Fossil Birds Research Articles

Paleoneurology of stem palaeognaths clarifies the plesiomorphic condition of the crown bird central nervous system.

Lithornithidae, an assemblage of volant Palaeogene fossil birds, provide our clearest insights into the early evolutionary history of Palaeognathae, the clade that today includes the flightless ratites and volant tinamous. The neotype specimen of Lithornis vulturinus, from the early Eocene (approximately 53 million years ago) of Europe, includes a partial neurocranium that has never been thoroughly investigated. Here, we describe these cranial remains including the nearly complete digital endocasts of the brain and bony labyrinth. The telencephalon of Lithornis is expanded and its optic lobes are ventrally shifted, as is typical for crown birds. The foramen magnum is positioned caudally, rather than flexed ventrally as in some crown birds, with the optic lobes, cerebellum, and foramen magnum shifted further ventrally. The overall brain shape is similar to that of tinamous, the only extant clade of flying palaeognaths, suggesting that several aspects of tinamou neuroanatomy may have been evolutionarily conserved since at least the early Cenozoic. The estimated ratio of the optic lobe's surface area relative to the total brain suggests a diurnal ecology. Lithornis may provide the clearest insights to date into the neuroanatomy of the ancestral crown bird, combining an ancestrally unflexed brain with a caudally oriented connection with the spinal cord, a moderately enlarged telencephalon, and ventrally shifted, enlarged optic lobes.

Cretaceous fossil birds from China

Abstract The explosive radiation of early birds has been well documented by the extraordinary discoveries of the Early Cretaceous fossil birds in China in the past three decades. They have greatly expanded the diversity, disparity and temporal distribution of Mesozoic birds, refining our knowledge of the evolutionary path leading to the characteristic avian body plan, including feathers and powered flight, locomotion and habitat differentiation, diet and digestion, reproduction and development, feather colours and display. In addition, studies on the geological background of the Jehol Biota that produced the majority of the Chinese Cretaceous birds have provided important clues to our understanding of the taphonomy as well as the interaction between deep geological process and biological evolution in northeastern China and East Asia during the Early Cretaceous. Future multidisciplinary studies are expected to advance our knowledge of the palaeogeography of Early Cretaceous birds, what impacted the changes in the diversity of early birds in China, and the roles that early birds played in the Early Cretaceous terrestrial ecosystem.

A tiny duck (<em>Sibirionetta formozovi</em> sp. nov.), a giant grey partridge (<em>Titanoperdix felixi</em> gen. et sp. nov.), a new rail (<em>Porzana payevskyi</em> sp. nov.), and other birds from the Early Pleistocene of Baikalian Siberia

The paper describes fossil birds from the Early Pleistocene (Gelasian) of Malye Goly locality in the Baikal area of the East Siberia (Irkutsk Region, Russia). This is the first studied bird fauna from the Early Pleistocene of the Northern Asia, shedding the first light on the early Quaternary bird associations of the Siberia. A tiny fossil duck Sibirionetta formozovi sp. nov. is the first fossil representative of the modern genus Sibirionetta, the modern endemic of Eastern Siberia. This find documents the long-time (at least since the Early Pleistocene) presence of these ducks in the region. A new large pheasant-sized phasianid bird Titanoperdix felixi gen. et sp. nov. is a large-sized representative of the grey partridge evolutionary lineage (Perdicini). This find is in agreement with the fact that modern relatively small grey partridges (genus Perdix) are phylogenetically nested within the larger-bodied pheasants. Among other birds from the locality are Tadorna tadorna, three other ducks (including one diving form), Perdix cf. dauurica, Porzana payevskyi sp. nov., Podicipedidae gen. indet., Scolopacidae gen. indet., and Corvidae gen. indet. The assemblage indicates a rather productive water body with mostly open landscapes in the vicinity. The avifauna from Malye Goly does not show any considerable affinity with the Late Pliocene avian assemblages from Southern Transbaikalia and Northern Mongolia, as well as with the Early Pleistocene bird fauna of Eastern China, and thus most likely represents a separate paleornithogeographical unit. Porzana payevskyi sp. nov. is one of the oldest confirmed representatives of Porzana s.s. in the fossil record, supporting the Asian origin of the genus and a probable out-of-Asia dispersal to North America in the Early Pleistocene.

