Fig. 27. Character trace for Character 1 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 27. Character trace for Character 1: Absence/presence of tympanic fenestra (0, white; 1, grey; 2, black). With this topology, C1:2, isolated, suture-delimited aperture emerges as a diagnostic feature of extant Chinchillidae + Amblyrhiza, with no examples of convergence and with Dinomys and Eumegamys showing an alternative state. Placing Amblyhiza among octodontoids as a relative of Geocapromys, as some authors have suggested, seems unparsimonious in light of the fact that in this superfamily neither this state nor (with the exception of Octodon) the less derived state, C1:1, notch only (bridged or unbridged), is known to occur. In this and the following figure ''Echimyidae'' refers to the four representative taxa of spiny rats selected for study (Echimys, Proechimys, Lonchothrix, Dactylomys), which are invariant for the characters traced.