What is the fossil evidence for evolution? Is it valid?

 

Fossil Evidence For Evolution

What is the fossil evidence for evolution and is it valid? There are two lines of fossil evidence for evolution. The first line of evidence concerns the order in which fossils are found buried. Fossils are generally found buried in a sequential order. The first fossilized fish appear buried below the first fossilized amphibians which appear below the first fossilized reptiles which appear below the first fossilized birds and mammals. This is consistent with the Darwinian model of origins which says that birds and mammals evolved from reptiles which evolved from amphibians which evolved from fish. The acronym to remember is FARM: Fish to Amphibian to Reptile to Mammal (and bird). 

Not everything about the order in which fossils are found supports Darwin’s theory however. Near the bottom of the fossil record we find the Cambrian explosion, the sudden appearance of at least two-thirds of all known animal phyla (28 out of the 42), all within a very brief period of geological time. There is some debate as to how many of the remaining 14 phyla also appear during the Cambrian (some scientists say as many as 13 of the remaining 14). Regardless, it is clear that many of the major innovations to the basic structure of known animal forms occurred during this very brief, enigmatic period. This does not support Darwin’s theory of gradual innovation. 

Darwin’s interpretation of the fossil record is by far the most well known perspective. There are alternatives however. For example, while Darwinists emphasize the order in which fossils are found buried, Traditional Catastrophists emphasize where they are found buried. The vast majority of all fossils are found buried in sedimentary rock layers. Sediments are known to be sorted and layered naturally through hydrologic sorting and liquefaction. Traditional Catastrophists believe that these natural sorting mechanisms are largely responsible for the sequential ordering of fossils, contrary to the Darwinian view which denies large scale fossil sorting. 

Fossil Evidence for Evolution – Transitional Fossils
The second line of fossil evidence for evolution concerns transitional fossils. Transitional fossils are fossils which are thought to document the evolutionary change, or transition, of one species into another. The orohippus, mesohippus, miohippus, merychippus, and pleshippus are all thought to be transitional fossils, documenting the evolution of the hyracotherium into the modern horse. 

The hyracotherium was a small fox-sized four-toed creature, similar to the modern day hyrax. The orohippus had four toes on its front two legs and three on its back, as if it were transitioning from a four-toed to a three-toed creature. The significantly larger mesohippus had three toes all the way around. The mesohippus was followed by the slightly larger miohippus which was followed by the merychippus. Two of the merychippus’ three toes were smaller than those of the mesohippus and the miohippus, as if it were transitioning to a single-toe. The merychippus was followed by the slightly larger single-toed pleshippus which was finally succeeded by the equus (the modern day horse). The equus has two splint bones which appear to be all that remains of the merychippus’ smaller two toes. And so we see a progression from a smaller four-toed creature to a larger single-toed creature with slight structural progression throughout, including the elongation of faces and change in tooth shape. 

This second line of fossil evidence for evolution is no less controversial than the first. For example, consider the ostensive evolution of the horse as described above, undoubtedly the single most popular and widely known sequence of transitional fossils. Critics point out that the fossils used to create the hyracotherium-to-horse sequence are found on opposite sides of the planet, oceans apart. This geographical discontinuity is an obstacle for advocates of the sequence. Those fossils which actually do appear on the same side of the ocean cause some difficulties as well. A species of three-toed horses were found together with a species of single-toed horses in the same rock formation in Nebraska, indicating that they lived side-by-side. As for the fossils’ progressive increase in size, this is a mute point. Modern horses vary greatly in size, from small dog-sized miniatures to massive Belgians, Clydesdales, and Percherons. 

And so the debate rages on. Darwinists interpret geological and biological data in a manner consistent with their theory. Critics dispute these interpretations, citing incongruities.