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Re: Revised Ornithischian Classification

If I thought hypsilophodonts could be divided into two clades (as you did), I would see no real need for a paraphyletic family. But the closer I look, I see more and more small clades splitting off sequentially (far more than 2). Therefore, I believe it is strict cladification that is the bad idea in this case, because it would require perhaps 10 small families or more (there could be one or two Australian clades splitting off separately that would require more families). Since most dinosaurologists continue to assign these forms to a Family Hypsilophodontidae, a broad "markered" semi-paraphyletic classification makes more sense to me (BTW, I put Drinker back in, but is it really all that distinct from Othniela?):

9  Hypsilophodontidae
      1  Plesion "Y." multidens
     2A  Othnielia
      B  Drinker (subgenus of Othnielia?)
     3A  Zephyrosaurus
      B  Orodromeus
      ?  Laeallynasaura
      4  Yandusaurus
      5  Hypsilophodon
      6  Rhabdodon
      7  Plesion "T." dossi
      8  Tenontosaurus
      9  Parksosaurus
      ?  Notohypsilophodon
      ?  Muttaburrasaurus
     10  Gasparinisaura
     11  {{Dryosauridae to
          Hadrosauridae}} (= dryomorphs)
_1_ Dryosauridae
2  Camptosauridae
3  Iguanodontidae
4  Hadrosauridae
Jaime Headden wrote:

9 A plesion "Y." multidens
      B  1  Othnielia
         2  Drinker
      C  1  Zephyrosaurus
         2  Orodromeus
         ?  Laeallynasaura
      D  Hypsilophodon
      E  plesion Yandusaurus
  10  A  1  Parksosaurus
         2  Gasparinisaura
      B  1  Rhabdodon
         2  Tenontosaurus
      ?  Muttaburrasaurus
  11  1  Dryosauridae
      2  Camptosauridae
      3  Iguanodontidae
      4  Hadrosauridae

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