Perspectives on lung visualization: Three‐dimensional anatomical modeling of computed and micro‐computed tomographic data in comparative evolutionary morphology and medicine with applications for <scp>COVID</scp>‐19

Schachner, Emma R.; Lawson, Adam B.; Martinez, Aracely; Grand Pre, Clinton A.; Sabottke, Carl; Abou‐Issa, Farid; Echols, Scott; Diaz, Raul E.; Moore, Andrew J.; Grenier, John‐Paul; Hedrick, Brandon P.; Spieler, Bradley

doi:10.1002/ar.25300

Cited by 6 publications

(3 citation statements)

References 122 publications

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“…Integrating pneumaticity into a future study would be possible, in principle. Quantitative data on pneumaticity is available for many taxa of extant birds [ 100 ], and studies have started tracking pneumatic diverticulae via CT scans [ 103 , 104 ]. Integrating pneumaticity into a Cg -based study of the bone ballast hypothesis could be difficult in practice, however.…”

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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“…The entire alligator was scanned in a prone position, during a natural apnea, at a resolution of two mm slices (80 kVp, 60 mA). The skeleton and lungs of this individual were segmented into a surface model using Avizo 7.1 (Thermo Fisher Scientific) and followed the methods of Lawson et al (2021) and Schachner et al (2023) . The diaphragmaticus muscle and liver were then illustrated on to the model using Adobe Photoshop ( Figs.…”

Section: Methodsmentioning

confidence: 99%

Validating osteological correlates for the hepatic piston in the American alligator (Alligator mississippiensis)

Grand Pré,

Thielicke,

Diaz Jr

et al. 2023

PeerJ

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Unlike the majority of sauropsids, which breathe primarily through costal and abdominal muscle contractions, extant crocodilians have evolved the hepatic piston pump, a unique additional ventilatory mechanism powered by the diaphragmaticus muscle. This muscle originates from the bony pelvis, wrapping around the abdominal viscera, extending cranially to the liver. The liver then attaches to the caudal margin of the lungs, resulting in a sub-fusiform morphology for the entire “pulmo-hepatic-diaphragmatic” structure. When the diaphragmaticus muscle contracts during inspiration, the liver is pulled caudally, lowering pressure in the thoracolumbar cavity, and inflating the lungs. It has been established that the hepatic piston pump requires the liver to be displaced to ventilate the lungs, but it has not been determined if the lungs are freely mobile or if the pleural tissues stretch ventrally. It has been hypothesized that the lungs are able to slide craniocaudally with the liver due to the smooth internal ceiling of the thoracolumbar cavity. We assess this through ultrasound video and demonstrate quantitatively and qualitatively that the pulmonary tissues are sliding craniocaudally across the interior thoracolumbar ceiling in actively ventilating live juvenile, sub-adult, and adult individuals (n = 7) of the American alligator (Alligator mississippiensis) during both natural and induced ventilation. The hepatic piston is a novel ventilatory mechanism with a relatively unknown evolutionary history. Questions related to when and under what conditions the hepatic piston first evolved have previously been left unanswered due to a lack fossilized evidence for its presence or absence. By functionally correlating specific characters in the axial skeleton to the hepatic piston, these osteological correlates can be applied to fossil taxa to reconstruct the evolution of the hepatic piston in extinct crocodylomorph archosaurs.

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“…Integrating pneumaticity into a future study would be possible, in principle. Quantitative data on pneumaticity is available for many taxa of extant birds [100], and studies have started tracking pneumatic diverticulae via CT scans [103,104]. Integrating pneumaticity into a Cgbased study of the bone ballast hypothesis could be difficult in practice, however.…”

Section: Plos Onementioning

confidence: 99%

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

Myhrvold

Sereno

Baumgart

et al. 2023

Preprint

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Measures of bone compactness in amniote tetrapods of varying lifestyle were used to infer that two spinosaurid dinosaurs (Spinosaurus aegyptiacus, Baryonyx walkeri) were diving "subaqueous foragers," whereas a third spinosaurid (Suchomimus tenerensis) and other sampled nonavian dinosaurs were non-diving terrestrial feeders entering water only as waders. We outline shortcomings in this analysis that involve bone compactness sampling and measurement, lifestyle categorization, the inclusion and exclusion of taxa in the dataset, and flawed statistical methods and inferences. These many shortcomings undermine the evidence used to conclude that two spinosaurid taxa were avid divers. Bone compactness indices remain a valuable tool for interpretation of lifestyle in extinct species when based on sound dataset composition, robust statistical analysis, and consilience with evidence from functional, biomechanical, or paleoenvironmental considerations.

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Perspectives on lung visualization: Three‐dimensional anatomical modeling of computed and micro‐computed tomographic data in comparative evolutionary morphology and medicine with applications for COVID‐19

Cited by 6 publications

References 122 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

Validating osteological correlates for the hepatic piston in the American alligator (Alligator mississippiensis)

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

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