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[dinosaur] Nedcolbertia as ornithomimosaur + azhdarid humerus from Saratov Region, Russia + more





Ben Creisler
bcreisler@gmail.com

A number of recent papers:

Free pdf:

Chase Doran Brownstein ​ (2016) 
Redescription of Arundel formation Ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an "Ostrich Dinosaur": Biogeographic implications. 
PeerJ Preprints 4:e2308v1
DOI:  https://doi.org/10.7287/peerj.preprints.2308v1
https://peerj.com/preprints/2308/

The fossil record of dinosaurs from the Early Cretaceous of eastern North America is scant, and only a few sediments to the east of the continent are fossiliferous. Among them is the Arundel Formation of the east coast of the United States, which has produced among the best dinosaur faunas known from the Early Cretaceous of eastern North America. The diverse dinosaur fauna of this formation has been thoroughly discussed previously, but few of the dinosaur species originally described from the Arundel are still regarded as valid genera. Much of the Arundel material is in need of review and redescription. Among the fossils of dinosaurs from this formation are those referred to ornithomimosaurs. Here, I redescribe ornithomimosaur remains from the Arundel Formation which may warrant the naming of a new taxon of dinosaur. These remains provide key information on the theropods of the Early Cretaceous of Eastern North America. The description of the Arundel material herein along with recent discoveries of basal ornithomimosaurs in the past 15 years has allowed for comparisons with the coelurosaur Nedcolbertia justinhofmanni, suggesting the latter animal was a basal ornithomimosaurian dinosaur rather than a “generalized” coelurosaur. Comparisons between the Arundel ornithomimosaur and similar southeast Asian ornithomimosaurian material as well as ornithomimosaur remains from western North America suggest that a lineage of ornithomimosaurs with a metatarsal condition intermediate between that of basal and derived ornithomimosaurs was present through southeast Asia into North America, in turn suggesting that such animals coexisted with genera having a more primitive metatarsal morphology as seen in N. justinhofmanni.


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English translation version not yet available. Rough translation from Russian:

Averyanov, A.O., Arkhangelsky, M.S. & Merkulov, S.M. (2016) 
Humerus of an azhdarchid (Pterosauria, Azhdarchidae)  from the Upper Cretaceous of the Saratov Region.
Paleontological Journal 50 (4): 93-97 (Russian edition)
DOI:  10.7868 / S0031031X16040036
http://elibrary.ru/item.asp?id=26301609


The proximal end of the humerus of a pterosaur (Azhdarchidae indet.)  is described from the Rybushka Formation sediments (Upper Cretaceous, Lower Campanian) of the White Lake locality in the Saratov Region. The proximal articular surface is saddle-shaped, with a slightly convex profile in the frontal plane. The most part of the set-back of the articular surface is shifted ventrally. A large hole in the front side of pneumatization is located ventral to the base deltopectoral ridge near the proximal articular surface. The humeral head slightly tilted from the diaphysis and almost hangs over the back of the diaphysis. The humerus may belong to Volgadraco bogolubovi Averianov, Arkhangelsky et Pervushov, 2008, described from the Rybushka Formation  Shirokii Karamysh 2 locality in the Saratov Region.

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Homer Montgomery & Scott Clark (2016)
Paleoecology of the Gaddis site in the Upper Cretaceous Aguja Formation, Terlingua, Texas.
PALAIOS 31(7): 347-357
DOI: 10.2110/palo.2015.099 
http://palaios.geoscienceworld.org/content/31/7/347