The galliform birds from the Lower Eocene London Clay of Walton-on-the-Naze (Essex, U.K.): New species suggest faunal connections to Asia

ABSTRACT We report stem group Galliformes from the lower Eocene (Ypresian) London Clay of Walton-on-the-Naze (Essex, U.K.), which are among the oldest known fossils of galliform birds. The specimens are assigned to two new species, ?Paraortygoides argillae, sp. nov. and Waltonortyx bumbanipodiides, gen. et sp. nov. The latter is classified in a new family-level taxon, Waltonortygidae, fam. nov., which differs from other higher-level clades of stem group Galliformes in a proximo-distally narrow caput humeri and a short tuberculum dorsale of the humerus. With regard to these plesiomorphic features and a characteristic morphology of the coracoid, Waltonortyx is similar to early Eocene stem group Galliformes from Mongolia. Wing and pectoral girdle bones of a third, undetermined galliform from Walton-on-the-Naze resemble the Quercymegapodiidae; this fossil also shows a similarity to early Eocene galliforms from Mongolia. The affinities of “Paraortygoides” radagasti Dyke and Gulas, 2002, the only previously described putative galliform from Walton-on-the-Naze, are uncertain and neither its classification in the Galliformes nor its assignment to the taxon Paraortygoides are unequivocally established. For the first time we subjected a larger taxonomic sample of early Paleogene Galliformes to a formal analysis, and even though the resulting phylogenies were poorly resolved, they supported paraphyly of the Quercymegapodiidae, with the Early Miocene taxon Ameripodius being more closely related to the crown group than the late Eocene species of Quercymegapodius. Waltonortyx bumbanipodiides was recovered as the sister taxon of the Mongolian Bumbanipodius transitoria, which indicates early Paleogene dispersal events across the Turgai Strait.

The first American occurrence of Phoenicopteridae fossil egg and its palaeobiogeographical and palaeoenvironmental implications

ABSTRACT Fossil bird eggs from the Pleistocene of the Americas are rare. Previous records include Uruguay, Bermuda, California (USA) and Mexico, including reports of complete fossil eggs from extinct puffin (Fratercula dowi) from California, Tinamou (Tinamidae indet.) from Uruguay, Brown Pelican (Pelecanus occidentalis) from Bermuda and Sandhill Crane (Grus canadensis) from México. The fossil record of flamingos in Mexico is restricted to palaeolakes in Central Mexico, which is very interesting because the current distribution of flamingos in North America is restricted to some areas of the Southeastern United States and Yucatan Peninsula, which are far from palaeontological sites. We report a fossil flamingo egg found during the construction of a new International Airport ‘Felipe Angeles’, Santa Lucía, State of México. This egg is the first Pleistocene fossil egg record for the family Phoenicopteridae, the first fossil egg record of this family in the Americas and the second record of a phoenicopterid fossil egg in the world. We re-identified the fossil eggs described by Martin del Campo in the 1940s, suggesting that they are also flamingo eggs. Using biogeographical and climate niche data for family Phoenicopteridae in North America, we infer the presence of a salinity and shallow palaeolake during the Late Pleistocene, with climatic condition being warmest and wetter than at present.

