For studies investigating trait evolution, there are at least two important questions. First, have traits under consideration influenced cladogenesis and extinction in the group? Second, how do fossil data alter inferences about trait evolution or diversification-rate dynamics? However, relatively few studies have assessed these questions. Here, we use recently developed methods to test for trait-dependent diversification in the New World colubrid snake tribe Lampropeltini. We also integrate data from fossil taxa into phylogenetic estimation of evolutionary parameters using a simple Monte Carlo randomization test. These analyses suggest that ecological conditions in temperate regions are tied to higher rates of cladogenesis, but that body size is not related to diversification in the group. We also find that the inclusion of fossil taxa alters absolute estimates of size and the rate of size evolution, but not the overall pattern of ecomorphological diversification, as well as estimates of evolutionary rates, particularly extinction.