[dinosaur] Kawanectes (elasmosaurid) recorded from Cretaceous of Argentina

Ben Creisler
[email protected]

A new paper:

José Patricio O’Gorman (2019)
First record of Kawanectes lafquenianum (Plesiosauria, Elasmosauridae) from
the La Colonia Formation of Argentina, with comments on the mandibular
morphology of elasmosaurids.
Alcheringa (advance online publication)
doi:  https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1080_03115518.2019.1687754&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=WKa5WITmEKZP1bFs4_Z8PZtPd7tG8IoNxoDGDNGA5vU&s=1_jpQeAEBMlNgQWN-qf9NmK7Nl4lJ6Gs8dnKBmCRWR4&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.tandfonline.com_doi_full_10.1080_03115518.2019.1687754&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=WKa5WITmEKZP1bFs4_Z8PZtPd7tG8IoNxoDGDNGA5vU&s=0XRO6KV_KLQ6Aj48I0535d4WnIp_0t6IEpcsPOQ0KZg&e= 



The elasmosaurid plesiosaur Kawanectes lafquenianum is recorded from the
upper Campanian–Maastrichtian levels of the La Colonia Formation in
Argentina for the first time, thus extending the stratigraphical range of
this taxon, which was previously recorded only from the geographically
proximal Allen Formation. The new fossils are referrable to K. lafquenianum
on the basis of the large posterodistal projection on the humerus
supporting an articular facet for a proximal supernumerary ossification,
the presence of a depression anterior to the main muscle scar on ventral
surface of the humeral shaft, and a high humerus/femur length ratio (~1.2).
Novel diagnostic character states for K. lafquenianum include the presence
of a high triangular and distally pointed coronoid process on the mandible,
a mandibular symphysis that incorporates 2.5 alveolar spaces on each ramus,
and a retroarticular process without dorsal or medial inflexion. Relatively
low b/a ratio (measure of coronoid–glenoid cavity length/preglenoid length)
could suggest a mechanical advantage toward fast jaw closure and weak bite
forces. Comparisons with other elamosaurids this imply that Southern
Hemisphere weddellonectian taxa, such as K. lafquenianum, Aristonectes
parvidens and Kaiwhekea katiki, were possibly adapted for rapid snapping
bites.