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A new Old World vulture from the late Miocene of China sheds light on Neogene shifts in the past diversity and distribution of the Gypaetinae
Abstract
Neogene fossils of Old World vultures (Aegypiinae and Gypaetinae) are known from both Old World and New World records. There are no extant Old World vultures in the Americas today, although a large diversity of Gypaetinae is known from Miocene to late Pleistocene records. Despite a comparatively large number of North American gypaetine fossils, complete specimens have rarely been reported from Eurasia and Africa. We describe the exceptional skeleton of a new gypaetine vulture from the late Miocene deposits of the Linxia Basin in northwestern China. The specimen is the oldest record of Gypaetinae from Eurasia or Africa. A reexamination of the geographic and temporal distribution of most Old World vultures from Neogene deposits indicates a diverse radiation, coincident with early-to mid-Miocene grassland expansion for Gypaetinae. Although the diversification of Aegypiinae has been linked to the transition from C 3 to C 4 grassland, Gypaetinae diversification predates that transition in both North America and Asia. A shift in the known latitudinal distribution is also noted. Neogene records of Old World vultures are found primarily in mid-and high-latitude regions of North America and Eurasia as well as in the middle and low latitudes of Eurasia and Africa. With very few records in the middle to late Miocene, a latitudinal distribution similar to that of extant species is first seen in the early Pliocene. The new fossil provides further temporal constraints on avian subclade diversification. It is also consistent with an emerging pattern of profound recent shifts in avian diversity and distribution more generally.
... Anchigyps voorhiesi (Zhang et al. 2012a), from Nebraska (USA), similar in size to Neophron percnopterus and to the congeneric species described here. Mioneophron longirostris (Li et al. 2016), from the Gansu Province (China), has been described from a quite complete skeleton and related to the extant Neophron percnopterus. The finding of Gypaetus barbatus Linnaeus, 1758, in the early Pleistocene of the Iberian Peninsula (Montoya et al. 1999(Montoya et al. , 2001Mlíkovský 2002) is so far the oldest record of the genus in the Old World. ...
... An almost complete skeleton of a gypaetine has been recently named Mioneophron longirostris by Li et al. (2016). Although it preserves a remarkable amount of the bones, these are badly broken, many of the anatomical features have been lost or remain hidden in the slab matrix and the magnification of the figures is insufficient. ...
... Two features distinguish the new species from its extant congeneric form. In Mioneophron longirostris, the pre-narial portion of the rostrum maxillare is longer than in Neophron percnopterus (Li et al. 2016), (Figure 3a). In the new species, it is proportionally similar. ...
Only three monospecific genera of extant accipitrids – Gypaetus, Neophron and Gypohierax – have been grouped into the Gypaetinae vultures, which currently presents an Eurasian and African geographic
distribution. The fossil record of these genera is meagre and not older than the Pleistocene of both landmasses. A surprising Old World vulture radiation occurred in North America from the early Miocene to
the late Pleistocene, with taxa more closely linked to Gypaetinae than to Aegypiinae. More recently new fossil gypaetines have been described for the late Miocene of North America and China. Two new species assigned to genera Gypaetus and Neophron are described here, and their links with other related taxa are evaluated. The new specimens were found at two sites in the Cerro de los Batallones, a rich late Miocene palaeontological complex located in the centre of Spain.
... The holotype specimen was collected from near Langwagou Village, Zhuangkeji Town, Guanghe County, in Gansu Province of northwestern China (Figure 1) from the Upper Miocene Liushu Formation, Linxia Basin. The known bird fossils of the Linxia Basin are of the same unit and have largely been acquired from local farmers and collectors (Li et al. 2016). ...
... The exact locality of the specimen is unknown as it was collected by locals in 2018. The locality and horizon are similar to that of Li et al. (2016). The Linxia Basin is an intracontinental foreland basin located on the northeastern margin of the Tibetan Plateau (Wang et al. 2014). ...
... Faunal shifts within Linxia since the late Miocene suggest that large environmental change occurred, and the presence of Eogruidae in this locality further emphasizes this (Li et al. , 2016. It is unclear why Eogruidae are only known until the early Pliocene while undoubted extinct crown gruids are not abundant in Asia until the Pliocene and Pleistocene (Zelenkov 2015). ...
Despite having one of the most robust fossil records within core-gruiform birds (rails, cranes, and allies), the biogeographic history of Gruidae (cranes) and key drivers of diversification within this group remain largely unknown. The Eogruidae of Eurasia represent some of the earliest known crane-like fossils. Here, we present description of a new species represented by a well-preserved specimen of a foot from the late Miocene (7–6.5 mya) Liushu Formation of Linxia Basin, Gansu, China. It is the only eogruid fossil that has been found in this formation and is the first eogruid known from northwest China. Linxia Basin is located along the margin of the northeastern Tibetan Plateau, which allows for new insight into Miocene dispersal of the Eogruidae and potential climatological and geological connections. It is also the first specimen with an associated tarsometatarsus and nearly complete phalanges, including a claw, which provides further morphological information on this taxon. Referral of the new specimen to Eogruidae is based on extreme reduction of the trochlea of metatarsal II, which is most similar to the condition present in the eogruid subclade traditionally termed Ergilornithidae.
... The rest of the postcranial skeleton caudal to the penultimate caudal cervical vertebrae is unmodified original fossil material. The fossil is embedded in reddish clay, identical to that of other avian fossil specimens collected in the Linxia Basin in units attributed to the Liushu Formation 23 . The occurrence of TE and a bony blunt process for the attachment of a spur on the tarsometatarsus indicate that this individual may have been male (see below for more discussion). ...
... Potential selective advantages of low frequency calls include territory defense and mate attraction 52,53 . Such vocalizations should have carried a long distance in the reconstructed temperate savannah habitat where Panraogallus lived in the Linxia Basin 23,24 . While the data are consistent with the 'size exaggeration' hypothesis, we cannot reject other hypotheses and functions for tracheal elongation in this extinct species such as it being a compensative mechanism for heat conservation and water retention in the late Miocene 54 . ...
Modifications to the upper vocal tract involving hyper-elongated tracheae have evolved many times within crown birds, and their evolution has been linked to a ‘size exaggeration’ hypothesis in acoustic signaling and communication, whereby smaller-sized birds can produce louder sounds. A fossil skeleton of a new extinct species of wildfowl (Galliformes: Phasianidae) from the late Miocene of China, preserves an elongated, coiled trachea that represents the oldest fossil record of this vocal modification in birds and the first documentation of its evolution within pheasants. The phylogenetic position of this species within Phasianidae has not been fully resolved, but appears to document a separate independent origination of this vocal modification within Galliformes. The fossil preserves a coiled section of the trachea and other remains supporting a tracheal length longer than the bird’s body. This extinct species likely produced vocalizations with a lower fundamental frequency and reduced harmonics compared to similarly-sized pheasants. The independent evolution of this vocal feature in galliforms living in both open and closed habitats does not appear to be correlated with other factors of biology or its open savanna-like habitat. Features present in the fossil that are typically associated with sexual dimorphism suggest that sexual selection may have resulted in the evolution of both the morphology and vocalization mechanism in this extinct species.
... The middle Miocene accipitrids from Asia are all aegypiine vultures (Hou et al. 2000;Zhang et al. 2010Zhang et al. , 2012Li et al. 2016) and so are not closely related (see phylogenetic analysis below). ...
