Scientists generally agree that the vast majority of species that have ever existed are now extinct, with some estimates as high as 99.9%. While the veracity of this estimation can likely never be tested, what it does underscore is that much of life is now extinct.
So what is the basis for such a claim? An important factor that drives such estimates is that we know of entire groups of organisms only from fossils. To many people, dinosaurs come to mind, but there are plenty of others, including mammals, fishes, reptiles, birds, amphibians, crustaceans, insects, corals and plants.
So why does this matter for creationists? If we know that all sorts of organisms existed from fossils that no longer exist today, an important question is raised: “where did they go?” Why did God bother to create them if they were just destroyed in the Flood? Or if they indeed get onto the ark (as cramped as such a boat would be), why did they go extinct in the last few thousand years, after they left the ark? Alternatively, if they are still alive today, why have our major efforts of exploration in the past few centuries resulted in only a handful of discoveries of such ‘living fossils’?
Evolutionary biologists typically rely on two major explanations for the extinction of groups:
1) The first involves localized interactions between different species and/or the environment. A species may be outcompeted by a better adapted rival, wiped out by a novel predator or pathogen, or fall victim to a localized natural disaster.
2) The second invokes mass extinction events. Mass extinctions are thought to be major, typically global, events caused by climatic change, whether due to volcanism, extraterrestrial impacts, plate tectonic shifts, etc. These events may in part randomly kill off certain groups of organisms, unfortunate to bear the brunt of the disaster, but they may also favor species, through natural selection, with key evolutionary novelties capable of surviving the event.
While scientists will indefinitely debate why some species have gone extinct and others haven’t, they are at least able to see patterns in the fossil record that suggest that evolutionary forces have shaped the changes in diversity over time.
What’s important for you, if you’re a creationist, is to ponder why entire groups have gone extinct, while others have not, if they were only created a few thousand years ago.
To prevent any misconceptions that the dinosaurs are the only major group of organisms to go extinct, I will be highlighting numerous groups that we know only, or almost entirely, from fossils.