Hypermorphosis in Irish Elk (Megaloceros)
The 13' antler rack in Megaloceros is sometimes argued to
be an example of Orthogenesis,
that is, continued growth of a structure past the point where it is
adaptive, or some other special explanation. Gould showed instead that
deer antlers are positively allometric with respect to body size [here,
height at the shoulder]. That is, antler size in Megaloceros is the expected size
for a species of its height (left), and requires no special
explanation. The same relationship holds within species, such that
larger Megaloceros have
proportionately larger antlers than smaller (right).
Text material © 2005 by Steven
M. Carr