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Plesiopterys, new plesiosaur from Germany



from: Ben Creisler bh480@scn.org

The new Journal of Paleontology has a new plesiosaur. I'm 
a bit queasy about the spelling of the name (getting 
from "pteryx" to "pterys" is pretty weird), but it will 
have to stand I guess.

O'KEEFE, F. ROBIN, 2004. PRELIMINARY DESCRIPTION AND 
PHYLOGENETIC POSITION OF A NEW PLESIOSAUR (REPTILIA: 
SAUROPTERYGIA) FROM THE TOARCIAN OF HOLZMADEN, GERMANY. 
Journal of Paleontology  78 (5):  973-988.
ABSTRACT
 This paper offers a preliminary description of a 
plesiosaur (Reptilia: Sauropterygia) from the Lower 
Toarcian Posidonienschiefer near the village of Holzmaden 
in Baden-Württemberg, Germany, and discusses its 
phylogenetic relevance. This new taxon, Plesiopterys 
wildi , new genus and species, is remarkable in its 
retention of several plesiomorphic features. A 
phylogenetic analysis places Plesiopterys as the sister 
group of the Plesiosauroidea, and as such the taxon is the 
most basal taxon yet known on the branch leading to this 
major clade. Plesiopterys  possesses a high count of 
cervical vertebrae and a relatively small head, yet the 
limbs and limb girdles are plesiomorphic in proportion. 
The skull displays a mosaic of features, reminiscent of 
both Thalassiodracon <and the rhomaleosaurids in some 
characters, yet similar to Plesiosaurus  in others. The 
basicranium is plesiomorphic and resembles that of 
nothosaur-grade sauropterygians in several respects. A 
faunal comparison between Holzmaden and the Lower Toarcian 
deposits on the Yorkshire coast of England concludes that 
the Holzmaden fauna is more plesiomorphic than the roughly 
coeval Yorkshire fauna in two of three plesiosaur 
subclades.
Type species
Plesiopterys wildi n. sp., by monotypy. 
Diagnosis
As for species. 
Etymology
Plesio-, Gr. near, close, old; -pterys ,Gr. wing. The 
latter also refers to the pterygoid bone, which is an 
important feature of this taxon. 
Diagnosis
A small plesiosaur possessing 39 cervical vertebrae, a 
relatively small skull (17 percent of neck length, 
compared to 28 percent of neck length in 
Thalassiodracon)...., and plesiomorphic proportions of the 
limbs and limb girdles. The skull is unique among 
plesiosaurs in the retention of grooves for the internal 
carotid artery on the dorsal surface of the pterygoid. The 
mandible possesses a short symphysis (number of tooth 
positions not determinable) without participation of the 
splenial, but retains a ventral mandibular ridge. 
Autapomorphies include: quadrate flange of the pterygoid 
is straight and narrow, and expands into a wide boss at 
its terminus; possession of flanges of the pterygoid 
dorsal to the plane of the palate in the anterior of the 
posterior interpterygoid vacuities; exposure of the 
cultriform process of the parasphenoid almost to margin of 
anterior pterygoid vacuity; large anterior interpterygoid 
vacuity with round posterior margin and pointed anterior 
margin. 
Etymology
Named for R. Wild, in recognition of his many 
contributions to the vertebrate paleobiology of the German 
Mesozoic. 
Type 
SMNS 16812, a complete skeleton on display in the 
Staatliches Museum für Naturkunde, Stuttgart, Germany.