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A new swan (Aves: Anatidae) in Africa, from the latest Miocene of Chad and Libya
Journal of Verterbrate Paleontology
Abstract
A new genus and species of swan (subtribe Cygnina) are described here from the late Miocene deposits of Toros Menalla (Chad, Africa), which have yielded the earliest known hominid. Afrocygnus chauvireae, gen. et sp. nov., is about the size of Cygnus atratus of the Australasian region, but differs morphologically from all living members of the genus Cygnus, and from all other extinct taxa of swans. Several extinct genera of swans or supposed extinct species of Cygnus actually appear not to belong to the Cygnini or to Cygnus, respectively, and should be revised. Afrocygnus chauvireae fills a biogeographical gap because there is no swan today in Africa except on the Mediterranean coast in winter, and the continent is now the only one—with Antarctica—lacking breeding swans. An unidentified swan is also represented in the Pliocene of Koro Toro (Chad). Remains previously identified as a goose-like member of Anserinae from the Mio-Pliocene boundary of Sahabi (Libya) are referred to Afrocygnus cf. A. chauvireae. Two records of a larger, unidentified swan are known in the early/middle Pleistocene of East Africa, but none for the southern part of the continent. Afrocygnus appears as the closest genus to Cygnus. The Chadian and Libyan swans indicate rather calm freshwater bodies in the vicinity of the deposits. Afrocygnus is indicative of some vertebrate endemism in the Chadian-Libyan area during the latest Miocene, in humid settings, through the incipient eastern Sahara desert.
... Remarks: Notochen bannockburnensis cannot be certainly referred to one or other of Cygnini or Anserini, as separation of these taxa on the distal humerus is principally by the distal projection of processus flexorius; it extends past the condylus ventralis in the Anserini but it does not in the Cygnini (Louchart et al. 2005), and this part of the fossil is missing. However, the large size, with distal width similar to that of Cygnus atratus, but with a stouter shaft, suggests a referral to Cygnini is likely. ...
... All similar-sized anserines of middle-late Miocene are placed in modern genera. The exception is the late Miocene-Pliocene Afrocygnus chauvireae Louchart, Vignaud, Likius, Mackaye & Brunet, 2005 from Africa, which has a similarly distally robust shaft and differs by the scar for the attachment anterior articular ligament being rather circular instead of proximodistally elongate as in the fossil (Louchart et al. 2005). ...
... All similar-sized anserines of middle-late Miocene are placed in modern genera. The exception is the late Miocene-Pliocene Afrocygnus chauvireae Louchart, Vignaud, Likius, Mackaye & Brunet, 2005 from Africa, which has a similarly distally robust shaft and differs by the scar for the attachment anterior articular ligament being rather circular instead of proximodistally elongate as in the fossil (Louchart et al. 2005). ...
A large fossil anserine-like anatid (Aves, Anatidae, Notochen bannockburnensis gen. et sp. nov.) is described based on a distal humerus from the lower Bannockburn Formation, early Miocene (19–16 Ma), St Bathans Fauna from New Zealand. Its morphology and size suggest that this taxon represents an early swan rather than a goose. Extant anserines are split into Northern and Southern Hemisphere clades. The St Bathans Fauna is known to have the oldest anserines in the Southern Hemisphere, unnamed cereopsines perhaps ancestral to species of Cnemiornis (New Zealand geese). The elongate and flat morphology of the tuberculum supracondylare ventrale of the new species, however, preclude affinities with cereopsines. It is a rare taxon and the eighth anatid represented in the fauna and is the largest known anseriform from the Oligo-Miocene of Australasia. We also reassess other large anatid specimens from the St Bathans Fauna and identify Miotadorna catrionae Tennyson, Greer, Lubbe, Marx, Richards, Giovanardi & Rawlence, 2022 as a junior synonym of Miotadorna sanctibathansi Worthy, Tennyson, Jones, McNamara & Douglas, 2007.
... Geronticus eremita is restricted today to Syria and Morocco (Serra et al., 2009), but it had a greater historical range that extended into northern Africa (Collar and Stuart, 1985), and the extinct ibis, Geronticus olsoni, was present in Morocco during the Pliocene (Mourer-Chauvir e and Geraads, 2010). The distribution range of Geronticus may have been broader in the past, as has been reported for other African bird taxa (e.g., Louchart et al., 2005bLouchart et al., , 2008Prassack, 2014). ...
