The Maiacetus ("Good Mother Whale") is known from two fossils, and was first described in 2009. From the evidence, scientists have suggested that this four-legged whale ancestor gave birth on land, but lived most of its life in the water.
I wanted to show this land/water lifestyle by portraying the Maiacetus and its young wading in the shallows. Here's the sketch I presented to the art director of Ranger Rick magazine (the finished picture appears in this month's issue). Friday I'll show you the maquette and the finished picture.
Wikipedia on Maiacetus.
More about Ranger Rick, with an interview about the process.