The Australian pre-Pleistocene fossil record of Accipitridae (eagles, hawks, old-world vultures) comprises one latest Oligocene or early Miocene and one middle Miocene species, each represented by partial bones. Globally, most fossil accipitrids are based on single bones. The recent discovery of an older and considerably more complete accipitrid from late Oligocene sediments in Australia is therefore significant. It is derived from the Pinpa Local Fauna from the Namba Formation at Lake Pinpa, South Australia (~26–24 Ma). The fossil, described as Archaehierax sylvestris gen. et sp. nov., represents a raptor that was larger than the black-breasted buzzard Hamirostra melanosternon but smaller and more gracile than the wedge-tailed eagle Aquila audax. Comprehensive morphological and molecular phylogenetic analyses resolved Archaehierax as a basal accipitrid, not closely related to any living subfamily and perhaps the sister taxon to all other accipitrids exclusive of elanines. Relatively short wings similar to species of Spizaetus and Spilornis suggest it was adapted for flight within enclosed forests. Additional accipitrid fossils from the Namba Formation, a distal femur and a distal humerus, are incomparable with the holotype of A. sylvestris; they may represent distinct species or smaller individuals of the new taxon. lsid:zoobank.org:pub:6A25C569-3E9F-43B8-AAF8-F36CE405C06E
... Numerous largebodied mammalian fossils are known from dozens of localities, and the fauna includes typical members of the Hipparion fauna, such as the bovid Hezhengia, the hyena Dinocrocuta, the antelope Gazella, and the rhinoceros Chilotherium (Deng, 2005;Deng et al., 2013). More recently, studies of the less common avian fauna have documented a diversity of taxonomic groups known from the Linxia Basin at various localities, including pheasants (Galliformes), vultures (Accitripidiformes), falcons (Falconidae), extinct crane relatives (Eogruidae), sandgrouse (Pteroclididae), an owl (Strigidae), and ostriches (Struthionidae) Li et al., 2014Li et al., , 2016Li et al., , 2018Musser et al., 2019). Based on an incomplete pelvic region (partial pelvis and synsacrum), Hou et al. (2005) described the extinct Linxia ostrich (Struthio linxiaensis) as the first documented avian species from the basin, and additional ostrich material from multiple localities, that will be published elsewhere, has been found since its initial identification (unpublished observation). ...
Here we report a new avian fossil from the Late Miocene Linxia Basin, Northwest China, with exceptional soft-tissue preservation. This specimen preserves parts of cervical vertebrae and tracheal rings that are typically ostrich-like, but cannot be diagnosed at the species level. Therefore, the fossil is referred to Struthio sp. The new specimen was preserved in association with a partial skull of Hipparion platyodus. To explore the soft tissue preservation in a fossil deposited in a terrestrial setting, we applied a combination of analytic methods to investigate the microscopic features of the fossilized avian bone. Bacterial alterations (bone bioerosion) were revealed by light microscopy and petrographic sections under SEM imaging. Soft-tissues (fossilized remnants of endogenous blood vessels and red blood cells) were preserved in one demineralized bone fragment and also observed in the in-situ ground-section. These are the first records of soft-tissue preservation in vertebrate remains from the Late Miocene Linxia Basin. Associated geological and sedimentological evidence combined with our new data provide insights into the postmortem taphonomic conditions of this ostrich specimen. A seasonal monsoon might have facilitated the microbial erosion penecontemporaneous with the burial of the specimen. This study encourages interdisciplinary research involving morphology, sedimentology, geochemistry, and histological soft-tissue analyses to better understand the Late Miocene faunal turnovers, climates, and fossil preservation in the Liushu Formation in northwestern China.
... Numerous largebodied mammalian fossils are known from dozens of localities, and the fauna includes typical members of the Hipparion fauna, such as the bovid Hezhengia, the hyena Dinocrocuta, the antelope Gazella, and the rhinoceros Chilotherium (Deng, 2005;Deng et al., 2013). More recently, studies of the less common avian fauna have documented a diversity of taxonomic groups known from the Linxia Basin at various localities, including pheasants (Galliformes), vultures (Accitripidiformes), falcons (Falconidae), extinct crane relatives (Eogruidae), sandgrouse (Pteroclididae), an owl (Strigidae), and ostriches (Struthionidae) Li et al., 2014Li et al., , 2016Li et al., , 2018Musser et al., 2019). Based on an incomplete pelvic region (partial pelvis and synsacrum), Hou et al. (2005) described the extinct Linxia ostrich (Struthio linxiaensis) as the first documented avian species from the basin, and additional ostrich material from multiple localities, that will be published elsewhere, has been found since its initial identification (unpublished observation). ...
Here we report a new avian fossil from the Late Miocene Linxia Basin, Northwest China, with exceptional soft-tissue preservation. This specimen preserves parts of cervical vertebrae and tracheal rings that are typically ostrich-like, but cannot be diagnosed at the species level. Therefore, the fossil is referred to Struthio sp. The new specimen was preserved in association with a partial skull of Hipparion platyodus. To explore the soft tissue preservation in a fossil deposited in a terrestrial setting, we applied a combination of analytic methods to investigate the microscopic features of the fossilized avian bone. Bacterial alterations (bone bioerosion) were revealed by light microscopy and petrographic sections under SEM imaging. Soft-tissues (fossilized remnants of endogenous blood vessels and red blood cells) were preserved in one demineralized bone fragment and also observed in the in-situ ground-section. These are the first records of soft-tissue preservation in vertebrate remains from the Late Miocene Linxia Basin. Associated geological and sedimentological evidence combined with our new data provide insights into the postmortem taphonomic conditions of this ostrich specimen. A seasonal monsoon might have facilitated the microbial erosion penecontemporaneous with the burial of the specimen. This study encourages interdisciplinary research involving morphology, sedimentology, geochemistry, and histological soft-tissue analyses to better understand the Late Miocene faunal turnovers, climates, and fossil preservation in the Liushu Formation in northwestern China.
... The presence of an extinct sandgrouse species in the late Miocene deposits of the Linxia Basin (Figure 1) adds to the growing knowledge of its diverse avifauna including an ostrich (Hou et al., 2005), a stem falcon , old world vultures (Zhang et al., 2010;Li et al., 2016), a pheasant with a hyperelongated trachea (Li et al., 2018), and an eogruid (Musser et al., 2019). The new fossil sandgrouse occupied dry, arid habitats alongside the well-known, diverse extinct mammalian fauna from the Linxia Basin. ...
The partial skeleton of a new extinct taxon, Linxiavis inaquosus, from the Liushu Formation (6–9 Ma) at the edge of the Tibetan Plateau in Gansu Province, China is the most substantial known fossil record of sandgrouse (Pteroclidae). While adding to the rapidly growing known Liushu avian fauna of vultures, falcons, pheasants, and ostrich, this new fossil is likely the oldest record of crown Pteroclidae (as a potential molecular clock calibration point), the oldest record of the group in Asia (from a probable African origin), and derives from a significant temporal gap in their Neogene history. The fossil specimen includes articulated and associated elements of the wings, shoulder girdle, vertebrae, and hind limb, exhibiting apomorphies of Columbiformes and Pteroclidae such as a notarium, and a short coracoid shaft. As part of the diverse Hipparion fauna, Linxiavis inaquosus reinforces the interpretation of the late Miocene Linxia Basin habitat as an arid savannah, associated with the uplift of the Tibetan Plateau. The holotype suggests that the arid high elevation Tibetan area habitats may have been continuously occupied since the late Miocene by sandgrouse carrying water in their modified breast feathers to their young.
