Catie Willard and Lindsey Baumoel

Question??? How have whales physiologically evolved from land to water? Whale Video

Pakicetus Three genera: Pakicetus, Nalacetus, and Ichthyolestes Eocene Kuldana Formation of Pakistan Evidence of Fossils

Ambulocetus million years ago Well developed fore- and hind-limbs Swam by pelvic paddling Hind feet large, with elongated, flattened toes suggesting webbed feet and the ability to walk on land

Dorudon Late-middle Eocene Smaller dolphin-sized animals Skeletal morphology of caudal region No sacrum and floating pelvis

Basilosaures 40 to 34 million years ago Hind limbs to short to support body mass 18 meters (60 feet) The hind limbs had fused tarsals Absence of articulation Possible functions of limbs

Mysticeti and Odontoceti Miocene Have baleen teeth used for filter-feeding Very large and do not dive to great depths Typically smaller than baleen whales Have teeth Swim rapidly and dive deep

Molecular Evidence Five mitochondrial DNA sequences and eleven nuclear-encoded protein sequences aligned from Cetacea, two Artiodactyl suborders and an outgroup Cetacean DNA sequences from Finback Whale Protein sequences come from different whales depending on who the sequence was known for in each of the eleven proteins Maximum parsimony and maximum likelihood where the methods of reconstruction used for alternative phylogenetic trees Only transversions were looked at for the DNA sequences Statistical testsCow-PigCow-CetaceanPig-Cetacean PARS ML08911

Molecular Evidence PROTPARS was used to calculate the number of amino acid replacements required for each alternative tree The reliability of these tests was determined by bootstrap re-sampling of parsimony and several other tests; for DNA sequences the max-likelihood trees were also tested by bootstrap re-sampling

Results Tree one is the presently accepted taxonomic scheme The DNA data using max parsimony and max likelihood combined with bootstrap resampling gives tree II For protein sequences the traditional tree was not supported by any of the tests; the only significant support was for tree II

Works Cited Bejder, Lars and Brian K. Hill Limbs in whales and limblessness in other vertebrates: mechanisms of evolutionary and developmental transformation and loss. Evolution and Development. 4(6): Gingerich, Philip D Land-to-sea transition in early whales: evolution of Eocene Archaeoceti (Cetacea) in relation to skeletal proportion and locomotion of living semiaquatic. Paleobiology. 29(3): Gingerich, Philip D Paleobiological perspectives on Mesonychia, Archaeoceti, and the origin of whales. Paleobiology

Works Cited cont’d Graur, D. and Higgens, D Molecular evidence for the inclusion of cetaceans within the order artiodactyla. Mol. Biol. Evol. 11(3): Thewissen, J. G. M., Hussain, S. T., and Arif, M Fossil evidence for the origin of aquatic locomotion in Archalocete whales. Science. 263(5144): Thewissen, J. G. M, Williams, E. M., Roe, L. J., and Hussain, S. T Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature. 413: