Archived at the Flinders Academic Commons: http://dspace.flinders.edu.au/dspace/ ‘This is the peer reviewed version of the following article: Mayr, G., De Pietri, V. L., Scofield, R. P., & Worthy, T. H. (2018). On the taxonomic composition and phylogenetic affinities of the recently proposed clade Vegaviidae Agnolín et al., 2017 ‒ neornithine birds from the Upper Cretaceous of the Southern Hemisphere. Cretaceous Research, 86, 178–185. https://doi.org/10.1016/ j.cretres.2018.02.013 which has been published in final form at http://dx.doi.org/10.1016/j.cretres.2018.02.013 © 2018 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ Accepted Manuscript On the taxonomic composition and phylogenetic affinities of the recently proposed clade Vegaviidae Agnolín et al., 2017 ‒ neornithine birds from the Upper Cretaceous of the Southern Hemisphere Gerald Mayr, Vanesa L. De Pietri, R. Paul Scofield, Trevor H. Worthy PII: S0195-6671(17)30523-2 DOI: 10.1016/j.cretres.2018.02.013 Reference: YCRES 3814 To appear in: Cretaceous Research Received Date: 29 November 2017 Revised Date: 19 February 2018 Accepted Date: 20 February 2018 Please cite this article as: Mayr, G., De Pietri, V.L., Scofield, R.P., Worthy, T.H., On the taxonomic composition and phylogenetic affinities of the recently proposed clade Vegaviidae Agnolín et al., 2017 ‒ neornithine birds from the Upper Cretaceous of the Southern Hemisphere, Cretaceous Research (2018), doi: 10.1016/j.cretres.2018.02.013. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT 1 On the taxonomic composition and phylogenetic affinities of the recently proposed clade 2 Vegaviidae Agnolín et al., 2017 ‒ neornithine birds from the Upper Cretaceous of the 3 Southern Hemisphere 4 5 Gerald Mayr a*, Vanesa L. De Pietri b, R. Paul Scofield b, Trevor H. Worthy c 6 7 aSenckenberg Research Institute and Natural History Museum Frankfurt, Ornithological 8 Section, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany 9 bCanterbury Museum, Rolleston Avenue, Christchurch 8013, New Zealand 10 cSchool of Biological Sciences, Flinders University, GPO 2100, Adelaide 5001, Australia 11 12 Abstract 13 Polarornis and Vegavis from the Upper Cretaceous of Antarctica are among the few 14 Mesozoic birds from the Southern Hemisphere. In the original descriptions, they were 15 assigned to two widely disparate avian clades, that is, Gaviiformes and crown group 16 Anseriformes, respectively. In a recent publication, however, specimens referred to both taxa 17 were classified into a new higher-level taxon, Vegaviidae, to which various other late 18 Mesozoic and early Cenozoic avian taxa were alsoMANUSCRIPT assigned. Here, we detail that classification 19 into Vegaviidae is poorly supported for most of the se latter fossils, which is particularly true 20 for Australornis lovei and an unnamed phaethontiform fossil from the Waipara Greensand in 21 New Zealand. Plesiomorphic traits of the pterygoid and the mandible clearly show that 22 Vegavis is not a representative of crown group Anseriformes, and we furthermore point out 23 that even anseriform or galloanserine affinities of Vegaviidae have not been firmly 24 established. 25 26 Keywords : Aves; fossil birds; Mesozoic; phylogeny; taxonomy 27 28 Highlights ACCEPTED 29 • The recently proposed taxon Vegaviidae includes two of the best-represented 30 neornithine taxa from the Upper Cretaceous of the Southern Hemisphere, Vegavis and 31 Polarornis *Corresponding author, Email-address: [email protected] 1 ACCEPTED MANUSCRIPT 32 • Australornis and an unnamed phaethontiform from the lower Paleocene of New 33 Zealand, as well as other fossils from the Upper Cretaceous and lower Cenozoic of the 34 Southern Hemisphere were incorrectly referred to Vegaviidae 35 • The repeated use of Vegavis for the calibration of molecular data notwithstanding, 36 neither anseriform nor galloanserine affinities of Vegaviidae have been firmly 37 established 38 39 1. Introduction 40 41 Little is known about the earliest evolution of neornithine (crown clade) birds, and most 42 Mesozoic fossils are very fragmentary (Mayr, 2017). In the past decades, however, Upper 43 Cretaceous marine strata of Seymour and Vega Island in Antarctica yielded several partial 44 avian skeletons that were assigned to extant neornithine higher-level taxa. 45 The report of a putative representative of Gaviiformes (loons) from the Upper Cretaceous 46 López de Bertodano Formation of Seymour Island kept running through the literature for 47 several years (Chatterjee, 1989; Olson, 1992) until this fossil, a partial and poorly preserved 48 skeleton, was formally described as Polarornis gregorii by Chatterjee (2002). Further 49 material from the López de Bertodano Formation wasMANUSCRIPT assigned to Polarornis by Acosta 50 Hospitaleche and Gelfo (2015), who also reported fragmentary limb bones of putative 51 Gaviiformes from Vega Island. 