TABLE 1. Geographic representation of number of species in select rodent Families. Based on fossil occurrence data in Supplementary Material.
| West US | % | East US | % | Both | % | Total | |
| Mylagaulidae | 1 | 50 | 1 | 50 | 0 | 0 | 2 |
| Castoridae | 4 | 44 | 2 | 22 | 3 | 33 | 9 |
| Hydrochoeridae | 1 | 50 | 1 | 50 | 0 | 0 | 2 |
| Erethizontidae | 3 | 60 | 1 | 20 | 1 | 20 | 5 |
| Aplodontidae | 1 | 100 | 0 | 0 | 0 | 0 | 1 |
| Sciuridae | 32 | 51 | 19 | 30 | 12 | 19 | 63 |
| Geomyidae | 12 | 44 | 11 | 41 | 4 | 15 | 27 |
| Heteromyidae | 22 | 59 | 5 | 14 | 10 | 27 | 37 |
| Cricetidae | 46 | 52 | 21 | 24 | 21 | 24 | 88 |
| Arvicolidae | 25 | 35 | 28 | 39 | 18 | 25 | 71 |
| Dipodidae | 0 | 0 | 6 | 86 | 1 | 14 | 7 |
| Totals | 147 | 47 | 95 | 30 | 70 | 22 | 312 |