... We modeled this calibration point using a lognormal distribution (stdev = 0.25 offset = 7.25). The second is the fossil Mioneophron longirostris (Li et al. 2016) for the first appearance of the Gypaetinae in the fossil record. The fossil was dated to the Upper Miocene Liushu Formation, Linxia Basin, and was used to calibrate the split between Polyboroides and the three Gypaetinae genera (Gypaetus, Neophron, Gypohierax). ...
An ideal taxonomy for organisms incorporates comprehensive knowledge of existing species diversity and their phylogenetic relationships. This knowledge is used in developing consistent criteria for recognizing and naming species as well as monophyletic groups (clades) above the species level, including genera, families, and orders. This provides well-justified, consensus names for taxa that can be used globally in studying and managing the health of species and their populations. Having the taxonomic hierarchy of names reflects evolutionary history and advances our understanding of the origins and causes of change over time in biological diversity.
... We modeled this calibration point using a lognormal distribution (stdev = 0.25 offset = 7.25). The second is the fossil Mioneophron longirostris ( Li et al. 2016) for the first appearance of the Gypaetinae in the fossil record. The fossil was dated to the Upper Miocene Liushu Formation, Linxia Basin, and was used to calibrate the split between Polyboroides and the three Gypaetinae genera (Gypaetus, Neophron, Gypohierax). ...
Understanding how and why lineages diversify is central to understanding the origins of biological diversity. The avian family Falconidae (caracaras, forest-falcons, falcons) has an uneven distribution of species among multiple well-supported clades, and provides a useful system for testing hypotheses about diversification rate and correlation with environmental changes. We analyzed ten independent loci for 1 to 7 individuals from each of the 64 currently recognized Falconidae species, together with two fossil falconid temporal calibrations, to assess phylogeny, absolute divergence times and potential shifts in diversification rate. Our analyses supported similar diversification ages in the Early to Middle Miocene for the three traditional subfamilies, Herpetotherinae, Polyborinae and Falconinae. We estimated that divergences within the subfamily Falconinae began about 16 mya and divergences within the most species-rich genus, Falco, including about 60% of all Falconidae species, began about 7.5 mya. We found evidence for a significant increase in diversification rate at the basal phylogenetic node for the genus Falco, and the timing for this rate shift correlates generally with expansion of C4 grasslands beginning around the Miocene/Pliocene transition. Concomitantly, Falco lineages that are distributed primarily in grassland or savannah habitats, as opposed to woodlands, and exhibit migratory, as opposed to sedentary, behavior experienced a higher diversification rate.
Zoology 53-2207 QL696 2014-35370 CIP Campbell, Michael O'Neal. Vultures: their evolution, ecology and conservation. CRC Press, 2015. 364p bibl index afp ISBN 9781482223613, $103.96; ISBN 9781482223620 ebook, $90.97. This authoritative volume provides detailed information on all vultures of the world, including condors. Campbell's thorough review of the literature is reflected in the 188-page bibliography (some 3,700 references, cited throughout). Part 1, "Vulture Classification, Genetics and Ecology," provides overviews of all species. For each, Campbell (Simon Fraser Univ.) provides details of physical appearance, classification, foraging and breeding behavior, population status, and a concluding essay. Graphics include color illustrations of each (and its egg) and a range map. Part 2 is titled "Vulture Ecology and Evolution." Part 3, "Vulture Ecology and Conservation," includes an invaluable discussion of the current catastrophic decline of Indian (and other) vultures due to ingestion of chemicals, especially diclofenac and lead. Campbell also discusses other threats to vultures: collisions with aircraft, wind turbines, habitat incursions (including urbanization), and human attitudes toward vultures. The somewhat pedantic, academic style makes for some awkward reading, but this is relieved by the volume's illustrations and good formatting (e.g., chapter subheadings). This fine volume joins Vulture Biology and Management (1983), W. R. Wilbur and J. A. Jackson's excellent (albeit dated) edited volume.
A new species of griffon vulture (Gyps bochenskii sp. n.) is described from the Late Pliocene (Middle Villafranchian) deposits of a locality near Varshets (NW Bulgaria). The site was discovered in 1987 and has the richest Late Pliocene (MN 17) vertebrate fauna in Europe. The more than 71 avian species are indicative of a forest-steppe landscape. Petrophylous species are widely represented among the fossil material. The finds represent the oldest remains of a griffon vulture, with four skeletal elements: sternum (coracoidal and costal parts), coracoid dex. (humeral and sternal parts), phalanx dist. dig. 1 pedis sin. and phalanx dist. dig. majoris sin. These remains verify the presence of vultures, and griffon vultures in particular, in Europe (and the Palearctic) before the glacial events of the Pleistocene. The morphology distinguishes (holotype, sternum) the specimens from recent species of Gyps by: steeply orientation of linea intermuscularis; relatively thicker incisurae intercostales; relatively longer incisura intercostalis IV; presence of a well developed fossa on the dorsal surface of the sternum above the manubrium; relatively larger (wider) rostrum sterni; cranially less protruding rostrum sterni; relatively wider sternum in dorsal view; narrower distance between the dorsal edges of the sulci articulares, and larger dimensions. Differences from Pleistocene G. melitensis: better developed hind limbs (about 1/10 in the measurements of distal pedal phalanges) and the same development of wings (phalanx dist. dig. majoris).
ABSTRACT—Fossil remains of at least seven individuals of a new species of Aegypius vulture from the Upper Varswater Formation at Langebaanweg, South Africa (early Pliocene), represent the earliest, unequivocal, and most substantial evidence for crown-group Aegypiinae in the world. Evaluation of available data on previously described vulture species from the Miocene of Africa and China such as Gansugyps linxiaensis, Mioaegypius gui, and Qiluornis taishanensis indicate that the corresponding fossils either lack any diagnostic characters of aegypiine vultures or are referable to the stem lineage of Aegypiinae. Aegypiine vultures, nevertheless, might be of Asian origin, and the extension of the range of this taxon into Africa south of the Sahara might be correlated with the spread of gregarious herbivores such as bovids and equids from Eurasia to Africa during the Miocene. The holotype of the new vulture species, an associated partial skeleton with elements of the pectoral girdle, the wing, and the hind limb preserved, is comparable in size to smaller individuals of A. monachus and A. tracheliotos. Evidence for an Aegypius vulture at Langebaanweg further indicates that open woodlands were an important component of the early Pliocene paleoenvironments at this particular site.
Understanding how and why lineages diversify is central to understanding the origins of biological diversity. The avian family Falconidae (caracaras, forest-falcons, falcons) has an uneven distribution of species among multiple well-supported clades, and provides a useful system for testing hypotheses about diversification rate and correlation with environmental changes. We analyzed ten independent loci for 1 to 7 individuals from each of the 64 currently recognized Falconidae species, together with two fossil falconid temporal calibrations, to assess phylogeny, absolute divergence times and potential shifts in diversification rate. Our analyses supported similar diversification ages in the Early to Middle Miocene for the three traditional subfamilies, Herpetotherinae, Polyborinae and Falconinae. We estimated that divergences within the subfamily Falconinae began about 16 mya and divergences within the most species-rich genus, Falco, including about 60% of all Falconidae species, began about 7.5 mya. We found evidence for a significant increase in diversification rate at the basal phylogenetic node for the genus Falco, and the timing for this rate shift correlates generally with expansion of C4 grasslands beginning around the Miocene/Pliocene transition. Concomitantly, Falco lineages that are distributed primarily in grassland or savannah habitats, as opposed to woodlands, and exhibit migratory, as opposed to sedentary, behavior experienced a higher diversification rate.
