TABLE 1. Dental measurements (in mm) of the m3 of Pseudotomus and Manitsha. Mean values for other taxa were derived from Wood (1962) and Storer (1988). Abbreviations: L, anteroposterior length; aW, transverse width of anterior portion of tooth; pW, transverse width of posterior portion of tooth.
| L | aW | pW | aW / L | |
| JODA 8900, Pseudotomus sp. | 9.35 | 8.92 | 7.82 | 0.954 |
| P. californicus (Wood, 1962) | 7.03 | 5.64 | 5.45 | 0.802 |
| P. horribilis (Wood, 1962) | 5.93 | 5.34 | 5.30 | 0.901 |
| P. littoralis (Wood, 1962) | 6.6 | 5.2 | 5.0 | 0.788 |
| P. petersoni (Wood, 1962) | 6.26 | 5.65 | 5.26 | 0.903 |
| P. robustus (Wood, 1962) | 6.46 | 5.46 | 5.52 | 0.845 |
| P. timmys (Storer, 1988) | 9.9 | 9.2 | 7.7 | 0.929 |
| Manitsha tanka (Wood, 1962) | 9.37 | 8.50 | 7.83 | 0.907 |
TABLE 2. Dental measurements (in mm) of the holotype of Proischyromys perditus n. gen., n. sp. (UCMP 170698), as well as species of Ischyromys and Spurimus. Mean values for other taxa were derived from listed literature sources. Length of the tooth row (p4-m3L) was measured at the alveolar level. Abbreviations: L, anteroposterior length; W, transverse width.
| iL | iW | m1L | m1W | m2L | m2W | m3L | m3W | p4-m3L | |
| Proischyromys perditus n. gen., n. sp. | 4.03 | 1.88 | 3.01 | - | 2.98 | 3.06 | 3.04 | 2.81 | 12.30 |
| Ischyromys typus (Wood, 1937) | - | - | 3.69 | 3.41 | 3.68 | 3.53 | 3.99 | 3.32 | 14.36 |
| I. blacki (Wood, 1974) | ~4.6 | - | - | - | 2.94 | 3.36 | 3.56 | 3.20 | 13.0 |
| I. douglassi (Black, 1968) | - | - | 3.65 | 3.61 | 3.71 | 3.82 | 3.84 | 3.81 | 15.6 |
| I. junctus (Russell, 1972) | - | - | - | - | 2.94 | 3.03 | 3.40 | 3.00 | - |
| I. parvidens (Wood, 1937) | - | - | 2.97 | 2.64 | 2.77 | 2.91 | 3.38 | 2.81 | 12.16 |
| I. pliacus (Wood, 1937) | - | - | 3.76 | 3.89 | 3.89 | 3.97 | 4.1 | 3.6 | 16.4 |
| I. veterior (Wood, 1974) | 3.23 | 1.74 | 3.47 | 3.21 | 3.57 | 3.48 | 2.98 | 2.72 | 14.4 |
| Spurimus scottii (Black, 1971) | - | - | 2.18 | 1.95 | - | - | - | 2 | - |
| S. selbyi (Black, 1971) | - | - | 2.23 | 2.11 | - | - | 2.3 | 2 | - |
TABLE 3. Comparison of some Eocene rodent faunas from Oregon and California.
| Fauna | Taxa | Age |
| Friars Fm., California | Microparamys minutus Microparamys woodi Pseudotomus californicus Pseudotomus littoralis ?Uintaparamys caryophilus Uriscus californicus Sciuravus powayensis Pareumys granger Metanoiamys agorus |
Early Uintan (Ui1) |
| Santiago Fm., California | Eohaplomys serus Eohaplomys tradux Microparamys minutus Microparamys tricus Microparamys woodi Pseudotomus sp. Rapamys fricki Sciuravus powayensis Metanoiamys agorus Griphomys alecer |
Uintan (Ui2 - Ui3) |
| Brea Canyon Local Fauna, Sespe Fm., California | Eohaplomys matutinus Eohaplomys serus Eohaplomys tradux Mytonomys burkei Metaparamys compressidens Rapamys fricki Reithroparamys sp. Tapomys tapensis Uintaparamys leptodus ?Uintaparamys caryophilus Pareumys milleri Metanoiamys marinus Griphomys alecer |
Late Uintan (Ui3) |
| Hancock Quarry, Clarno Fm., Oregon | Rodentia incertae sedis | Late Uintan (Ui3) or Duchesnean |
| Whitecap Knoll, John Day Fm., Oregon | Pseudotomus sp. | Duchesnean |
| Pearson Ranch Local Fauna, Sespe Fm., California | Microparamys tricus Microparamys woodi Uintaparamys sp. Pareumys milleri Presbymys lophatus Griphomys alecer |
Duchesnean |
| Simi Valley Landfill Local Fauna, Sespe Fm., California | Simimys landeri Simimys simplex ?Simiacritomys whistleri Metanoiamys korthi Paradjidaumo reynoldsi Heliscomys walshi |
Duchesnean |
| Upper Conglomerate Member,
Pomerado Conglomerate, California |
Ischyromys sp. Metanoiamys sp. Protadjidaumo sp. cf. Paradjidaumo sp. cf. Griphomys sp. Heliscomys sp. Nonomys gutzleri Unnamed Nonomyinae |
Late Duchesnean or Early Chadronian (Ch1) |
| Lost Creek, John Day Fm., Oregon | Proischyromys perditus n. gen., n. sp. | Chadronian (Ch2 or later) |
