Sex and Ontogenetic Variation in the Crest of Numida meleagris: Implications for Crested Vertebrates

Abstract

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. Anat Rec, 303:1018–1034, 2020. © 2019 American Association for Anatomy

Multivariate characterisation of morpho-biometric traits of indigenous helmeted Guinea fowl (Numida meleagris) in Nigeria

“…Our findings on helmet shape are in agreement with the report on indigenous Guinea fowls in Ghanian where single shape (42.70%) predominated. The current observation on helmet shape where more females exhibited single shape is congruous withthe submission of Angst et al [ 51 ] that females have bony helmet more compact dorsoventrally while the males have taller helmet, with a more complex shape including curvature of the posterior part along the dorsoventral axis. Similarly, Agbolosu et al [ 21 ] reported that helmet shape is more pronounced in males than females.…”

Multivariate Characterization of Morpho-biometric Traits of Indigenous Helmeted Guinea Fowl (Numida meleagris) in Nigeria

“…Our findings on helmet shape are in agreement with the report on indigenous guinea fowls in Ghanian where single shape (42.70%) predominated. The current observation on helmet shape where more females exhibited single shape is congruous to the submission of Angst et al [57] that females have bony helmet more compact dorsoventrally while the males have taller helmet, with a more complex shape including curvature of the posterior part along the dorsoventral axis. Similarly, Agbolosu et al [24] reported that helmet shape is more pronounced in males than females.…”

A comprehensive anatomical and phylogenetic evaluation ofDilophosaurus wetherilli(Dinosauria, Theropoda) with descriptions of new specimens from the Kayenta Formation of northern Arizona

“…As was pointed out previously (Brusatte et al, 2010), the presence of a clade of crested early theropods is more than likely the outcome of character construction and coding. Cranial ornamentation such as these crests likely served an important role in species identification (Hopson, 1975; Molnar, 1977; Padian and Horner, 2014; Xing et al, 2015; Gates et al, 2016) or perhaps in intersexual or intrasexual selection as they do in some extant dinosaurs (Jones and Hunter, 1993, 1999; Angst et al, 2019).…”

“…A horizontal shelf extends medially towards the midline to contact the other nasal. The crests of Dilophosaurus wetherilli were almost certainly covered with keratin or keratinized skin, and a recent study on the cranial ontogeny of the extant guinea fowl Numida meleagris (Linnaeus, 1758) (Angst et al, 2019) suggests that the keratin on the crests of D. wetherilli could have been much more prominent than what the bony tissue indicates.…”