The three eras of geological time (Paleozoic, Mesozoic, and Cenozoic) are characterized by different fossil assemblages (Refer to Figure 2.2). Before these eras, there was the Precambrian, which is not regarded as an era and contains fossils of blue-green algae and some fungi. The Paleozoic Era is known for its abundant marine life ranging from brachiopods and trilobites to sharks and bony fishes in the Devonian, as well as amphibians and reptiles in the Carboniferous. This era is also known for its extensive coal beds, consisting largely of extinct plants such as giant horsetails, ferns, some seedless plants, and club mosses. The Mesozoic era is divided into three periods, the Triassic, Jurassic, and Cretaceous, and is known for its dinosaurs and many other reptiles. At the close of this era, we have the extensive chalk deposits, which we have discussed earlier. It is not surprising then that the close of this era is associated with massive extinctions. In a catastrophic flood model, this era would be associated with the close of the flood period prior to the re-emergence of the continents from the waters which covered the earth. The plants of the Mesozoic era comprise cycads, conifers, and deciduous trees many of which still exist today. In the Cenozoic era, we find largely the fossils of mammals and birds, and Cenozoic plants are essentially similar to the species that exist today.
The question arises as to why there is this particular order in the fossil record which is interpreted as a progressive advance from simple to complex organisms? The type of fossil found in the various layers changes as one ascends the geological column, from invertebrates, fish, amphibians and reptiles, to the mammals and birds in the uppermost strata. This order in the fossil record is one of the prime evidences used by scientists to establish evolu- tion as a fact. However, the sequence is not from simple organ- isms to complex organisms (there is no such thing as a “simple” organism in biological terms), but rather from marine sessile to pelagic (free-swimming) to terrestrial life forms. The fact then is, that there is no such thing as a simple undifferentiated animal in the fossil record that may be cited as proof for the development of organisms from simple to complex. George Gaylord Simpson, the famous proponent of the evolution theory, already witnessed to this fact when he stated in his book The Meaning of Evolution:
It has been suggested that all animals are now spe- cialized and that the generalized forms on which major evolutionary developments depend are ab- sent. In fact, all animals have always been more or less specialized and a really generalized living form is merely a myth or an abstraction.3
The earliest organisms in the fossil record were thus complex organisms and there is no evidence for the progressive advance required by the theory of evolution. Yes, there were many organisms such as trilobites and ammonites that existed in the past that do not exist today, but this does not make them primitive. They were just as complex as anything living today. In fact, the fossil record shows a past wealth of organisms which is staggering. Surprisingly, most of the organisms of the past were much larger and impressive than present-day animals even, where they belong to the same groups of animals. In fact, in this regard, the fossil record shows evidence for devolution rather than evolution.
There are many reasons beside progressive development which could be cited for the order in the sequence of fossils. The sequence from sessile to free-swimming to terrestrial is indicative of ecological zones being destroyed progressively as can be illustrated by a simple example. If a bulldozer rapidly covered a duck pond with soil, then the organisms in the pond would be buried in sequence. The bottom dwelling worms and snails would be at the bottom, the fish somewhat higher, and the ducks on top. The sequence represents the ecological zones in which the animals lived and definitely not the order in which they evolved. The same holds true for the fossil record. Indeed, we find assemblages of fossils e.g. radiolarians and foraminiferans in the same sequence in the fossil record as they occur in a present day ecological zonation.4 The ability to float or not would also produce zonation. Mammals and birds float due to bloating or trapped air in feathers and hair and are thus to be found in higher strata. Coal layers reflect this same phenomenon. The Paleozoic coal seams consist largely of non-floating plant species whereas those found in higher strata consist of floating species. No model provides all the answers, but the flood model can provide a very satisfactory explanation for the series found in the fossil record.