Data from: Iterative adaptive radiations of fossil canids show no evidence for diversity-dependent trait evolution

A long-standing hypothesis in adaptive radiation theory is that ecological
opportunity constrains rates of phenotypic evolution, generating a burst
of morphological disparity early in clade history. Empirical support for
the early burst model is rare in comparative data, however. One possible
reason for this lack of support is that most phylogenetic tests have
focused on extant clades, neglecting information from fossil taxa. Here, I
test for the expected signature of adaptive radiation using the
outstanding 40-My fossil record of North American canids. Models implying
time- and diversity-dependent rates of morphological evolution are
strongly rejected for two ecologically important traits, body size and
grinding area of the molar teeth. Instead, Ornstein–Uhlenbeck processes
implying repeated, and sometimes rapid, attraction to distinct dietary
adaptive peaks receive substantial support. Diversity-dependent rates of
morphological evolution seem uncommon in clades, such as canids, that
exhibit a pattern of replicated adaptive radiation. Instead, these clades
might best be thought of as deterministic radiations in constrained
Simpsonian subzones of a major adaptive zone. Support for adaptive peak
models may be diagnostic of subzonal radiations. It remains to be seen
whether early burst or ecological opportunity models can explain broader
adaptive radiations, such as the evolution of higher taxa.