High-resolution sedimentological and stratigraphic framework for the Pehuen Co Paleoichnological site, late Pleistocene, Buenos Aires, Argentina

The Pehuen Co Paleoichnological site (Buenos Aires Province, Argentina) contains one of the more diverse and well-preserved mammal and bird fossil footprint assemblages from the Late Pleistocene. The purposes of this paper were a detailed paleoenvironmental assessment of the footprint-bearing unit (middle member of the Agua Blanca Sequence) and to date key stratigraphic surfaces to constraint the temporal development of the site. A total of twenty-two detailed sedimentological sections were measured and correlated and five sediment and fossil remain samples were dated by the Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR) methods, respectively. The lower part of the local sequence represents dense to dilute alluvial deposits that were pedogenized. The middle part contains an alternance of sandy sheet-flood and lacustrine mudflat deposits with sand patches of eolian origin. Most of the fossil footprints with better preservation quality were recorded in the mudflats of a shallow lake sourced by unconfined fluvial currents. The participation of eolian deposits increases up section. Locally, a sandy plain of fluvial origin is developed at the top of the section. The new OSL ages along with a previous radiocarbon date led us to propose that sedimentation of footprint-bearing levels would have extended approximately between 28.5 and 12.0 ka. Reworked marine shell remains from the lowermost levels of site with fossil footprints gave considerably older analytical ages in the range of 97.6–62.5 ka, which is probably the maximum age for the middle member of the Agua Blanca Sequence. The “marine levels of Pehuen Co”, which are exposed at very low tides and contains in situ specimens of Ophiomorpha nodosa, are dated 7.0 ± 0.4 ka (OSL method). They reflect a Middle Holocene sea level rise in the area.

The Rise and Fall of Ancient Neornithes. Paleogene Fossil Birds – 2nd Edition.

The Rise and Fall of Ancient Neornithes. Paleogene Fossil Birds – 2nd Edition.

Putative avian teeth from the Late Cretaceous of Alberta, Canada, are more likely from crocodilians.

Isolated teeth, previously referred to Aves, are more common than other bird fossils from the Late Cretaceous of Alberta. However, there are no known morphological synapomorphies that distinguish isolated bird teeth, and features of these teeth are generally shared with those of non-avian theropods and crocodilians. Here, specimens ranging from Late Santonian to Late Maastrichtian in age are described and qualitatively categorized into morphotypes, most of which strongly resemble teeth of extant juvenile and some fossil crocodilians. Variation within this sample of teeth may therefore reflect the heterodont dentition of crocodilians, rather than avian species diversity. Quantitative analysis Principal Component Analysis was mostly uninformative, with limited overlap between putative avian teeth and those of known Cretaceous birds, crocodilians, and non-avian theropods. The reassignment of these putative avian teeth to Crocodylia has important ramifications for our understanding of the evolutionary history of Cretaceous birds.

Changes in body size in some bird species from the Yucatán peninsula since the Late Pleistocene

AbstractDuring the Pleistocene, the Yucatán Peninsula reached its greatest geographic extension, with 457,650 km2, but the rise of sea level after the Last Glacial Maximum (ca. 20,000–12,000 years ago) reduced its area to 225,182 km2(50.8% reduction). These geographic extension changes likely modified the extension of different habitats throughout the peninsula, which may have also promoted morphological changes in the species that inhabit this region. Here, we tested if the reduction of the geographic size of the Yucatán Peninsula may have promoted changes in the body size of three fossil bird species and two modern bird species. We compared Late Pleistocene bird fossils specimens from Loltún, Yucatán, Mexico (ca. 28,000–11,700 ya), San Josecito Cave and Tlapacoya, and study skins of collected specimens. To assess the area‐scale ratio and to establish if body size changes occurred over time from a large to a small body size, we relied on the “island rule” as a framework; we also relied on Bergmann's rule, which postulates a decreasing in size from north to south in homeothermic species to recognize if these birds show a north to south cline. Based on body mass and measurements of the tarsometatarsi, a reliable proxy for the estimation of body size, we performed statistical analyses to test for differences between fossil and non‐fossil birds, as well as to test a gradient in body mass north to south. We found a statistically significant trend in body size changes through time, from small body sizes in fossil birds to larger body sizes in non‐fossil birds. These results suggest that relatively recent ecological factors related to the environmental carrying capacity may have promoted body size variations in birds from the Yucatán Peninsula. We also found that modern population of bird species follow Bergmann's rule.

Radial porosity profiles are a powerful tool for tracing locomotor maturation in developing limb bones.

