It was with great pleasure that I read of the discovery of a fossil representing an amphibious basal ichthyosaur. The ichthyosaurs were "fish-lizards", basically the "reptilian" ("reptile" being an outdated term due to paraphyly) equivalent of the mammalian cetaceans. The ichthyosaurs eventually evolved to become so committed to a solely aquatic existence that, while some early forms gave birth on land, the more derived forms gave birth to live young underwater. The ichthyosaurs became a diverse group of critters, featuring such amazing beasts as the huge-eyed Ophthalmosaurus, which probably dove into the stygian darkness of deep waters, and the sperm whale-sized Shonisaurus
The discovery of a primitive ichthyosaur that could function on land much like a seal is significant because it potentially allows paleontologists to determine what terrestrial lineage the transition ichthyosaur evolved from.
Recently, many gaps in the evolutionary history of whales have been filled in. To see a similar expansion of our knowledge of another great lineage's "back to the sea" trajectory makes me positively giddy. Despite the bleatings and blatherings of creationists, the gaps in the great chain of being keep getting filled in, making for a more complete evolutionary narrative.