An isolated, well-preserved tarsometatarsus of a huge aegypiine vulture from the early Pliocene (MN 15) of Pelinei, Moldova was originally described as Aegypius melitensis (Lydekker, 1890) by Tugarinov (1940:199). It was listed under Gyps melitensis by Mlíkovský (2002:189), who expressed his doubts that this fossil could actually be referred to this species. Re-examination of the specimen and more detailed comparisons with extinct and modern Aegypiinae confirm that it is part of Aegypius, and that Tugarinov’s (1940) placement of the Pleistocene Gyps melitensis Lydekker, 1890 into Aegypius is evidently unsubstantiated. The vulture from Pelinei is the earliest unequivocal evidence of Aegypiinae in Europe.
Excavations and studies of existing collections during the last decades have significantly increased the abundance as well as the diversity of the avian fossil record for Insular Southeast Asia. The avian fossil record covers the Eocene through the Holocene, with the majority of bird fossils Pleistocene in age. Fossil bird skeletal remains represent at least 63 species in 54 genera and 27 families, and two ichnospecies are represented by fossil footprints. Birds of prey, owls and swiftlets are common elements. Extinctions seem to have been few, suggesting continuity of avian lineages since at least the Late Pleistocene, although some shifts in species ranges have occurred in response to climatic change. Similarities between the Late Pleistocene avifaunas of Flores and Java suggest a dispersal route across southern Sundaland. Late Pleistocene assemblages of Niah Cave (Borneo) and Liang Bua (Flores) support the rainforest refugium hypothesis in Southeast Asia as they indicate the persistence of forest cover, at least locally, throughout the Late Pleistocene and Holocene.
This chapter describes the Late Cenozoic biostratigraphy of the Linxia Basin in northwestern China. The Linxia Basin harbors a variety of Late Cenozoic fossils of different plants and animals as well as land mammals. Reptiles are represented mainly by a great number of specimens of Testudo from the late Miocene red clay deposits, which is an important member of the Hipparion fauna. After sketching the geological setting, magnetostratigraphy, and biochronology of the Linxia Basin, the chapter analyzes the abundant mammalian fossils from the Linxia Basin, with particular emphasis on their exact localities and horizons. By doing so, it is able to update the faunal lists from specific localities, establish lithological and biostratigraphic criteria for correlation, and conduct paleomagnetic studies of key sections of the area.
Between 8 and 6 million years ago, there was a global increase in the biomass of plants using C 4 photosynthesis as indicated by changes in the carbon isotope ratios of fossil tooth enamel in Asia, Africa, North America and South America. This abrupt and widespread increase in C 4 biomass may be related to a decrease in atmospheric CO 2 concentrations below a threshold that favoured C 3-photosynthesizing plants. The change occurred earlier at lower latitudes, as the threshold for C 3 photosynthesis is higher at warmer temperatures.
Liang Bua, a limestone cave on the Indonesian island of Flores, has a depositional sequence that spans the last 95,000 years and includes well-preserved faunal remains. Birds are well represented throughout the stratigraphic sequence at Liang Bua. Here, we present the results of the first comprehensive study of avian remains retrieved from Sector XI, a 2 m by 2 m archaeological excavation along the east wall of the cave. A total of 579 specimens were identified as avian, with 244 belonging to at least 26 non-passerine taxa in 13 families. The late Pleistocene assemblage (23 taxa) includes the first recorded occurrence of vultures in Wallacea, as well as kingfishers, snipes, plovers, parrots, pigeons, and swiftlets. Together, these taxa suggest that during this time the surrounding environment was floristically diverse and included several habitat types. Two of these taxa, the giant marabou Leptoptilos robustus and the vulture Trigonoceps sp., are extinct. Eight taxa were identified in the Holocene assemblage, and five of these were also present in the late Pleistocene. Imperial pigeons Ducula sp. and the Island Collared Dove Streptopelia cf. bitorquata appear only in the Holocene assemblage. The differences in faunal composition between the late Pleistocene and Holocene assemblages may reflect a change in avifaunal composition due to climatic and environmental changes near the Pleistocene–Holocene transition, possibly amplified by impacts associated with the arrival of modern humans; however, the small Holocene sample prevents a firm conclusion about faunal turnover from being made.
The member names for the Ogallala Formation (including the Valentine, Ash Hollow, and Kimball) in Kansas of Zeller (1968) are abandoned. The Ogallala Formation in Kansas includes strata of Miocene and earliest Pliocene age, revising earlier correlation to the Pliocene only (Zeller, 1968). The Kansas Geological Survey is abandoning use of the term "Tertiary," to be replaced by the term "Neogene." International stage boundaries for the Neogene have not been established in Kansas.
As top predators, falcons possess unique morphological, physiological and behavioral adaptations that allow them to be successful hunters: for example, the peregrine is renowned as the world's fastest animal. To examine the evolutionary basis of predatory adaptations, we sequenced the genomes of both the peregrine (Falco peregrinus) and saker falcon (Falco cherrug), and we present parallel, genome-wide evidence for evolutionary innovation and selection for a predatory lifestyle. The genomes, assembled using Illumina deep sequencing with greater than 100-fold coverage, are both approximately 1.2 Gb in length, with transcriptome-assisted prediction of approximately 16,200 genes for both species. Analysis of 8,424 orthologs in both falcons, chicken, zebra finch and turkey identified consistent evidence for genome-wide rapid evolution in these raptors. SNP-based inference showed contrasting recent demographic trajectories for the two falcons, and gene-based analysis highlighted falcon-specific evolutionary novelties for beak development and olfaction and specifically for homeostasis-related genes in the arid environment-adapted saker.
Background
Old World vultures are likely polyphyletic, representing two subfamilies, the Aegypiinae and Gypaetinae, and some genera of the latter may be of independent origin. Evidence concerning the origin, as well as the timing of the divergence of each subfamily and even genera of the Gypaetinae has been elusive.
Methodology/Principal Findings
Compared with the Old World, the New World has an unexpectedly diverse and rich fossil component of Old World vultures. Here we describe a new accipitriform bird, Anchigyps voorhiesi gen. et sp. nov., from the Ash Hollow Formation (Upper Clarendonian, Late Miocene) of Nebraska. It represents a form close in morphology to the Old World vultures. Characteristics of its wing bones suggest it was less specialized for soaring than modern vultures. It was likely an opportunistic predator or scavenger having a grasping foot and a mandible morphologically similar to modern carrion-feeding birds.
Conclusions/Significance
The new fossil reported here is intermediate in morphology between the bulk of accipitrids and the Old World gypaetine vultures, representing a basal lineage of Accipitridae trending towards the vulturine habit, and of its Late Miocene age suggests the divergence of true gypaetine vultures, may have occurred during or slightly before the Miocene.
Two new fossil crania of Old World vultures (Accipitridae, Aegypiinae), from the middle Pleistocene Jinniushan site of Liaoning Province, northeastern China, were studied. A new species of Aegypius, A. jinniushanensis, is erected and characterized by possessing a less developed processus zygomaticus and processus suprameaticus, as well as a relatively larger condylus occipitalis, compared with A. monachus. Another specimen, assigned to Torgos, is the first record of this genus from outside Africa. The presence of two large vultures, apparently in the same feeding group, in the Jinniushan faunal assemblage suggests that there were more opportunities for interspecific competition among scavengers in the middle Pleistocene of northeastern China than at present. By analogy with phylogenetically related modern vultures, we suggest that niche differentiation between the two extinct species may have reduced the degree of competition between them. The disappearance of the genus Torgos from northeast China might be the result of the Pleistocene extinction of a suite of large mammalian herbivores, and the loss of grassland and savannah from this region.
