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The phylogenetic significance of the morphology of the syrinx, hyoid and larynx, of the Southern Cassowary, Casuarius casuarius (Aves, Palaeognathae)

Phoebe Louise McInerney, Mike S. Y. Lee, Alice M. Clement, Trevor H. Worthy

Abstract

The Palaeognathae are a basal clade within Aves and include the large and flightless ratites and the smaller, volant tinamous. Although much research has been conducted on various aspects of palaeognath morphology, ecology, and evolutionary history, there are still areas which require investigation. This study aimed to fill gaps in our knowledge of the Southern cassowary, Casuarius casuarius, for which information on the syrinx, hyoid and larynx is lacking despite these structures having been recognised as performing key functional roles associated with vocalisation, respiration and feeding. Previous research into the syrinx and hyoid have also indicated these structures to be valuable for determining evolutionary relationships among neognath taxa, and thus may also shed light on palaeognath phylogeny, which still exhibits strong conflict between morphological and molecular trees. We thus documented variation across palaeognaths in syringeal, hyoidal, and laryngeal character states, using both the literature and novel new observations (e.g. of cassowary). Notably the molecular moa-tinamou clade was found to share derived morphological traits including the ossification of the cricoid and arytenoid cartilages, and an additional cranial character, the articulation between the maxillary process of the nasal and the maxilla. Syringeal, hyoidal and laryngeal characters better optimised onto the topology resulting from phylogenetic analyses of a combined molecular and morphology analysis, than molecular-only or morphological-only trees. One primary factor for this support was the aforementioned shared character states between the moa and tinamou, also present in Lithornis and outgroup taxa.

Keywords
Palaeognathae, Cassowary, Syrinx, Hyoid, Larynx, Morphology, Phylogenetics, Optimisation

Figures

Background

Results

Discussion

Methods

Abbreviations

Declarations

References

Supplementary Information

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Preprint: Please note that this article has not completed peer review.

The phylogenetic significance of the morphology of the syrinx, hyoid and larynx, of the Southern Cassowary, Casuarius casuarius (Aves, Palaeognathae)

Phoebe Louise McInerney, Mike S. Y. Lee, Alice M. Clement, Trevor H. Worthy

STATUS: In Review

Comments: 0
PDF Downloads: 1
HTML Views: 5

Integrity Check:

  • Article

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Abstract

The Palaeognathae are a basal clade within Aves and include the large and flightless ratites and the smaller, volant tinamous. Although much research has been conducted on various aspects of palaeognath morphology, ecology, and evolutionary history, there are still areas which require investigation. This study aimed to fill gaps in our knowledge of the Southern cassowary, Casuarius casuarius, for which information on the syrinx, hyoid and larynx is lacking despite these structures having been recognised as performing key functional roles associated with vocalisation, respiration and feeding. Previous research into the syrinx and hyoid have also indicated these structures to be valuable for determining evolutionary relationships among neognath taxa, and thus may also shed light on palaeognath phylogeny, which still exhibits strong conflict between morphological and molecular trees. We thus documented variation across palaeognaths in syringeal, hyoidal, and laryngeal character states, using both the literature and novel new observations (e.g. of cassowary). Notably the molecular moa-tinamou clade was found to share derived morphological traits including the ossification of the cricoid and arytenoid cartilages, and an additional cranial character, the articulation between the maxillary process of the nasal and the maxilla. Syringeal, hyoidal and laryngeal characters better optimised onto the topology resulting from phylogenetic analyses of a combined molecular and morphology analysis, than molecular-only or morphological-only trees. One primary factor for this support was the aforementioned shared character states between the moa and tinamou, also present in Lithornis and outgroup taxa.

Figures

Background

Results

Discussion

Methods

Abbreviations

Declarations

References

Supplementary Information

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