[dinosaur] Marine bonebed from Upper Cretaceous Bearpaw - Dinosaur Park Formation + freshwater plesiosaur from China (free pdfs)

Ben Creisler
[email protected]


New papers:

Free pdf:

Hallie P. Street, Emily L. Bamforth and Meagan M. Gilbert (2019)
The Formation of a Marine Bonebed at the Upper Cretaceous Dinosaur Park -
Bearpaw Transition of West - Central Saskatchewan, Canada.
Frontiers in Earth Science 7:209
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.3389_feart.2019.00209&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=EQqrPy1lZRmqVDJt2pQCu9wF2WZ2xpCErRiQSMVMjlk&s=3ogiTo47G8_HChUPU_vdRKAv7OS81tBcJpEkD5w-2iE&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.frontiersin.org_articles_10.3389_feart.2019.00209_full&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=EQqrPy1lZRmqVDJt2pQCu9wF2WZ2xpCErRiQSMVMjlk&s=CZKudGX5mmGj7FRlyjHhkaUqBYyGDrZnsaXvSzFu8xg&e= 


A marine bonebed from the Campanian (Upper Cretaceous) Bearpaw – Dinosaur
Park Formation transition, containing both micro- and macrovertebrate
fossils and trace fossils, was discovered in west-central Saskatchewan,
Canada. The bonebed formed during transgression of the Western Interior
Seaway, with the stratigraphy of the area displaying extensive
interfingering of these terrestrial and marine facies. The macrovertebrate
fossils occur in a layer of fine-grained, unconsolidated sand. Directly
overlying this stratum is a layer of sulfur-rich, medium-grained sandstone,
containing microvertebrate fossils. Most of the material in both layers is
highly encrusted in gypsum. We propose that the bonebed formed in a barrier
island system over three stages: original deposition of marine reptile
bones in a silled basin over a period of sediment starvation, redeposition
and burial of the bone material due to higher energy flow through the
basin, and deposition of bony and cartilaginous fish material during a
period of water stratification and subsequent euxinic (anoxic and sulfuric)
conditions. Because sediment deposition rates were low when the marine
reptile bones accumulated, these elements spent extended periods at the
sediment-water interface, allowing them to become bioeroded. The bioerosion
at this site takes two main forms: parallel-sided boreholes about one cm
wide, and extensive hollowing out of the cancellous bone. Although the
invertebrate tracemakers were not preserved the boreholes resemble clavate
borings made by bivalves, and the hollowing could have been caused by
polychaete worms or grazing gastropods. The presence of sulfur-rich
deposits and chemosymbiotic Chondrites isp. traces in the layer above the
bonebed suggest the development of a stratified water column in the basin,
with euxinic (anoxic and sulfuric) conditions near the seafloor. Disruption
of the water column culminated in a mass die-off of non-air breathing
vertebrates in the surface waters and constitutes the microvertebrate layer
of the bonebed. Marine reptile bonebeds are rare in the fossil record, and
this site represents the first time a vertebrate assemblage has been
described from a barrier island system in Saskatchewan.

===

Free pdf:

Ting Gao, Da-Qing Li, Long-Feng Li & Jing-Tao Yang (2019)
The first record of freshwater plesiosaurian from the Middle Jurassic of
Gansu, NW China, with its implications to the local palaeobiogeography.
Journal of Palaeogeography 8:27
DOI: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1186_s42501-2D019-2D0043-2D5&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=EQqrPy1lZRmqVDJt2pQCu9wF2WZ2xpCErRiQSMVMjlk&s=Nfpo3Ra2CPcFk3UEjxNa3eFl0k_6I-3IHewESa8NRKU&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__journalofpalaeogeography.springeropen.com_articles_10.1186_s42501-2D019-2D0043-2D5&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=EQqrPy1lZRmqVDJt2pQCu9wF2WZ2xpCErRiQSMVMjlk&s=hr-D1GOWI8qITUZPngyc9FhoXb78C9YIRWirlPV3kDs&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__link.springer.com_content_pdf_10.1186-252Fs42501-2D019-2D0043-2D5.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=EQqrPy1lZRmqVDJt2pQCu9wF2WZ2xpCErRiQSMVMjlk&s=vMlxFVKnHkRdIb2xqrmIjGaTfqTHWNboCmg5k0GRvcc&e= 



Plesiosaurs are one of the common groups of aquatic reptiles in the
Mesozoic, which mainly lived in marine environments. Freshwater plesiosaurs
are rare in the world, especially from the Jurassic. The present paper
reports the first freshwater plesiosaur, represented by four isolated teeth
from the Middle Jurassic fluviolacustrine strata of Qingtujing area,
Jinchang City, Gansu Province, Northwest China. These teeth are considered
to come from one individual. The comparative analysis of the corresponding
relationship between the body and tooth sizes of the known freshwater
plesiosaur shows that Jinchang teeth represent a small-sized plesiosaurian.
Based on the adaptive radiation of plesiosaurs and the
palaeobiogeographical context, we propose a scenario of a river leading to
the Meso-Tethys in the Late Middle Jurassic in Jinchang area, which may
have provided a channel for the seasonal migration of plesiosaurs.



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