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Elasmosaurs from Chile and New Zealand + Crocodylomorphs from Brazil (free pdfs)



Ben Creisler
bcreisler@gmail.com


A number of papers (recent and not so recent) that have not been
mentioned yet on the DML; with links to free pdfs:

Rodrigo A. Otero, Sergio Soto-Acuña, Christian Salazar S. & José Luis
Oyarzún (2015)
New elasmosaurids (Sauropterygia, Plesiosauria) from the Late
Cretaceous of the Magallanes Basin, Chilean Patagonia: Evidence of a
faunal turnover during the Maastrichtian along the Weddellian
Biogeographic Province.
Andean Geology 42(2): 237-267
doi: 10.5027/andgeoV42n2-a05
http://www.andeangeology.cl/index.php/revista1/article/view/V42n2-a05

Free pdf:

http://www.andeangeology.cl/index.php/revista1/article/view/V42n2-a05/pdf


Several Upper Cretaceous plesiosaur specimens recovered from
southernmost Chile are described here. These were collected from upper
levels of the Dorotea Formation exposed on three different localities
(Sierra Baguales, Cerro Castillo, and Dumestre). The new material
includes the first record of Aristonectes (Plesiosauria,
Elasmosauridae), previously recorded from Argentina, central Chile,
and Antarctica. Additional specimens include associated postcranial
skeletons as well as isolated elements. Among these, we recognize the
presence of aristonectines in the three studied localities, while
non-aristonectine elasmosaurids were only collected from Cerro
Castillo. The specimen from Dumestre is remarkable by being a
small-sized adult, indeterminate aristonectine, and could be related
to known representatives from Antarctica. These new finds prove the
abundance of aristonectines as well as intermediate elasmosaurids
along the Magallanes Basin during the uppermost Cretaceous, while
extreme long-necked elasmosaurids as well as polycotylids seems to be
completely absent during this time span. This key record from
southernmost Chile and its strategic placement in the middle part of
the Weddellian Province gives the chance for complementing the
paleobiogeography of Upper Cretaceous plesiosaurs from the Southern
Hemisphere. As a first result, a faunal turnover is observed during
the early Maastrichtian, when extreme (very-long necked) elasmosaurids
and polycotylids disappeared from the austral record. Since the early
Maastrichtian and towards the late Maastrichtian, aristonectines
became differentially abundant along the southeastern Pacific and
Antarctica, but moderately represented in the southwestern Atlantic.
On contrary, intermediate elasmosaurids were scarce in the
Antarctic-Pacific realm, but abundant in the Atlantic. The updated
record of austral plesiosaurs suggest a first stage of interchange
from the Northern into the Southern Hemisphere, and through the
Atlantic seaway, at least since the Coniacian to the late
Campanian-early Maastrichtian. During the early Maastrichtian,
aristonectines were relatively frequent in the New Zealand-Antarctica
archipelago, becoming abundant along southern South America during the
late Maastrichtian.



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R.A. Otero, J.P. O'Gorman & N. Hiller (2015)
Reassessment of the upper Maastrichtian material from Chile referred
to Mauisaurus Hector, 1874 (Plesiosauroidea: Elasmosauridae) and the
taxonomical value of the hemispherical propodial head among austral
elasmosaurids.
New Zealand Journal of Geology and Geophysics (advance online publication)
DOI:10.1080/00288306.2015.1037775
http://www.tandfonline.com/doi/full/10.1080/00288306.2015.1037775#abstract

Free pdf:

http://www.researchgate.net/publication/274253383_Reassessment_of_the_upper_Maastrichtian_material_from_Chile_referred_to_Mauisaurus_Hector_1874_(Plesiosauroidea_Elasmosauridae)_and_the_taxonomical_value_of_the_hemispherical_propodial_head_among_austral_elasmosaurids



The femoral hemispherical articular head was regarded as autapomorphic
of Mauisaurus haasti Hector, 1874 from the upper Campanian of New
Zealand. Review of three Maastrichtian taxa, Aristonectes
quiriquinensis from Chile, Aristonectes sp. from Antarctica and
Kaiwhekea katiki from New Zealand, reveals that the femoral
hemispherical head is a common character among aristonectines. This
feature can therefore be discarded as an autapomorphy of Mauisaurus
haasti. Propodials of A. quiriquinensis are shown to be the same as
those in two coeval Chilean specimens previously referred to
Mauisaurus sp.; in consequence, these are now referred to A.
quiriquinensis. Additionally, specimens referred to A. quiriquinensis
allow confirmation that during ontogeny the humerus and the femur
change from a flat capitulum in juveniles to hemispherical heads of
both the humeri and femora in the adult stage. The evidence shows that
the presence of Mauisaurus along the southeastern Pacific margin
cannot be verified to date.



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Douglas Riff,  Rafael Gomes de Souza, Giovanne Mendes Cidade, Agustín
Guillermo Martinelli & Jonas Pereira de Souza-Filho (2015)
Crocodilomorfos: a maior diversidade de répteis fósseis do Brasil
[Crocodylomorphs:  Brazil's fossil reptiles with the greatest
diversity]
Terrae 9 (1-2): 12-40 (in Portuguese)
http://www.ige.unicamp.br/terrae/V9/T_V9_A3.html

Free pdf:

https://www.ige.unicamp.br/terrae/V9/PDFv9/crocodilomorfos.pdf


Most textbooks and divulgation medias devoted to the teaching of
Geosciences and Biosciences explores the apparent familiarity of
readers concerning dinosaurs to illustrate the process of
fossilization, the paleontological heritage and the geological history
of life. However, another lineage of reptiles, the crocodylomorphs,
stands out when compared to other iconic fossil groups, and presents a
remarkable species diversity, morphological disparity and ecological
variety. With about 50 fossil species known in Brazil (almost three
times the dinosaur record) and other under study, this group is
particularly representative in the country, which also has six living
species of caimans. Here we present a contextualized overview of the
accumulated knowledge about these remarkable animals and their
implications for understanding preterite biota and ecosystems, as well
as demonstrating the inadequacy of considering the group as unchanged,
or as "living fossils".


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