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

Burton, Maria Grace; Benson, Roger; Field, Daniel J.

doi:10.1098/rspb.2023.0160

Cited by 7 publications

(7 citation statements)

References 65 publications

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“…Studies of pneumaticity in birds as a correlate to lifestyle show that pneumaticity is positively correlated with body mass in flying birds; heavier birds have higher pneumaticity [ 100 ]. Pneumaticity has been lost in multiple lineages of diving birds [ 99 ].…”

Section: Resultsmentioning

confidence: 99%

Diving dinosaurs? Caveats on the use of bone compactness and pFDA for inferring lifestyle

Myhrvold,

Baumgart,

Vidal

et al. 2024

PLoS ONE

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The lifestyle of spinosaurid dinosaurs has been a topic of lively debate ever since the unveiling of important new skeletal parts for Spinosaurus aegyptiacus in 2014 and 2020. Disparate lifestyles for this taxon have been proposed in the literature; some have argued that it was semiaquatic to varying degrees, hunting fish from the margins of water bodies, or perhaps while wading or swimming on the surface; others suggest that it was a fully aquatic underwater pursuit predator. The various proposals are based on equally disparate lines of evidence. A recent study by Fabbri and coworkers sought to resolve this matter by applying the statistical method of phylogenetic flexible discriminant analysis to femur and rib bone diameters and a bone microanatomy metric called global bone compactness. From their statistical analyses of datasets based on a wide range of extant and extinct taxa, they concluded that two spinosaurid dinosaurs (S. aegyptiacus, Baryonyx walkeri) were fully submerged “subaqueous foragers,” whereas a third spinosaurid (Suchomimus tenerensis) remained a terrestrial predator. We performed a thorough reexamination of the datasets, analyses, and methodological assumptions on which those conclusions were based, which reveals substantial problems in each of these areas. In the datasets of exemplar taxa, we found unsupported categorization of taxon lifestyle, inconsistent inclusion and exclusion of taxa, and inappropriate choice of taxa and independent variables. We also explored the effects of uncontrolled sources of variation in estimates of bone compactness that arise from biological factors and measurement error. We found that the ability to draw quantitative conclusions is limited when taxa are represented by single data points with potentially large intrinsic variability. The results of our analysis of the statistical method show that it has low accuracy when applied to these datasets and that the data distributions do not meet fundamental assumptions of the method. These findings not only invalidate the conclusions of the particular analysis of Fabbri et al. but also have important implications for future quantitative uses of bone compactness and discriminant analysis in paleontology.

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Section: Resultsmentioning

confidence: 99%

Diving dinosaurs? Caveats on the use of bone compactness and pFDA for inferring lifestyle

Myhrvold,

Baumgart,

Vidal

et al. 2024

PLoS ONE

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“…among surveyed crown birds (Clarke, 2004). The degree of vertebral pneumaticity observed in Janavis is extreme, seemingly comparing with some of the most extensively pneumatised vertebrae observed among extant birds (e.g., frigatebirds), although thorough quantitative comparisons employing modern approaches for quantifying pneumaticity have yet to be applied to the skeleton of Janavis (Burton et al, 2023). The extensive pneumatisation of the vertebral column in Janavis presumably reflects an adaptation for weight reduction and flight efficiency as seen in many extant large-bodied soaring birds.…”

Section: Discussionmentioning

confidence: 99%

“…In light of this presumed selection for mass reduction, the lack of any indication of appendicular pneumaticity in Janavis is notable, suggesting that the evolutionary origin of a developmental capacity for pneumatisation of the appendicular skeleton postdates the phylogenetic divergence between Ichthyornithes and more crownward avialans. Given that pneumatisation of the appendicular skeleton appears to be plesiomorphic for crown birds (Clarke, 2004; Turner et al, 2012; Burton et al, 2023), the evolutionary acquisition of this developmental capacity must therefore have taken place along the crownward-most portion of the avian stem lineage.…”

Section: Discussionmentioning

confidence: 99%

Remarkable insights into modern bird origins from the Maastrichtian type area (north-east Belgium, south-east Netherlands)

