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

[Tim Williams <twilliams_alpha@hotmail.com>]

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