A large-sized and almost complete fossil vulture was discovered from the Late Miocene Liushu Formation of Linxia Basin in
northwestern China. It is the best-preserved and the most complete fossil vulture yet discovered. The new genus and species
Gansugyps linxiaensis is proposed and assigned to the family Accipitridae; morphology and limb proportions suggest it was chiefly an arboreal and
soaring bird. It is more advanced than the other two known Miocene vultures from China. This new fossil increases our knowledge
of the evolutionary history of vultures, and has implications for reconstructing the paleoecology of this region.
Keywords
Gansugyps linxiaensis gen. et sp. nov.-Late Miocene-Liushu Formation-Northwestern China-Old World vulture-Paleoecology
Between 8 and 6 million years ago, there was a global increase in the biomass of plants using C-4 photosynthesis as indicated by changes in the carbon isotope ratios of fossil tooth enamel in Asia, Africa, North America and South America. This abrupt and widespread increase in C-4 biomass may be related to a decrease in atmospheric CO2 concentrations below a threshold that favoured C-3-photosynthesizing plants. The change occurred earlier at lower latitudes, as the threshold for C-3 photosynthesis is higher at warmer temperatures.
Background
Populations of the Oriental White-backed Vulture (Gyps bengalensis) have declined by over 95% within the past decade. This decline is largely due to incidental consumption of the non-steroidal anti-inflammatory veterinary pharmaceutical diclofenac, commonly used to treat domestic livestock. The conservation status of other Gyps vultures in southern Asia is also of immediate concern, given the lack of knowledge regarding status of their populations and the continuing existence of taxonomic uncertainties. In this study, we assess phylogenetic relationships for all recognized species and the majority of subspecies within the genus Gyps. The continuing veterinary use of diclofenac is an unknown but potential risk to related species with similar feeding habits to Gyps bengalensis. Therefore, an accurate assessment of the phylogenetic relationships among Gyps vultures should aid in their conservation by clarifying taxonomic uncertainties, and enabling inference of their respective relatedness to susceptible G. bengalensis.
Results
Phylogenetic results using mitochondrial cytB, ND2 and control region sequence data indicate a recent and rapid diversification within the genus Gyps. All recognized species formed monophyletic groups with high statistical support, with the exception of the Eurasian Vulture, for which specimens identified as subspecies G. fulvus fulvescens appear closely related to the Himalayan Vulture (G. himalayensis). In all analyses, the earliest divergence separated the Oriental White-backed Vulture from other Gyps taxa, with the next diverging taxon being either the African White-backed Vulture (G. africanus), or the Himalayan Vulture. All analyses supported a sister relationship between the Eurasian Vulture (G. f. fulvus), and Rüppell's Vulture (G. rueppellii), with this clade being sister to another consisting of the two taxa of "Long-billed" Vulture (G. indicus indicus and G. i. tenuirostris), and the Cape Vulture (G. coprotheres). These molecular phylogenies strongly support the treatment of indicus and tenuirostris as separate species, as does morphological data showing that these two taxa of similar overall size differ in proportions, especially in rostral, alar, and pedal characters. In addition, grouping of bengalensis and africanus together in the genus Pseudogyps, as historically proposed, is not upheld based on mitochondrial data.
Conclusion
Both molecular and morphological data provide strong support for considering the "Long-billed" Vulture to be comprised of two species (G. indicus and G. tenuirostris), and further analysis is warranted to determine the taxonomic distinctiveness of G. f. fulvescens. Our phylogenetic analyses and conservative estimates suggest the diversification of Gyps taxa to be within the past 6 million years. Diclofenac susceptibility has been previously demonstrated for four Gyps species (G. indicus, G. fulvus, G. africanus, G. bengalensis), and the phylogenetic position of these species each forming a sister relationship with at least one of the remaining species, support concern that other Gyps taxa may be susceptible as well. Determining genetic and evolutionary distinctiveness for Gyps lineages is increasingly important as a breeding program is being established to prevent extinction.
Progressive changes are observed in both the composition of mammal faunas and vegetation during the Miocene epoch [24-5 mega-annum (Ma)]. These changes are usually interpreted as a response to climatic changes. In the traditional view, forests or woodlands gradually gave way to more open habitats, with grazing (grass-eating) ungulate (hoofed) mammal species replacing the browsing (leafy-vegetation-eating) species as grasslands expanded. However, data from fossil assemblages in the Great Plains region of North America show that this faunal change was not a one-for-one replacement of browsers by grazers, as usually thought. Typical late early Miocene (17 Ma) fossil communities included extraordinarily high numbers of browsing ungulate species, comprising a fauna that cannot be directly analogized with any present-day community. Both maximum species richness of all ungulates and the proportion of browsers declined steadily in ungulate communities through the middle Miocene, to levels comparable to those of the present by the late Miocene. The resulting dramatic, cumulative loss of browsing species constitutes one of the strongest faunal signals of the late Tertiary (but was not a single "event"). We suggest that the early Miocene browser-rich communities may reflect higher levels of primary productivity in Miocene vegetation, compared with equivalent present-day vegetation types. The observed decline in species richness may represent a gradual decline in primary productivity, which would be consistent with one current hypothesis of a mid-Miocene decrease in atmospheric CO2 concentrations from higher mid-Cenozoic values.
We assessed phylogenetic relationships for birds of prey in the family Accipitridae using molecular sequence from two mitochondrial genes (1047 bases ND2 and 1041 bases cyt-b) and one nuclear intron (1074 bases beta-fibrinogen intron 7). We sampled representatives of all 14 Accipitridae subfamilies, focusing on four subfamilies of eagles (booted eagles, sea eagles, harpy eagles, and snake eagles) and two subfamilies of Old World vultures (Gypaetinae and Aegypiinae) with nearly all known species represented. Multiple well-supported relationships among accipitrids identified with DNA differ from those traditionally recognized based on morphology or life history traits. Monophyly of sea eagles (Haliaeetinae) and booted eagles (Aquilinae) was supported; however, harpy eagles (Harpiinae), snake eagles (Circaetinae), and Old World vultures were found to be non-monophyletic. The Gymnogene (Polyboroides typus) and the Crane Hawk (Geranospiza caerulescens) were not found to be close relatives, presenting an example of convergent evolution for specialized limb morphology enabling predation on cavity nesting species. Investigation of named subspecies within Hieraaetus fasciatus and H. morphnoides revealed significant genetic differentiation or non-monophyly supporting recognition of H. spilogaster and H. weiskei as distinctive species.
We have documented elsewhere, and briefly reviewed here, the anomalously high species richness of browsing ungulates (hoofed mammals) in the mid Miocene (∼18–12 Ma) woodland savanna habitats of North America. In the mid Miocene these habitats supported substantially more brachydont (browsing) species than do any present-day savanna habitats. We present some preliminary data to show that such species-rich browser communities are not observed after the mid Miocene. The data also suggest that these mid Miocene browser communities and their subsequent disappearance may have been a global phenomenon. We then focus on possible explanations for these observations. We discuss the possibility that the high species numbers are a preservational artifact, and conclude that taphonomic factors are unlikely to be responsible for the level of species richness observed. We then consider various possible explanations for high species richness, including the unique aspects of climatic change (cooling, drying, increased seasonality), unique biotic interactions (the effects of competition, keystone herbivores, changes in predator pressure), and consider that none of these are fully consistent with the available data. The most likely explanation for the observed species-rich browser palaeocommunities is an elevated level of primary productivity, relative to the present day, within (at least some) mid Miocene grassland habitats. Such an increase in productivity could possibly have been the result of higher-than-present levels of atmospheric carbon dioxide in the mid Miocene, but this conflicts with current interpretations of geochemical evidence, and a satisfactory mechanism for the inferred increased primary productivity is an unresolved issue.
