Rodent, rabbit, tree shrew and multituberculate skulls compared

In an effort to understand 
a clade that was giving me trouble on the LRT, I put together the following set of skulls (Fig. 1, click here to enlarge) from the redefined clade Glires (still rodents and rabbits, but also their closest kin).

Figure 1. Click to enlarge. See text for explanation.

Figure 1. Click to enlarge. See text for explanation.

In the above illustration.
Select members of the Glires (rodents, rabbits and relatives, all derived, ultimately from the basal placental, Monodelphis, not to scale. Numbers refer to columns:

  1. Tupaia is a tree shrew. Macroscelides is an elephant shrew. Chrysochloris is a golden mole.
  2. Scutisorex is a hero shrew. Apatemys is a an arboreal apatemyid. Trogosus is a terrestrial apatemyid or tillodont. 
  3. Solenodon is a solendontid. Zalambdalestes is another solenodontid. 
  4. Nambaroo is a primitive rabbit and a kangaroo mimic. Brachyerix is an extinct hedgehog. Gomphos is an extinct rabbit. Orytolagus is an extant rabbit.
  5. Carpolestes is an arboreal plesiadapiform. Plesiadapis is another arboreal plasiadapiform. Taeniolabis is a multituberculate. 
  6. Shenshou is a pre-rodent. Paramys is an extinct rodent. Rattus is an extant rodent. Ignacius has not been tested but usually nestes with plesiadapiform. 
  7. Kryptobaatar is a multituberculate. Ptilodus is a multituberculate. Rugosodon is a multituberculate. Megconus is another multituberculate often considered a mammaliaform.

Still have not found evidence
that multituberculates nested in a clade more primitive than placentals. You’ll note that Zalambdalestes now nests with Solenodon despite the epipubes (found occasionally in other placentals, too). Glires nests between Carnivora and Ptilocercia. See yesterday’s post on basal placentals for basalmost taxa.



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