Cheng-Hsiu Tsai and R. Ewan Fordyce 2015 Ancestor-descendant relationships
Ancestor–descendant relationships (ADRs), involving descent with modification,
are the fundamental concept in evolution, but are usually difficult to
recognize. We examined the cladistic relationship between the only reported
fossil pygmy right whale, †Miocaperea pulchra, and its sole living relative, the
enigmatic pygmy right whale Caperea marginata, the latter represented by
both adult and juvenile specimens. †Miocaperea
is phylogenetically bracketed
between juvenile and adult Caperea marginata
in morphologically based analyses,
thus suggesting a possible ADR—the first so far identified within
baleen whales (Cetacea: Mysticeti). The †Miocaperea–Caperea
lineage may
show long-term morphological stasis and, in turn, punctuated equilibrium.