WEBVTT 1 00:00:00.033 --> 00:00:02.064 http://beyondpenguins.nsdl.org 2 00:00:02.064 --> 00:00:08.059 An interview with Dr. Ross MacPhee, curator and researcher at the American Museum of Natural History. 3 00:00:08.059 --> 00:00:13.000 What is a mammal? 4 00:00:13.000 --> 00:00:16.050 Mammals are a group of vertebrates 5 00:00:16.050 --> 00:00:19.000 that is to say, animals with backbones 6 00:00:19.000 --> 00:00:22.000 who are distinguished by having four legs or 7 00:00:22.000 --> 00:00:24.093 four appendages that are like legs 8 00:00:24.093 --> 00:00:30.016 and whose young develop within a complicated series of birth membranes. 9 00:00:30.016 --> 00:00:36.033 By contrast, fish are vertebrates, but true fish lack four appendages 10 00:00:36.033 --> 00:00:38.091 so they're not tetrapod as we call them 11 00:00:38.091 --> 00:00:43.033 and animals like amphibians who do have four legs 12 00:00:43.033 --> 00:00:48.020 and do have backbones are not members of that particular group 13 00:00:48.020 --> 00:00:51.064 because they don't have these complicated birth membranes. 14 00:00:51.064 --> 00:00:58.014 We are distinguished from all other vertebrates by that general set of features. 15 00:00:58.014 --> 00:01:01.083 More specifically, we're the only group that has the combination 16 00:01:01.083 --> 00:01:08.000 of hair, mother's milk and three tiny bones in the middle ear 17 00:01:08.000 --> 00:01:11.083 that are responsible for conducting sound from the outside 18 00:01:11.083 --> 00:01:15.050 to where it can be interpreted in the brain. 19 00:01:15.050 --> 00:01:17.078 http://beyondpenguins.nsdl.org 20 00:01:17.078 --> 00:01:21.031 For more: Go online to the January 2009 issue on mammals. 21 00:01:21.031 --> 00:01:25.017 Special thanks to Dr. MacPhee and the American Museum of Natural History for the making of this recording. 22 00:01:25.017 --> 00:01:28.032 Recorded at AMNH, October 2008. Karen Taber, Producer 23 00:01:28.032 --> 00:01:33.015 Podcast produced by Robert Payo National Science Digital Library