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Re: Hypselospinus (Iguanodontia) from Early Cretaceous of Britain revised



I'm intrigued by the use of Linnaean ranks in this paper:  "Superorder
Dinosauria", "Order Ornithischia", "Suborder Ornithopoda", "Infraorder
Clypeodonta", "Division Iguanodontia", "Subdivision Ankyllopollexia",
"Infradivision Styracosterna".  At first I thought this was a quirk of
the journal (it is the Zoological Journal of the *Linnean* Society,
after all).  But the paper by Lautenschlager & Rauhut on _Rauisuchus_
in the same journal lacks these ranks - instead, it simply lists the
clades hierarchially.  The rationale behind the use of outmoded ranks
(superorder, order, etc) in Norman's _Hypselospinus_ paper eludes me.

More noteworthy is that Norman takes a flamethrower to GSP's army of
iguanodontian taxa.  The once over-lumped _Iguanodon_ seems to have
swung to the other extreme, with an explosion of new Wealden taxa over
the past several years.  Norman pushes the pendulum back, hopefully
closer to the taxonomic 'center'.  Although sadly, genera named after
Darwin, Huxley and Dollo have been sunk.

There is also some support (albeit weak) for a clade comprising
_Iguanodon_, _Mantellisaurus_, _Barilium_, _Proa_, _Jinzhousaurus_,
and _Bolong_ (the latter two possibly being synonymous).  The clade
Clypeodonta ("shield tooth") was erected elsewhere by Norman to
include all ornithopods except the most basal ornithopod taxa (e.g.,
thescelosaurids).  So Clypeodonta = Hypsilophodontia + Iguanodontia.





Cheers
Tim


On Tue, Dec 2, 2014 at 4:01 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreislerf@gmail.com
>
> A new online paper:
>
> David B. Norman FLS (2014)
> On the history, osteology, and systematic position of the Wealden
> (Hastings group) dinosaur Hypselospinus fittoni (Iguanodontia:
> Styracosterna).
> Zoological Journal of the Linnean Society (advance online publication)
> DOI: 10.1111/zoj.12193
> http://onlinelibrary.wiley.com/doi/10.1111/zoj.12193/abstract
>
>
> The history of discovery and interpretation of several dinosaurs
> collected from quarries near the town of Hastings during the latter
> half of the 19th century is more complicated than it should be. Samuel
> Husbands Beckles and Charles Dawson collected several large ornithopod
> skeletons from this area, but just a few bones from these skeletons
> were subsequently described and interpreted (principally) by Richard
> Owen and Richard Lydekker. All these specimens merited recognition
> because they had the potential to contribute to an on-going debate
> about the anatomical structure and relationships of the iconic Wealden
> dinosaur Iguanodon. Unfortunately, no detailed description of these
> important skeletons was published in later years. Furthermore,
> previously known associations of bones and even provenance
> information, linked to the specimens that were gradually acquired by
> the Natural History Museum, are unclear. Confusion may have arisen
> because Richard Lydekker used the private collector Charles Dawson as
> a voluntary curatorial assistant. This account documents the past work
> on the osteology of material that can be attributed to Hypselospinus
> fittoni. Nearly all such material is described here for the first
> time, and every effort has been made to re-establish associations
> between bones as well as provenance information. A skeletal
> reconstruction of Hypselospinus is attempted on the basis of the
> hypodigm. Most of the on-going confusion concerning the affinity of
> this material with either Hy. fittoni or its sympatric contemporary
> Barilium dawsoni has been resolved. Hypselospinus fittoni (Lydekker,
> 1889) is rediagnosed on the basis of this new and relatively
> comprehensive anatomical description, and this animal is compared with
> known contemporary and closely related taxa. Some recently published
> accounts claiming to be revisions of the taxonomy of Wealden
> ‘iguanodonts’, including material belonging to the hypodigm of Hy.
> fittoni, have failed to adhere to basic taxonomic principles and have
> caused more confusion than was strictly necessary. The systematic
> position of Hypselospinus is reassessed cladistically. The cladistic
> analysis forms the basis for a revised hierarchical classification of
> derived ornithopods. The consensus topology generated by the
> systematic analysis has been used to explore the phylogenetic history
> of these dinosaurs and create an internally consistent classificatory
> hierarchy (phylogenetic definitions and Linnaean diagnoses are given
> for critical positions in the topology). This analysis suggests that
> there is a fundamental split amongst the more derived (clypeodontan)
> ornithopod ornithischians into the clades Hypsilophodontia and
> Iguanodontia. There is evidence for anatomical parallelism and
> convergence (homoplasy) particularly between large-bodied
> representatives of both clades. Hypselospinus is one of the earliest
> known styracosternan iguanodontians and displays anatomical
> characteristics that presage the evolution of the extraordinarily
> abundant and diverse hadrosaurs of the latest Cretaceous
> (Campanian−Maastrichtian). These observations cast fresh light on the
> phylogeny, classification, diversity, and biology of derived
> ornithopods. There is little doubt that Hy. fittoni could have been
> understood far better more than a century ago. That this statement is
> undoubtedly true is reflected in the century of doubt and confusion
> that has surrounded this taxon and its original incarnation as
> Iguanodon fittoni.