, such as rhinoceros-like reptiles called placerias and 10-foot-long amphibians called metoposaurs.

The temptation to pick up petrified wood at the national park was one that we easily resisted. It’s illegal, and besides, if every one of the millions of visitors took a piece of petrified wood, eventually there would be none left. However, only 10% of the petrified forest is in the national park; fossilized wood and animals collected from privately owned land are available for purchase. We visited Jim Gray’s Petrified Wood Company just outside of Holbrook, Ariz., near the south entrance of the park. They not only had an incredible collection of petrified wood for sale, they had some spectacular animal fossils from the Cambrian Era (500 million years ago) to the more recent ice ages.

Vic worried that I might want one of the $25,000 coffee tables made of a polished slab of petrified wood mounted on a petrified wood stump, but that wasn’t what interested me. Instead, I bought a couple of fossilized teeth from the western horse, a species that went extinct in North America about 8,000 years ago. Most people aren’t aware that horses originated in North America. Western horses migrated over the land bridge and survived in Eurasia, but the horses that stayed here went extinct. North America didn’t see horses again until the Spaniards brought modern horses here in the 1500s.

We bought a few other fossils to use in our respective classes, including a couple of nicely preserved trilobites from Utah. Trilobites look a bit like big roly-polies or pill bugs. We learned that there were about 15,000 different species of trilobites at one time. These invertebrates crawled around on the bottom of the ocean until they died off during the great Permian extinction 250 million years ago. That mass extinction wiped out nearly 90% of life on earth and ended the Paleozoic Era, but it ushered in the Mesozoic Era and opened the way for the evolution of dinosaurs.

Extinction and evolution are natural parts of life on earth. If you look at the progression of animal life over the past 570 million years, you see entire groups of animals coming into existence and then dying off. Relative dating based on where a fossil occurs in rock strata and radiometric dating can determine the ages of various fossils, allowing them to be placed in their proper geologic time period. (For a good explanation of relative dating and radiometric dating, see www.museum.vic.gov.au/ prehistoric/what/fossilage.html or science.enotes.com/ earth-science/fossil-record/.)

Most discussions of evolution focus on the long procession of genetic changes needed to produce a given species. To us, the important feature of evolution is the remarkable diversification that has resulted in millions of types of living things all descended from the original ancestral cells eons ago.

The species that are alive today are the result of a long evolutionary process. If many of today’s species die off in a mass extinction ? as scientists are now predicting for the end of this century ? it will take millions of years to replace them with new species.

Creationists should be even more concerned about species extinction than those of us who believe in evolution, because they don’t believe that new species will evolve to replace existing species.

Many religious people today, however, are concerned about the environment. Showing a concern for the planet and a stewardship of God’s creations are the responsibility of us all. We can’t afford to ignore the current mass extinction that is occurring right under our noses.