Tuesday, July 23, 2019

[PaleoOrnithology • 2019] Conflicto antarcticus • A Stem Anseriform from the early Palaeocene of Antarctica provides New Key Evidence in the Early Evolution of Waterfowl


Conflicto antarcticus  
Tambussi, Degrange, De Mendoza, Sferco & Santillana, 2019

Illustration by H. Santiago Druetta  facebook.com/HSantiagoDruetta

Abstract
A new AnseriformesConflicto antarcticus gen. et sp. nov., represented by associated bones of a single individual, from the early Palaeocene of Antarctica is described. The new taxon is unlike any other known member of the order. Conflicto antarcticus is a medium-sized (2 kg) stem anseriform. The forelimb and pectoral girdle bones suggest that it was a flying bird, and the bones of the hindlimb show that it had elongated legs. The os quadratum represents a unique combination of features; some are similar to the features of the ancestral quadrate for galloanserines and some are similar to Anseriformes, but features such as the presence of three foramina are exclusive among Neornithes. The incisura or foramen nervi suracoracoidei is absent in C. antarcticus, as in most anatids and all Galliformes. Phylogenetic analysis shows that C. antarcticus + Anatalavis oxfordi is the most basal stem Anseriformes clade. This implies that the duck-type beak must have developed at an early stage of anseriform evolution. Conflicto antarcticus represents one (and possibly the most) substantial record of a non-marine Palaeocene bird from the Southern Hemisphere and supports the hypothesis that Neognathae had already diversified in the earliest Palaeocene.

Keywords: Antarctica, Anseriformes, Conflicto antarcticus, Palaeocene, phylogeny

The skull of Conflicto antarcticus gen. et sp. nov. A, left lateral view. B, right lateral view. The arrows point at the bulges of the os frontale.
Abbreviations: cnt, crista nuchalis transversa; fal, facies articularis lacrimalis; fg, fossae glandularum; fnII, nerve II exit foramen; fnV2-3, nerve V2–3 exit foramen; foc, fonticuli orbitocraniales; foi, fonticulus interorbitalis; fst, fossa subtemporalis; ft, fossa temporalis; na, nares; pbt, processus basipterygoideus; pc, prominentia cerebellaris; pco, processus coronoideus; plm, processus lateralis mandibulae; pp, processus paroccipitalis; ppo, processus postorbitalis; pr, processus retroarticularis; psn, pila supranasalis; rp, rostrum parasphenoidale; ta, tuba auditiva. Scale bar: 1 cm.


SYSTEMATIC PALAEONTOLOGY

Aves Linnaeus, 1758
Neognathae Pycraft, 1900
Galloanseres Sibley & Ahlquist, 1990
Order Anseriformes (Wagler, 1831)

Incertae familiae

Conflicto gen. nov.

Derivation of name: Conflicto, from the Latin conflictus (contradiction, masculine in gender), owing to the controversial systematic position of the taxon. 

 Conflicto antarcticus sp. nov.

Derivation of name: Relative to the geographical area of origin, Antarctica.

Skeletal anatomy of Conflicto antarcticus gen. et sp. nov. MLP 07-III-1-1. Bones coloured in grey are missing. Some of the bones have been mirrored (e.g. os quadratum, os coracoideum) or restored based on both homologous bones (e.g. humerus) Scale bar: 5 cm.


 


Claudia P. Tambussi, Federico J. Degrange, Ricardo S. De Mendoza, Emilia Sferco and Sergrio Santillana. 2019. A Stem Anseriform from the early Palaeocene of Antarctica provides New Key Evidence in the Early Evolution of Waterfowl. Zoological Journal of the Linnean Society. 186(3); 673–700. DOI: 10.1093/zoolinnean/zly085  

Nueva clave para comprender la evolución del pico de pato conicet.gov.ar/nueva-clave-para-comprender-la-evolucion-del-pico-de-pato/


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