52 The first description of an avian fossil from Vega Island, however, was given by Noriega 53 and Tambussi (1995), who assigned a partial skeleton to the extinct anseriform taxon 54 Presbyornithidae. The specimen was subsequently described as Vegavis iaai by Clarke et al. 55 (2005), and more recently a second, well preserved partial skeleton of this species from Vega 56 Island was reported by Clarke et al. (2016). A phylogenetic analysis performed by Clarke et al. 57 (2005) recovered a clade including Vegavis , Presbyornis , and Anatidae (ducks, geese, and 58 relatives). This analysis therefore supported a deeply nested position of Vegavis within crown 59 group Anseriformes,ACCEPTED which are composed of three extant higher-level taxa: the Neotropic 60 Anhimidae (screamers), the Australian Anseranatidae (Magpie Goose), and the globally 61 distributed Anatidae. Presbyornithids are now, however, recovered in a more basal 62 phylogenetic position within Anseriformes (De Pietri et al., 2016; Worthy et al., 2017), and 63 although Vegavis was regarded as a “phylogenetically vetted” fossil calibration by Ksepka 64 and Clarke (2015), close affinities to Anatidae had already been questioned (Mayr, 2013; 2 ACCEPTED MANUSCRIPT 65 Feduccia, 2014) and the fossil was deliberately omitted as a calibration point from some 66 studies (Ericson et al., 2006; Prum et al., 2015). 67 Within extant Anseriformes, the distinctive Anhimidae are the sister taxon of Anatoidea, 68 that is, the clade including the goose- or duck-like Anseranatidae and Anatidae. Externally, 69 Anhimidae exhibit an overall resemblance to Galliformes (landfowl), which are the extant 70 sister group of Anseriformes, with which they form the taxon Galloanseres. Galloanseres, in 71 turn, are one of the two major clades of neognathous birds, the other being Neoaves, which 72 includes most extant avian taxa. 73 A recent study by Worthy et al. (2017), who analyzed a comprehensive sampling of fossil 74 and extant galloanserine birds under various analytical settings supported a position of 75 Vegavis outside crown group Anseriformes but did not conclusively resolve its position 76 within Galloanseres. In some analyses Vegavis was recovered as the weakly supported sister 77 taxon of a clade including the large flightless Cenozoic Gastornithidae and Dromornithidae, in 78 others it resulted as an equally weakly supported sister taxon of crown group Anseriformes. 79 The analysis of Worthy et al. (2017) temporally coincided with a study by Agnolín et al. 80 (2017), which likewise supported a position of Vegaviidae as the sister taxon of crown group 81 Anseriformes. Agnolín et al. (2017) classified Vegavis and Polarornis into a new clade, 82 Vegaviidae, to which they also assigned various othMANUSCRIPTer fossils from the Upper Cretaceous and 83 lower Cenozoic of the Southern Hemisphere. Here we point out that this convenient 84 placement of all described Southern Hemisphere Mesozoic neognaths in a single clade is 85 neither justifiable nor useful. We furthermore address the phylogenetic affinities of 86 Vegaviidae, although it is not the aim of the present study to perform another formal analysis, 87 which ‒ in addition to a large sampling of extant taxa ‒ would also require the inclusion of 88 numerous fossil taxa (see below). 89 The figured fossils are deposited in the Canterbury Museum, Christchurch, New Zealand 90 (CM) and in the Museo Argentino de Ciencias Naturales “Bernadino Rivadavia”, Buenos 91 Aires, Argentina (MACN). 92 ACCEPTED 93 2. Taxonomic composition of Vegaviidae 94 95 We concur with Agnolín et al. (2017) that Vegavis and Polarornis share characteristic 96 derived traits that may support a sister group relationship between these two taxa. The 97 Vegavis and Polarornis material comes from geographically and stratigraphically close 3 ACCEPTED MANUSCRIPT 98 localities and those bones that are known from both taxa are so similar that we consider 99 classification of Vegavis and Polarornis in the same clade to be reasonably probable. 100 However, contra Agnolín et al. (2017), there is no overlap of these taxa in humeral features 101 as