Ben Creisler | 26 Jul 05:56 2016
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[dinosaur] Pteranodon complex


Ben Creisler

New from Mark Witton:


The 'Pteranodon complex' and dismantling our understanding of the most famous flying reptile


Ben Creisler | 26 Jul 05:55 2016
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[dinosaur] Fresnosaurus (Plesiosauria) redescribed and first Northern Hemisphere artistonectine


Ben Creisler


A new paper:


José P. O'Gorman (2016)
Reappraisal of Fresnosaurus drescheri (Plesiosauria; Elasmosauridae) from the Maastrichtian Moreno Formation, California, USA.
Cretaceous Research (advance online publication)
doi:10.1016/j.cretres.2016.07.009

The elasmosaurid Fresnosaurus drescheri, Welles from the contact between the Tierra Loma/Marca members of the Moreno Formation (Maastrichtian), California, USA is reviewed. Most of the features included in Welles's original diagnosis are considered related only to the juvenile ontogenetic stage of the holotype and only specimen. The new diagnosis is based on diagnostic characters of the ilia, including long rectangular shaped sacral facets located in the dorsal part of the shaft, two gentle knobs in the shafts and unexpanded dorsal end. Additional material from the Moreno Formation (numbered under the same number as the F. drescheri holotype but not mentioned by Welles and therefore considered part of a different specimen) are described for the first time. The latter are referred to the aristonectine, being the first evidence of aristonectines from the North Hemisphere.
Ben Creisler | 26 Jul 01:14 2016
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[dinosaur] Huge Bolivian theropod track + giant Psittacosaurus on display + demands for return of Berlin Giraffatitan + more


Ben Creisler

Some recent items:

Huge theropod footprint (1.2 m)  found in Bolivia (I already posted an earlier news item about the find on Saturday)


In Spanish:

with photo:





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Reconstructed replica skeleton of "giant" Psittacosaurus from Siberia goes on display at the Kemerovo Regional Museum (with videos) (in Russian)





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Demands by Tanzanian politicians for return of Berlin Giraffatitan [Brachiosaurus] bones (in German)




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Pachycephalosaurs (in Czech)



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Radio interview with Jean Le Loeuff about Tyrannosaurus and more dinosaur stuff (in French)



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Hierosaurus


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Chongqing Museum of Natural History new Dinosaur Hall recent opening (In Chinese)


Photos taken by a recent  visitor:


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Dinosaur extinction double punch


Poekilopleuron | 25 Jul 23:23 2016
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[dinosaur] Yutyrannus feathers color

Good day,

I would like to ask, if there is a possibility of deciphering color(s) of feathery integument of a chinese tyrannosauroid _Yutyrannus huali_? Thank you in advance, Tom
Ben Creisler | 25 Jul 21:17 2016
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[dinosaur] Stegosaurid tracks from Late Jurassic-Early Cretaceous of Cameros Basin, Spain (free pdfs)



Ben Creisler

A paper from last year that has not been posted yet, along with a correction:

Carlos Pascual-Arribas and Nieves Hernández-Medrano (2015)
Nuevas huellas de estegosaúridos en el Titoniense-Berriasiense de la Cuenca de Cameros (Fm. Magaña). [New stegosaurid tracks from the Tithonian-Berriasian of Cameros Basin (Magaña Fm.)] 
Revista de la Sociedad Geológica de España 28(2): 15-27
ISSN (versión impresa): 0214-2708
ISSN (Internet): 2255-1379

For the first time in the Magaña Fm. (Tithonian-Berriasian), Tera Group (Cameros Basin, Iberian Range, Spain) it has been found tracks of stegosaurids. The new site (San Felices, Soria) has provided a trackway with foot- and hand-prints whose shape and morphometric characteristics permit to classify them as Deltapodus isp. The coexistence in facies of the transit Upper Jurassic-Lower Cretaceous, in the Iberian Peninsula, of this ichnogenus tracks and bones of stegosaurids, permit to establish a relationship between Deltapodus tracks on this site and thyreophorans, probably belonging to the genus Dacentrurus or related taxon.

