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ornithischian classification (modified; more detailed)





Dear All,
Okay, here is my modified and expanded classification (with more plesions/plesia---anyone know for sure which is correct?). To avoid confusion I will cladistically split the euornithopod clade. It will also avoid a possible priority issue with Iguanodontidae (but I am still fighting off the strong urge to lump some of these).
I am going to remain conservative (for the time being) on the issues which George has brought up:
(1) Pisanosauridae (a possible marginocephalian??); and (2) possible paraphyly of Thyreophora sensu lato----i.e. Stegosauridae forming a clade between an ankylosaurid clade 3A-C (Thyreophora sensu stricto) and the ceropodan clade [presently coded 4+]. Look forward to hearing more from George ("in due time"). If George is right, I'm not sure if Emausaurus will group with the stegosaurs or the ankylosaur clade. Also wondering if Jeholosaurus and Echinodon are part of this thyreophoran mess or if one or both of them split off just basal to it (so I didn't put those two in yet).
Decided to keep the main clade coding in a vertical column, but indented the subsidiary clades like Jaime did. Does this make it more cladogram-like and easier to read? I might even indent the main clades too if it is useful (without getting confusing).
Hey look, only one paraphyletic family (Protoceratopsidae) in the whole bunch now. More notes below the classification.
----Interesting stuff, Ken Kinman
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ORDER ORNITHISCHIFORMES
1 Pisanosauridae
2 Lesothosauridae (= Fabrosauridae)
3 Plesion _Scutellosaurus_
B Pl. _Scelidosaurus_
C Ankylosauridae
D Pl. _Emausaurus_
E Stegosauridae (incl. Huayangosaurus)
4 Thescelosauridae (not near ornithopods??)
5 Plesion _Agilisaurus_
6 Heterodontosauridae
B Pl. _Stenopelix_
C Pachycephalosauridae
? Pl. _Chaoyangsaurus_ (incertae sedis)
D Psittacosauridae
E Protoceratopsidae
_a_ Ceratopsidae
7 Zephyrosauridae
B Othielliidae
8 Hypsilophodontidae
9 Pl. _Tenontosaurus_
B Pl. _Rhabdodon_
10 Pl. _Gasparinisaura_
11 Dryosauridae
12 Camptosauridae
13 Iguanodontidae
14 Pl. _Probactrosaurus_
15 Hadrosauridae
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NOTES: Not sure why Jaime has Thescelosauridae splitting off before the marginocephalians (clade 6), but I'm willing to give this topology a try. But I must admit it makes me a little uneasy.
I noticed Jaime places Plesion Chaoyangsaurus more basally in marginocephalians (presumably next to Stenopelix). Any chance Stenopelix and Chaoyangsaurus are sister groups? You usually see the latter placed closer to Protoceratopsids.
And to answer Jaime's question about family vs. plesion status. That is a compromise I make with PT taxonomists (many who don't like monotypic families). A plesion is a convenient way to classify "problematic" genera that may or may not eventually be recognized as separate families. By the way, has anyone proposed a family "Tenontosauridae" (which would probably include Rhabdodon?).
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