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Re: [dinosaur] Montirictus, new tritylodont synapsid from Early Cretaceous of Japan + new Purgatorius species + Antarctic pelagornithids



A news item for the first paper:

Non-mammal tritylodont synapids survived longer than thought

http://phys.org/news/2016-04-mammal-like-reptile-survived-longer-thought.html

On Tue, Mar 22, 2016 at 3:44 PM, Ben Creisler <bcreisler@gmail.com> wrote:

Ben Creisler
bcreisler@gmail.com

Some new non-dino papers that may be of interest:

Montirictus

Hiroshige Matsuoka, Nao Kusuhashi & Ian J. Corfe (2016)
A new Early Cretaceous tritylodontid (Synapsida, Cynodontia, Mammaliamorpha) from the Kuwajima Formation (Tetori Group) of central Japan.
Journal of Vertebrate Paleontology (advance online publication) 
DOI: 10.1080/02724634.2016.1112289

We describe tritylodontid remains from the Lower Cretaceous Kuwajima Formation (Tetori Group) in central Japan as representing a new genus, Montirictus kuwajimaensis, gen. et sp. nov. Montirictus is a medium-sized tritylodontid genus characterized by upper cheek teeth having the cusp formula 2-2-2 with subequal cusps, buccal and lingual cusps retaining a crescentic shape with both buccal and lingual ridges anteriorly, and ‘V’-shaped buccolingual cross-sections of two anteroposterior grooves between the three cusp rows. Tentative dating of the Kuwajima Formation to the Barremian–Aptian makes it the stratigraphically youngest representative of a long-lived, globally distributed and abundant mammaliamorph lineage and extends the known geographic range of tritylodontids.


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Purgatorius pinecreeensis 

Craig S. Scott, Richard C. Fox &  Cory M. Redman (2016)

A new species of the basal plesiadapiform Purgatorius (Mammalia, Primates) from the early Paleocene Ravenscrag Formation, Cypress Hills, southwest Saskatchewan, Canada: further taxonomic and dietary diversity in the earliest primates.

Canadian Journal of Earth Sciences (advance online publication)

doi: 10.1139/cjes-2015-0238




The fossil record of the earliest primates, purgatoriid plesiadapiforms, has become increasingly well documented during the past two decades, but their dietary preferences remain poorly understood. While the available evidence, which consists mostly of isolated teeth and incomplete jaws with teeth, suggests that purgatoriids were insectivorous to omnivorous, we describe here a new species of Purgatorius, Purgatorius pinecreeensis sp. nov., that extends the range of purgatoriid dental disparity toward greater omnivory than had been known before. Purgatorius pinecreeensis sp. nov., from the early Paleocene (Puercan) Ravenscrag Formation of southwestern Saskatchewan, differs from other species of Purgatorius in having slightly lower crowned teeth with a lower trigonid relative to talonid, blunter and more swollen major cusps, more transverse lower molar paracristids, and m3 with a more robustly developed posterior lobe. Taken together, these specializations enhanced the capacity for crushing and grinding at the expense of orthal shear, and represent the first instance of a modest degree of bunodonty in the family. The discovery of P. pinecreeensis sp. nov., along with other recently reported basal plesiadapiforms from the Puercan and Torrejonian of the northern Western Interior, lends additional support to the notion of a significant primate radiation soon after the Cretaceous–Paleogene extinction event.




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Marcos Cenizo, Carolina Acosta Hospitaleche and Marcelo Reguero (2016)

Diversity of pseudo-toothed birds (Pelagornithidae) from the Eocene of Antarctica.

Journal of Paleontology (advance online publication

DOI: http: //  dx.doi.org/10.1017/jpa.2015.48 

http: // journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10249950&fulltextType=RA&fileId=S0022336015000487


The Antarctic pelagornithid record is restricted to few isolated remains from the Eocene of Seymour Island in the Antarctic Peninsula. Here we report the oldest Antarctic pseudo-toothed bird. It is represented by an incomplete humerus lacking its proximal end, which comes from the lower Eocene levels of the La Meseta Formation (Seymour Island). This new specimen facilitates a review of all known pelagornithids from this continent. Antarctic pelagornithids were classified into two morphotypes that exhibit a mix of putative plesiomorphic and derived characters. Considering the worldwide pelagornithid record and according to estimated wingspans, four approximate size-types were identified. The oldest Antarctic specimens (two fragmentary humeri, middle Ypresian) were assigned to morphotype 1 and correspond to the large size-type. The younger materials (Bartonian/?Priabonian) here assigned to morphotype 2 (some cranial remains, fragmentary tarsometatarsus and humerus) correspond to the giant size-type and represent one of the largest known pseudo-toothed birds. Even though species level phylogenetic affinities of Pelagornithidae remain poorly resolved, three key evolutionary events can be recognized: (1) the disappearance of Dasornis in the Early Eocene and the appearance of more advanced forms with a trend to the specialization of large soaring capacity, (2) the origin of Pelagornis sensu lato species in the early Oligocene, and (3) the appearance and dominance of a highly specialized terminal group at Mio/Pliocene time span.