Vegavis

Taxonomy

The genus name, Vegavis, is a combination of the name of Vega Island and "avis", the Latin word for bird, while the species name, "iaai", is after the acronym for Instituto Antartico Argentino (IAA), the Argentine scientific expedition to Antarctica. The holotype is held by the Museo de La Plata, Argentina. It was only described as a new species in 2005, because it consists of the very delicate remains of one bird embedded in a concretion, which had to be meticulously prepared for study. CT scans were utilized to gain a clearer picture of the bone structure without running danger of damaging or destroying the fossil.

A second specimen, MACN-PV 19.748 (formerly MLP 93-I-3-2), was found beside the holotype specimen. Other potential specimens have also been reported, including a distal tarsometatarsus (AMNH FARB 30913) tentatively identified as cf. Vegavis, an isolated femur (SDSM 78247) referred to as Vegavis sp., and a synsacrum (MN 7832-V) referred to as cf. V. iaai.

Two decades after the formal naming of Vegavis, a nearly complete skull specimen (AMNH FARB 30899) discovered by Eric M. Roberts in 2011 from the Sandwich Bluff Member of the López de Bertodano Formation on Vega Island was officially described in 2025. The authors argued that the morphology of this skull supports the placement of Vegavis within crown-group Aves, specifically as a member of the Anseriformes, and provides novel insight into its feeding ecology. In 2026, Irazoqui and colleagues described this specimen as the holotype of a new species of Vegavis, named V. notopothousa. The specific name combines the Greek words nótos, meaning and póthos, referring to , alluding to the discovery of the holotype in the Southern Hemisphere but now housed in the Northern Hemisphere. The authors also named V. geitononesos, a third species in the genus, based on another partial skull and skeleton (MLP-PV 15-I-7-52). The specific name combines the Greek geítōn, meaning and nêsos, meaning , referencing the discovery of this species on Marambio Island, whereas V. iaai was found on the nearby Vega Island.

Classification

Vegavis was initially described as a member of the crown group Anseriformes within Galloanserae, indicating that some representatives of the modern bird groups lived in the Mesozoic.

However, some paleontologists questioned its affinities to Anseriformes or Galloanserae, with some classifying it as a stem-group bird within Ornithurae, a crown group bird outside Galloanserae, a sister taxon of the Neornithes or at the base of Neognathae with an unresolved position. In contrast, Vegavis was recovered as a sister taxon of Anatidae or Anseriformes within Galloanserae based on other phylogenetic analyses. In a 2025 study which assigned AMNH FARB 30899 to Vegavis, Torres et al. supported its placement within crown group Anseriformes, sister to Conflicto and Anas, based on their revised phylogenetic analyses. In 2026, Irazoqui et al. suggested that Vegavis can only be confidently placed as a neognath of uncertain affinities.

Agnolín et al. (2017) proposed the family Vegaviidae as stem-group Anseriformes containing Vegavis, Polarornis and several other extinct avian genera, but the monophyly of this clade was questioned by subsequent studies. but this is a disused clade that has never been mentioned by other researchers except for the describers of Conflicto antarcticus.

Paleobiology

Vegavis was a bird with a high metabolism, which allowed it to live at high latitudes in Antarctica. It also shows a degree of osteosclerosis, a condition shared with Polarornis. This different degrees of osteosclerosis could be related to variations in diving behaviour.

Paleoenvironment

The Sandwich Bluff Member (unit klb 1) of the Lopez de Bertodano Formation on Vega Island, the type locality of V. iaai and V. notopothousa, is dated to the middle Maastrichtian, approximately . Indeterminate non-avian dinosaur fossils have been discovered from this unit, including the remains of hadrosaurids, elasmarians, parankylosaurians and megaraptorans.

The upper Molluscan Allomember (unit klb 9) of the Lopez de Bertodano Formation on Seymour (Marambio) Island, the type locality of V. geitononesos, is dated to the uppermost Maastrichtian. It is known to preserve a diverse fauna of marine reptiles including the large mosasaur Kaikaifilu, and the elasmosaurid plesiosaurs Aristonectes, Marambionectes, and Morturneria. Various indeterminate species of bony and cartilaginous fish genera have been recovered from this unit, with only a few being definitively identified to the specific level including Antarctiberyx seymouri and Xampylodon diastemacron. The other neornithine birds, Polarornis and Pujatopouli, are also known from this unit.

References

References

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