[dinosaur] New lepidosaur species: Clevosaurus hadroprodon + Hoeckosaurus mongoliensis

Ben Creisler
[email protected]

New non-dino papers:

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Clevosaurus hadroprodon sp. nov.

Annie S. Hsiou, Randall L. Nydam, Tiago R. Simões, Flávio A. Pretto, Silvio
Onary, Agustín G. Martinelli, Alexandre Liparini, Paulo R. Romo de Vivar
Martínez, Marina B. Soares, Cesar L. Schultz & Michael W. Caldwell (2019)
A New Clevosaurid from the Triassic (Carnian) of Brazil and the Rise of
Sphenodontians in Gondwana.
Scientific Reports 9, Article number: 11821
DOI: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1038_s41598-2D019-2D48297-2D9&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=hUPsj9Zq-BzxqHEPj7hfBi_zVnaQN_CUvjEs-dMuTv8&s=GzESa5eGbnI_fF9Jgq4Di26MlvOgS4bSQOu9AS0CZ_o&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_s41598-2D019-2D48297-2D9&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=hUPsj9Zq-BzxqHEPj7hfBi_zVnaQN_CUvjEs-dMuTv8&s=vO9qZtyhIjAAUkw1lDKDfuWZ_jhm3y_1Djqr3YD85-c&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_s41598-2D019-2D48297-2D9.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=hUPsj9Zq-BzxqHEPj7hfBi_zVnaQN_CUvjEs-dMuTv8&s=1r8GA4mox1EPA1XXnyJBXEF58mYIdMDs3n4y7UZolPo&e= 


The early evolution of lepidosaurs is marked by an extremely scarce fossil
record during the Triassic. Importantly, most Triassic lepidosaur specimens
are represented by disarticulated individuals from high energy accretion
deposits in Laurasia, thus greatly hampering our understanding of the
initial stages of lepidosaur evolution. Here, we describe the fragmentary
remains of an associated skull and mandible of Clevosaurus hadroprodon sp.
nov., a new taxon of sphenodontian lepidosaur from the Late Triassic
(Carnian; 237–228 Mya) of Brazil. Referral to Sphenodontia is supported by
the combined presence of a marginal dentition ankylosed to the apex of the
dentary, maxilla, and premaxilla; the presence of ‘secondary bone’ at the
bases of the marginal dentition; and a ventrally directed mental process at
the symphysis of the dentary. Our phylogenetic analyses recover Clevosaurus
hadroprodon as a clevosaurid, either in a polytomy with the Late Triassic
to Early Jurassic Clevosaurus and Brachyrhinodon (under Bayesian
inference), or nested among different species of Clevosaurus (under maximum
parsimony). Clevosaurus hadroprodon represents the oldest known
sphenodontian from Gondwana, and its clevosaurid relationships indicates
that these sphenodontians achieved a widespread biogeographic distribution
much earlier than previously thought.

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Hoeckosaurus mongoliensis sp. nov.

Andrej Čerňanský (2019)
The first potential fossil record of a dibamid reptile (Squamata:
Dibamidae): a new taxon from the early Oligocene of Central Mongolia.
Zoological Journal of the Linnean Society, zlz047
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1093_zoolinnean_zlz047&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=hUPsj9Zq-BzxqHEPj7hfBi_zVnaQN_CUvjEs-dMuTv8&s=CUitEBTUlpumkFJVXxM2e1W-CrMi9z5bl0AxGa0Uj4Q&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__academic.oup.com_zoolinnean_advance-2Darticle-2Dabstract_doi_10.1093_zoolinnean_zlz047_5549606&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=hUPsj9Zq-BzxqHEPj7hfBi_zVnaQN_CUvjEs-dMuTv8&s=6rXopKiVsJemoWAHmMhql9YmNacPB8l-qUPxWwvUtpI&e= 


Dibamid reptiles have a known current distribution on two continents (Asia
and North America). Although this clade represents an early-diverging group
in the Squamata and thus should have a long evolutionary history, no fossil
record of these peculiar burrowing squamate reptiles has been documented so
far. The fossil material described here comes from the early Oligocene of
the Valley of Lakes in Central Mongolia. This material consists of jaws and
is placed in the clade Dibamidae on the basis of its morphology, which is
further confirmed by phylogenetic analyses. In spite of the fragmentary
nature of this material, it thus forms the first, but putative, fossil
evidence of this clade. If correctly interpreted, this material
demonstrates the occurrence of Dibamidae in East Asia in the Palaeogene,
indicating its distribution in higher latitudes than today. The preserved
elements possess a unique combination of character states, and a new taxon
name is therefore erected: Hoeckosaurus mongoliensis sp. nov. The dentary
of Hoeckosaurus exhibits some characters of the two extant dibamid taxa.
However, the open Meckel’s groove, together with other characters, show
that this group was morphologically much more diverse in the past.

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