Stephen Jay Gould (1989/2002) argued that replaying the ‘tape of life’ would result in radically different evolutionary outcomes. Gould’s ‘radical contingency thesis’ focused primarily on animal morphology, and in particular on the specific parameters of animal body plans, which, he argued, reflect but a small fraction of the larger set of equally functional morphological possibilities that for historically contingent reasons were never actualised. Were the tape replayed from different crucial junctures in the history of life, Gould contended, animal evolution would be channeled into radically different pathways, its topography would assume a markedly different shape, and many properties associated with extant animal life would never have arisen. Imagine how the history of animal life would have unfolded, for example, were it not for the improbable survival of Pikaia, the understated ancestor to all modern vertebrates, or for the fortuitous survival of the lobe-finned fish that would eventually give rise to tetrapods, or for the meteor-induced extinction of the non-avian dinosaurs whose emptied niches permitted the unlikely radiation and macro-faunal dominance of mammals. These examples suggest that the radical contingency thesis is best interpreted as a modal thesis, or a claim about the stability of certain evolutionary outcomes across nomically possible worlds. In particular, it is a claim about the causal dependency of evolutionary outcomes on small changes in initial conditions, such as quirky survival and extinction or mutation events, particularly in the early stages of the evolution of higher taxa (Powell forthcoming; Powell and Mariscal 2015). In addition, unpredictability (McGhee 2013; Beatty 2006), stochasticity (Turner 2012), path-dependency (Desjardins 2011), developmental constraints (Powell and Mariscal 2015), and the lack of laws governing the evolution of phyla-distinguishing morphology (Haufe 2015) are also important dimensions of the Gouldian view of life.