I was browsing about mammals again, especially their phylogeny. Here are some thoughts on preparing a educational resource of high school students.
The Life Story of Mammals
1. The Life Cycle of Apes
2. The Family Tree of Mammals
- 10 species-rich orders: economic impact, biogreography, 4 placental clades
- the most unique species, endangered biodiversity, hot spots (species portraits from 30 small families)
- a family level survey, principles of cladistic revision (cetartiodactyla)
- a case study of murine tribes (because this is targeting a Philippine audience)
- mammals in the tree of life
3. Organ systems and diseases
4. Ecosystems and climate change
Wilson and Reeder 2005 (
MSW 3) lists 21 orders, splitting the monophyletic Lipotyphla and and treating the two clades of Xenartha as orders. If retains the paraphyletic Artiodactyla, not merging in Cetacea.
I support the trend to smaller orders, and would suggest that the following subordinal clades be treated like orders in the Life Story, and I anticipate that authorities like
Mammal Species of the World might support something similar in its 4th edition.
Split Rodentia into 5 clades:
- Hystricomorpha (Pocupine, Cavy and Gundi clade)
- Sciuromorpha (Squirrel and Dormouse clade)
- Anomaluromorpha (Animalurid and Springhare clade)
- Castorimorpha (Beaver and Gopher clade)
- Myomorpha (Mouse and Jerboa clade)
Split Artiodactyla into 4 clades
- Camelids
- Suimorpha (Pigs and Peccaries)
- Hippopotamids
- Ruminantia
Including the monotremes and 7 orders of marsupials, this would result in 36 ordinal level clades, the largest of which (Chiropterans and Hysticomorpha) have 18 families. Chiroptera could potentially be split, but it is unclear whether Pteropodids are basal or part of a larger sister group with the bulk of microbats. (A BMC article "
A higher-level MRP supertree of placental mammals" suggests that Megadermatidae, Rhinolophidae and Rhinopomatidae form a clade with fruitbats.)
A 2007 article by Bininda-Emonds in Nature reconstructs the age of divergence of mammalian families, and could provide some additional basis for revising the set of order taxa. It contains 4,510 of the 4,554 extant species listed in the 1993 ed. of MSW, or 99%. It suggests that 43 placental lineages predate the K/T boundary, so this could potentially motivate another 15 orders. For example, it suggests moles and solenodons is more basal than ancient hedgehog and shrew split in that lineage. It now places pteropodids and emballonurids as successively basal to two large microbat clades (which could be called rhinolophiforms and vespertilloniforms). It supports splitting feliform and caniform clades in Carnivora. Primates could be split 4 ways (the loris-galago clade split off from lemurs before K/T). There are early splits of jerboas from mice, and beavers from pocket gophers, adding two more rodent clades that could be elevated.
It also suggests that only the opossums, caenolestids (shrew opossums) and bandicoots are pre K/T splits among the marsupials, but the other four well-established orders are split not soon after. Camels and suiforms split early, but hippos split from cetaceans well after K/T, so Whippomorpha (or Cetacodonta) may be better than Cetacea, but probably not.