Field,

Benito,

Werning

et al. 2024

Netherlands Journal of Geosciences

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For centuries, fossils from the Maastrichtian type locality and adjacent quarries have provided key evidence of vertebrate diversity during the latest Cretaceous, yet until recently the Maastrichtian type area had revealed no important insights into the evolutionary history of birds, one of the world’s most conspicuous groups of extant tetrapods. With the benefit of high-resolution micro-CT scanning, two important avian fossils from the Maastrichtian type area have now been examined in detail, offering profound, complementary insights into the evolutionary history of birds. The holotype specimens of these new taxa, Janavis finalidens Benito, Kuo, Widrig, Jagt and Field, 2022, and Asteriornis maastrichtensis Field, Benito, Chen, Jagt and Ksepka, 2020, were originally collected in the late 1990s, but were only investigated in detail more than twenty years later. Collectively, Janavis and Asteriornis provide some of the best evidence worldwide regarding the factors that influenced stem bird extinction and crown bird survivorship through the Cretaceous-Palaeogene transition, as well as insights into the origins of key anatomical features of birds such as an extensively pneumatised postcranial skeleton, a kinetic palate, and a toothless beak. Asteriornis also provides scarce evidence of a Cretaceous-aged divergence time calibration within the avian crown group, while together, Janavis and Asteriornis constitute the only documented co-occurrence of crown birds and non-neornithine avialans. Here, we review key insights into avian evolutionary history provided by these discoveries from the Maastrichtian stratotype, document undescribed and newly discovered Maastrichtian fossils potentially attributable to Avialae and provide the first histological data for the holotype of Asteriornis, illustrating its skeletal maturity at the time of its death.

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“…PGLS analyses were conducted using the Caper package in R (Orme et al, 2013), with a maximum likelihood estimate of Pagel's λ (Pagel, 1999). The time-scaled phylogenetic topology we used for our PGLS analyses follows Cooney et al (2017) and Prum et al (2015), as performed by Burton et al (2023). We used the y-axis residuals from these regressions to examine the relative proportions of these features.…”

Section: Methodsmentioning

confidence: 99%

Comparative morphology of the avian bony columella

Peacock

Spellman

Field

et al. 2023

The Anatomical Record

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In birds, the columella is the only bony element of the sound conducting apparatus, conveying vibrations of the cartilaginous extracolumella to the fluid of the inner ear. Although avian columellar morphology has attracted some attention over the past century, it nonetheless remains poorly described in the literature. The few existing studies mostly focus on morphological descriptions in relatively few taxa, with no taxonomically broad surveys yet published. Here we use observations of columellae from 401 extant bird species to provide a comprehensive survey of columellar morphology in a phylogenetic context. We describe the columellae of several taxa for the first time and identify derived morphologies characterizing higher‐level clades based on current phylogenies. In particular, we identify a derived columellar morphology diagnosing a major subclade of Accipitridae. Within Suliformes, we find that Fregatidae, Sulidae, and Phalacrocoracidae share a derived morphology that is absent in Anhingidae, suggesting a secondary reversal. Phylogenetically informed comparisons allow recognition of instances of homoplasy, including the distinctive bulbous columellae in suboscine passerines and taxa belonging to Eucavitaves, and bulging footplates that appear to have evolved at least twice independently in Strigiformes. We consider phylogenetic and functional factors influencing avian columellar morphology, finding that aquatic birds possess small footplates relative to columellar length, possibly related to hearing function in aquatic habitats. By contrast, the functional significance of the distinctive bulbous basal ends of the columellae of certain arboreal landbird taxa remains elusive.

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

Cited by 7 publications

References 65 publications

Diving dinosaurs? Caveats on the use of bone compactness and pFDA for inferring lifestyle

Diving dinosaurs? Caveats on the use of bone compactness and pFDA for inferring lifestyle

Remarkable insights into modern bird origins from the Maastrichtian type area (north-east Belgium, south-east Netherlands)

Comparative morphology of the avian bony columella

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