The Sacramento Zoo's lecture series on evolution is set to continue March 22 with a presentation by UC Davis professor emeritus Richard Cowen — but if you don't have a ticket already, you'll have to settle for the waiting list.

Not only is Cowen's lecture sold out, so is the third and final installment of the series, set for April 26.

Cowen, a geologist, has titled his lecture "The Hard Evidence of Evolution," the hard evidence being the fossils that he plans to talk about. Cowen attended last week's lecture by Professor Maureen Stanton, who was asked by an audience member why some animals — like the crocodile — do not seem to have changed much.

Stanton said Cowen's talk would probably answer that question. Indeed, he told Dateline: Fossil evidence shows that "the first crocodiles ran around on land."

"Once they went into the water, they got good at it and stayed that way."

The zoo's education director, Robin Whittall, is scheduled to present the last lecture in the series, "History of Evolutionary Thought."

To get on the waiting list for either lecture, call (916) 264-5889.