|| | | || || | | | || canada pharmacy viagra 25mg The following
passage by the great paleontologist is worth quoting, as it
elucidates very well the difficulties inherent in any system of
biological classification, and the different, indeed opposite,
approaches of the ("horizontal") and the ("vertical") systems.
This be it noted was written in 1945, many years before was
founded. Here, "vertical" means phylogenetic - extending through
time from ancestor to descendents. "Horizontal" means living at
the same time. It is a peculiarity of geologists, and, following
them, paleontologists, that time should be measured as an upward
march from bottom to top. This is due obviously to the practical
fact that the earliest rock strata were deposited first, and
hence lie at the bottom of the sequence; the younger strata
being deposited above them, leading to the traces of ancient
time (as measured in successive rock deposits and the fossils
they contain) as measured in terms of vertical succession. This
mistaken spatial i