[dinosaur] Eomatsoia, new madtsoiid snake from Cretaceous of Argentina + Axestemys infernalis new Cretaceous turtle species

Ben Creisler
[email protected]

Some recent non-dino papers:

Eomatsoia ragei gen. nov.

Raúl O. Gómez, Fernando F. Garberoglio & Guillermo W. Rougier (2019)
A new Late Cretaceous snake from Patagonia: Phylogeny and trends in body
size evolution of madtsoiid snakes.
Comptes Rendus Palevol (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1016_j.crpv.2019.09.003&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=86XazQ0O8cDID3_pNd_MsgUsivpzaH16mcAqsHhgSOA&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.sciencedirect.com_science_article_abs_pii_S1631068319301770&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=bbiAn2Mzp7nn32hTZ5bm3Ci8G72pKEbVdVkr2PAL7fs&e= 


Madtsoiids constitute a successful group of extinct snakes widely
distributed across Gondwana and the European archipelago during Late
Cretaceous times, surviving in reduced numbers to the Pleistocene. They are
renowned for including some of the largest snakes that have ever crawled on
earth, yet diverse small madtsoiids are also known. Uncovering the
evolutionary trends that led these snakes into disparate body sizes has
been hampered mainly by the lack of phylogenetic consensus and the paucity
of taxa with novel combinations of features. Here we describe a new large
madtsoiid snake based on isolated vertebrae from the La Colonia Formation
(Maastrichtian–Danian) of Patagonia, Argentina. A comprehensive
phylogenetic analysis recovers Madtsoiidae as a basal ophidian lineage and
the new snake as sister to a clade of mostly big-to-gigantic taxa,
providing insights into early stages and evolutionary trends towards
madtsoiid gigantism.

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Free pdf:

Axestemys infernalis sp. nov.

Joyce, Walter G., Brinkman, Donald B., and Lyson, Tyler R. 2019.
A new species of trionychid turtle, Axestemys infernalis sp. nov., from the
Late Cretaceous (Maastrichtian) Hell Creek and Lance formations of the
Northern Great Plains, USA.
Palaeontologia Electronica 22.3.72 1–28.
doi:  https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.26879_949&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=0JubudCemgxHlCueqyRKlpsoDP8Fi9nZMtPZJg1ZdiU&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__palaeo-2Delectronica.org_content_2019_2827-2Da-2Dnew-2Dspecies-2Dof-2Dtrionychid&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=bsrEJrhaakKu2DKpyplrQRGsJ7iMKOiV_6ypPj5DyKk&e= 


The Late Cretaceous (Maastrichtian) Hell Creek and Lance formations in the
states of North Dakota, South Dakota, Montana, and Wyoming, USA, have
yielded rich remains of trionychid turtles, but the alpha taxonomy of the
group is still poorly resolved, as most fossils are fragmentary. We here
describe a new species of trionychid, Axestemys infernalis sp. nov., based
on a rich assortment of skulls, shells, and postcranial remains collected
from nine fossiliferous sites spread throughout these formations. The new
species is attributable to the Axestemys lineage based on the combined
presence of large size, a preneural, and a single lateral hyoplastral
process. Axestemys infernalis sp. nov. differs from all Paleogene
representatives of Axestemys by lacking elongate free ribs and by
possessing costal sculpturing that reaches the margin of the shell. It
further differs from the only other Mesozoic representative of the lineage,
Axestemys splendidus, a species herein restricted to the Campanian, by
possessing a rounded carapace. The available Axestemys infernalis sp. nov.
material shows much variation, in particular in regards to the maximum size
of individuals and the relative size of callosities, but not enough to
warrant recognizing multiple species. Instead, this variation is likely
caused by random drift or phenotypic variation that accrued over the course
of the approximately 1.36 Ma represented in the Hell Creek Formation.

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Free pdf:

Cretodus houghtonorum sp. nov.

Kenshu Shimada & Michael J. Everhart (2019)
A New Large Late Cretaceous Lamniform Shark from North America, with
Comments on the Taxonomy, Paleoecology, and Evolution of the Genus Cretodus.
Journal of Vertebrate Paleontology Article: e1673399
doi:  https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1080_02724634.2019.1673399&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=LnouYebxRyKMoeCNJD8P4HkfnM9cjaqJfmC5vJsG4Hs&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.tandfonline.com_action_showAxaArticles-3FjournalCode-3Dujvp20&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=8i17D3pNE6BDzOQIZOhWxFWhuclI6seacTmHihul8jc&e= 


We describe a partial skeleton of the Late Cretaceous shark, Cretodus,
collected from the Blue Hill Shale (middle Turonian) in north-central
Kansas, U.S.A. It consists of 134 disarticulated teeth, 61 vertebrae, 23
placoid scales, and fragments of calcified cartilage. The scale morphology
suggests that Cretodus was a rather sluggish shark, and the vertebral
morphology affirms its placement into Lamniformes. With a strong tendency
towards monognathic heterodonty, the dental morphology indicates that the
specimen belongs to a new species, C. houghtonorum, sp. nov., increasing
the total known species of Cretodus to five. The five species can be
divided into three distinct groups: the longiplicatus/semiplicatus-grade,
gigantea/houghtonorum-grade, and crassidens-grade. Cretodus, that
successively evolved by broadening the tooth crown. The individual of C.
houghtonorum, sp. nov., is estimated to be about 515 cm in total length
(TL). Our vertebra-based growth analysis suggests that the shark was about
118 cm TL at birth and that the species had an estimated maximum growth
length of 684 cm TL. The large size at birth indicates that the
intrauterine cannibalism behavior of embryos seen in extant lamniforms had
already evolved by the Late Cretaceous. Where C. houghtonorum, sp. nov.,
preferred nearshore environments, the specimen co-occurred with isolated
teeth of Squalicorax and fragments of two dorsal fin spines of a hybodont
shark, circumstantially indicating that the individual of Cretodus fed on
the much smaller hybodont and was scavenged by Squalicorax.

***
News:

Fossil dig leads to unexpected discovery of 91-million-year-old shark new
to science

https://urldefense.proofpoint.com/v2/url?u=https-3A__phys.org_news_2019-2D11-2Dfossil-2Dunexpected-2Ddiscovery-2Dmillion-2Dyear-2Dold-2Dshark.html&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=h-7kUXszpnp5ZBPDOhyglbFeOZxmwdz9PGVOeEb3XiA&s=JvN1p2esoccy_b13D2oHSBNTdQWp4UHG7-FpX73KTyg&e=