but not actually known. The term ‘ghost lineage’ has also been used in a similar sense
(e.g. Wagner 1998). Here I use the term ‘ghost range’ (Benton and Storrs 1996), because
often what is really being implied is that the stratigraphic range of a fossil taxon should be
extended back below the stratigraphically earliest occurrence of the taxon. Techniques
have been developed to put confidence intervals on known stratigraphic ranges (e.g. Paul
1982; Strauss and Sadler 1989; Marshall 1990, 1994, 1997, 1998) and therefore the
reality of ghost ranges should be amenable to study.
Ghost rangesGhost ranges occur where phylogenetic reconstructions predict fossil ranges beyond the
known stratigraphic occurrence of the fossils. In particular, cladistic methodology refers
all closest relationships to sister groups and assumes that the sister groups arose at the
same time. For example, Figure 5.1A shows the true phylogenies of three pairs of species.
Figure 5.1B shows the cladograms for these species, which produce ghost ranges from
Figure 5.1 Diagrams illustrating the origin of artificial ghost ranges. A. Real phylogenies of three
pairs of species (solid lines). B. Corresponding stratigraphic ranges (solid lines) and artificial ghost
ranges (broken lines, GR), which can be any length from zero to 100 per cent of the stratigraphic
range of the ancestral species.
94 CHRISTOPHER R.C.PAUL