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Two new dinosaurs in JVP: Arcusaurus and Haya



Yates, A.M, M.F. Bonnan & J. Neveling, 2011.  A new basal sauropodomorph 
dinosaur from the Early Jurassic of South Africa.  Journal of Vertebrate 
Paleontology 31: 610-625.
Abstract: A new basal sauropodomorph dinosaur, *Arcusaurus pereirabdalorum*, 
sp. nov., is named and described on the basis of a partial, disarticulated but 
associated skull and dispersed cranial and postcranial elements from at least 
two individuals. *Arcusaurus* is part of a distinctive local fauna from the 
upper Elliot Formation (Lower Jurassic) in the Senekal District, Free State, 
South Africa. It can be diagnosed by various details of the premaxilla, nasal, 
and dentary in the skull and the shape of the distal caudal vertebrae. The 
taxon displays an unusual mix of characteristics. It lacks several 
synapomorphies of Plateosauria (*Plateosaurus* + *Massospondylus* and all 
descendants of their most recent common ancestor) but does display other 
derived characteristics that are otherwise known only from less inclusive 
clades within Plateosauria. In a cladistic analysis a position outside 
Plateosauria as the sister group of the clade of *Efraasia* + more-derived 
sauropodomorphs is supported; however, this position was not found to be a 
significantly better explanation of the data as a relatively derived position 
within Plateosauria. If the basal position for *Arcusaurus* is accepted, then a 
divergence from other sauropodomorphs in the middle Norian and a ghost lineage 
up to 35 Ma is implied. No other non-plateosaurian sauropodomorphs are known 
from the Jurassic, making *Arcusaurus* a potentially relictual taxon in the 
Early Jurassic.
Makovicky, P.J., B.M. Kilbourne, R.W. Sadleir & M.A. Norell, 2011.  A new basal 
ornithopod (Dinosauria, Ornithischia) from the Late Cretaceous of Mongolia. 
 Journal of Vertebrate Paleontology 31: 626-640.
Abstract:  Basal ornithopods exhibit a very low diversity in Cretaceous 
deposits of Asia, with only two diagnostic taxa published to date. A new basal 
ornithopod, *Haya griva*, gen. et sp. nov., is described here based on several 
well-preserved specimens from the Late Cretaceous Javkhlant Formation of 
Mongolia. *Haya* is diagnosed by a unique combination of characters, some of 
which are also present in other Asian Cretaceous basal ornithopods such as a 
bifid caudal ramus of the jugal and a tapering and beveled predentary. Traits, 
such as presence of separate maxillary fenestra, otherwise only known in 
Hypsilophodon, show more homoplastic distributions. Phylogenetic analysis 
provides weak support for grouping *Haya* with the Chinese Cretaceous taxa 
*Jeholosaurus* and *Changchunsaurus*, suggesting a greater hidden diversity of 
such animals in Asia. The most complete prepared specimen of *Haya* exhibits a 
sizeable gastrolith mass, representing only the second occurrence among 
ornithopods.