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[dinosaur] Chinese thalattosaur + Rionegrochelys from Cretaceous of Argentina + baenid turtles from Eocene of Utah (free pdfs)




Ben Creisler
bcreisler@gmail.com


Some recent non-dino papers (with free pdfs):


RAN Chang, HU Shixue, HUANG Jinyuan, ZHANG Qiyue & ZHOU Changyong (2017)

The discovery of Thalattosauria (Reptilia:Diapsida) from the Late Triassic strata of Luxi County, Yunnan Province.

Geological Bulletin of China 36(6): 913-917 (in Chinese)

http://dzhtb.cgs.cn/ch/reader/view_abstract.aspx?file_no=20170602&flag=1





This paper reposts a thalattosaur specimen collected from the Late Triassic Xiaowa Formation in Xiaoxingan Village, Luxi County, Yunnan Province.It is the first record of Thalattosauria fossil outside Guanling, Guizhou Province.The specimen consists of 9 well preserved dorsal vertebrae, 21 dorsal ribs, and several gastralia. 4 dorsal vertebrae are present and arranged as a sequence of natural order.The length of dorsal vertebrae is about 12cm. The transverse process is well developed.The two ends of the dorsal vertebrae are slightly biconcave, distinctly different from ichthyosauria vertebrae with obvious biconcave.The specimen is tentatively assigned to the Thalattosauria. The new discovery provides new information for paleobiographic distribution of the Thalattosauria and the search for new fossil localities of the Guangling biota

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Rionegrochelys 

Marcelo S. De La Fuente, Ignacio Maniel, Juan Marcos Jannello, Juliana Sterli, Alberto C. Garrido, Rodolfo A. Garcia, Leonardo Salgado, José I. Canudo, and Raúl Bolatti (2017)
Unusual shell anatomy and osteohistology in a new Late Cretaceous panchelid turtle from northwestern Patagonia, Argentina.
Acta Palaeontologica Polonica (in press)
doi:https://doi.org/10.4202/app.00340.2017
http://app.pan.pl/article/item/app003402017.html


Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2–11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni.

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Heather F. Smith, J. Howard Hutchison, K. E. Beth Townsend, Brent Adrian & Daniel Jager (2017)
Morphological variation, phylogenetic relationships, and geographic distribution of the Baenidae (Testudines), based on new specimens from the Uinta Formation (Uinta Basin), Utah (USA).
PLoS ONE 12(7): e0180574.


We described newly discovered baenid specimens from the Uintan North American Land Mammal Age (NALMA), in the Uinta Formation, Uinta Basin, Utah. These specimens include a partial skull and several previously undescribed postcranial elements of Baena arenosa, and numerous well-preserved shells of B. arenosa and Chisternon undatum. Baenids from the Uintan NALMA (46.5–40 Ma) are critical in that they provide valuable insight into the morphology and evolution of the diverse and speciose baenid family near the end of its extensive radiation, just prior to the disappearance of this clade from the fossil record. These Uintan specimens greatly increase the known variation in these late-surviving taxa and indicate that several characters thought to define these species should be reassessed. The partial cranium of B. arenosa, including portions of the basicranium, neurocranium, face, and lower jaw, was recently recovered from Uinta B sediments. While its morphology is consistent with known specimens of B. arenosa, we observed several distinct differences: a crescent-shaped condylus occipitalis that is concave dorsally, tuberculum basioccipitale that flare out laterally, and a distinct frontal-nasal suture. The current sample of plastral and carapacial morphology considerably expands the documented variation in the hypodigms of B. arenosa and C. undatum. Novel shell characters observed include sigmoidal extragular-humeral sulci, and small, subtriangular gular scutes. Subadult specimens reveal ontogenetic processes in both taxa, and demonstrate that diagnostic morphological differences between them were present from an early developmental age.