Cenozoic Birds Research Articles

A roller-like bird (Coracii) from the Early Eocene of Denmark.

The fossil record of crown group birds (Neornithes) prior to the Cretaceous-Paleogene boundary is scarce and fragmentary. Early Cenozoic bird fossils are more abundant, but are typically disarticulated and/or flattened. Here we report the oldest roller (Coracii), Septencoracias morsensis gen. et sp. nov. (Primobucconidae), based on a new specimen from the Early Eocene (about 54 million years ago) Fur Formation of Denmark. The new fossil is a nearly complete, three-dimensionally preserved and articulated skeleton. It lies at the lower end of the size range for extant rollers. Salient diagnostic features of Septencoracias relative to other Coracii include the proportionally larger skull and the small, ovoid and dorsally positioned narial openings. Our discovery adds to the evidence that the Coracii had a widespread northern hemisphere distribution in the Eocene. Septencoracias is the oldest substantial record of the Picocoraciae and provides a reliable calibration point for molecular phylogenetic studies.

Systematic and taphonomic insights of fossilized feathers: A new occurrence from the Oligocene of Taubaté Basin (SE, Brazil)

Feathers are rare in the fossil record because they have a low fossilization potential. Despite their palaeobiological significance, they also provide important palaeoecological and taphonomic information. Here, we report a new occurrence of three isolated feathers from the shales of the Oligocene Tremembé Formation (Taubaté Basin, SE Brazil). Their possible taxonomic affinities and taphonomic features are also discussed. Analyses identified the specimens as representatives of two pennaceous morphotypes (i.e., a contour and a rectrice feather). Both are preserved as carbonized traces, although, due taphonomic processes, they show different degrees of preservation. Since the Tremembé Formation is responsible for the most diverse record of Cenozoic birds, and because water-adapted birds (e.g., anseriformes and phoenicopteriformes) occur in this unit, it is highly possible that these feathers belonged to these aquatic taxa. Further investigations should concentrate on geochemical and microscopic techniques in order to reveal additional taxonomic and paleoecological features currently unknown in Paleogene birds of Brazil.

Fragmentary but distinctive: three new avian species from the early Eocene of Messel, with the earliest record of medullary bone in a Cenozoic bird

Fragmentary but distinctive: three new avian species from the early Eocene of Messel, with the earliest record of medullary bone in a Cenozoic bird

Egg shape changes at the theropod–bird transition, and a morphometric study of amniote eggs

The eggs of amniotes exhibit a remarkable variety of shapes, from spherical to elongate and from symmetrical to asymmetrical. We examine eggshell geometry in a diverse sample of fossil and living amniotes using geometric morphometrics and linear measurements. Our goal is to quantify patterns of morphospace occupation and shape variation in the eggs of recent through to Mesozoic birds (neornithe plus non-neornithe avialans), as well as in eggs attributed to non-avialan theropods. In most amniotes, eggs show significant deviation from sphericity, but departure from symmetry around the equatorial axis is mostly confined to theropods and birds. Mesozoic bird eggs differ significantly from extant bird eggs, but extinct Cenozoic bird eggs do not. This suggests that the range of egg shapes in extant birds had already been attained in the Cenozoic. We conclude with a discussion of possible biological factors imparting variation to egg shapes during their formation in the oviduct.

Cranial and vertebral morphology of the straight-billed Miocene phoenicopteriform bird Palaelodus and its evolutionary significance

Palaelodidae are the extinct sister taxon of flamingos (Phoenicopteridae). These Cenozoic birds are of significance for an understanding of flamingo evolution, because they have a short and straight beak and exhibit swimming adaptations, thus possibly bridging the morphological gap between flamingos and their closest extant relatives, the grebes (Podicipedidae). Palaelodus bones are very abundant in some fossil localities, but critical osteological details remained unknown, and for the first time more detailed descriptions of the neurocranium, quadrate, mandible, vertebrae, and pedal phalanges are given in the present study. Although the postcranial osteology of Palaelodus closely resembles that of extant flamingos, the skull is utterly different. The morphology of the mandible casts some doubt on previous assumptions that Palaelodus already evolved a filter feeding apparatus. The shape of the pedal phalanges supports swimming habits and differences in the vertebral column are described, which suggest a different feeding position than in extant flamingos. Derived features are identified, which are shared by flamingos, grebes, and some “gruiform” taxa, and which may constrain the candidate taxa for the closest extant relatives of flamingos and grebes.

A Late Pliocene occurrence of the Thick-billed Murre (Alcidae: Uria lomvia) on St. George Island, Pribilofs, Alaska

An associated partial skeleton from the Late Pliocene (3.0–2.6 million years) of St. George Island, Pribilofs, Alaska, is identified as the modern Thick-billed Murre (Uria lomvia). This is the oldest occurrence of either modern species of Uria and probably the oldest Cenozoic bird yet known from Alaska. A split between the two modern species of >3 million years is in accordance with divergence times derived from DNA sequences.

A Strigogyps-like bird from the middle Paleocene of China with an unusual grasping foot

ABSTRACT We describe a new avian species, Qianshanornis rapax, gen. et sp. nov., from the middle Paleocene Wanghudun Formation of the Qianshan Basin in Anhui Province, China. The holotype consists of an incomplete articulated foot and a few associated bones, mainly of the leg, wing, and pectoral girdle. Qianshanornis rapax is characterized by a derived foot morphology and may have had a hyperextendible second toe, which has so far only been reported for some Mesozoic taxa. The new species is markedly different from all other known Cenozoic birds and is here classified in the new taxon Qianshanornithidae. The leg bones, especially the distal end of the tibiotarsus, most closely resemble those of Strigogyps (Ameghinornithidae) from the Eocene, and possibly Oligocene, of Europe, but unlike the latter, the much smaller Q. rapax appears to have had well-developed flight capabilities.

