Delphine Angst, Jonathan Barnoud, RaphaÃl 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://doi.org/10.1002/ar.24275https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.24275Crested 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 2Dâmorphometry. 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.
============
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://doi.org/10.1093/zoolinnean/zlz064https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlz064/5614930Pareiasaurs 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.