We used nuclear and mitochondrial genes to generate a phylogenetic hypothesis for the Palearctic-Oriental starlings and mynas (genera Sturnus, Acridotheres, Leucopsar, Creatophora and Fregilupus: Sturnidae). Our results indicate that the group has undergone a rapid diversification in Asia since the late Miocene. A reassessment of the morphological and ecological characters used in previous taxonomic revisions shows that all characters are highly homoplastic. We suggest that the elevated morphological and ecological plasticity favoured the adaptation of starlings and mynas to the local environment, the exploitation of all niches and their successful radiation in south-east Asia. Under the current limits the genera Sturnus and Acridotheres are not monophyletic, and we propose a revised phylogenetic taxonomy for the entire clade. We confirm that the extinct Fregilupus varius is a starling and it colonized Réunion Island (Mascarenes) by transoceanic dispersal from Asia.
Consensus is elusive regarding the phylogenetic relationships among neornithine (crown clade) birds. The ongoing debate over their deep divergences is despite recent increases in available molecular sequence data and the publication of several larger morphological data sets. In the present study, the phylogenetic relationships among 43 neornithine higher taxa are addressed using a data set of 148 osteological and soft tissue characters, which is one of the largest to date. The Mesozoic non-neornithine birds Apsaravis, Hesperornis, and Ichthyornis are used as outgroup taxa for this analysis. Thus, for the first time, a broad array of morphological characters (including both cranial and postcranial characters) are analyzed for an ingroup densely sampling Ne-ornithes, with crown clade outgroups used to polarize these characters. The strict consensus cladogram of two most parsimonious trees resultant from 1000 replicate heuristic searches (random stepwise addition, tree-bisection-reconnection) recovered several previously identified clades; the at-one-time contentious clades Galloanseres (waterfowl, fowl, and allies) and Palaeognathae were supported. Most notably, our analysis recovered monophyly of Neoaves, i.e., all neognathous birds to the exclusion of the Galloanseres, although this clade was weakly supported. The recently proposed sister taxon relationship between Steatornithidae (oilbird) and Trogonidae (trogons) was recovered. The traditional taxon "Falconiformes" (Cathartidae, Sagittariidae, Accipitridae, and Falconidae) was not found to be monophyletic, as Strigiformes (owls) are placed as the sister taxon of (Falconidae + Accipitridae). Monophyly of the traditional "Gruiformes" (cranes and allies) and "Ciconiiformes" (storks and allies) was also not recovered. The primary analysis resulted in support for a sister group relationship between Gaviidae (loons) and Podicipedidae (grebes)-foot-propelled diving birds that share many features of the pelvis and hind limb. Exclusion of Gaviidae and reanalysis of the data set, however, recovered the sister group relationship between Phoenicopteridae (flamingos) and grebes recently proposed from molecular sequence data.
This book aims to present fossil horses in a modern context that makes use of the recent advances in palaeontology and related disciplines. The emphasis is on fossil horses from North America because the principal evolutionary history of this group occurred there. The majority of the book is intended to be a synthesis of previous work but some original research results are also included. The book is organized into several informal sections: chapters 1-4 provide an extended introductory background; chapters 5-7 cover the systematics and distribution of horses in time and space; chapters 8-10 examine how fossil horses contribute to an understanding of processes and patterns in evolution; the final section, chapters 11-13, discusses functional morphology and ecology. Two appendices, on abbreviations used and classification of the Equidae, references, and subject and taxonomic indexes are provided. -G.E.Hodgson
Although the family Falconidae, which includes extant falcons and caracaras, has a long evolutionary history, most previously reported fossils referred to this family are isolated single elements. We report a new species, Falco hezhengensis sp. nov., represented by a nearly complete and articulated skeleton from the Late Miocene deposits of Linxia Basin in northwestern China. The new fossil shares an array of derived morphologies with the genus Falco, and analysis of the largest morphological dataset for Falconidae, sampling most genera, identifies the specimen as a new stem kestrel. The phylogeny shows a high degree of congruence with published molecular phylogenies and time trees supporting a Miocene radiation of Falconidae. The species provides a new calibration for the divergence of extant kestrels from other Falco. Remains of a small mammal, a jerboa (Dipodidae), are preserved in the abdominal region of the specimen. Integrated with data from other avian remains from the Linxia Basin, the new fossil provides further support for changes in the open steppe environment of Central Asia since the Late Miocene. Changes in falconid ecology and diet, shifts in small-mammal abundances, as well as the extinction of the Central Asian ostrich may be involved in community turnover in the Late Neogene.
Preface 1. Introduction: why study fossil horses? 2. A renaissance in paleontology 3. Orthogenesis and scientific thought: old notions die hard 4. Collections, museums, and exceptional discoveries 5. Systematics and phylogeny: Ungulata, Perissodactyla, and Equidae 6. Isotopes, magnetic reversals, fossils, and geological time 7. Ancient geography, changing climates, dispersal, and vicariance 8. Evolutionary processes: Variation, speciation, and extinction 9. Rates of morphological and taxonomic evolution 10. Trends, laws, direction, and progress in evolution 11. What's the use? functional morphology of feeding and locomotion 12. Population dynamics, behavioral ecology, and 'paleoethology' 13. Fifty-eight million years of community evolution 14. Epilogue: summary and perspective Appendix References Subject index Taxonomic index.
Stable isotopes in horse teeth from the North American Great Plains show that equids began to incorporate C4 plants in their diets about 6.5 million years ago as C4 grasslands expanded. However, the ecological response of many other ungulates to this expansion is poorly documented. We use stable carbon isotopes in mammalian tooth enamel to test whether other ungulates adapted by incorporating C4 vegetation in their diets. The openness of habitats before the expansion of C4 grasslands is uncertain, with plant phytolith studies suggesting a patchy environment with open-habitat grasses and forest, and pollen and macrofloral studies suggesting more forested habitats. To address this problem we use a model that predicts carbon isotope values for tooth enamel for a variety of environments, based on values in modern plants. Carbon and oxygen isotopes were analyzed in medium to large herbivores from three late Miocene and three Pliocene local faunas comprising a total of 13 and 7 genera, respectively, and 59 and 42 individuals. Results indicate that before the expansion of C4 grasslands, taxa with high-crowned teeth were consuming predominantly C3 vegetation. In contrast, by the late Pliocene most taxa studied were consuming a component of C4 vegetation and only the peccary Platygonus sp. had a pure C3 diet. C4 consumption increased in the late Pliocene (~ 3.0 Ma) Big Springs local fauna probably in response to increased C4 biomass. Most landscapes in the late Miocene of Nebraska were open, such as woodland-savanna or C3 grassland, although low carbon values from the Pratt Slide local fauna suggest a denser, presumably forested area. This general pattern suggests an expansion of open-habitats no later than 12 Ma (early Clarendonian). Through the Miocene-Pliocene transition there was an overall shift to lower δ18O enamel values, which parallels the long-term decrease in global mean annual temperature inferred from the marine record. Our results indicate that major changes in the diets of medium and large herbivores broadly corresponded with increased C4 biomass and cooling climate from the latest Miocene to the late Pliocene.
