Comments on “The Osteology of Hypselospinus” Norman, 2015

I find a few things troubling about the recent publication on the Osteology of Hypselospinus, published recently in the Zoological Journal of the Linnean Society, authored by David Norman. Most importantly are the systematics. The new clade Clypeodonta is defined, as HypsilophodonEdmontosaurus. Norman also redefines Hypsilophodontia, to be HypsilophodonTenontosaurus. This is very problematic, as even though it works for Norman’s phylogeny, many, many other analyses find Tenontosaurus just outside Iguanodontia, so in those many, many other phylogenies these groups are synonymous by definition, as they are also both node-based.

Even more troubling is Norman’s redefining of Iguanodontia. It was relatively well-defined before, and the included taxa were relatively stable. But Norman topples this, redefining it as Edmontosaurus > Hypsilophodon + Tenontosaurus. This is ridiculous. The definition is totally useless unless Hypsilophodon and Tenontosaurus are grouped together, and this is the only time they have been.

Norman used a definition of Ankylopoxellia that I have no problem with, but then again he causes issues with his definition of Stracosterna. As far as I know, only Norman’s phylogeny finds Batyrosaurus the most basal Iguanodontian more derived than Camptosaurus, yet Norman still redefines Styracosterna as Batyrosaurus + Edmontosaurus. The previous definition of Edmontosaurus > Camptosaurus makes much more sense and is much more stable.

Norman’s other definitions are much less troubling than these, yet I do not know why he changed the Edmontosaurus > Iguanodon definition of Hadrosauriformes to make it node based Altirhinus + Edmontosaurus.

*Note: I assume the definitions of Hadrosauriformes and Styracosterna to be as I have put them, but they may be slightly different.

Update 5/13/2015: I now see how little is known of Batyrosaurus, which makes me feel there is even less support for Norman’s Styracosterna. As well, I believe Norman needs to include many more taxa, such as the many other Styracosternan’s (by the conventional definition) and other Hadrosauroids. And a final note, Norman does not even use Hadrosauroidea as a group, which he very well should as it is much more used than his new Hadrosauromorpha.

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About ijreid

I am an amateur palaeontologist thats hobbies include studying extinct amniotes, specifically dinosaurs, birds, and mammals. Occasionally, I focus my time on detailed and accurate illustrations of dinosaurs, and I have completed drawings of Dysalotosaurus, Micropachycephalosaurus, Zhuchengtyrannus, Troodon, Eotyrannus, Europelta, and Achillobator. I do not believe in copyrights, and think that the world would be better if everything was open access.
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