CAS BB 191 Lecture Notes - Lecture 16: Renal Artery, Xenarthra, Insectivora
Document Summary
In terms of the number of living species, mammals are not a particularly diverse group - there are only 4,629 described species listed in the most recent taxonomic checklist (although more have been discovered since). For perspective, this is just over half the number of bird species. However, if we look at morphological diversity, mammalian diversity is really quite remarkable. For example if we just look at size, the smallest mammal is craseonycteris thonglongyai, the bumble-bee bat. It weighs just less than 2 grams: basically, the weight of a couple of paper clips. The largest, balaenoptera musculus, the blue whale can weigh up to 200,000 kg, which is 200 million g. this represent a size range spanning 8 orders of magnitude. In addition, these two species represent both flying and marine forms; there are also gliding forms, saltatorial (hopping) forms, fossorial (burrowing) forms, arboreal forms, and forms that specialize on a diet of ants.