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| Eudyptes atatu Thomas, Tennyson, Scofield & Ksepka in Thomas, Tennyson, ... et Ksepka, 2020. Life reconstruction: twitter.com/GiovaFavazzi |
Abstract
New Zealand is a globally significant hotspot for seabird diversity, but the sparse fossil record for most seabird lineages has impeded our understanding of how and when this hotspot developed. Here, we describe multiple exceptionally well-preserved specimens of a new species of penguin from tightly dated (3.36–3.06 Ma) Pliocene deposits in New Zealand. Bayesian and parsimony analyses place Eudyptes atatu sp. nov. as the sister species to all extant and recently extinct members of the crested penguin genus Eudyptes. The new species has a markedly more slender upper beak and mandible compared with other Eudyptes penguins. Our combined evidence approach reveals that deep bills evolved in both crested and stiff-tailed penguins (Pygoscelis) during the Pliocene. That deep bills arose so late in the greater than 60 million year evolutionary history of penguins suggests that dietary shifts may have occurred as wind-driven Pliocene upwelling radically restructured southern ocean ecosystems. Ancestral area reconstructions using BioGeoBEARS identify New Zealand as the most likely ancestral area for total-group penguins, crown penguins and crested penguins. Our analyses provide a timeframe for recruitment of crown penguins into the New Zealand avifauna, indicating this process began in the late Neogene and was completed via multiple waves of colonizing lineages.
Keywords: New Zealand, Bayesian phylogeny, penguin, Pliocene, Eudyptes, ancestral area
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| Eudyptes atatu sp. nov. showing key diagnostic features. Holotype specimen NMNZ S.046318 showing (a) right lateral view of skull and block with (c) mandible and (d) postcranial elements. (b) Right lateral view of Snares crested penguin Eudyptes robustus NMNZ OR.023746 for comparison. Referred material of E. atatu including (e) S.046315 dorsal view of skull, (f) CM 2017-62-8-1 left lateral view of skull, (g) NMNZ S.046320 right humerus caudal view, and (h) dorsal and (i) plantar views of NMNZ S.046319 right tarsometatarsus. Ano, apertura nasale ossea (naris). Clh, crista lateralis hypotarsi (lateral hypotarsal crest); Co, coracoid; Cmh, crista medialis hypotarsi (medial hypotarsal crest); F*, frontal with wide shelf bordering the salt gland fossa; Fte*, fossa temporalis (temporal fossa) that is relatively deep; Fvpl, foramen vasculare proximale lateralis (medial proximal vascular foramen); Fvpm, foramen vasculare proximale mediale (medial proximal vascular foramen); Hu, humerus; Ic, incisura capitus (capital incisure); Imp, impressio musculus pectoralis (pectoral muscle impression); Mr, ramus mandibula (mandibular ramus); Oj*, os jugale (jugal bar) showing distinct curvature; Op, os palatinum (palatine); Ma, articular end of mandible; Mr*, mandibular ramus that is relatively narrow at midpoint; Ra, radius; Sc, scapula; Sldl, sulcus longitudinalis dorsalis lateralis (lateral dorsal longitudinal sulcus); Sldm*, sulcus longitudinalis dorsalis medialis (medial dorsal longitudinal sulcus) which is moderately deep; St, sternum; Tmtc, tuberositas musculus tibialis cranialis (tuberosity for cranial tibial muscle); Tv, tuberculum ventral (ventral tubercle); Ve, vertebra. Asterisks denote diagnostic characters. Photographs (a)–(e), (g)–(i) from Jean-Claude Stahl at Museum of New Zealand Te Papa Tongarewa, photograph (f) from R. Paul Scofield at Canterbury Museum. |
Systematic palaeontology
Aves Linnaeus, 1758
Sphenisciformes Sharpe, 1891
Spheniscidae Bonaparte, 1831
Eudyptes Vieillot, 1816
Eudyptes atatu sp. nov. Thomas, Tennyson, Scofield and Ksepka.
Etymology. From Te reo Māori, ata tū (‘dawn’), referencing the stem position within Eudyptes and the earliest recorded appearance of Eudyptes in New Zealand.
Type locality and horizon. Late Pliocene (Piacenzian) Tangahoe Formation in the southern Taranaki region of the North Island of New Zealand. ...
Daniel B. Thomas, Alan J. D. Tennyson, R. Paul Scofield, Tracy A. Heath, Walker Pett and Daniel T. Ksepka. 2020. Ancient Crested Penguin Constrains Timing of Recruitment into Seabird Hotspot. Proceedings of the Royal Society B. DOI: 10.1098/rspb.2020.1497
