Origin and Evolution of Birds

Fascinating life sciences, Journal Year: 2023, Volume and Issue: unknown, P. 1 - 154

Published: Jan. 1, 2023

Language: Английский

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The influence of soft tissue volume on estimates of skeletal pneumaticity: implications for fossil archosaurs

Philosophical Transactions of the Royal Society B Biological Sciences, Journal Year: 2025, Volume and Issue: 380(1920)

Published: Feb. 27, 2025

Air space proportion (ASP), the volume fraction in bone that is occupied by air, frequently applied as a measure for quantifying extent of skeletal pneumaticity extant and fossil archosaurs. Nonetheless, ASP estimates rely on key assumption: soft tissue mass within pneumatic bones negligible, an assumption has rarely been explicitly acknowledged or tested. Here, we provide first comparisons between estimated air (where internal cavity assumed to be completely air-filled) true (ASPt, where tissues present cavities fresh specimens are considered). Using birds model archosaurs exhibiting postcranial pneumaticity, find ASPt significantly lower than ASP, raising important consideration should investigations evolution bulk density extinct archosaurs, well volume-based archosaur body mass. We advocate difference studies seeking quantify avoid risk systematically overestimating composed air. This article part theme issue ‘The biology avian respiratory system’.

Language: Английский

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Whence the birds: 200 years of dinosaurs, avian antecedents

Biology Letters, Journal Year: 2025, Volume and Issue: 21(1)

Published: Jan. 1, 2025

Among the most revolutionary insights emerging from 200 years of research on dinosaurs is that clade Dinosauria represented by approximately 11 000 living species birds. Although origin birds among has been reviewed extensively, recent have witnessed tremendous progress in our understanding deep evolutionary origins numerous distinctive avian anatomical systems. These advances enabled exciting new fossil discoveries, leading to an ever-expanding phylogenetic framework with which pinpoint characteristic features. The present review focuses four notable systems whose Mesozoic history greatly clarified discoveries: brain, kinetic palate, pectoral girdle and postcranial skeletal pneumaticity.

Language: Английский

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Macroevolutionary drivers of morphological disparity in the avian quadrate

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2024, Volume and Issue: 291(2017)

Published: Feb. 21, 2024

In birds, the quadrate connects mandible and skull, plays an important role in cranial kinesis. Avian morphology may therefore be assumed to have been influenced by selective pressures related feeding ecology, yet large-scale variation its potential relationship with ecology never quantitatively investigated. Here, we used geometric morphometrics phylogenetic comparative methods quantify morphological of key ecological features across a wide sample. We found non-significant associations between shape different scales comparison; indeed, allometry phylogeny exhibit stronger relationships than features. show that similar shapes are associated widely varying dietary ecologies (one-to-many mapping), while divergent (many-to-one mapping). Moreover, avian evolves as integrated unit exhibits strong morphologies neighbouring bones. Our results collectively illustrate has evolved jointly other elements kinetic system, major crown bird lineages exploring alternative morphologies, highlighting diagnostic value investigations systematics.

Language: Английский

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Tip dating and Bayes factors provide insight into the divergences of crown bird clades across the end-Cretaceous mass extinction

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2024, Volume and Issue: 291(2016)

Published: Feb. 14, 2024

The origin of crown birds (Neornithes) remains contentious owing to conflicting divergence time hypotheses obtained from alternative sources data. fossil record suggests limited diversification Neornithes in the Late Mesozoic and a substantial radiation aftermath Cretaceous–Palaeogene (K–Pg) mass extinction, approximately 66 Ma. Molecular clock studies, however, have yielded estimates for neornithine origins ranging Early Cretaceous (130 Ma) less than 10 Myr before K–Pg. We use Bayes factors compare fit node ages different molecular studies an independent morphological dataset. Our results allow us reject scenarios bird deep Cretaceous, as well within last Cretaceous. scenario best supported by our analyses is one where originated between ( ca 100 Ma), while numerous divergences major neoavian clades either span or postdate This study affirms importance K–Pg on modern birds, potential combined-evidence tip-dating illuminate recalcitrant ‘rocks versus clocks’ debates.

Language: Английский

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Forty new specimens of Ichthyornis provide unprecedented insight into the postcranial morphology of crownward stem group birds

PeerJ, Journal Year: 2022, Volume and Issue: 10, P. e13919 - e13919

Published: Dec. 16, 2022

Ichthyornis has long been recognized as a pivotally important fossil taxon for understanding the latest stages of dinosaur–bird transition, but little significant new postcranial material brought to light since initial descriptions partial skeletons in 19 th Century. Here, we present information on morphology from 40 previously undescribed specimens, providing most complete morphological assessment skeleton date. The includes four partially and numerous well-preserved isolated elements, enabling anatomical observations such muscle attachments Mesozoic euornitheans. Among elements that were unknown or poorly represented , specimens include an almost-complete axial series, hypocleideum-bearing furcula, radial carpal bones, fibulae, tarsometatarsus bearing rudimentary hypotarsus, one first-known nearly three-dimensional sterna avialan. Several pedal phalanges are preserved, revealing remarkably enlarged pes presumably related foot-propelled swimming. Although diagnosable exhibit substantial degree variation, some which may relate ontogenetic changes. Phylogenetic analyses incorporating our data employing alternative datasets recover stemward Hesperornithes Iaceornis line with recent hypotheses regarding topology crownward-most portion avian stem group, establish phylogenetically-defined clade names relevant avialan subclades help facilitate consistent discourse future work. provided by these improves evolution among non-neornithine avialans immediately preceding origin crown group birds.

