1. 1 Nautilus and Allonautilus: Two Decades of Progress W. Bruce Saunders Department of Geology Bryn Mawr College Bryn Mawr PA 19010 wsaunder@brynmawr. edu Neil H. Landman Division of Paleontology American Museum of Natural History New York, New York 10024 landman@amnh. org When Nautilus: Biology and Paleobiology of a Living Fossil was published in 1987, it marked a milestone in cross-disciplinary collaboration. More than half of the contributing authors (36/65) were paleontologists, many of whom were collaborating with neontological counterparts. Their interest in studying this reclusive, poorly known animal was being driven by a search for clues to the mode of life and natural history of the once dominant shelled cephalopods, through study of the sole surviving genus. At the same time, Nautilus offered an opportunity for neontologists to look at a fundamentally different, phylogenetically basal member of the extant Cephalopoda. It was a w- win situation, combining paleontological deep-time perspectives, old fashioned expeditionary zeal, traditional biological approaches and new techniques. The results were cross-fertilized investigations in such disparate fields as ecology, functional morphology, taphonomy, genetics, phylogeny, locomotive dynamics, etc. As one reviewer of the xxxvi Introduction xxxvii book noted, Nautilus had gone from being one of the least known to one of the best understood of living cephalopods.