Diverse faunas at the Gaddis site near Terlingua, Texas are present at four stratigraphic levels along a hill in the Upper Cretaceous Aguja Formation providing a rich fossil record of the transition from an aquatic environment to dry land while recording exceptional events such as predation and wildfires. Given evidence for minimal transport the microvertebrates, macrovertebrates, coprolites, and plants may be reliably utilized for paleoecological analysis. Paleoenvironments shift upsection from nearshore marine, through tidal channel, to swamp, and, finally, to well-vegetated dry land. The faunas change from a basal layer of oysters with shark teeth to a microvertebrate assemblage just above logs with Teredolites borings and pristine leaves. Above the microvertebrates are diverse macrovertebrates including numerous dinosaurs associated with leaves, logs, and scrambling vines. The macrovertebrate layer is a rich assemblage of herbivorous and carnivorous dinosaurs, crocodiles, turtles, and rare pterosaurs. Several skeletal elements exhibit signs of predation that include punctures and gouges that precisely match crocodile and theropod teeth also recovered at the site. Abundant plant material that includes charred vines and logs is likely evidence of wildfires having ranged across the area. The preponderance of young dinosaur remains may support a wildfire scenario. An exposed surface with 24 coprolites, two hadrosaur vertebrae, logs, and in situ stumps caps the section. The larger coprolites are likely dinosaurian. Most contain plant materials while one contains a bone fragments suggesting the presence of herbivorous and carnivorous dinosaurs on the same surface, an occurrence that echoes herbivore/carnivore interactions in the underlying bonebed.

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Lara Sciscio & Emese M. Bordy (2016)

Palaeoclimatic conditions in the Late Triassic-Early Jurassic of southern Africa: A geochemical assessment of the Elliot Formation.

Journal of African Earth Sciences 119: 102–119

doi:10.1016/j.jafrearsci.2016.03.014

http://www.sciencedirect.com/science/article/pii/S1464343X16301005

 

Highlights


First quantitative palaeoclimatic assessment of the continental Triassic-Jurassic boundary succession in southern Africa. 

Integrated mineralogical, sedimentological and geochemical proxies (e.g., major, trace, rare earth elements).

Calculated indices of chemical alteration and compositional variability.

Deposition occurred under increasingly dry environmental conditions that inhibited chemical weathering.

Results support predictions of long-term global warming after continental flood basalt emplacements.




Abstract


The Triassic-Jurassic boundary marks a global faunal turnover event that is generally considered as the third largest of five major biological crises in the Phanerozoic geological record of Earth. Determining the controlling factors of this event and their relative contributions to the biotic turnover associated with it is on-going globally. The Upper Triassic and Lower Jurassic rock record of southern Africa presents a unique opportunity for better constraining how and why the biosphere was affected at this time not only because the succession is richly fossiliferous, but also because it contains important palaeoenvironmental clues. Using mainly sedimentary geochemical proxies (i.e., major, trace and rare earth elements), our study is the first quantitative assessment of the palaeoclimatic conditions during the deposition of the Elliot Formation, a continental red bed succession that straddles the Triassic-Jurassic boundary in southern Africa. Employing clay mineralogy as well as the indices of chemical alteration and compositional variability, our results confirm earlier qualitative sedimentological studies and indicate that the deposition of the Upper Triassic and Lower Jurassic Elliot Formation occurred under increasingly dry environmental conditions that inhibited chemical weathering in this southern part of Pangea. Moreover, the study questions the universal validity of those studies that suggest a sudden increase in humidity for the Lower Jurassic record and supports predictions of long-term global warming after continental flood basalt emplacement.



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Free pdf:


M.O. Clarkson, R.A. Wood,  S.W. Poulton, S. Richoz, R. J. Newton, S.A. Kasemann, F. Bowyer & L. Krystyn (2016)
Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery.
Nature Communications 7, Article number: 12236 
doi:10.1038/ncomms12236
http://www.nature.com/ncomms/2016/160719/ncomms12236/full/ncomms12236.html

The end-Permian mass extinction, ~252 million years ago, is notable for a complex recovery period of ~5 Myr. Widespread euxinic (anoxic and sulfidic) oceanic conditions have been proposed as both extinction mechanism and explanation for the protracted recovery period, yet the vertical distribution of anoxia in the water column and its temporal dynamics through this time period are poorly constrained. Here we utilize Fe–S–C systematics integrated with palaeontological observations to reconstruct a complete ocean redox history for the Late Permian to Early Triassic, using multiple sections across a shelf-to-basin transect on the Arabian Margin (Neo-Tethyan Ocean). In contrast to elsewhere, we show that anoxic non-sulfidic (ferruginous), rather than euxinic, conditions were prevalent in the Neo-Tethys. The Arabian Margin record demonstrates the repeated expansion of ferruginous conditions with the distal slope being the focus of anoxia at these times, as well as short-lived episodes of oxia that supported diverse biota.

News:

https://www.sciencedaily.com/releases/2016/07/160719123023.htm