... Anatidae (ducks, geese, and swans) The Anatidae are a large and diverse family with over 60 species from eight tribes found in Africa (Johnsgard, 1978). Anatids are not common in the African fossil record, but do occur in the early Miocene of Namibia (Mourer-Chauvir e, 2008), the late Miocene of Ethiopia (Louchart et al., 2005b(Louchart et al., , 2008 and Libya (Louchart et al., 2005b), and the Pliocene of Chad (Louchart et al., 2004), Morocco (Mourer-Chauvir e and Geraads, 2010), and South Africa (Manegold et al., 2013). Fossil anatids become more abundant during the Middle and Late Stone Age (Pleistocene) in South Africa (e.g., Avery and Underhill, 1986;Klein et al., 1999Klein et al., , 2004Manegold and Brink, 2011). ...
... Anatidae (ducks, geese, and swans) The Anatidae are a large and diverse family with over 60 species from eight tribes found in Africa (Johnsgard, 1978). Anatids are not common in the African fossil record, but do occur in the early Miocene of Namibia (Mourer-Chauvir e, 2008), the late Miocene of Ethiopia (Louchart et al., 2005b(Louchart et al., , 2008 and Libya (Louchart et al., 2005b), and the Pliocene of Chad (Louchart et al., 2004), Morocco (Mourer-Chauvir e and Geraads, 2010), and South Africa (Manegold et al., 2013). Fossil anatids become more abundant during the Middle and Late Stone Age (Pleistocene) in South Africa (e.g., Avery and Underhill, 1986;Klein et al., 1999Klein et al., , 2004Manegold and Brink, 2011). ...
Fossil bird data (community composition and taphonomic profiles) are used here to infer the environmental context of the Oldowan-Acheulean transitional period at Olduvai Gorge, Tanzania. This is the first comprehensive report on the Middle Bed II avifauna and includes fossils excavated by the Olduvai Geochronology and Archaeology Project (OGAP) and recently rediscovered fossils collected by Mary Leakey. Crane, ibis, darter, owl, raptor, crow, and vulture are reported from Bed II for the first time. The presence of these taxa, absent earlier in this Bed, point to a general opening and drying of the landscape with grassland and open woodland expansion. Taxa associated with dense, emergent wetland vegetation, such as dabbling ducks and rails, are uncommon and less diverse than earlier in Bed II. This suggests more mature wetlands with clearer waters. Cormorants continue to be common, but are less diverse. Cormorants and other roosting taxa provide evidence of trees in the area. Compared to lowermost Bed II, the Middle to Upper Bed II landscape is interpreted here as more open and drier (but not necessarily more arid), with matured wetlands, scattered trees, and a greater expansion of grasslands.
... Among the ducks of the first half of the Oligocene (~34-28 Ma), it is possible to reliably determine only small (teal-sized) representatives of Romainvilliinae (Mayr, 2009(Mayr, , 2017. In addition, a large form Cygnopterus affinis (the size of a swan) was found in the early Oligocene of Belgium, but the relationships of this taxon remains unclear (Louchart et al., 2005;Mayr, 2009;Mayr and Smith, 2017). In any case, the unusual morphology of this bird suggests that, like Romainvilliinae, it does not belong to the crown group Anatidae. ...
An analysis of the Eurasian Cenozoic (late Eocene-Neogene) fossil record of anatids (Anatidae s. l.; including Romainvilliinae and Dendrocygninae) is presented. The evolutionary origin of Anatidae s. l. may be associated with the appearance of large shallow waterbodies in Asia during the Late Eocene as a result of the fall in the global sea level and the resulting retreat of the epicontinental seas. Four major temporal stages can be recognized in the evolution of the Cenozoic Eurasian anatids communities, without any traceable continuity between particular stages (at the current stage of knowledge). Some recent anatid genera (e.g., Tadorna) first appear in the paleontological record at the level of the early and middle Miocene (17-15 Ma), but temperate faunas of essentially modern ecological composition became widespread only in the late Mio-cene (9-6 Ma). The details of transitions between various faunistic stages, as well as the origin of modern communities, remain largely unstudied.
... Another endemic and extinct genus and species of swan, Afrocygnus chauvireae, was identified from much older localities in central and northern Africa at least (Louchart et al., 2005;Manegold et al., 2013). As an Anserinae, and probably a swan, this taxon indicates a water body or slow water course. ...
