Nocturnal bottleneck

Artist's impression of the Purbeck lagoon at dusk: Durlstotherium (right and center foreground) and Durlstodon (left foreground) ventured out at night to hunt insects. The theropod Nuthetes holding a captured Durlstotherium (centre middle distance).
The tapetum lucidum of a European badger reflects the photographer's flash, one of many nocturnal traits ubiquitous in mammals

The nocturnal bottleneck hypothesis is a hypothesis to explain several mammalian traits. In 1942, Gordon Lynn Walls described this concept which states that placental mammals were mainly or even exclusively nocturnal through most of their evolutionary history, from their origin 225 million years ago to after the Cretaceous–Paleogene extinction event, 66 million years ago.[1] While some mammal groups later adapted to diurnal (daytime) lifestyles to fill newly unoccupied niches, the approximately 160 million years spent as nocturnal animals has left a lasting legacy on basal mammalian anatomy and physiology, and most mammals are still nocturnal.[2]

  1. ^ Gerkema, M. P.; Davies, W. I. L.; Foster, R. G.; Menaker, M.; Hut, R. A. (3 July 2013). "The nocturnal bottleneck and the evolution of activity patterns in mammals". Proceedings of the Royal Society B: Biological Sciences. 280 (1765): 20130508. doi:10.1098/rspb.2013.0508. PMC 3712437. PMID 23825205.
  2. ^ Sinn, J. "New Study Shows Effects of Prehistoric Nocturnal Life on Mammalian Vision". University of Texas. Retrieved 24 November 2014.