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Kawanectes, new small elasmosaurid from Late Cretaceous of Patagonia



Ben Creisler
bcreisler@gmail.com

A new paper:

José P. O'Gorman (2015)
A small body sized non-aristonectine elasmosaurid (Sauropterygia,
Plesiosauria) from the Late Cretaceous of Patagonia with comments on
the relationships of the Patagonian and Antarctic elasmosaurids.
Ameghiniana (advance online publication)
doi:10.5710/AMGH.29.11.2015.2928
http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/1006


The systematics of the Late Cretaceous non-aristonectine elasmosaurids
from Argentinean Patagonia are poorly known as there is no valid
species currently recognized. Here a new non-aristonectine
elasmosaurid: Kawanectes lafquenianum nov. comb. from the late
Campanian–early Maastrichtian Allen Formation is diagnosed. Kawanectes
lafquenianum is a distinctively small-bodied sized non-aristonectine
elasmosaurid characterized by caudal vertebrae with marked laterally
projected parapophyses, presence of pelvic bar, high ratio (~1.2)
between humerus/femur length and a large posterodistal projection of
the humerus which bears a posterior accessory articular facet. A
phylogenetic analysis recovered K. lafquenianum closely related with
Morenosaurus stocki, Vegasaurus molyi and Aristonectinae, showing the
relationships between the elasmosaurids from Patagonia, Western
Antarctic, and the Pacific coast of the USA. Kawanectes lafquenianum
is part of the fauna of the coeval Allen and La Colonia formations
that also comprises indeterminate aristonectines and polycotylids .
This relatively high diversity plesiosaur fauna includes the three
main morphotypes (aristonectines, non-aristonectines elasmosaurids and
polycotylids), which is remarkable since the depositational
environments of the Allen have been inferred as marginal marine to
non-marine environments.