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CORRECTION TO:

Carlos Pascual-Arribas and Nieves Hernández-Medrano (2016)
Nuevas huellas de estegosáuridos en el Titoniense-Berriasiense de la Cuenca de Cameros (Formación Magaña). [New stegosaurid tracks from the Tithonian-Berriasian of Cameros Basin (Magaña Fm.) ]
Revista de la Sociedad Geológica de España 29(1): 125

Ben Creisler | 25 Jul 19:24 2016
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[dinosaur] Dinosaurs crossed North Atlantic land bridges in Late Jurassic and Early Cretaceous


Ben Creisler

Originally posted on the DML in manuscript form back in May, the article is now officially published:


Leonidas Brikiatis (2016)
Late Mesozoic North Atlantic land bridges.
Earth-Science Reviews 159: 47–57
doi:10.1016/j.earscirev.2016.05.002

Current palaeogeographical reconstructions suggest that since the onset of the Late Jurassic and during the whole Cretaceous Period, the landmasses of North America and West Eurasia have been separated by seaway(s) exposed on the North Atlantic rift system. Such a palaeogeographical setting should have limited the possibility of direct overland dispersals between the biotas of the two continents. Strong faunal affinities between the two sides of the North proto-Atlantic Ocean presuppose faunal exchanges between the landmasses, however, suggesting the existence of ephemeral land bridges around the Jurassic/Cretaceous boundary and the mid-Early Cretaceous. This study reviews the current faunal evidence and discusses palaeogeographical evidence that might better elucidate the existence of the postulated land bridges. Evaluation of the evidence leads to the conclusion that two land bridges were exposed: 1) between East North America and Iberia during the Late Kimmeridgian (~ 154 Ma) and 2) between North America and Fennoscandia, via the Barents Shelf, around the Hauterivian-Barremian boundary (~ 131 Ma). The former land bridge was terminated in the earliest Tithonian (~ 151 Ma), and the latter was terminated in the late Early Barremian (~ 129 Ma). Furthermore, the latter land bridge was contemporaneous with regressive stages in both the Mid-Polish Trough and the sea strait crossing the Russian Platform, allowing broad, direct terrestrial communication among North America, Europe, and Asia in the earliest Barremian.

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News:


Ben Creisler | 24 Jul 22:15 2016
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[dinosaur] Fauna for Adelolophus type locality + dinosaur gigantism (free pdfs)


Ben Creisler


Recent papers in open access:



Patricia A. Holroyd and J. Howard Hutchison (2016)
Fauna and setting of the Adelolophus hutchisoni type locality in the Upper Cretaceous (Campanian) Wahweap Formation of Utah.
PaleoBios 33: 1-9



We report new data on the type locality of the hadrosaurid ornithischian Adelolophus hutchisoni Gates et al., 2014 from the Campanian-aged Wahweap Formation of southern Utah, and the remainder of the vertebrate assemblage from the site. The type locality (UCMP V98173) is a previously-reported U.S. Geological Survey locality (USGS D815) and is stratigraphically low in the upper member of the Wahweap Formation. Additional taxa from the same site include acipenseriforms (sturgeon), amiiforms (bowfin), and lepisosteiforms (gar fish), baenid and trionychid turtles, and both theropod and ornithischian dinosaurs.



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XU Xing &  ZHAO Qi (2016)
Advances in research on dinosaur gigantism.
Chinese Science Bulletin 61(7): 695-700   (Chinese Edition)
DOI: 10.1360/N972015-01332 

 
Animal gigantism is an important evolutionary phenomenon. Cope's rule postulates that organisms in evolving lineages tend to increase in body size over time, but many animals don't show these tendencies. Many of the most well-known examples of animal gigantism are found amongst dinosaurs. The carnivorous theropod Spinosaurus aegyptiacus (~14-18 m in length, ~7-21 t in mass), the herbivorous sauropod Argentinosaurus huinculensis (~30-40 m in length, 60-100 t in mass) and the herbivorous ornithopod Shantungosaurus giganteus (~15-19 m in length, ~10-23 t in mass) are amongst the largest terrestrial animals ever to have walked the Earth. Studies on bone histology show that dinosaurs attained giant size using one of three growth strategies: accelerated growth, delayed maturity or a combination of these strategies. Previous studies have mostly focused on explaining why dinosaurs became so large in terms of environmental and biological factors. In the former aspect, latitude, habitat size, temperature conditions and oxygen levels were all found to be related to dinosaur gigantism. In the latter aspect, diet and selective advantages in biomechanics, respiration, digestion and bone development (osteocyte size) were all found to affect dinosaur gigantism. Significant progress has been made in these regards, but a unanimously agreed consensus has yet to be reached. This has been hampered by difficulties including those encountered when comparing giant non-dinosaurian living animals with dinosaurs as well as incomplete knowledge of some dinosaur palaeoenvironments. In recent years, research on sauropod gigantism has advanced more significantly compared to other dinosaur groups. An evolutionary cascade model (ECM) has been developed to understand the uniquely gigantic body size of sauropods. This model comprises of five evolutionary cascades with each one linked to at least one other: “Reproduction”, “Feeding”, “Head and neck”, “Avian-style lung”, and “Metabolism”. All cascades start with observed or inferred basal traits and end in the trait “very high body mass”. Future research that extends EMC-style approaches to all dinosaur groups and integrates them with additional palaeoenvironmental and biological information to produce more holistic evolutionary perspectives will help to bring consensus to our understanding of dinosaur gigantism. This would be especially welcome, particularly if this can deepen knowledge of herbivore-carnivore co-evolution and understanding of tetrapod gigantism more generally.

