Fossil evidence of several species has been found linking modern day whales to their ancient land mammals ancestors. This series of fossils provide evidence for

Whale evolution - There is ample evidence of translational forms. The whale is a perfect example: We see a succession of ever more whale-like fossils in the fossil record, the most primitive, which is closest to the stem mesonychids, are also the oldest, as we move through successively younger rocks, the teeth come more simple and more numerous, the naris fuses and moves ever more posterior, the pelvis reduces, the tail elongates, the joins [sic] between the vertebrate [sic] modify to allow increasing flexion, the hind limbs reduce, the forelimbs become more robust, with shorter proximal parts and enlarged carpals and phalanges, the auditory bulla enlarges and becomes more dense (see: Indohyus, Archaeocetus, Ambulocetus, Pakicetus, Basiliosaurus etc.).