[dinosaur] Vertebrate crests with bone and keratin + Embrithosaurus (Pareiasauria) cranial morphology

Ben Creisler
[email protected]

New papers:

Delphine Angst, Jonathan Barnoud, Raphaël Cornette & Anusuya Chinsamy (2019)
Sex and Ontogenetic Variation in the Crest of Numida meleagris:
Implications for Crested Vertebrates.
The Anatomical Record (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1002_ar.24275&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=vWVb4cshdkqNbsTRsg-7pNfQS5JaRmLeZ67CdDDeZ4M&s=VBeJtqdfv3kgPD9e69QQExwph9epg2oey3TQWfnXU_c&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__anatomypubs.onlinelibrary.wiley.com_doi_10.1002_ar.24275&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=vWVb4cshdkqNbsTRsg-7pNfQS5JaRmLeZ67CdDDeZ4M&s=nfgqrNoqEUbgcxGySuDofImp3BPuLfXJepo7GhmjoEA&e= 

Crested vertebrates are known from a wide variety of modern and fossil
taxa, however, the actual formation and function of the crest is still
debatable. Among modern birds, the globally distributed guinea fowl (Numida
meleagris) is characterized by having a cranial bony crest (overlain by
keratin), but surprisingly little is known about its development. Here, we
studied the crest of 202 wild guinea fowl from the same population, using
anatomical measurements as well as 2D‐morphometry. Our results show that
juveniles have smaller skulls than adults and have smaller, simpler crests
that are visible even in very young individuals. Among adults, female
skulls are smaller than males, and they have smaller, simpler shaped
crests, which permit a discrimination between the sexes of 93% when the
keratin is preserved with the bony crest, and of 89% when only the bony
crest is available. By extrapolation, these results confirm that the crest
can be used as an ontogenetic character, as well as for sex discrimination
in the fossil record. Our results also show that the overlying keratin does
not always mimic the underlying bony crest, which should be considered when
reconstructing extinct crested vertebrates.


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Marc Johan Van den Brandt, Fernando Abdala & Bruce Sidney Rubidge (2019)
Cranial morphology and phylogenetic relationships of the Middle Permian
pareiasaur Embrithosaurus schwarzi from the Karoo Basin of South Africa.
Zoological Journal of the Linnean Society, zlz064 (advance online
publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1093_zoolinnean_zlz064&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=vWVb4cshdkqNbsTRsg-7pNfQS5JaRmLeZ67CdDDeZ4M&s=Q0qOUvkdn5u6VIQCr1NlwOHU4I7-WdbttUCB6JW6UfU&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__academic.oup.com_zoolinnean_advance-2Darticle-2Dabstract_doi_10.1093_zoolinnean_zlz064_5614930&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=vWVb4cshdkqNbsTRsg-7pNfQS5JaRmLeZ67CdDDeZ4M&s=4GQJvzpICzoF8IoDjXH4NwFInTw0GgnvkRMJRuc9FMA&e= 

Pareiasaurs were globally distributed, abundant, herbivorous parareptiles
of the Middle to Late Permian, with the basal-most members found in the
Middle Permian of South Africa. These basal taxa were particularly abundant
and went extinct at the end of the Gaudalupian (Capitanian) at the top of
the Tapinocephalus Assemblage Zone. Currently four taxa are recognized in
this group: Bradysaurus seeleyi, B. baini, Nochelesaurus alexanderi and
Embrithosaurus schwarzi, but they are all poorly understood. We here
present the first detailed cranial description and updated diagnosis for
Embrithosaurus schwarzi. No cranial autapomorphies were identified.
However, Embrithosaurus schwarzi is a distinct taxon in this group, based
on its unique dentition and using a combination of cranial features. It has
nine marginal cusps on all maxillary and mandibular teeth, and wider
maxillary teeth than in the co-occurring taxa, due to the marginal cusps
being arranged more regularly around the crown, and the apex of the crown
lacking the long, central, three-cusped trident. Our updated phylogenetic
analysis recovers the four Middle Permian South African taxa as a
monophyletic group for the first time, which we call Bradysauria,
comprising a clade including Embrithosaurus, Bradysaurus baini and a
polytomy including Nochelesaurus and Bradysaurus seeleyi.