Two-phase extinction of “Southern Hemispheric” birds in the Cenozoic of Europe and the origin of the Neotropic avifauna

Abstract

A considerable number of fossil birds from the Cenozoic of Europe belong to taxa whose extant representatives are only found in the Southern Hemisphere. This study presents the first detailed analysis of the stratigraphic occurrences of these groups. Two well-separated extinction phases can be distinguished: one in the Paleogene, which concerned birds with crown group representatives in South America, Madagascar and Australia, and the second in the Miocene, which involved taxa that are today found in Africa or have a pantropic distribution. It is hypothesised that this unusual pattern is the result of a successive action of biotic and abiotic factors. South America was least affected by both extinction phases and served as a refugium for bird groups, which had a more widespread distribution in the Paleogene.

An ameghinornithid-like bird (Aves, Cariamae, ?Ameghinornithidae) from the early Oligocene of Egypt

“…That key temporal interval has been correlated with significant turnover in the mammalian fauna of Europe (i.e., the Grande Coupure), global climate change (cooling), and significant biogeographic changes (Holroyd and Maas, 1994;Liu et al, 2009;Mayr, 2011). Furthermore, molecular divergence estimates and the fossil record congruently suggest that the EOCT was a time of global avian radiation and avifaunal turnover (van Tuinen et al, 2006;Brown et al, 2007).…”

“…From both of these Eocene-Oligocene fossiliferous deposits come some of the oldest records of avian groups (e.g., jacanas and cormorants), as well as fossils of enigmatic extinct groups of uncertain phylogenetic affinities (e.g., ameghinornithids and Eremopezus; Rasmussen et al, 1987;Mayr, 2009). Paralleling the known mammalian fossil record, the late Eocene and early Oligocene appears to be a transitional period between extinct avian groups restricted to the early Paleogene and the appearance of many modern/extant clades within the later Oligocene and Neogene (Mayr, 2011). Despite the importance of this temporal interval for understanding the origin of the modern avifauna and the distribution of birds in the past, much of the avian record from the Fayum (i.e., Late Eocene and early Oligocene Jebel Qatrani Formation) remains unpublished.…”

A hoatzin fossil from the middle Miocene of Kenya documents the past occurrence of modern-type Opisthocomiformes in Africa

“…Hoatzin fossils have not been reported from any of the betterstudied late Miocene African avifaunas (Rich 1974, Stidham 2007, Louchart et al 2008, and current data thus suggest their extinction on this continent in the middle Miocene. Various avian taxa with closest extant relatives in South America, such as Trochilidae, Nyctibiidae, and Cariamiformes, were also reported from the Paleogene of the Northern Hemisphere, and it has been hypothesized that the extinction of at least some of these were triggered by newly immigrated faunal elements (Mayr 2009(Mayr , 2011. Hoatzin extinction in Africa may also be attributable to ecological competition with species that did not reach South America, but the patchy fossil record of African vertebrates does not allow for well-founded considerations on the causes of their final disappearance from the continent.…”

“…The earliest and most substantial New World fossil record of a hoatzin is Hoazinavis lacustris from the late Oligocene-early Miocene (22-24 mya) of Brazil (Mayr et al 2011). This species is likewise represented by wing and pectoral girdle bones only, which closely resemble those of the modern O. hoazin.…”

A new specimen of the Early Eocene Masillacolius brevidactylus and its implications for the evolution of feeding specializations in mousebirds (Coliiformes)

“…In the Early Cenozoic, however, these birds were more widely distributed and much more diversified (Mayr, 2009). At least six coliiform species coexisted in the Early Eocene (Lenz et al, 2015) lacustrine paleoenvironment of the Messel fossil site in Germany alone, which belong to a minimum of four genus-level taxa (Eoglaucidium, Chascacocolius, Selmes, Masillacolius;Mayr, 2000Mayr, , 2005Mayr and Peters, 1998).…”