First Record of Cenozoic Bird Footprints from East Asia (Tibet, China)

Cenozoic bird tracks are known largely from North America, Europe, and the Middle East. There have been no reports of Cenozoic bird tracks from East Asia. This paper describes a series of two trackways produced by a galliform-like or gruiform-like bird from the Oligocene to Early Miocene of Tibet. The tracks are represented by tracings collected from a coal mine in Shigatse, Tibet, during the late 1970s. The tracks are comparable to Ornithoformipes and Pavoformipes and likely represent a medium-sized to large cursorial or flightless bird. In relation to modern bird tracks, the tracks bear a striking resemblance to those produced by the North American Wild Turkey (Meleagris gallopavo) except that M. gallopavo tracks often possess a small, elevated hallux impression. Due to the fact that these are tracings, however, a hallux may have been present and simply have been overlooked. The Shigatse trackways were, unfortunately, lost when the mine was closed and then backfilled during the 1980s, and there is little to no likelihood of recovery. Casts can be catalogued as holotype specimens but tracings cannot; however, all the original tracings have been donated to a public institution by their discoverer, Yimin Wu.

An overview of the dinosaur fossil record from Chile

Abstract In Chile, the record of dinosaurs in Jurassic and Cretaceous sediments is often restricted to footprints, with few skeletal remains. Tetanuran theropods are known in the Upper Jurassic, and bones of titanosaur sauropods in the Late Cretaceous, including partial skeletons (e.g. Atacamatitan chilensis Kellner et al.). Also from the late Cretaceous, an ornithopod vertebra, a pair of theropod teeth and one tarsometatarsus of a gaviiform bird ( Neogaeornis wetzeli Lambrecht) have been reported. The Cenozoic fossil record comprises abundant and well-preserved marine birds from Eocene and Miocene units, with a specially abundant record of Sphenisciformes and less frequently, Procellariiformes. There is an excellent Miocene–Pliocene record of other birds such as Odontopterygiformes, including the most complete skeleton ever found of a pelagornithid, Pelagornis chilensis Mayr and Rubilar-Rogers. Fossil birds are also known from Pliocene and Pleistocene strata. A remarkable collection of birds was discovered in lacustrine sediments of late Pleistocene age associated to human activity. The perspectives in the study of dinosaurs in Chile are promising because plenty of material stored in institutional collections is not described yet. The record of Chilean dinosaurs is relevant for understanding the dynamics and evolution of this group of terrestrial animals in the western edge of Gondwana, while Cenozoic birds from the Region may contribute to the understanding of current biogeography for instance, the effect of the emergence and establishment of the Humboldt Current.

Earliest zygodactyl bird feet: evidence from Early Cretaceous roadrunner-like tracks

Fossil footprints are important in understanding Cretaceous avian diversity because they constitute evidence of paleodiversity and paleoecology that is not always apparent from skeletal remains. Early Cretaceous bird tracks have demonstrated the existence of wading birds in East Asia, but some pedal morphotypes, such as zygodactyly, common in modern and earlier Cenozoic birds (Neornithes) were unknown in the Cretaceous. We, herein, discuss the implications of a recently reported, Early Cretaceous (120-110 million years old) trackway of a large, zygodactyl bird from China that predates skeletal evidence of this foot morphology by at least 50 million years and includes the only known fossil zygodactyl footprints. The tracks demonstrate the existence of a Cretaceous bird not currently represented in the body fossil record that occupied a roadrunner (Geococcyx)-like niche, indicating a previously unknown degree of Cretaceous avian morphological and behavioral diversity that presaged later Cenozoic patterns.

Paleornithology of China: A general review

Study of fossil birds in China was first conducted by western scholars in last century, and extensive study of Cenozoic birds by Chinese scholars since the 1970s. However, it is the finding of Mesozoic birds, mostly from northeast China since the 1990s, that has become the focus and highlight of paleornithology of China. Enantiornithine birds from the Late Jurassic-Early Cretaceous of China provide the most complete record of the early evolution of this extinct group. The co-existence of the most primitive ornithurine bird Liaoningornis with the oldest known Confuciusornis indicates an earlier and more significant diversification of birds than previously recognized. Evidence from the Chinese Mesozoic birds seems to support the arboreal hypothesis of the origin of avian flight. Despite the controversy, the recent discovery of various feathered dinosaurs in China may provide the most compelling evidence for the hypothesis of the dinosaurian origin of birds.

Late Cenozoic birds of Buenos Aires province (Argentina): an attempt to document quantitative faunal changes

An analysis of quantitative evolution of the late Cenozoic bird communities of Buenos Aires Province (Argentina) indicates that there is a general tendency for taxonomic diversity to increase from the Huayquerian to the Montehermosan, to peak in the Chapadmalalan, to decrease in the Uquian, and to increase steadily from the Ensenadan to the Recent. It can be inferred from the results of faunal turnover that the present compositional patterns at the familial and generic levels were already established by the Montehermosan and post-Chapadmalalan times respectively. Likewise, extant species of birds are post-Ensenadan in origin. The high diversity parameters calculated from the Montehermosan may be related to stability of environmental-clinic conditions. The abrupt impoverishment in taxonomic diversity during the Chapdmalalan and the Uquian is probably correlated with an important global climatic change during the late Pliocene.

The present state of knowledge of the Cenozoic birds of Argentina

The present state of knowledge of the Cenozoic birds of Argentina