Ben Creisler | 24 Jul 02:42 2016
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[dinosaur] Utahraptor block funding problems + Hatzegopteryx model + giant theropod tracks in Bolivia + more


Ben Creisler

Some recent items:


Work on Utahraptor fossil block stalled by funding drop


http://www.heraldextra.com/news/local/north/lehi/lehi-palentologist-shares-passion-for-dinosaurs-waits-for-utahraptors-to/article_3b792309-96b7-5b49-b4cd-5d6992903c69.html


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Giant Hatzegopteryx model on display at Antipa Museum in Bucharest, Romania



http://www.romania-insider.com/largest-flying-dinosaur-display-bucharest-museum/

 

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Preparing for Henry the Triceratops skeleton display at Missouri Institute of Natural Science (video)

 

http://www.ky3.com/content/news/Addition-to-Missouri-Institute-of-Natural-Science-almost-complete-387780931.html


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Dutch student studies geology of Triceratops site (video in Dutch)

 

http://www.nationalgeographic.nl/video/geologisch-onderzoek-triceratops


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Mary Schweitzer interview


http://thewell.intervarsity.org/voices/unlikely-paleontologist-interview-mary-schweitzer-part-1


http://thewell.intervarsity.org/voices/unlikely-paleontologist-interview-mary-schweitzer-part-2

 

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Tyler Lyson  on digging turtle ancestors, radio interview

 

https://www.cpr.org/news/story/why-did-ancient-turtles-grow-shells-denver-paleontologist-found-out


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Mark Witton book on Age of Reptiles art


https://www.theguardian.com/science/gallery/2016/jul/20/palaeoart-recreating-an-age-of-reptiles-mark-witton-dinosaurs?CMP=share_


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New study and preservation efforts for dinosaur tracksite at Cal Orck'o at Sucre in Bolivia; new finds include gigantic theropod tracks and possible ceratopsian tracks (in Spanish) 


https://correodelsur.com/cultura/20160720_nuevo-estudio-revela-mas--sobre-sucre-paleontologica.html


https://correodelsur.com/cultura/20160719_sucre-certifican-riqueza-de-cal-orcko-y-del-d-8.html


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Flooding in Australia strands dinosaur museum staff at Winton



http://www.brisbanetimes.com.au/queensland/staff-at-queensland-dinosaur-museum-stranded-after-flooding-20160721-gqaysd.html


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New Bay of Fundy fossils include sphenodonts and a theropod


http://www.cbc.ca/news/canada/nova-scotia/parrsboro-fossil-cliffs-discovery-1.3689214


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Coal Age tetrapod tracks from Alabama


http://alabamanewscenter.com/2016/07/22/footprints-in-stone-fossils-of-coal-age-animals-attract-global-visitors/


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Blue Beach in Nova Scotia, Canada, tetrapod fossils from the Lower Carboniferous "Romer's Gap" (podcast)


http://www.palaeocast.com/episode-67-blue-beach-tetrapods/



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How Did the Ancestors of Modern-Day Birds Survive?



http://www.scientificamerican.com/article/how-did-the-ancestors-of-modern-day-birds-survive/


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Videos


A History of Antarctica, w/ Dinosaurs



http://sploid.gizmodo.com/the-history-of-antarctica-is-actually-a-really-fun-tale-1784067739



https://www.youtube.com/watch?v=1z6jkkvRvVQ


(Slighty muddled paleontology, with dinosaurs and Lystrosaurus mixed together)


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Ben Creisler | 23 Jul 23:08 2016
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[dinosaur] Cretaceous marine amniotes of Australia + Kollikodon + more (free pdfs)


Ben Creisler



In open access, a new memoir from the Museum Victoria in Australia in honor of Thomas Rich:




Mainly Mesozoic tetrapod-related papers:


Benjamin P. Kear (2016)
Cretaceous marine amniotes of Australia: perspectives on a decade of new research.
Memoirs of Museum Victoria 74: 17-28 

pdf:


