Biology subjects

Plateau, O.

Publications and source records attributed to Plateau, O..

5 recordsLinked to original sources

bioRxiv2026

Macroevolutionary shifts in post-hatching ontogeny and the origin of craniofacial disparity in fowl (Aves: Galloanserae)

Anseriformes (waterfowl) and Galliformes (landfowl) are among the worlds most recognisable groups of birds, together comprising the clade Galloanserae. Despite their close evolutionary relationship, the skulls of adult anseriforms and galliforms exhibit strikingly distinct morphologies, the developmental basis and evolutionary history of which is poorly understood. To illuminate the developmental and evolutionary underpinnings of cranial disparity between and within these major extant bird clades, we quantitatively investigated ontogenetic changes in cranial morphology across galloanseran phylogenetic diversity, focusing on the previously unexplored post-hatching interval during which adult morphology takes shape. Our results reveal the combined effects of multiple heterochronic shifts early in galloanseran evolutionary history including anseriform hypermorphosis, along with influential non-heterochronic changes leading to substantially more disparate ontogenetic trajectories--and greater cranial variability--in anseriforms than galliforms. Key galloanseran fossils help clarify the polarity of evolutionary shifts in cranial development through galloanseran phylogenetic history and demonstrate that extant galliform cranial morphology is more constrained and retains a more plesiomorphic morphology than that of anseriforms. Our work helps illuminate the developmental basis of the iconic differences in cranial form between waterfowl and landfowl and illustrates the importance of broad phylogenetic and ontogenetic sampling for clarifying patterns of post-hatching developmental divergence among major vertebrate clades.

evolutionary biology↗

bioRxiv2026

Developmental variation in pterygoid segmentation clarifies patterns of avian bony palate evolution

The morphology of the palate has long constituted the primary basis for differentiating between the two deepest clades of crown group birds, Neognathae and Palaeognathae. However, published literature on the bird palate is dominated by classical anatomical descriptions pre-dating the advent of contemporary three-dimensional imaging techniques, hindering our understanding of bird palate disparity and development. Pterygoid segmentation, the process by which the rostral portion of the pterygoid separates and fuses with the palatine during ontogeny in neognathous birds, remains a poorly understood aspect of avian cranial development despite giving rise to an important component of the cranial kinetic system. Here, we use micro-computed tomography to explore ontogenetic change of the palate during the process of pterygoid segmentation across an unprecedentedly broad taxonomic sample of immature and mature birds. With this large dataset, we present direct evidence for the full process of post-hatching pterygoid segmentation being exclusively restricted to the major avian subclade Neoaves. Further, our investigation helps refine several hypotheses of homology related to the pterygoid-palatine contact in crown birds and their close stem-group relatives: we hypothesise that the rostral projection of the pterygoid observed in Anseres (and potentially Anhimidae and Megapodiidae) is homologous with the hemipterygoid of neoavians, and that the discrete and unfused hemipterygoids of some crownward stem-birds suggest that a discrete hemipterygoid originated prior to the origin of the process of pterygoid segmentation. However, whether pterygoid segmentation represents a synapomorphy of Neornithes, Neognathae, or Neoaves remains ambiguous in light of elusive data from the fossil record and early stages of cranial development. Overall, our study clarifies the process of pterygoid segmentation in crown birds and raises new questions regarding the major morphological modifications that have characterized the evolutionary history of the avian bony palate.

paleontology↗

bioRxiv2025

Developmental underpinnings of morphological disparity in the avian bony palate

The deepest phylogenetic divergence in crown birds gave rise to Palaeognathae and Neognathae, clades exhibiting divergent bony palate morphologies. This observation led to the longstanding hypothesis that the distinctive palate arrangement of palaeognaths retains the ancestral crown bird condition, but recent fossil evidence instead suggests that aspects of palaeognath palate morphology are derived from a neognath-like ancestral condition. While neoteny has been hypothesised as a mechanism underpinning the distinctive palatal morphologies of palaeognaths, this hypothesis has never been tested with a broad phylogenetic assessment of morphological variation through avian palate ontogeny. Here, we quantitatively assess morphological variation of the palate through the post-hatching ontogenies of 70 bird species representing all major extant phylogenetic subclades, clarifying the ontogenetic mechanisms giving rise to avian palate disparity. Though palaeognaths exhibit distinct ontogenetic changes in the PPC relative to neognaths, we find no signatures of heterochrony--including neoteny--underlying these developmental differences. However, important patterns of morphological change in the avian palate appear to be dictated by variation in developmental mode. Our results document the effects of post-hatching development on a key morphofunctional system in the avian skull, and, more broadly, highlight the influence of developmental mode on morphological evolvability across crown group birds.

evolutionary biology↗

bioRxiv2025

Shouldering the challenge of deciphering avian palate evolution

Wilken et al. (1) investigate the evolution of avian palatal kinesis using comparative morphology and biomechanical modelling. While the studys topic and approach are timely, its conclusions are marred by inadequate taxon sampling and morphological misinterpretations.

evolutionary biology↗

bioRxiv2020

The impact of allometry on vomer shape and its implications for the taxonomy and cranial kinesis of crown-group birds

Crown birds are subdivided into two main groups, Palaeognathae and Neognathae, that can be distinguished, among other means, by the organization of the bones in their pterygoidpalatine complex (PPC). Shape variation of the vomer, which is the most anterior part of the PPC, was recently analysed with help of geometric morphometrics to discover morphological differences between palaeognath and neognath birds. Based on this study, the vomer was identified as sufficient to distinguish the two main groups (and even some inclusive neognath groups) and their cranial kinetic system. As there are notable size differences between the skulls of Palaeognathae and Neognathae, we here investigate the impact of allometry on vomeral shape and its implication for taxonomic classification by re-analysing the data of the previous study. Different types of multivariate statistical analyses reveal that taxonomic identification based on vomeral shape is strongly impaired by allometry, as the error of correct identification is high when shape data is corrected for size. This finding is evidenced by a great overlap between palaeognath and neognath subclades in morphospace. Correct taxonomic identification is further impeded by the convergent presence of a flattened vomeral morphotype in multiple neognath subclades. As the evolution of cranial kinesis has been linked to vomeral shape in the original study, the correlation between shape and size of the vomer across different bird groups found in the present study questions this conclusion. In fact, cranial kinesis in crown birds results from the loss of the jugal-postorbital bar in the temporal region and ectopterygoid in the PPC and the combination of a mobilized quadratezygomatic arch complex and a flexible PPC. Therefore, we can conclude that vomer shape itself is not a suitable proxy for exploring the evolution of cranial kinesis in crown birds and their ancestors. In contrast, the evolution of cranial kinesis needs to be viewed in context of the braincase, quadrate-zygomatic arch and the whole pterygoid-palatine complex.

zoology↗