9714923 Gingerich The origin and early evolution of whales is one of the most profound evolutionary transitions that can be studied in the fossil record. The transition to whales involved a major shift of adaptive zone from life on land to life in water, with concomitant changes in feeding, hearing cognition, and locomotion that affected conspicuous features of dental, cranial, endocranial, and postcranial skeletal morphology. Evidence of change in all of these characteristics is well preserved in fossils of the extinct Eocene suborder Archaeoceti, permitting direct investigation in the context of geological time. Archaeocetes are best known from the Tethys Sea Neo-Tethys separating India and North Africa from Eurasia during Eocene time. Tethyan whales to be studied here are found on passive continental margins in a succession of strata of different lithologies deposited at different points in cycles of sea level change. These may reflect global change in eustatic sea level, which is the first hypothesis to be tested here with better foraminiferal control. The origin of whales from land-mammal ancestors is not a controversial idea, but the evolutionary trajectory is sometimes conceived proceeding from a wolf-like ancestor through bear-like, otter-like, and a seal or sea lion-like stages to modern whales. The second hypothesis to be tested is how realistic such a 'null succession' of living carnivores is as a model for the actual diversification of early whales through geological time. Model and paleontological patterns are to be compared graphically and quantitatively. Finally, evolutionary transitions are often thought of as simple and straight, at more or less constant rate, and the third hypothesis to be tested is the simplicity (versus 'bushiness') of the transition and uniformity of rates during the transition to whales. Methods to be employed include those of discovery: new Eocene archaeocete whales are to be collected from eastern Tethyan stratigraphic sequences in Pak istan, and possibly Egypt and Tunisia because these are countries where shallow marine facies are widely distributed, well exposed, and known to yield well preserved archaeocete skeletons. The principal investigator has organized field expeditions in Pakistan and Egypt over the past 20 years yielding one-third of the documented generic diversity and the most complete skeletons of archaeocetes found anywhere. Archaeocetes are diverse morphologically and their study cannot be advanced without more specimens of such quality. Other methods to be employed here include 18O isotopic study of ontogenetic and phyletic series to document adaptation to sea water on both time scales, and newly developed quantitative graphical methods for illustration and paleobiological interpretation, with multivariate quantification of 'distance' and rates of change between these to be developed as part of this research. The proposed research is important because whales enjoy great public interest and their origin provides an opportunity to illustrate and explain evolution to a wide audience. The origin of whales can and should serve as a model for investigation of major evolutionary transitions in the fossil record in terms of morphological and temporal intermediates, graphic representation of these, and quantitative comparison through geological time.