Cretaceous marine amniote fossils have been documented from Australia for more than 150 years, however, their global significance has only come to the fore in the last decade. This recognition is a product of accelerated research coupled with spectacular new discoveries from the Aptian–Albian epeiric sequences of the Eromanga Basin – especially the opal-bearing deposits of South Australia and vast lagerstätten exposures of central-northern Queensland. Novel fragmentary records have also surfaced in Cenomanian and Maastrichtian strata from Western Australia. The most notable advances include a proliferation of plesiosaurian taxa, as well as detailed characterization of the ‘last surviving’ ichthyosaurian Platypterygius, and some of the stratigraphically oldest protostegid sea turtles based on exceptionally preserved remains. Compositionally, the Australian assemblages provide a unique window into the otherwise poorly known Early Cretaceous marine amniote faunas of Gondwana. Their association with freezing high latitude palaeoenvironments is also extremely unusual, and evinces a climate change coincident diversity turnover incorporating the nascent radiation of lineages that went on to dominate later Mesozoic seas.


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Alistair R. Evans (2016)
What is ‘Pseudo’ in Pseudotribosphenic Teeth?
Memoirs of Museum Victoria 74: 93-96 

pdf:


The discovery of a ‘pseudotribosphenic’ lower tooth row in 1982, with a basin anterior to the trigonid rather than posterior, caused a large stir in mammalian palaeontology. This indicated that a tooth shape of equivalent complexity to the tribosphenic tooth form could evolve more than once. The upper tooth predicted to occlude with the pseudotribosphenic molar was reconstructed with a ‘pseudoprotocone’ to occlude with the pseudotalonid basin. Here I discuss the relative merits of naming the major upper lingual cusp of pseudotribosphenic molars as ‘protocone’ due to its likely similar developmental and functional relations as the protocone of tribosphenic molars. The use of a different name implies greater morphological distance between tribosphenic and pseudotribosphenic upper molars than is perhaps warranted, and likely exaggerates the perception of the difficulty in evolving both tribospheny and pseudotribospheny. The choice between the evolution of the alternative forms of tribospheny may in fact be related to the degree of anterior-posterior bias in lower molar development – tribospheny with a posterior bias, while pseudotribospheny with an anterior one.


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Rebecca Pian, Michael Archer, Suzanne J. Hand, Robin M.D. Beck and Andrew Cody (2016)
The upper dentition and relationships of the enigmatic Australian Cretaceous mammal Kollikodon ritchiei.
Memoirs of Museum Victoria 74: 97-105 

pdf:


Mesozoic mammals from Australia are rare, so far only known from the Early Cretaceous, and most are poorly represented in terms of dentitions much less cranial material. No upper molars of any have been described. Kollikodon ritchiei is perhaps the most bizarre of these, originally described on the basis of a dentary fragment with three molars. Here we describe a second specimen of this extremely rare taxon, one that retains extraordinarily specialised upper cheekteeth (last premolar and all four molars). Each molar supports rows of bladeless, rounded cuspules many of which exhibit apical pits that may be the result of masticating hard items such as shells or chitin. Reanalysis of the phylogenetic position of this taxon suggests, based on a limited number of apparent synapomorphies, that it is an australosphenidan mammal and probably the sister group to Monotremata. This reanalysis also supports the view that within Monotremata, tachyglossids and ornithorhynchids diverged in the early to middle Cenozoic.

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Ralph E. Molnar and Felipe Mesquita de Vasconcellos (2016)
Cenozoic dinosaurs in South America – revisited.
Memoirs of Museum Victoria 74:  363-377 

pdf:


Of course there were Cenozoic dinosaurs (theropods) in South America, phorusrhacid (‘terror’) birds among others, but that is not the subject here. Why did anyone think there were Cenozoic (non-avian) theropods in South America? Because of a misinterpretation of Ameghino’s belief that derived mammals lived along with dinosaurs in Late Cretaceous Argentina. But also because isolated theropod teeth were found associated with derived (Eocene) mammal fossils. These turned out to be the teeth of Sebecus icaeorhinus. This is a small crocodylomorph, skull length c. 450 mm. More recently discovered sebecosuchians were substantially larger: Barinasuchus arveloi had an (estimated) skull length of c. 1000 mm, similar to that of Daspletosaurus (1000 mm). These crocodylomorphs are generally believed to have been terrestrial animals, presumably preying on large mammals. Thus, although there were no large non-avian theropods in Cenozoic South America, there were crocodylomorphs that seem to have been ecological vicars of large theropods. The reconstruction of terrestrial trophic networks for large terrestrial tetrapods after the Cretaceous-Paleogene extinctions seems to have been slower than often supposed. At (or near) the Cretaceous-Paleogene boundary, large herbivores turned over from archosaurs to mammals, but turnover of large carnivores was slower. In South America, dinosaur-size crocodylomorphs lived as late as the Miocene. Thus modern terrestrial ecosystems do not, trophically, reflect those of even the Early Neogene in some southern continents. Sebecosuchians, at least in South America, seem to have been unaffected by the Cretaceous-Paleogene extinctions.


