Phylogenetic significance of the morphology of the syrinx, hyoid and larynx (1 Viewer)

Phoebe L. McInerney, Michael S. Y. Lee, Alice M. Clement and Trevor H. Worthy, 2019

The phylogenetic significance of the morphology of the syrinx, hyoid and larynx, of the southern cassowary, Casuarius casuarius (Aves, Palaeognathae

BMC Evolutionary Biology 19, Article number: 233
doi: https://doi.org/10.1186/s12862-019-1544-7
https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-019-1544-7

Free pdf:
https://bmcevolbiol.biomedcentral.com/track/pdf/10.1186/s12862-019-1544-7

Abstract

Background: Palaeognathae is 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 skeletal systems of 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 suggest they would also be informative for palaeognath phylogenetic analyses, which still exhibits strong conflict between morphological and molecular trees.

Results: The morphology of the syrinx, hyoid and larynx of C. casuarius is described from CT scans. The syrinx is of the simple tracheo-bronchial syrinx type, lacking specialised elements such as the pessulus; the hyoid is relatively short with longer ceratobranchials compared to epibranchials; and the larynx is comprised of entirely cartilaginous, standard avian anatomical elements including a concave, basin-like cricoid and fused cricoid wings. As in the larynx, both the syrinx and hyoid lack ossification and all three structures were most similar to Dromaius. We documented substantial variation across palaeognaths in the skeletal character states of the syrinx, hyoid, and larynx, using both the literature and novel observations (e.g. of C. casuarius). Notably, new synapomorphies linking Dinornithiformes and Tinamidae are identified, consistent with the molecular evidence for this clade. These shared morphological character traits include 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.

Conclusion: Syrinx, hyoid and larynx characters of palaeognaths display greater concordance with molecular trees than do other morphological traits. These structures might therefore be less prone to homoplasy related to flightlessness and gigantism, compared to typical morphological traits emphasised in previous phylogenetic studies.

Enjoy,

Fred

Palaeognath syringeal elements with tracheosyringeal cartilages differentiated by brown shading (b-e), interannular tissues are shaded in grey. a-b Cassowary, Casuarius casuarius, FUR180; ventral, scale bar = 10mm. c Tinamou, Nothura darwinii, adapted from Garitano-Zavala ([40], fig. 1C); ventral. d Rhea, Rhea americana, adapted from Forbes ([18], fig. 7, 8); ventral and dorsal. e Kiwi, Apteryx mantelli, adapted from Forbes ([18], fig. 3), ventral. f Ostrich, Struthio camelus, adapted from Forbes ([18], fig. 1); ventral. Abbreviations: bs.cs: bronchosyringeal cartilages, ia.i: interannular interval, tr.c: tracheal cartilages, trs.cs: tracheosyringeal cartilages. c-f scaled to same size approximately

Fred

Hi Fred, most of those technicalities exceed my care factor and make my head hurt ! You might be able to find some interest /leads to pursue from the following snippets /links.

Is that a way of saying that Cassowary's sound like dinosaurs? :cat:
I will never forget hearing that low frequency call for the first time .... T-Rex much !

There seems to be lots of accumulating evidence /hypotheses that life evolved out of Australia /Gondwana.

Aboriginal elders tell me they have been here forever, and there are oral stories of the times that meteorites set the sky ablaze, leveled the land all around, and created 'nuclear' winters - traced to craters that were perhaps formed hundreds of thousands of years ago. Similarly Aboriginies co-existed with Megafauna for 10's of 1000's of years. Thus it was life out of Australia rather than Africa.

Along with this is the hypothesis (not sure how rigorously the scientific literature proves it) that bird song began in Australia millions of years before the rest of the world. Tim Low has authored a book titled "Where Song Began" . https://www.google.com.au/search?so.....8..41i22i30j41i13j41i131j46i131.VKKcw3jxxQs

Perhaps some interest for you there? Or if you are already aware /have read it - I'd be interested in your thoughts (I've only just started flicking through the book at the library) :cat:




Chosun :gh:

Hi Chosun,

Welcome to this subforum. I will try to answer your interesting, but difficult questions. But first of all, this paper is not about the sounds of Palaeognathae, it is about the anatomy of the syninx, the larynx and the hyoid of Palaeognathae and to see whether thay are giving a phylogenetic signal. Becouse these birds (except the Tinamiformes) are flightless, the opinion of the authors is that there is a lot of convergence involved in the skeleton of these birds, they all have the same addaptations to flightlessness. So they have taken the syninx, the larynx and the hyoid to study the phylogenetics. They suppose that that structure has less convergence that the rest of the skeleton. They conclude that their results are closer to the molecular trees than those resulting from anatomical studies on the skeleton.

They don’t say anything about the sound of Dinosaurs or the sound of Tyrannosaurus rex Osborn, 1905. Nobody knows what they sounded like (except of course Mr. Spielberg) becouse the structure and the anatomy of Tyrannosaurus rex and other Dinosaurs is not known as far as I know. Soft tissue is not often preserved in the fossil record. (if you want to abreviate Tyrannosaurus rex, please write T. rex, not T-Rex, a genus name is always with a capital, a species name always has a lower case letter as a start.)

About bird song I can tell you that Passeriformes most likely originated in Australia. If we look at the fossil record of Passeriformes, we see Jamna szybiaki Bocheński, Tomek, Bujoczek et Wertz, 2011, Wieslochia weissi G. Mayr et Manegold, 2006, Resoviaornis jamrozi Bocheński, Tomek, Wertz et Swidnicka, 2013 and Winnicavis gorskii Bochenski, Tomek, Wertz, Happ, Bujoczek et Swidnicka, 2018 from the Early Oligocene of Europe, and the oldest fossils from Australia are older (Boles, 1995), but not yet named. Also many biogeographical studies point in that derection.

Walter E. Boles, 1995
The Worlds Oldest Songbird
Nature 374: 21-22

I hope to have answered your questions,

Fred