List of endocranial character states from Nesophontes (several characters were adopted and modified from Macrini et al., 2007a).
Olfactory bulb cast percent composition: 6% or greater = 0; less than 6% =1
Nesophontes olfactory lobe percent composition from total brain volume ranges from 20-25% (score of = 0). Nesophontes approaches the overall percent composition of Tenrec and Hemicentetes the most (Stephan and Andy, 1982). That of Solenodon is 17.95%, and from other insectivorans reported by Stephan and Andy (1982).
Width to length ratio of olfactory lobes: longer than wide (aspect ratio < 0.9) = 0; wider than long (aspect ratio > 1.1) = 1; equivalent (aspect ratio between 0.9 and 1.1) = 2. Nesophontes sp. scores = 2.
Accessory olfactory bulb casts: absent=0; present=1.
Accessory olfactory bulbs are not always present in the endocranial casts of extinct or extant mammals (Bauchot and Stephan, 1967; Macrini et al., 2007a). Stephan and Andy (1982) reported “no accessory bulbs” on the olfactory lobes of Solenodon paradoxus. This state is scored = 0 here, was considered unique in Solenodon in comparison to other insectivoran-grade mammals such as Erinaceus, Sorex, Tenrec, Hemicentetes, and Microgale. It also scores = 0 in Nesophontes .
Such accessory bulbs apparently receive nerve fibers (or projections) from the vomero-nasal organ and are involved in the detection of pheromones (Nieuwenhuys et al., 1998; Macrini et al., 2007a).
Olfactory bulb tracts (or peduncles): not visible on endocasts = 0; visible on endocasts = 1. Nesophontes sp. scores = 1.
This character is problematic in Nesophontes because there are slight discrepancies between the natural and digital endocasts. Natural endocasts show a slight indentation or gap between the neocortex and cerebellum that seems very shallow in the digital endocast. However, imprints within this region of the osseous braincase support a shallow gap between these structures.
Extent of vermis cerebelli: cast of vermis extending to or even with the parafloccular casts = 0; vermis remains behind the parafloccular casts = 1; vermis extends beyond parafloccular casts = 2. Nesophontes sp. scores = 2.
Prootic canal visible on squamosal bone of the skull (character taken from Wible, 2008): absent = 0; present = 1. Both Cuban Nesophontes score = 1. The orbitotemporal grove may be associated with this structure in Nesophontes , as it is in Solenodon (ecps: Wible, 2008: figure 21, p. 349).
Prootic canals are not known from any other placental mammal. They are reported from Mesozoic mammaliaforms and several Cenozoic eutherians, monotremes, and some marsupials. See Wible (2008) for discussion of this character and literature.