Ambulocetus natans was an early whale ancestor capable of moving on land and underwater. Named from an almost complete skeleton from Pakistan, A. natans was sea lion-sized and likely ambushed its prey. Since it did not have a tail fluke, this amphibious cetacean ancestor used its prominent hind limbs as oars to propel itself underwater. Its dense limb bones(osteosclerotic) tells us that it moved well in estuarine habitats, but was probably clumsy on land. Its face was long, and crocodile-like, with eyes set dorsally and probably fed by drowning larger prey.
It was an important discovery in piecing together the cetacean family tree, as it showed how whales went from "land-lubbers" to blubber-laden fully aquatic ecomorphs.
How do we know it was a whale? The one feature that consistently unites whales and their kin are the ear bones (auditory bullae) and A. natans is no exception. Analysis of its ear reveals that Ambulocetus heard well underwater.
How I Did It
I wanted to show Ambulocetus in its element using the latest science. I began with a rough gesture drawing (Fig. 1) to which I then added digital textures in Photoshop. To understand the surface anatomy better, I created a muscle reconstruction (Fig. 2).
Understanding of the musculature allowed me to work out lighting over the forms better. Although the coat pattern of Ambulocetus is speculative, I was inspired to use facial markings similar to those of modern whales. Lastly, I wanted to add very contrasted lighting for two reasons: 1.) to simulate the soft shadows seen in murky underwater photographs 2.) represent the former "mystery" of whale evolution and consequent "light" of discovery brought about by Ambulocetus.
Kemp, T. S. (2005). The Origin and Evolution of Mammals (PDF). Oxford University Press. ISBN 0-19-850760-7. OCLC 232311794. Retrieved June 2016.
Konami Ando, Shin-ichi Fujiwara, Farewell to life on land – thoracic strength as a new indicator to determine paleoecology in secondary aquatic mammals.
Thewissen et al. 2009, Ambulocetidae: the First Marine Cetaceans.