Rodent community change at the Pliocene–Pleistocene transition in southwestern Kansas and identification of the Microtus immigration event on the Central Great Plains

A preliminary diversity-divergence model for North American arvicolid rodents

“…1. These numbers represent best estimates of global first appearance data in the fossil record Lindsay et al 2002;Bell et al 2004;Tesakov et al 2007;Martin 2008Martin , 2010Martin et al 2008;Hordijk and De Bruijn 2009), and of course there is likely an attendant, undetermined error value associated with each. Nevertheless, the origin of a phenotypically recognisable arvicolid in the fossil record likely does not antedate 6.0 Ma, and the entire radiation of North American arvicolids took place within the last 5.5 million years.…”

Pedogenic carbonate stable isotope record of environmental change during the Neogene in the southern Great Plains, southwest Kansas, USA: Oxygen isotopes and paleoclimate during the evolution of C4-dominated grasslands

“…Here, we discuss the basic stratigraphy, sampling strategy, analytical methods, and δ 13 C values of pedogenic carbonates in the area of Meade, Kansas, which are interpreted in detail by Fox et al (2011) in a companion paper in this issue. In brief, the sections sampled range in age from early late Miocene to early Pleistocene based on detailed small mammal biostratigraphy (Martin et al, 2000(Martin et al, , 2008Honey et al, 2005), magnetostratigraphy for some sections (Lindsay et al, 1975;Martin et al, 2008), and several interbedded ashes in the Pleistocene sections (Izett et al, 1981;Izett and Honey, 1995;Lanphere et al, 2002). The carbon isotope record indicates that the evolution of the modern, C 4 -dominated grassland ecosystem of that region of the southern Great Plains was protracted and took place in several stages (Fig.…”

Ground squirrels (Rodentia, Sciuridae) of the late Cenozoic Meade Basin sequence: diversity and paleoecological implications

“…Ictidomys tridecemlineatus first appeared in the Meade Basin along with an extinct prairie dog, C. hibbardi. Cynomys hibbardi was present by the late Pliocene in northern Kansas (Goodwin, 1995b), but apparently did not expand its range southward until the early Pleistocene, essentially coincident with the Microtus Schrank, 1798 immigration event in the Meade Basin (Martin et al, 2008).…”

“…Second, oxygen isotopic analysis of paleosol carbonates suggests an association between the stepwise increase in C 4 abundance and a combination of cooling temperatures, increased winter precipitation, and/or increased soil moisture, with particularly significant change across the PliocenePleistocene transition (Fox et al, 2012a)-a change reflected in the replacement of a more southern-adapted rodent community with one more adapted to temperate conditions (Martin et al, 2008). Based on the distribution and ecology of modern representatives, the same pattern holds for sciurids; Pliocene species with modern congeners either permit (I. meadensis) or support (O. rexroadensis and Ammospermophilus sp.)…”