Ben Creisler | 23 Jul 23:03 2016
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[dinosaur] Megaraptor and Australoraptor manual anatomy + new Valdosaurus specimen (free pdfs)


Ben Creisler

In open access, a new memoir from the Museum Victoria in Australia in honor of Thomas Rich:



Dinosaur articles:


Fernando E. Novas, Alexis M. Aranciaga Rolando and Federico L. Agnolín (2016)
Phylogenetic relationships of the Cretaceous Gondwanan theropods Megaraptor and Australovenator: the evidence afforded by their manual anatomy.
Memoirs of Museum Victoria 74: 49–61

pdf:


General comparisons of the manual elements of megaraptorid theropods are conducted with the aim to enlarge the morphological dataset of phylogenetically useful features within Tetanurae. Distinctive features of Megaraptor are concentrated along the medial side of the manus, with metacarpal I and its corresponding digit being considerably elongated. Manual ungual of digit I is characteristically enlarged in megaraptorids, but it is also transversely compressed resulting in a sharp ventral edge. We recognize two derived characters shared by megaraptorans and coelurosaurs (i.e., proximal end of metacarpal I without a deep and wide groove continuous with the semilunar carpal, and metacarpals I and II long and slender), and one derived trait similar to derived tyrannosauroids (i.e., metacarpal III length <0.75 length of metacarpal II). However, after comparing carpal, metacarpal and phalangeal morphologies, it becomes evident that megaraptorids retained most of the manual features present in Allosaurus. Moreover, Megaraptor and Australovenator are devoid of several manual features that the basal tyrannosauroid Guanlong shares with more derived coelurosaurs (e.g., Deinonychus), thus countering our own previous hypothesis that Megaraptora is well nested within Tyrannosauroidea.

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Paul M. Barrett (2016)
A new specimen of Valdosaurus canaliculatus (Ornithopoda: Dryosauridae) from the Lower Cretaceous of the Isle of Wight, England.
Memoirs of Museum Victoria 74: 29-48 

pdf:


The anatomy of Valdosaurus canaliculatus is incompletely known and until recently was based exclusively upon the holotype femora. Additional discoveries from the Wessex Formation (Barremian) of the Isle of Wight during the past decade have considerably expanded the amount of material available and offered insights into the morphology of the vertebral column and pelvis. However, all of these specimens consist primarily of hind limb material. Here, I describe a newly discovered individual of this taxon, the most complete yet found, which was found in articulation and includes a partial dorsal series, an almost complete tail, pelvic material, and both hind limbs. Although the specimen is partially crushed it offers new information on the anatomy of Valdosaurus, facilitating comparisons with other dryosaurid taxa.

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Anthony J. Martin (2016)
A close look at Victoria's first known dinosaur tracks.
Memoirs of Museum Victoria 74: 63-71 

pdf:


Lower Cretaceous (Aptian-Albian) rocks of Victoria, Australia are well known for their dinosaur body fossils, but not so much for their trace fossils. For example, the first known dinosaur track from the Eumeralla Formation (Albian) of Knowledge Creek, Victoria, was not discovered until 1980. This specimen, along with two more Eumeralla tracks found at Skenes Creek in 1989, constituted all of the dinosaur tracks recognised in Lower Cretaceous strata of southern Australia until the late 2000s. Unfortunately, none of these first-known dinosaur tracks of Victoria were properly described and diagnosed. Hence, the main purpose of this study is to document these trace fossils more thoroughly. Remarkably, the Knowledge Creek and one of the Skenes Creek tracks are nearly identical in size and form; both tracks are attributed to small ornithopods. Although poorly expressed, the second probable track from Skenes Creek provides a search image for less obvious dinosaur tracks in Lower Cretaceous strata of Victoria. The Skenes Creek tracks were also likely from the same trackway, and thus may represent the first discovered dinosaur trackway from Victoria. These tracks are the first confirmed ornithopod tracks for Victoria, augmenting abundant body fossil evidence of small ornithopods (‘hypsilophodontids’) in formerly polar environments during the Early Cretaceous.

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Ben Creisler | 22 Jul 20:04 2016
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[dinosaur] Nedcolbertia as ornithomimosaur + azhdarid humerus from Saratov Region, Russia + more



Ben Creisler

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

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


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 


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

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.

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