Re: Crown Mammals with Multituberculates?

[David Marjanovic <david.marjanovic@gmx.at>]

>   Abstract: 
>   "Morphological and physiological differences and paleontological data 
> suggest the independent origin of the Prototheria and the Theria. The 
> Prototheria gave rise to the most specialized groups of Mesozoic 
> mammals. 
> The reasons for this are discussed. 
 
Here they are: 
 
Hm... 14 terminal taxa (3 of them para- or polyphyletic), 11 characters (6 
of them autapomorphic and therefore uninformative), but no polytomies, 
despite 7 unsupported nodes. (If I counted correctly.) And several 
interesting taxa are missing. Something is rotten in the state of 
Denmark... 
 
> An important role in the evolutionary 
> fate of these subclasses was played by the structural difference in the 
> region of the middle ear, since it influenced the structure of the 
> basicranium. 
 
Ah, the good old times. Phylogeny based on one single character complex, 
ignoring all others. Right? 
 
> The development of a perfect placental pattern in the therian 
> stem at the end of the Cretaceous was a key character determining the 
> fate of mammals. This gave rise to changes in the central nervous system 
> and provided for the domination of the Placentalia in the Cenozoic." 
 
Or not. 
 
>   The paper proposes the following phylogeny on the basis of some shared 
> and rather plesiomoprhic conditions outlined in the abstract: 
> 
> --Procynosuchia 
 
That's supposed to be a terminal taxon, *Procynosuchus*, right? 
 
>    `--+--Theria 
>       |   `--+--Chiniquodontidae 
 
Oh, wow. 
 
>       |      `-a-+--Kuehneotheria 
 
*Kuehneotherium* and what else? *Woutersia*? 
What is the a? 
 
>       |          `--+-4,7,8-Symmetrodonta 
 
Heavily paraphyletic. 
 
>       |             `-7-+-5,8-Eupantotheria 
 
Less heavily paraphyletic, but still impressive. 
 
>           `--+--Gomphodontia 
 
What, all of them? Diademodontidae, Traversodontidae and Tritylodontidae? 
That's... strong. 
 
>              `--+--Eotheria 
>                 |   `--+-1-Morganucodontia 
>                 |      `-4-Triconodonta 
 
And their synapomorphies? Character 1 maybe? 
 
>                 `--Allotheria 
 
That's normally just Haramiyida + Multituberculata. 
 
>                     `--+-2-+--Haramiyida 
>                        |   `-7,9-Multituberculata 
>                        `-7-+-3-Docodonta 
>                            `--Monotremata 
 
Triconodonts sensu strictissimo, Multis and monotremes have a single jaw 
joint, *Kueneotherium*, docodonts and haramiyids retain a double one like 
*Morganucodon*. Chiniquodontids and "gomphodonts" retain a single jaw 
joint, the "reptilian" one, of course. Makes 2 gains of the "mammalian" 
joint and 4 losses of the "reptilian" one. 
 
>   Numbers refer to apomorphies, as in the text and figure 7 of the 
>   paper: 
>   1) tricuspid cheek teeth; 
 
Obvious plesiomorphy. 
 
>   2) multituberculate cheek teeth; 
 
Pretty undeniable, but this is the only character complex that keeps 
Allotheria together... against all other evidence I know of. 
 
>   5) tribosphenid tooth crowns; 
 
Also in monotremes. 
 
>  11) abrupt increase in brain size. 
 
*Eomaia* has such a bigger brain than *Deltatheridium*? :-S 
 
>   A [...] competantly [sic] done paper. 
 
:-/ 

-- 
+++ GMX - Mail, Messaging & more  http://www.gmx.net +++
Bitte lächeln! Fotogalerie online mit GMX ohne eigene Homepage!