... Crown-group Anatidae have an especially rich fossil record that dates to at least the late Oligocene (Worthy, 2008;Zelenkov, 2012), and the oldest undoubted members of Anhimidae and Anseranatidae are also known since that time (Alvarenga, 1999;Worthy and Scanlon, 2009). An older possible anseriform, the swan-sized Cygnopterus affinis (Van Beneden, 1883) from the early Oligocene of Belgium, was previously considered to be a relative of modern swans (Lambrecht, 1933), but even ordinal affinities of this taxon are currently regarded as highly uncertain (Louchart et al., 2005;Mayr, 2009;Mayr and Smith, 2017). The earlier fossil record of anseriform birds is mainly represented by the aberrant Presbyornithidae, which are known predominately from the Paleocene and the first half of the Eocene of the Americas and Central Asia (Ericson, 2000;Stidham, 2001;Mayr, 2009Mayr, , 2017, but members of this group also were found in both older (latest Cretaceous) and much younger (late Oligocene through early Miocene) deposits (Kurochkin et al., 2002;De Pietri et al., 2016). ...
The early evolutionary history of waterfowl (Anseriformes) is poorly understood. Aside from the morphologically aberrant Presbyornithidae, the only other known early Paleogene anseriform taxon is Anatalavis oxfordi from the early Eocene of England. Here, I describe two bones from the late Paleocene of southern Mongolia (localities Naran-Bulag and Tsagaan-Khushuu), which belong to a very large swan-sized swimming waterfowl (Anseriformes) and are described as Naranbulagornis khun, gen. et sp. nov. This is the first non-presbyornithid anseriform bird found in the early Paleogene (Paleocene through early Eocene) of Asia and one of the few currently known Paleocene birds from Central Asia. It is also the largest volant bird from the Paleogene of Asia. Naranbulagornis khun documents a mosaic of autapomorphic and plesiomorphic features that are otherwise present in modern Anhimidae, Anseranatidae, and Anatidae, indicating a greater morphological diversity of early Cenozoic anseriforms than previously thought. The new taxon is morphologically closer to Anatoidea than to Presbyornithidae and represents the earliest global evidence of a spatial coexistence between presbyornithids and other basal waterfowl during the early Paleogene.
Humans evolved in the dynamic landscapes of Africa under conditions of pronounced climatic, geological and environmental change during the past 7 million years. This book brings together detailed records of the paleontological and archaeological sites in Africa that provide the basic evidence for understanding the environments in which we evolved. Chapters cover specific sites, with comprehensive accounts of their geology, paleontology, paleobotany, and their ecological significance for our evolution. Other chapters provide important regional syntheses of past ecological conditions. This book is unique in merging a broad geographic scope (all of Africa) and deep time framework (the past 7 million years) in discussing the geological context and paleontological records of our evolution and that of organisms that evolved alongside our ancestors. It will offer important insights to anyone interested in human evolution, including researchers and graduate students in paleontology, archaeology, anthropology and geology.
Humans evolved in the dynamic landscapes of Africa under conditions of pronounced climatic, geological and environmental change during the past 7 million years. This book brings together detailed records of the paleontological and archaeological sites in Africa that provide the basic evidence for understanding the environments in which we evolved. Chapters cover specific sites, with comprehensive accounts of their geology, paleontology, paleobotany, and their ecological significance for our evolution. Other chapters provide important regional syntheses of past ecological conditions. This book is unique in merging a broad geographic scope (all of Africa) and deep time framework (the past 7 million years) in discussing the geological context and paleontological records of our evolution and that of organisms that evolved alongside our ancestors. It will offer important insights to anyone interested in human evolution, including researchers and graduate students in paleontology, archaeology, anthropology and geology.
Galloanseres, the clade including galliform and anseriform birds, is supported by virtually all analyses of different kinds of molecular data and also resulted from analyses of morphological data. A recent study obtained an early Eocene date for the split of galliform and anseriform birds, some 55 million years. However, this divergence estimate is in clear conflict with the fossil record, which includes morphologically disparate stem group representatives of both Galliformes and Anseriformes from deposits of that age (anseriform birds have an even earlier fossil record). Extant Galloanseres are mainly characterized by morphological apomorphies that concern skull features. The postcranial skeleton of extant Galliformes and Anseriformes is quite different, but the morphology of Paleogene stem group Galliformes bridges the morphological gap between the extant taxa. Various ecomorphologically disparate Paleogene taxa were assigned to the Galloanseres. The morphological and ecological diversity within Paleogene Galloanseres, therefore, appears to have been extraordinarily high, including giant flightless ground birds with greatly reduced wings, long-legged filter-feeders, and pelagic taxa with wingspans of 4–5 m.