Language: Английский

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Direct quantification of skeletal pneumaticity illuminates ecological drivers of a key avian trait

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2023, Volume and Issue: 290(1995)

Published: March 15, 2023

Skeletal pneumaticity is a key feature of extant avian structure and biology, which first evolved among the non-flying archosaurian ancestors birds. The widespread presence air-filled bones across postcranial skeleton unique to birds living vertebrates, but true extent skeletal has never been quantitatively investigated—hindering fundamental insights into evolution this feature. Here, we use microCT scans fresh, frozen directly quantify fraction humerus volume occupied by air phylogenetically diverse taxon sample test longstanding hypotheses regarding function pneumatization. Among other insights, document weak positive allometry internal with humeral size pneumatized humeri provide strong support that size, body mass, aquatic diving, or absence all have independent effects on cortical bone thickness. Our quantitative evaluation phylogeny sheds new light ontogenetic progression an important aspect architecture, suggests last common ancestor crown possessed highly humerus.

Language: Английский

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Basal Anseriformes from the Early Paleogene of North America and Europe

Diversity, Journal Year: 2023, Volume and Issue: 15(2), P. 233 - 233

Published: Feb. 7, 2023

We describe nearly complete skeletons of basal Anseriformes from the Latest Paleocene to early Eocene North America and Europe. Collectively, these birds appear be representative anseriforms near divergence Anhimae Anseres, but their exact positions relative clades remains uncertain. A new family, Anachronornithidae nov. fam., is erected on basis one these, Anachronornis anhimops gen., gen. et sp., which others cannot confidently assigned. The fossils augment a growing collection Pan-Anseriformes, in diversity do not paint an unambiguous picture phylogeny or character state evolution path within crown-Anseriformes. similar some aspects both cranial postcranial anatomy other well-represented Paleogene members such as Presbyornis Wetmore, 1926. However, it exhibits more landfowl-like bill, like that unlike spatulate bill Anseres. Additional specimens uncertain affinities Europe further complicate interpretation polarity due mosaicism primitive derived characters they exhibit.

Language: Английский

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Taphonomic damage obfuscates interpretation of the retroarticular region of the Asteriornis mandible

Geobios, Journal Year: 2024, Volume and Issue: unknown

Published: Aug. 1, 2024

Asteriornis maastrichtensis, from the latest Cretaceous of Belgium, is among oldest known crown bird fossils, and its three-dimensionally preserved skull provides most substantial insights into cranial morphology early birds to date. Phylogenetic analyses recovered as a total-group member Galloanserae, clade uniting Galliformes Anseriformes. One important feature supporting this placement was enlargement retroarticular processes, which form elongate caudal extensions mandible in extant Galloanserae. Here, we reinterpret jaw illustrate that caudalmost portion mandibles are fact not preserved. Instead, extremities both left right mandibular rami extend surface fossil block containing holotype skull, where they have eroded away. The originally identified process – exhibits orientation strikingly similar processes certain galloanserans, including Palaeogene total-clade anseriforms Conflicto Nettapterornis instead represents twisted caudally displaced medial process. Nonetheless, anatomical comparisons with taxa reveal cannot exclude possibility exhibited robust comparable those In light reinterpreted mandible, update original character matrix used investigate phylogenetic relationships perform revised analyses, continue support galloanseran, initially interpreted. We demonstrate additional morphological traits position provide new data on nature distribution birds.

Language: Английский

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The Lithornithiformes (Aves) from the early Eocene London Clay of Walton‐on‐the‐Naze (Essex, UK)

Papers in Palaeontology, Journal Year: 2025, Volume and Issue: 11(1)

Published: Jan. 1, 2025

Abstract We describe multiple partial skeletons and isolated bones of the palaeognathous Lithornithiformes from early Eocene London Clay Walton‐on‐the‐Naze (Essex, UK). The well‐preserved specimens are assigned to at least four species taxa Lithornis Pseudocrypturus. Two identified as L. nasi cf. grandei . latter species, which was established for fossils North American Green River Formation, initially monotypic taxon Calciavis , is here considered synonymous with further new tentatively referred Pseudocrypturus described ? P. danielsi gracilipes In previous analyses, lithornithiforms most often resulted sister either Tinamiformes or all crown group Palaeognathae. detail that current morphological evidence conforms best a position these birds outside Palaeognathae discuss previously unrecognized plesiomorphic features foot pelvis, support this phylogenetic placement.

Language: Английский

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