Wetmore (1943) described two new species of Miocene Accipitridae, a new species of Neophrontops, N. vetustus, and a new genus and species, Palaeastur atavus, based on specimens provided by Harold J. Cook, from Cook's personal collection, indicated by the prefix HC. Wetmore noted that the Neophrontops specimen, HC691, a distal end of a right humerus, was said to have been collected from 'Stonehouse Draw Quarry', Sioux County, Nebraska, USA. The specimen was collected by Cook in March 1938, at which time the only major quarry in Stonehouse Draw was Thomson Quarry (as figured in Skinner et al. 1977: Fig. 2). Other quarries in Stonehouse Draw include the North Thomson Quarry (a direct extension of Thomson Quarry) and Target Quarry at the head of the draw, which was discovered in 1947 and so cannot be the source of Wetmore's specimen. Likewise, Buck Quarry in East Stonehouse Draw was not discovered until 1941 so it too cannot be the site of collection. Thomson Quarry is in the middle Sheep Creek Formation (Skinner et al. 1977), which dates to the late Hemingfordian North American Land Mammal Age, c.16.5 Ma. The best age estimate for HC691 is 16.4 + 0.07 Ma (Tedford et al. 2004: 220) based on an orthoclase from the Sheep Creek #3 Ash, the most reliably dated of the four Sheep Creek ashes. Thomson Quarry is not far below this ash, so the fauna is slightly older than the 16.4 Ma date. The specimen of Palaeastur, HC693, a distal end of a right tarsometatarsus, was collected at the Stenomylus Quarry (also known as the Amherst Quarry), Sioux County, Nebraska. The Stenomylus Quarry is in the Harrison Formation, which dates to the late Arikareean North American Land Mammal Age, c.23 Ma. The age of the quarry is based on a 22.9 Ma date for the Agate Ash from the argon 40 /argon 39 in sanidine (Izett & Obradovich 2001).
Vultures comprise two geographically isolated and taxonomically distinct groups, Old World accipitrids and New World vulturids, and provide a classic case of convergent evolution. In both regions, several species of vultures often feed together in large numbers on carcasses. Behavioral studies of East African and Amazonian vultures have documented parallels in apparent ecological separation within this guild of specialized scavengers. Here morphological differences in skull, beak, and manibular dimensions are compared among sympatric vultures in East Africa, South Africa, the Indian subcontinent, Amazonia, and the Pleistocene Rancho La Brea deposits in California. A discriminant function analysis based on morphological indices separates three basic feeding types: rippers, gulpers, and scrappers. Vultures of the three feeding types are present in both Pleistocene and Recent assemblages and show a similar distribution of body sizes into three size classes, suggesting that competition has favored similar pathways of ecological separation. This is true even when phylogenetic differences among some of the assemblages are partially accounted for. Comparisons between the fossil and extant New World vultures indicate that more specialized species were prone to extinction and that there has been a reduction in body size since the Pleistocene.
The avian family Accipitridae has historically been divided into subfamilies or tribes based on features such as general resemblance, feeding ecology, and behavior. Consequently, the monophyly of those groups has been questionable. Recently, three phylogenetic analyses of a majority of the genera have appeared, one based on osteology, one on DNA sequences from a single mitochondrial gene, and the third on mitochondrial plus nuclear DNA sequences, and the resulting phylogenies were in substantial disagreement concerning the composition and basal branching patterns of the clades and hence require further analysis and confirmation. Here we use DNA sequences from the large nuclear RAG-1 exon to investigate the phylogenetic relationships of these birds. Our results largely corroborated the prior study that included nuclear genes. We found strong support for a monophyletic clade comprising the secretarybird Sagittarius serpentarius, the osprey Pandion haliaetus, and the traditional accipitrids. However, every one of the traditionally recognized subfamilies of accipitrids was found to be polyphyletic. The most basal nodes in the phylogeny separate small clades of insectivorous and scavenger species, such as kites and Old World vultures, from the rest of the family. The speciose genera of bird and mammal predators are all relatively derived (terminal) in the phylogeny. Many of the basal clades are cosmopolitan in their distributions, consistent with the great mobility of these raptors. A new classification is proposed that eliminates the problem of polyphyletic intrafamilial taxa.
Consensus is elusive regarding the phylogenetic relationships among neornithine (crown clade) birds. The ongoing debate over their deep divergences is despite recent increases in available molecular sequence data and the publication of several larger morphological data sets. In the present study, the phylogenetic relationships among 43 neornithine higher taxa are addressed using a data set of 148 osteological and soft tissue characters, which is one of the largest to date. The Mesozoic non-neornithine birds Apsaravis, Hesperornis, and Ichthyornis are used as outgroup taxa for this analysis. Thus, for the first time, a broad array of morphological characters (including both cranial and postcranial characters) are analyzed for an ingroup densely sampling Neornithes, with crown clade outgroups used to polarize these characters. The strict consensus cladogram of two most parsimonious trees resultant from 1000 replicate heuristic searches (random stepwise addition, tree-bisection-reconnection) recovered several previously identified clades; the at-one-time contentious clades Galloanseres (waterfowl, fowl, and allies) and Palaeognathae were supported. Most notably, our analysis recovered monophyly of Neoaves, i.e., all neognathous birds to the exclusion of the Galloanseres, although this clade was weakly supported. The recently proposed sister taxon relationship between Steatornithidae (oilbird) and Trogonidae (trogons) was recovered. The traditional taxon “Falconiformes” (Cathartidae, Sagittariidae, Accipitridae, and Falconidae) was not found to be monophyletic, as Strigiformes (owls) are placed as the sister taxon of (Falconidae + Accipitridae). Monophyly of the traditional “Gruiformes” (cranes and allies) and ”Ciconiiformes” (storks and allies) was also not recovered. The primary analysis resulted in support for a sister group relationship between Gaviidae (loons) and Podicipedidae (grebes)—foot-propelled diving birds that share many features of the pelvis and hind limb. Exclusion of Gaviidae and reanalysis of the data set, however, recovered the sister group relationship between Phoenicopteridae (flamingos) and grebes recently proposed from molecular sequence data.
We have documented elsewhere, and briefly reviewed here, the anomalously high species richness of browsing ungulates (hoofed mammals) in the mid Miocene (∼18–12 Ma) woodland savanna habitats of North America. In the mid Miocene these habitats supported substantially more brachydont (browsing) species than do any present-day savanna habitats. We present some preliminary data to show that such species-rich browser communities are not observed after the mid Miocene. The data also suggest that these mid Miocene browser communities and their subsequent disappearance may have been a global phenomenon. We then focus on possible explanations for these observations. We discuss the possibility that the high species numbers are a preservational artifact, and conclude that taphonomic factors are unlikely to be responsible for the level of species richness observed. We then consider various possible explanations for high species richness, including the unique aspects of climatic change (cooling, drying, increased seasonality), unique biotic interactions (the effects of competition, keystone herbivores, changes in predator pressure), and consider that none of these are fully consistent with the available data. The most likely explanation for the observed species-rich browser palaeocommunities is an elevated level of primary productivity, relative to the present day, within (at least some) mid Miocene grassland habitats. Such an increase in productivity could possibly have been the result of higher-than-present levels of atmospheric carbon dioxide in the mid Miocene, but this conflicts with current interpretations of geochemical evidence, and a satisfactory mechanism for the inferred increased primary productivity is an unresolved issue.
