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[dinosaur] Fraserosphenodon, new rhynchocephalian + Basilemys morrinensis + more

Ben Creisler

Some recent non-dino papers and items:

Free pdf:

Fraserosphenodon gen. nov. ("Clevosaurus" latidens Fraser, 1993)

Jorge A. Herrera-Flores, Thomas L. Stubbs, Armin Elsler & Michael J. Benton (2018)
Taxonomic reassessment of Clevosaurus latidens Fraser, 1993 (Lepidosauria, Rhynchocephalia) and rhynchocephalian phylogeny based on parsimony and Bayesian inference.
Journal of Paleontology (advance online publication)
doi: https://doi.org/10.1017/jpa.2017.136

The Late Triassic rhynchocephalian Clevosaurus latidens Fraser, 1993 is known from the fissure deposits of Cromhall Quarry, England. Many studies have questioned its referral to the genus Clevosaurus Swinton, 1939 and some phylogenetic analyses suggest a close relationship with herbivorous rhynchocephalians. We re-examine the type specimens and referred material of C. latidens to elucidate its taxonomic identity. Additionally, we provide new phylogenetic analyses of the Rhynchocephalia using both parsimony and Bayesian approaches. Our taxonomic review and both phylogenetic analyses reveal that C. latidens is not referable to Clevosaurus, but represents a new genus. We reassess C. latidens and provide an amended diagnosis for Fraserosphenodon new genus. Both parsimony and Bayesian analyses recover similar topologies and we propose formal names for two higher clades within Rhynchocephalia: Eusphenodontia new infraorder and Neosphenodontia new clade.

UUID: http://zoobank.org/65f29bd1-47e3-4a73-af8c-9181c19319e4


Free pdf:

Basilemys morrinensisÂsp. nov.

Jordan C. Mallon & Donald B. Brinkman (2018)
Basilemys morrinensis, a new species of nanhsiungchelyid turtle from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada.Â
Journal of Vertebrate Paleontology. Article: e1431922
DOI: 10.1080/02724634.2018.1431922.

We describe a new species of nanhsiungchelyid turtle, Basilemys morrinensis, based on a nearly complete shell from the Horsethief Member (lower Maastrichtian) of the Horseshoe Canyon Formation of Alberta. The species is intermediate in age between the Campanian forms B. variolosa and B. gaffneyi and the upper Maastrichtian forms B. sinuosa and B. praeclara. It is also intermediate in its morphology, possessing a unique suite of both plesiomorphic (e.g., divided extragulars) and derived (e.g., square epiplastral beak, pygal wider than long) traits. It is further characterized by an autapomorphic square cervical scale. Phylogenetic analysis assuming parsimony recovers B. morrinensis in a polytomy with B. variolosa and B. gaffneyi, outside the clade formed by the upper Maastrichtian forms B. sinuosa and B. praeclara. The holotype of Basilemys morrinensis provides the first evidence that this genus reached large size (~1 m long) in the Horseshoe Canyon Formation and was not diminutive as previously thought based on less complete shell material. Although Basilemys is usually regarded as terrestrial in habit based on its skull and limb morphology, we note that the low profile of its shell is a derived feature usually indicative of an aquatic mode of life. This suggests that there is yet much to learn about the life habits of this interesting turtle.



KÃvin Rey, Michael O. Day, Romain Amiot, Jean Goedert, Christophe LÃcuyer, Judith Sealy & Bruce & S.Rubidge (2018)
Stable isotope record implicates aridification without warming during the late Capitanian mass extinction.
Gondwana Research 59: 1-8
doi: https://doi.org/10.1016/j.gr.2018.02.017Â


Terrestrial late Capitanian extinction linked to Î13C increase in South Africa.
Î13C and Î18O indicate local aridification without temperature change.
This may result from orogenesis causing change in water availability.


The late Capitanian mass extinction (~260 million years ago) represents one of the greatest biotic perturbations of the Phanerozoic and was the earliest mass extinction to affect terrestrial tetrapods and ecosystems. In the past, this extinction has been largely associated with taxonomic loss and ecological restructuring in marine environments but more recently it has also been recognised in terrestrial ecosystems. Though various environmental mechanisms have been proposed for the former, little evidence has yet been presented for the cause of terrestrial extinctions. We determined the stable oxygen and carbon isotope compositions of dentine apatite from twenty-eight specimens of the dicynodont therapsid Diictodon feliceps, to investigate the potential role of climate in driving terrestrial tetrapod extinctions. Studied specimens were recovered from a 270 m stratigraphic interval constraining the peak in tetrapod extinction rates in the uppermost Abrahamskraal Formation in the well-sampled main Karoo Basin of South Africa. Our results demonstrate a positive excursion of Î13C values coinciding with the extinction peak that is followed by a return to pre-extinction Î13C values, suggesting a local increase in aridity at the time of the extinction. For the same time interval, the Î18O values did not demonstrate statistically significant changes, suggesting constant temperature in the South African paleoenvironment. This unusual increase in aridity but not in temperature has been interpreted as the possible result of orogenesis in the Cape Fold Mountain source along the southern margin of Gondwana.


Free pdf:

South America Vertebrate Paleontology Reference List (1774-2018)