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Special Papers in Palaeontology
73,
159-183 (2005) Jerzy
Dzik Abstract.
Palaeontological evidence on the
course of evolution is represented by fossil samples of ancient
populations arranged according to their objective time-and-space
coordinates. In the method of stratophenetics, morphological differences
between successive samples that accumulate along a geological section
are accepted as evolutionary in nature. Evolution is then reconstructed
as a series of hypotheses of the ancestor-descendant relationship.
Assuming a strict enough correspondence between morphological and
molecular evolution, the lack of any statistically significant
difference between samples neighbouring in time and taken from the same
geographical location (a geological section) suggests a genetic
continuity between the populations represented by them. With increasing
time and space separating samples, the strength of such inference
decreases, but the reasoning (referred to as chronophyletics) remains,
in principle, the same. Different hypotheses of ancestry are in an
unavoidable logical conflict because any lineage remains rooted in only
one ancestral lineage although it may split into several descendant
lineages. Testing phylogenetic trees with fossil evidence thus requires
that a cladogram or phenogram is transformed into a set of hypotheses on
the ancestor-descendant relationship (evolutionary scenario) and the
inference has to proceed back in time (by retrodiction). The proposed
methodology is illustrated with data on the Ordovician balognathid and
Devonian palmatolepidid conodonts.
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