Understand, Discover is not a scientific journal. You have to verify the things that are written in it. It's good to have a variety of sources giving you information.
Anyway, the January/February 2010 issue of Discover is a review of the 100 top discoveries of 2009. Here's one of may favorites:
Philip Gingerich, who is the leading authority on whale evolution—unless you reject evolution, in which case you probably don't agree with him on anything—discovered a fossil of a pregnant whale dating from 47 million years ago. Amazingly, both the mother and her fetus are preserved.
What's fascinating about this discovery is that the fetus is oriented for head first delivery. This is the opposite of what happens in whales today. Whales give birth tail first so that their pups, which breathe air like all whales, don't drown while being delivered underwater.
This Maiacetus inuus, though, apparently gave birth head first, indicating they were still giving birth on land 47 million years ago, perhaps like sea lions.
In fact Maiacetus bears a resemblance to a sea lion.
This is just one more piece of evidence that whales descended from land mammals. The fossil lineage of whales is remarkably complete and is among the better and easiest to understand evidence for evolution.