Views in the 1930s
As background for later developments, this chapter will describe some of the reigning views from the latter 1930s concerning cells, membranes, proteins, and metabolic systems. A brief account of some of the methods then available is also included.
Some Pliocene Fishes from Kansas, Oklahoma, and Nebraska
served in dead specimens are the series of bright blue streaks on the scaleless portions of the dorsal and dorsolateral surfaces, the white anterior edge of the first dorsal fin, the silvery tongue, and the dark vertical bands on the dorsolateral surfaces, the latter seen only in feeding skipjack. The two size groups schooled together. School disruption occurred only during feeding. The fish swam with their mouths constantly agape. They were never observed to stop swimming. No rheotaxis was demonstrated.
Late Cenozoic molluscan faunas from the High Plains
Mollusks are described from nine late Cenozoic assemblages in the High Plains region: the late middle Pliocene Buis Ranch local fauna of northwestern Oklahoma; the late Pliocene Saw Rock Canyon, Rexroad, and Bender local faunas of southwestern Kansas; the late Pliocene Red Corral local fauna of the Panhandle of Texas; the early Pleistocene Dixon, Deer Park, and Sanders local faunas of southern Kansas; and the early Pleistocene Sand Draw local fauna of north-central Nebraska. In nearly all assemblages associated mammals provide an independent age determination. The control provided by fossil mammals and stratigraphie succession permits evaluation of the mollusks for age determination and correlation. Vertebrates and mollusks are complementary, and never antagonistic, in giving age and ecologic information. The late Pliocene and Pleistocene faunal sequence of southwestern Kansas and northwestern Oklahoma is especially significant for regional and intercontinental correlation because it is the most nearly complete sequence known from such a small area. Collecting the great number of specimens and species which represent these faunas has been possible by washing large quantities of fossiliferous matrix through screens. Eeologic interpretation of the mollusks is combined with other information from the vertebrates and inferences from the depositional sequence to summarize the late Pliocene and Pleistocene climatic and faunal sequence of southwestern Kansas. Fossils from three horizons in the Rexroad formation indicate a relatively long interval in which the climate was warmtemperate, equable, and relatively moist. Above these assemblages the depositional and erosional sequence, and several faunas, indicate 4 periods of erosion and deposition of coarse clastic sediments in cool climates separated by 3 periods of deposition of finer materials during warmer climates. The alternate warm and cool climates are correlated with the Mississippi Valley interglacial and glacial ages. The Ballard formation, which is separated from the Rexroad formation by an erosional unconformity and contains the earliest evidence of marked climatic cooling, is correlated with the earliest Pleistocene sediments of the area in central Italy selected by the 18th International Geological Congress as definitive for the Pliocene-Pleistocene boundary. The successive phases in the history of North American land mammals which have been called the Blancan, Irvingtonian, and Rancholabrean ages can be correlated with the Pliocene and Pleistocene sequence of southwestern Kansas, and thus indirectly with the glacial-interglacial intervals of the Mississippi Valley. The Blancan is late Pliocene and early Pleistocene. The Blancan-Irvingtonian boundary is about in the middle of the Kansan age, and the IrvingtonianRancholabrean boundary about in the middle of the Illinoian