We use the carbon and oxygen isotopic compositions of fossil tooth enamel and paleosols to reconstruct the late Cenozoic history of vegetation and environmental change in the Linxia Basin at the northeastern margin of the Tibetan Plateau. The δ13C values of fossil enamel from a diverse group of herbivores and of paleosol carbonate and organic matter indicate that C4 grasses were either absent or insignificant in the Linxia Basin prior to ∼2–3 Ma and only became a significant component of local ecosystems in the Quaternary. This is in striking contrast to what was observed in Pakistan, Nepal, Africa and the Americas where C4 plants expanded rapidly in the late Miocene as indicated by a positive δ13C shift in mammalian tooth enamel and paleosols. The δ18O results from the same herbivore species show several significant shifts in climate in the late Cenozoic. Most notably, a positive δ18O shift after ∼7 Ma indicates a shift to warmer and/or drier conditions and is comparable in timing and direction to the δ18O shift observed in paleosol carbonates in Pakistan and Nepal. This late Miocene climate change observed in the Indian sub-continent and in the Linxia Basin, however, seems to be a regional manifestation of a global climate change. The lack of evidence for C4 plants in the Linxia Basin prior to ∼2–3 Ma suggests that the East Asian summer monsoon, which brings precipitation into northern China during the summer and creates optimal conditions for the growth of C4 grasses, was probably not strong enough to affect this part of China throughout much of the Neogene. This implies that the Himalayan-Tibetan Plateau may not have reached the present-day elevation across its vast extent to support a strong East Asian monsoon system before ∼2–3 Ma. Our data also suggest that regional climatic conditions played an important role in controlling the expansion of C4 plants.
Clarendonian (12 Ma) fossil soils, plants, molluscs, fish, and mammals of eastern Oregon allow reconstruction of late Miocene paleogeography, paleoclimate, and paleoecology on land between the global thermal maximum of the middle Miocene (16 Ma) and global cooling and drying of the late Miocene (7 Ma). Six different pedotypes of paleosols recognized near Unity and Juntura allow reinterpretation of local mammalian paleoecology. Fossil beavers dominated gleyed Entisols of riparian forest. Abundant camels and common hipparionine horses dominated Alfisols of wooded grassland and grassy woodland. Diatomites overlying mammal-bearing beds have bullhead catfish [Ictalurus (Ameiurus) vespertinus], as well as fossil leaves dominated by live oak (Quercus pollardiana). Fossil plants and soils of Unity and Juntura are most like those of grassy live oak woodland and savanna on the western slopes of the Sierra Nevada in northern California today. Fossil plants and soils indicate mean annual temperature of 12.9 (7.7–17.7) °C and mean annual precipitation of 879 (604–1098) mm. Miocene paleoclimatic changes in eastern Oregon show no relationship to changes in oxygen isotopic composition of marine foraminifera, usually taken as an index of global paleoclimatic change. Mismatch between land and sea paleoclimatic records is most likely an artefact of global ice volume perturbation of oxygen isotopic values. Instead, Miocene paleoclimatic change in eastern Oregon parallels changes in carbon isotopic composition of marine foraminifera, presumably through fluctuations in greenhouse gases.
The evolution of grasses using C4 photosynthesis and their sudden rise to ecological dominance 3 to 8 million years ago is among the most dramatic examples
of biome assembly in the geological record. A growing body of work suggests that the patterns and drivers of C4 grassland expansion were considerably more complex than originally assumed. Previous research has benefited substantially
from dialog between geologists and ecologists, but current research must now integrate fully with phylogenetics. A synthesis
of grass evolutionary biology with grassland ecosystem science will further our knowledge of the evolution of traits that
promote dominance in grassland systems and will provide a new context in which to evaluate the relative importance of C4 photosynthesis in transforming ecosystems across large regions of Earth.
The avian family Accipitridae includes 240 species and 60 genera of hawks, eagles, Old World vultures, kites, accipiters, goshawks and harriers. Phylogeny for Accipitridae has been difficult to resolve with morphological data such that non-monophyly of subfamilies and genera was suspected. This study used mitochondrial and nuclear sequence data to resolve the phylogeny for Accipitridae taxa. Extensive sampling of nominal species and genera (75% of all species and 97% of genera) identified non-monophyly for most genera and subfamilies/subgroups and some species.
Monophyly of sea eagles (Haliaeetinae), booted eagles (Aquilinae), Aegypinae Old World Vultures, goshawks (Melieraxinae) and harriers (Circinae) was supported; however, none of the kite subfamilies (Milvinae, Perninae and Elaninae), Accipiters (Accipitrinae), harpy eagles (Harpiinae) and snake eagles (Circaetinae) formed monophyletic groups. Specialized limb morphology relating to predation on cavity-nesting species shared by the gymnogene (Polyboroides typus) and the Crane Hawk (Geranospiza caerulescens) is an example of convergent evolution as the two species were not closely related.
The nominal genera Buteo, Buteogallus, Accipiter, Circaetus, Hieraaetus, Spizaetus, Aquila, Haliaeetus and Leucopternis were not monophyletic. Investigations at or within the level of species revealed non-monophyly for Hieraaetus fasciatus and H. morphnoides, supporting recognition of H. spilogaster and H. weiskeii as distinct species. Complicated and non-monophyletic relationships among the subspecies of Leucopternis albicollis and L. occidentalis require further investigation to resolve taxonomic nomenclature. Such extensive non-phylogenetic taxonomy at multiple levels emphasizes the need for major taxonomic revision within the Accipitridae.
Investigations of genetic diversity and population structure within the harpy eagle (Harpia harpyja) found moderate to high levels of genetic diversity with 417 bases of the mitochondrial control region from 66 harpy eagles. There was no evidence of complete barriers to historical gene flow, however significant genetic differentiation between harpy eagles from Central America and South America was found. Estimates of gene flow were asymmetric with the vast majority of migration in the direction from Central America into South America, suggesting that habitat reduction and fragmentation in Central America may have forced southern migration. Conservation strategies for harpy eagles should aim to maintain gene flow between southern Central America and northern South America.
The phylogeny of 11 species of Old World vultures (Aves: Accipitriformes, Aegypiinae), three species of New World vultures (Cathartidae) and theri nearest relatives within and outside the order Accipitriformes was investigated based on 1026 nucleotides of the mitochondrial cytochrome b gene. The data support the contention that New World vultures are not birds of prey, but phylogenetic information was insufficient to identify whether they are closer to storks (Ciconiidae) or to Accipitriformes. Four species of Gyps are all closely related and probably speciated within the Pleistocene. Molecular data do not support the split of 'white-backed' vultures from Gyps in a separate genus Pseudogyps. The monotypic genera of large, heavy-billed vultures, Aegypius, Torgos, Trigonoceps and Sarcogyps, are of monophyletic origin. We propose to merge Torgos with Aegypius, but retain Trigonoceps and Sarcogyps as separate genera, Sarcogyps being clearly the most primitive of the four. All four, together with Gyps and Necrosyrtes, form a monophyletic subfamily or 'core group', to which the subfamily Aegypiinae should be restricted. This group shares a more recent common ancestor with several non-vulture genera of Accipitrids, among them Buteo, Aquila, Haliaeetus and Circaetus, than it does with the two aberrent vultures Gypaetus barbatus and Neophron percnopterus. The last two are much more primitive; they seem to be each other's sister species and are closer to Pernis than to other Accipitrids. We propose separating Gypaetus and Neophron in the subfamily Gypaetinae. If the cytochrome b gene tree accurately reflects vulture phylogeny, Old World vultures are polyphyletic with the Aegypius-Gyps clade having evolved convergently to the more ancient Gypaetus and Neophron vultures. Polyphyly of Old World vultures, although in conflict with the DNA-DNA hybridization phylogeny of Sibley & Ahlquist (1990), is well supported by molecular, karyotypic, morphological and other phenotypic evidence (behaviour, voice) indicating fundamental differences between the two evolutionary lines.