The gradual evolution of new symmetrical segments within organisms is not feasible. The direct evidence implies that throughout evolutionary history the number of skeletal parts in segmented organisms has been decreasing. Extrapolating the pattern of reduction and distortion of segments into the past suggests that the progenitors of segmented organisms had many symmetrical parts. I suggest that the rapid formation of these progenitors of segmented organisms took place in the manner described in the foregoing text and figures; this seems the simplest possibility.
The symmetry and repetition within the vertebrate skeleton is a vestige of the more perfect symmetry and more extensive repetition within the vertebrate progenitor. Soft parts have been distorted by evolution, yet repetition is still evident in muscular, circulatory, and nervous systems. Departure from the prototype is most extreme in internal organs. The prototype had organ systems for each segment; eventually most of these were lost, their functions taken over by a few enlarged organs from a few segments. Thus the formation of multi-chambered hearts and other lobed or paired organs.
The theory uses known mechanisms and is based on the direct evidence of evolutionary change, the fossil series from which the principle of reduction and specialization of serial homologs was derived. I hope the reader will find it worth consideration. The object is to look at segmented organisms with a new understanding.
"The real voyage of discovery consists not in seeking new landscapes but in having new eyes."
- - Marcel Proust
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Copyright 1995 Cliff Lundberg. All rights reserved.