Re: [dinosaur] Adratiklit, new stegosaur from Middle Jurassic of Morocco

Not to take anything away from _Adratiklit_, the first North African
stegosaur, but the claim that it's "the oldest definitive stegosaur from
anywhere in the world" depends on whether or not  _Isaberrysaura_ is a
stegosaur.  Maidment &c's own phylogenetic analyses (MPTs) recover
_Isaberrysaura_ as a basal stegosaur (not the first study to show this, as
they note).  Their basal _Isaberrysaura_-_Gigantspinosaurus_ clade actually
has more support than their _Adratiklit_-_Dacentrurus_-_Miragaia_ clade
(Figure 12).  Nevertheless, Maidment &c don't seem particularly convinced
that Isaberrysaura_ is a definitive stegosaur ("however, further study and
a postcranial description of the skeleton, are needed to elucidate the
taxonomic status of the specimen."), which is fair enough.

Regarding Gondwanan stegosaurs, from the Discussion: "The vast majority of
eurypodan taxa so far recognized have been described from Laurasia, with
just three stegosaurs (_Isaberrysaura_, _Kentrosaurus_, _Paranthodon_) and
two ankylosaurs (_Antarctopelta_, _Kunbarrasaurus_) being known from
Gondwanan continents throughout the entire Mesozoic (Fig. 14). The
discovery of _Adratiklit_ in Africa therefore adds significantly to the
known diversity of Gondwanan eurypodans."

Poor _Minmi_ is not included in this list of Gondwanan ankylosaurs.
Instead, _Kunburrasaurus_ is regarded as the sole valid ankylosaur from
Australia.  This is no doubt following Arbour & Currie (2016), who regarded
_Minmi_ as a nomen dubium; but Arbour & Currie (2016) regarded
_Antarctopelta_ as a nomen dubium as well.  (Arbour & Currie, 2016, were
quite brutal when it came to assessing the validity of ankylosaur taxa.)
Leahey et al. (2016) re-asserted that _Minmi_ is a valid and distinct
genus, and I wouldn't write off _Minmi_ quite yet (or the family Minmiidae,
as a clade of basal ankylosaurs).

Also, Galton & Ayyasami (2017) are pretty convinced that there are
stegosaur remains  (_Dravidosaurus_ ?), from India (Coniacian); but without
the promised re-description, I can see why Maidment &c are keeping an open
mind.




On Sat, Aug 17, 2019 at 2:03 PM Ben Creisler <[email protected]> wrote:

>
> Ben Creisler
> [email protected]
>
>
> A new paper:
>
>
> Adratiklit boulahfa gen. et sp. nov.
>
> Susannah C. R. Maidment, Thomas J. Raven, Driss Ouarhache & Paul M. Barret
> (2019)
> North Africa's first stegosaur: Implications for Gondwanan thyreophoran
> dinosaur diversity.
> Gondwana Research (advance online publication)
> doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1016_j.gr.2019.07.007&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=Em1Zu5vkjGDJxVORfS4D4xYpJD8CxsoKocN-VmLH-9E&s=bTW1gXlYljqDlu0vJZ8rN7imdEb_4v47xJIPd_bApRU&e= 
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>
> Highlights
>
> Adratiklit boulahfa is a new genus of stegosaur from Morocco.
> Adratiklit is the oldest definitive stegosaur and the first from north
> Africa.
> It is closely related to the European stegosaurs Dacentrurus and Mirigaia.
> The dinosaur fossil record of Gondwana is biased.
> Armoured dinosaurs may have been as diverse in Gondwana as they were in
> Laurasia.
>
>
> Abstract
>
> Eurypoda, the major radiation of armoured dinosaurs, comprises the
> ankylosaurs and their sister group, the stegosaurs. As the
> earliest-branching major clade of ornithischian dinosaurs, the evolutionary
> history of Eurypoda is significant for understanding both the palaeobiology
> of bird-hipped dinosaurs and the composition of middle Mesozoic ecosystems.
> Eurypodans were diverse and abundant throughout the Late Jurassic and
> Cretaceous in Laurasia; in contrast, their remains are extremely rare in
> Gondwana. Herein, we describe a new genus and species of stegosaur from the
> Middle Jurassic of Morocco, Adratiklit boulahfa. Adratiklit is the first
> eurypodan from north Africa and the oldest definitive stegosaur from
> anywhere in the world. The genus is more closely related to the European
> stegosaurs Dacentrurus and Miragaia than it is to the southern African taxa
> Kentrosaurus and Paranthodon. Statistically significant correlations
> between the number of dinosaur-bearing formations, dinosaur-bearing
> collections, and eurypodan occurrences in Gondwana indicates that their
> fossil record is biased by both geological and anthropogenic factors.
> Tantalizing but fragmentary remains and trackways suggest that eurypodan
> diversity in Gondwana may have been as rich as that of Laurasia, and the
> prospects for future discoveries of new genera across Gondwana are
> therefore very good.
>
>
>
>
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