After rodents, bats are the second largest group of mammals, representing a staggering 20% of all mammal species. They can be found all over the world, with the exception of cold climates, where they often play incredibly important ecological roles. Their ecologies (ways in which they live) go well beyond the cave-hanging, moth-eating stereotypes and diets can also be based on fruits, nectar or even blood. In fact, some tropical plants rely solely upon bats for pollination!

But when did bats evolve and who are their closest relatives? Do they have a good fossil record? Is vampirism an effective feeding strategy?

In this episode, we're joined by Dr Nancy Simmons, Curator-In-Charge of Mammalogy at the American Museum of Natural History, who introduces us to the wonderful world of bats and their fossil record.

Whether it be because of their unique shape, comical walking or extreme ecology, there can be no denying that penguins are incredibly popular and charismatic animals. But what actually makes a penguin a penguin and how are they different from other birds? Have penguins always been, well, 'penguiny'?

Joining us for this interview are Simone Giovanardi and Daniel Thomas who have just described a new species of giant penguin from New Zealand. Together, we explore penguin evolution and how their new species Kairuku waewaeroa fits into this story.