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The figure shows a simplified phylogeny of mice (Mus sp.), rats (Rattus sp.), pouched rats (Cricetomys sp.), and squirrels (Ictidomys sp.). Pouched rats are Nesomyid rodents that are distantly related to Murids. Silhouettes show approximate size differences among species. Time periods are listed along the x-axis, and estimated from previous research [31,32,39]. MYA: million years ago, Plioc: Pliocene, IV: Quaternary period.