Radial porosity profiles (RPP) are a new quantitative osteohistological parameter designed to capture the dynamic changes in the primary porosity of limb bones through ontogeny, providing insights into skeletal growth and functional development of extant and extinct vertebrates. Previous work hypothesized that RPP channelization-the intraskeletal alignment of RPPs across different bones resulting from similar cortical compaction patterns-indicates increasing locomotor performance of the developing limbs. By investigating RPPs in ontogenetic series of pheasants, pigeons and ducks representing distinct locomotor developmental strategies, we test this hypothesis here and show that RPPs are indeed powerful osteohistological correlates of locomotor ontogeny. Qualitative and quantitative analyses reveal strong association between RPP channelization and fledging, the most drastic locomotor transition in the life history of volant birds. The channelization signal is less clear in precocial leg function; however, when additional intraskeletal and intercohort RPP characteristics are considered, patterns related to leg precocity can also be identified. Thus, we demonstrate that RPPs can be used in future by palaeobiologists to generate breakthroughs in the study of the ontogeny and evolution of flight in fossil birds and pterosaurs. With further baseline data collection from modern terrestrial vertebrates, RPPs could also test hypotheses regarding ontogenetic postural shifts in dinosaurs and other terrestrial archosaurs.

Evaluation of Iranipeda abeli (Avian track) from the Zagros Mountains, SW Iran: re-examination of the original material and overview of primary sources

ABSTRACT A slab with three tetradactyl avian footprints was excavated from the Agha Jari Formation (Mio-Pliocene) in the Zagros Mountains, southwest Iran, in the early last century and named as Urmiornis abeli. The name Urmiornis had been used for the didactyl bird fossil and ichnogenus name was later revised to Iranipeda. Validity of Iranipeda abeli has been discussed by authors in recent decades, and revision of the original material is necessary. Based on re-examination the holotype I. abeli reveals that this name is valid and it differs by long hallux, separate digit imprints and size of lateral digit II and IV traces with other large wading bird footprints. Iranipeda include three ichnospecies: I. abeli and I. millumi and I. intermedia by emended diagnosis of Iranipeda. Ciconiidae is the nearest track-maker candidate for Iranipeda. I. abeli type specimen has been collected from the lower part of the Agha Jari Formation and based on lithostratigraphic position and radiometric data, it is of Late Miocene age.

New Pleistocene bird fossils in Taiwan reveal unexpected seabirds in East Asia

New Pleistocene bird fossils in Taiwan reveal unexpected seabirds in East Asia

The endocast of the insular and extinct Sylviornis neocaledoniae (Aves, Galliformes), reveals insights into its sensory specializations and its twilight ecology

Sylviornis neocaledoniae (Galliformes, Sylviornithidae), a recently extinct bird of New-Caledonia (Galliformes, Sylviornithidae) is the largest galliform that ever lived and one of the most enigmatic birds in the world. Herein, for the first time, we analyze its neuroanatomy that sheds light on its lifestyle, its brain shape and patterns being correlated to neurological functions. Using morphometric methods, we quantified the endocranial morphology of S. neocaledoniae and compared it with extinct and extant birds in order to obtain ecological and behavioral information about fossil birds. Sylviornis neocaledoniae exhibited reduced optic lobes, a condition also observed in nocturnal taxa endemic to predator-depauperate islands, such as Elephant birds. Functional interpretations suggest that S. neocaledoniae possessed a well-developed somatosensorial system and a good sense of smell in addition to its specialized visual ability for low light conditions, presumably for locating its food. We interpret these results as evidence for a crepuscular lifestyle in S. neocaledoniae.

