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RE: Stormbergia dangershoeki, new Early Jurassic ornithischian from South Africa




Michael Mortimer wrote:

     `--+--Lesothosaurus
        |--SAM-PK-K8025
        `--+--Stormbergia
           `--+--Agilisaurus
              `--+--"Yandusaurus" multidens
                 `--+--+--Heterodontosaurus
                    |  `--Abrictosaurus
                    `--+--Jeholosaurus
                       |--Hypsilophodon
                       |--Gasparinisaura
                       |--Thescelosaurus
                       |--Parksosaurus
                       |--Iguanodontia
                       `--+--Pachycephalosauria
                          `--Ceratopsia

Genasaurian (and neornithischian) Lesothosaurus, non-cerapodan heterodontosaurids...

... and ceratopsians and pachycephalosaurs as derived ornithopods. At least, that's how I read Butler's tree. Putting marginocephalians inside the Ornithopoda pares back that enormous ghost lineage that haunts most ornithischian phylogenies - in which ornithopods and marginocephalians are positioned as sister taxa. By contrast, if we have pachies and ceratopsians as ornithopods, the apparent absence of marginocephalians prior to the Late Jurassic is not that surprising.


I very much doubt this is the last word on ornithischian/ornithopod relationships. As Butler says, the heterodontosaurs (at the very least) require much closer study.

Cheers

Tim