Date of this Version
BULLETIN 20 VOLUME I June, 1931
Respecting the giant beaver, Castoroides, in Nebraska, four occurrences can be reported. Of rodents in general the dawn. was in the early Eocene, at which time there were in existence certain squirrel-like members of the order. Rodents are a persistent group, and are among the smallest, most distinctive, most numerous and widely distributed orders of terrestrial mammals. No other order boasts of so many species, the number being between nine hundred and one thousand. In spite of wide divergencies and modifications adapting them to various modes of life, such as climbing, burrowing, swimming, flying, leaping, and running, there is remarkable unity of plan in their general structure. This rule applies to living and extinct forms alike.