Presentation of so far undetermined bird remains from the Upper Miocene (MN13) of Polgárdi 4 and 5 (Fejér county, West Hungary)

Abstract The authors have identified the mostly very fragmentary bird fossils from the uncatalogued material of the Hungarian Institute of Geology and Geophysics to the level that the condition of the bones allows. Almost half of the 102 bone pieces (42 fragments) could be completely or partially identified, while the rest (60 fragments represented either by bone fragments or by toe phalanges, claws, mandibles, etc.) could not be identified. The material identified includes taxa previously published and known from the site, but a good number of these are represented by other bones or parts of bones, as in previous publications (Palaeortyx phasianoides Milne-Edwards, 1869, Palaeocryptonix hungaricus Jánossy, 1991, Porzana † kretzoii Kessler, 2009, Glaucidium † baranensis Kessler, 2010, Apus † baranensis Jánossy, 1977, Lullula † minor Kessler, 2013, Delichon † polgardiensis Kessler, 2013, Riparia † major Kessler, 2013, Sitta † gracilis Kessler, 2013). The taxa identified at order, family or genus level are listed in the main text and complemented by one figure, as well as a rich bibliographic material.

Psittacopedids and zygodactylids: The diverse and species-rich psittacopasserine birds from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK)

ABSTRACT The Daniels collection of fossil birds from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK) contains multiple specimens of the Psittacopedidae and Zygodactylidae, which are here for the first time studied in detail. The Psittacopedidae include Parapsittacopes bergdahli, Psittacomimus eos, gen. et sp. nov., ?Psittacopes occidentalis, sp. nov., and at least one further unnamed species. The Zygodactylidae comprise Primozygodactylus cf. danielsi, Primoscens cf. minutus, Primoscens carolinae, sp. nov., as well as several unnamed species, which are represented by fragmentary remains. A very small zygodactylid-like species, which was previously identified as P. minutus, is described as Minutornis primoscenoides, gen. et sp. nov. A phylogenetic analysis showed the Zygodactylidae and Psittacopedidae to be stem group representatives of the Passeriformes (passerines), but the exact interrelationships of the fossil taxa are poorly resolved. In particular, no compelling character evidence supports a monophyletic Zygodactylidae, with distinctive features of these birds being likely to be plesiomorphic for Psittacopasseres or also found in crown group Passeriformes. In the majority rule consensus tree of our analysis, Minutornis is the sister taxon of a clade including the Zygodactylidae and Passeriformes, whereas the affinities of the Psittacopedidae were insufficiently resolvedhttp://zoobank.org/urn:lsid:zoobank.org:pub:81800349-5DE9-468B-81D7-6A5664526DF1.

КРЕМЕНЕЦЬКИЙ ПЕРІОД ТВОРЧОСТІ ВІДОМОГО ВЧЕНОГО ТА ПЕДАГОГА – КОСТЯНТИНА АДРІАНОВИЧА ТАТАРИНОВА

K. A. Tatarinov was a multifaceted personality, he made a significant contribution to the development of paleozoology, hunting science, ornithology and teriology in Ukraine. The article describes the main events of the Kremenets period of the scientist's life and work. The described period dates from August 1958 to August 1963. While working in Kremenets, he not only a scientist, but also develops as a manager, starting his career in August 1958 as a senior lecturer at the Department of Zoology Kremenets Pedagogical Institute, after two years - an associate professor, and since February 1961 - head of the specified department. Konstantin Adrianovych during his work at the Kremenets Pedagogical Institute, showed himself as a talented teacher with deep theoretical knowledge, hardworking and persistent scientist. Already at that time he understood the need for domestic and foreign creative scientific cooperation scientists with the aim of developing a unified program of stationary faunistic and zoogeographic studies. During the short 6 years of work at the Department of Zoology of the Kremenets Pedagogical Institute, Kostyantyn Adrianovych systematically organized annual educational field trips, worked on the creation and replenishment of the educational (museum) collection of bird and mammal skins, and conducted intensive speleozological research. At this time the scientist begins the cycle paleozoological studies, in particular the study of the fossil fauna of caves Podillia, modern and fossil vertebrate fauna of the mountain system Prykarpattia and Ukrainian Carpathians. In general, the field of scientific research in this period is very diverse from paleontology, zoogeography, zoology to phenology nature and ecology of vertebrates. During this time, he prepared and published the textbooks "Textbook of Zoology" and "Vertebrate Zoology", published a number of scientific works on fossil birds, small mammals and dolphins of Podillia (60 publications in total). Scientific results studies quite fully represent faunal diversity and faunal wealth of vertebrate animals of Kremenets and its surroundings and cover the forest massifs of the Eastern Carpathians and Hologoro-Kremenetskyi highlands, dry meadows, cave groups of mammals.
 In his pedagogical activities, he pays a lot of attention to highlighting contemporary achievements of zoology, the role of Ukrainian scientists in the study of the species and zoogeographic diversity of the vertebrate fauna of Kremenech region.

