334 Evolution? The Fossils Say YES!
have more strongly developed cross crests. My friend Matt Colbert described a new species
of tapir, Hesperaletes, from the Eocene deposits of San Diego (not far from the old headquar-
ters of the ICR) that is the oldest fossil to show evidence of a nasal notch on the skull for
attachment of the proboscis. Through the past 40 million years, tapir skulls show a deeper
and deeper retraction of the nasal notch, suggesting a larger and better-developed proboscis,
until we reach the condition in living tapirs, which have the largest proboscis of all. During
this time their molars become more and more highly specialized, until they are simple cross
crests ideally suited for chopping leaves.
Finally, we should mention one more example from the perissodactyls: the brontoth-
eres, also known as the titanotheres (figs. 14.9 and 14.10). At the climax of their evolution in
FIGURE 14.9. Conventional linear view of brontothere
evolution through the Eocene from primitive forms
like Palaeosyops that are barely distinguishable from
contemporary horses (fig. 14.5) through larger and
larger forms that eventually developed two blunt
horns (H) on their noses. (After Osborn 1929)
HHHH