The St Bathans Fauna is a highly diverse non-marine vertebrate assemblage derived from the lower Miocene (19–16 Ma) Bannockburn Formation exposed in Central Otago, New Zealand. Deposited in palaeolake Manuherikia, remains of waterfowl dominate the avian assemblage, which, with eight known species in four genera, is one of the more diverse globally. Here we describe Manuherikia primadividua nov. sp., the fourth species in the genus. The stratigraphic distribution of fossils assignable to M. primadividua nov. sp. and a previously known species of Manuherikia, M. lacustrina, allow for the recognition of two distinct biozones within the Bannockburn Formation. Fossils of Manuherikia lacustrina are shown to be restricted to beds in the lower 26 m of the Bannockburn Formation in the Manuherikia River Section while fossils of the new species only occur in beds higher than 34 m in this section. This zonation allows correlation of the disparate sites in nearby Mata Creek with the stratigraphy in the Manuherikia River Section. This is the first such biostratigraphical zonation recognised in the fossil-bearing horizons at St Bathans; all other vertebrates have distributions spanning the stratigraphical range of both species. We tentatively correlate this vertebrate zonation with the previously identified pollen zonation, namely the Casuarinaceae Zone and its overlying Asteraceae-Chenopodiaceae or Chenopodipollis chenopodiaceoides Zone. This transition marks a relatively minor environmental change towards drier and more seasonal climates that appears to have driven the palaeoecological replacement of M. lacustrina by M. primadividua nov. sp. in palaeolake Manuherikia.
A tarsometatarsus of a large anseriform bird from the late Oligocene/early Miocene of the Saint-Gérand-le-Puy area in France is assigned to the distinctive taxon Paranyroca, which was before only known from the early Miocene of North America. Paranyroca may be a stem group representative of Anatidae and its tarsometatarsus exhibits a peculiar character mosaic, with an Anhimidae-like hypotarsus and an Anatidae-like distal end. With regard to these features, the bone resembles the tarsometatarsus of another anseriform bird from Saint-Gérand-le-Puy, which was described as Cygnopterus alphonsi but has not yet been compared with Paranyroca in the original description. C. alphonsi was originally identified as a swan, but this classification has subsequently been contested and here it is proposed that the species is more closely related to Paranyroca.
The site, discovered in 1995, reveals the s.c. Lozents suite, dated Early Pliocene (Ruscinian), MN 14. Three species of vertebrate (a fish, a reptile and a bird) have been established. One bone fragment (a proximal part of a left humerus, No NMNHS 1644 - holotype) belongs to an undescribed swan. A review of fossil swans and a morphological
comparison of the find are presented.
Sahabi is a latest Miocene/earliest Pliocene vertebrate fauna from Libya. It includes a mixture of Eurasian and African vertebrates, and as such is important for biogeographic reconstruction and paleoecologic comparisons. We undertake a morphometric analysis of Sahabi hipparion metacarpal 3s, metatarsal 3s and 1(st) phalanges 3 in order to reevaluate and revise this assemblages' systematics, biogeographic relationships and paleoecologic setting. In so doing we recognize two hipparion taxa at Sahabi: a slender-limbed form adapted for open country cursoriality, "Cremohipparion" aff. matthewi; and a robust-limbed form, a likely woodland denizen with likely less cursorial capability, "Hipparion" sp. (Sivalhippus Complex). "Cremohipparion" aff. matthewi exhibits its closest affinity with the Samos and Maramena slender-limbed hipparions of the Cremohipparion matthewi/nikosi lineage. We believe that this lineage also likely includes the Indo-Pakistan hipparion, "Cremohipparion" antelopinum. This lineage provides evidence for a late Miocene hipparion biogeographic connection between Indo-Pakistan, Southwest Asia, the Eastern Mediterranean and North Africa. The large Sahabi form "Hipparion" sp. (Sivalhippus Complex) would appear to belong to a lineage whose late Miocene distribution was between Indo-Pakistan, North Africa and East Africa. The East African slender-limbed form Eurygnathohippus feibeli would appear to be convergent on the "Cremohipparion" small slender-limbed hipparion, having synapomorphies of the lower dentition with the Eurygnathohippus radicle of the "Sivalhippus" Complex.