Ontogenetic changes in cortical bone vascular microstructure in the domestic duck (Anas platyrhynchos) and ring-necked pheasant (Phasianus colchicus).

Age-related changes in bone microstructure can inform our understanding the biology of both extant and fossil birds, but to date, histological work in birds, and particularly work using high-resolution 3D imaging, has largely been restricted to limited growth stages. We used minimally destructive synchrotron radiation-based X-ray computed tomography to visualise and measure key morphological and histological traits in 3D across development in the domestic duck and ring-necked pheasant. We use these measurements to build on the database of key reference material for interpreting bone histology. We found that growth patterns differed between the two species, with the ducks showing rapid growth in their lower limbs and early lower limb maturation, while pheasants grew more slowly, reflecting their later age at maturity. In the pheasant, both walking and flight occur early and their upper and lower limbs grew at similar rates. In the duck, flight and wing development are delayed until the bird is almost at full body mass. Through juvenile development, the second moment of area for the duck wing was low but increased rapidly towards the age of flight, at which point it became significantly greater than that of the lower limb, or the pheasant. On a microstructural level, both cortical porosity and canal diameter were related to cortical bone deposition rate. In terms of orientation, vascular canals in the bone cortex were more laminar in the humerus and femur compared with the tibiotarsus, and laminarity increased through juvenile development in the humerus, but not the tibiotarsus, possibly reflecting torsional vs compressive loading. These age-related changes in cortical bone vascular microstructure of the domestic duck and pheasant will help understanding the biology of both extant and fossil birds, including age estimation, growth rate and growth patterns, and limb function.

Rapid preservation of Jehol Biota in Northeast China from high precision 40Ar/39Ar geochronology

In Liaoning Province, Northeastern China, the Early Cretaceous Jehol Biota records significant evolution and radiation of fauna in terms of diversity, abundance and complexity. The alluvial-to-fluvial Lujiatun and lacustrine Jianshangou beds of the lower Yixian Formation yield exceptionally well-preserved three-dimensional and articulated dinosaur and mammal fossils, and two-dimensional primitive birds/feathered dinosaurs, respectively. Published 40Ar/39Ar ages for the two fossil beds have uncertainties of ± 0.4 to 1.0 Ma (± 2σ analytical uncertainty), and these reflect the measurement of large, and potentially heterogeneous, populations of feldspar crystals. More precise constraints on the timing and duration of biological radiation recorded by this sequence can further quantify evolutionary patterns and rates of diversification of important Early Cretaceous animals and plants. Single crystal 40Ar/39Ar fusion experiments on sanidine from intercalated ash beds yield dates that constrain the deposition of the Jianshangou and Lujiatun fossil beds to between 125.374 ± 0.085 and 125.572 ± 0.120 Ma, and 125.541 ± 0.099 and 125.793 ± 0.127 Ma, respectively. These ages indicate that the lower part of Jianshangou fossil bed was deposited nearly contemporaneously with the Lujiatun fossil bed. Thus, mass mortality events reflected by dinosaur fossil concentrations in the Lujiatun fossil bed and feathered dinosaur/primitive bird fossils in the Jianshangou fossil bed were nearly coeval and short-lived. These 40Ar/39Ar ages, combined with astrochronologic and paleomagnetic results from the lacustrine sediments in the Jianshangou fossil bed, not only refine the duration and rapid radiation of primitive birds and feathered dinosaurs in the deposit, but also suggest that the distribution of magnetic polarity chron boundaries within the Barremian stage in the current geologic time scale (GTS 2020) requires a revision.

