On today’s show, our guest is Anthony J. Martin, author of Dinosaurs Without Bones: Dinosaur Lives Revealed by Their Trace Fossils (Pegasus, paperback March 2015). Martin is an ichnologist, which means he studies the traces of animals in conjunction with fossils of the animals themselves. This could mean tracks or it could mean puke—and ichnology is a very powerful tool for learning more about ancient creatures. Later in the hour, contributing editor Mark Hay casts his doubts about the possibility of a human head transplant in 2017, despite whatever one determined doctor might think.

Music this hour: