The extreme insular adaptation of Garganornis ballmanni Meijer, 2014: a giant Anseriformes of the Neogene of the Mediterranean Basin.

Marco Pavia,Ursula B Göhlich,Maria Adelaide Rossi,Hanneke J M Meijer

doi:10.1098/rsos.160722

Marco Pavia, Ursula B Göhlich + Show 2 more

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https://doi.org/10.1098/rsos.160722

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Abstract

New skeletal elements of the recently described endemic giant anseriform Garganornis ballmanni Meijer, 2014 are presented, coming from the type-area of the Gargano and from Scontrone, southern and central Italy, respectively. The new remains represent the first bird remains found at Scontrone so far, and another shared element between these two localities, both part of the Apulia-Abruzzi Palaeobioprovince. The presence of a very reduced carpometacarpus confirms its flightlessness, only previously supposed on the basis of the very large size, while the morphologies of tarsometatarsus and posterior phalanges clearly indicate the adaptation of G. ballmanni to a terrestrial, non-aquatic, lifestyle. Its very large body size is similar to that observed in different, heavily modified, insular waterfowl and has been normally interpreted as the response to the absence of terrestrial predators and a protection from the aerial ones. The presence of a carpal knob in the proximal carpometacarpus also indicates a fighting behaviour for this large terrestrial bird species.

Highlights

Since Darwin’s and Wallace’s works, the study of islands has been a powerful tool in many evolutionary studies, and birds are a key group in understanding the biological changes in island environments
Among the giant insular species of Anseriformes was Garganornis ballmanni, a species recently described from the Neogene fissure-filling deposits of the Gargano on the basis of a single distal tibiotarsus [16]
We describe new skeletal elements of G. ballmanni from Gargano and Scontrone, southern and central Italy, respectively, the main localities of the so-called Apulia-Abruzzi Palaeobioprovince [17], which during the Miocene was characterized by insular conditions and a highly endemic fauna

Summary

Introduction

Since Darwin’s and Wallace’s works, the study of islands has been a powerful tool in many evolutionary studies, and birds are a key group in understanding the biological changes in island environments. Birds on islands often display dramatic size increases, allometric variations and, in some cases, flightlessness. The latter is known in different bird group like ibises, cormorants, rails, pigeons, parrots, passerines and waterfowl [1,2,3,4]. The waterfowl, crown-group Anseriformes, includes Anhimidae (South American screamers), Anseranatinae (Australasian magpie-geese) and Anatidae with a worldwide distribution [5]. The fossil record of Anatidae is very rich and comprises several endemic species, which evolved flightlessness in insular conditions, both on remote oceanic islands [4,6,7,8] as well as in intermediate-type islands, such as those of the Mediterranean Sea [9,10,11]. Among the giant insular species of Anseriformes was Garganornis ballmanni, a species recently described from the Neogene fissure-filling deposits of the Gargano (southern Italy) on the basis of a single distal tibiotarsus [16]

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