In this chapter I chronicle the emergence of different phylogenetic traditions in invertebrate zoology that coalesced around attractive hypothetical ancestors. The first half of the chapter discusses different scenarios for the origin of Bilateria that emerged in the late nineteenth and early twentieth centuries, including the enterocoel and archicoelomate theories, and the importance of the contested character of amphistomy for these scenarios. These scenarios became phylogenetic totems in different parts of the world, with Gastraea at the core of the European zoological tradition, and Phagocytella rooting both the Russian and American traditions. In the mid-twentieth century an alternative theory was proposed that derived bilaterians directly from ciliate ancestors. Remarkably, this attraction to ciliate ancestors emerged three times independently in quick succession, which illustrates the epistemic importance accorded to the precursor potential of hypothetical ancestors in narrative phylogenetic debates. The second half of the chapter discusses why many authors have felt so strongly attracted to annelid-like ancestors. These were proposed to have crawled at the cradles of many taxa, including molluscs, arthropods, vertebrates, and Bilateria. The arguments used to promote annelid-like ancestors form a conspicuous strand in the history of narrative phylogenetics, and it can still be traced today.

The work of mapping the processes of geological formation is entangled with the process of extraction from deep time – a conquest figured in relation to the coal measures. Building on Alfred Gell’s approach to the relationship between time and the ways in which it is culturally constructed, this chapter addresses the question ‘Whose time is deep time?’ through a consideration of the politics of marking the boundaries of time in nineteenth-century Imperial Britain, with a particular focus on the Cambridge geologist Adam Sedgwick.