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.
Ancient Origin of the Modern Deep-Sea Fauna
The origin and possible antiquity of the spectacularly diverse modern deep-sea fauna has been debated since the beginning of deep-sea research in the mid-nineteenth century. Recent hypotheses, based on biogeographic patterns and molecular clock estimates, support a latest Mesozoic or early Cenozoic date for the origin of key groups of the present deep-sea fauna (echinoids, octopods). This relatively young age is consistent with hypotheses that argue for extensive extinction during Jurassic and Cretaceous Oceanic Anoxic Events (OAEs) and the mid-Cenozoic cooling of deep-water masses, implying repeated re-colonization by immigration of taxa from shallow-water habitats. Here we report on a well-preserved echinoderm assemblage from deep-sea (1000–1500 m paleodepth) sediments of the NE-Atlantic of Early Cretaceous age (114 Ma). The assemblage is strikingly similar to that of extant bathyal echinoderm communities in composition, including families and genera found exclusively in modern deep-sea habitats. A number of taxa found in the assemblage have no fossil record at shelf depths postdating the assemblage, which precludes the possibility of deep-sea recolonization from shallow habitats following episodic extinction at least for those groups. Our discovery provides the first key fossil evidence that a significant part of the modern deep-sea fauna is considerably older than previously assumed. As a consequence, most major paleoceanographic events had far less impact on the diversity of deep-sea faunas than has been implied. It also suggests that deep-sea biota are more resilient to extinction events than shallow-water forms, and that the unusual deep-sea environment, indeed, provides evolutionary stability which is very rarely punctuated on macroevolutionary time scales.