Diet of Mesozoic toothed birds (Longipterygidae) inferred from quantitative analysis of extant avian diet proxies

BackgroundBirds are key indicator species in extant ecosystems, and thus we would expect extinct birds to provide insights into the nature of ancient ecosystems. However, many aspects of extinct bird ecology, particularly their diet, remain obscure. One group of particular interest is the bizarre toothed and long-snouted longipterygid birds. Longipterygidae is the most well-understood family of enantiornithine birds, the dominant birds of the Cretaceous period. However, as with most Mesozoic birds, their diet remains entirely speculative.ResultsTo improve our understanding of longipterygids, we investigated four proxies in extant birds to determine diagnostic traits for birds with a given diet: body mass, claw morphometrics, jaw mechanical advantage, and jaw strength via finite element analysis. Body mass of birds tended to correspond to the size of their main food source, with both carnivores and herbivores splitting into two subsets by mass: invertivores or vertivores for carnivores, and granivores + nectarivores or folivores + frugivores for herbivores. Using claw morphometrics, we successfully distinguished ground birds, non-raptorial perching birds, and raptorial birds from one another. We were unable to replicate past results isolating subtypes of raptorial behaviour. Mechanical advantage was able to distinguish herbivorous diets with particularly high values of functional indices, and so is useful for identifying these specific diets in fossil taxa, but overall did a poor job of reflecting diet. Finite element analysis effectively separated birds with hard and/or tough diets from those eating foods which are neither, though could not distinguish hard and tough diets from one another. We reconstructed each of these proxies in longipterygids as well, and after synthesising the four lines of evidence, we find all members of the family but Shengjingornis (whose diet remains inconclusive) most likely to be invertivores or generalist feeders, with raptorial behaviour likely in Longipteryx and Rapaxavis.ConclusionsThis study provides a 20% increase in quantitatively supported fossil bird diets, triples the number of diets reconstructed in enantiornithine species, and serves as an important first step in quantitatively investigating the origins of the trophic diversity of living birds. These findings are consistent with past hypotheses that Mesozoic birds occupied low trophic levels.

Fossil birds from Cooper's D aid in reconstructing the Early Pleistocene paleoenvironment in the Cradle of Humankind (Gauteng, South Africa)

Several large-bodied hominin and nonhuman primates have coexisted in the Cradle of Humankind in South Africa during the Early Pleistocene. Previous paleoenvironmental studies regarding the Plio-Pleistocene of South Africa have focused heavily on mammal assemblages. Here, we conducted a comprehensive taxonomic analysis of the fossil bird remains from Cooper's D, the most fossiliferous locality of the hominin-bearing Cooper's Cave complex in South Africa. Our taxonomic evaluation of 505 remains reveals the presence of 23 bird taxa, two of which are extinct and already reported from the nearby fossil locality of Kromdraai. The taxonomically diverse bird assemblage is dominated by Francolinus sp. and other species associated with open grassland habitats, followed by rock-dwelling species, including Tyto cf. alba and the extinct Corvus bragai, and by woodland species such as Agapornis sp., Accipiter melanoleucos, and the extinct Glaucidium ireneae. The occurrence of these taxa and their respective proportions in the assemblage, in terms of both numbers of bones and individuals, point to the presence of extensive open grassland and/or savannah with rocky outcrops and woodland. These findings corroborate previous analyses of mammals from Cooper's D, with the exception of aquatic species, which are rare in the bird assemblage. Comparison with older deposits from Kromdraai confirms the definitive establishment of open habitats in the Cradle of Humankind during the Early Pleistocene following a transition from woodier habitats during the Late Pliocene. This study constitutes a further step in investigating the fossil bird diversity in the Cradle of Humankind during the Plio-Pleistocene. Our results add to the larger body of work using avian fossils for paleoenvironmental reconstructions in Africa and support the utility of birds as paleoenvironmental proxies. Similar future studies will refine our understanding of the paleoenvironments and landscape transformation during the Plio-Pleistocene, a critical timeframe for hominin evolution in southern Africa.