Sinking a giant: quantitative macroevolutionary comparative methods debunk qualitative assumptions

Fabbri, Matteo; Navalón, Guillermo; Benson, Roger; Pol, Diego; O’Connor, Jingmai K.; Bhullar, Bhart‐Anjan S.; Erickson, Gregory M.; Norell, Mark A.; Orkney, Andrew; Lamanna, Matthew C.; Zouhri, Samir; Becker, Justine; Sasso, Cristiano Dal; Bindellini, Gabriele; Maganuco, Simone; Auditore, Marco; Ibrahim, Nizar

doi:10.1101/2022.05.05.490811

Cited by 5 publications

(18 citation statements)

References 12 publications

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“…Color variations prevent proper evaluation of many thin sections, including those examined here, without stereoscopic or at least magnified examination. Our examination of the Suchomimus section in the original high-resolution images found clear evidence of differentially distributed cancellous bone invading the medullary cavity, especially in the lower two thinsection quadrants (Fig 11A and inset), contrary to Fabbri et al [16]. We differentiated cancellous bone from adjacent dark-stained mineral deposits under stereoscopic magnification of the thin section (Fig 11B).…”

Section: Plos Onementioning

confidence: 64%

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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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Section: Plos Onementioning

confidence: 64%

“…Although this CT-based femoral section (Fig 7A ) was not available to Fabbri et al for their initial analysis [15], they later reported its Cg as 0.941 [16] but did not present the binarized image that was used for Cg measurement. We are unable to replicate that value, even…”

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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show abstract

“…Fabbri et al . responded that the term “subaqueous foraging” meant habitual “subaqueous submersion” [ 16 ],…”

Section: Resultsmentioning

confidence: 99%

“…The materials and methods we used in our study are best understood in the context of those employed by Fabbri et al ., so we first summarize the relevant datasets and methods reported in their paper and a subsequent preprint [ 15 , 16 ].…”

Section: Methodsmentioning

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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“…Indeed, despite their apparent ties to water, spinosaurid specimens are known from several semi‐arid or arid palaeoenvironments (Amiot et al, 2010b ; Ruiz‐Omeñaca et al, 2005 ), and direct evidence indicates that small dinosaurs and pterosaurs, in addition to fish, were consumed (Buffetaut et al, 2004 ; Charig & Milner, 1997 ). Spinosaurines may well have exhibited increased aquatic specialisation (in some respects) relative to baryonychines, but the degree to which they were adapted to water, and how this adaptation was reflected in behaviour and ecology, remains the subject of ongoing research and controversy (Arden et al, 2019 ; Barker et al, 2017 ; Fabbri et al, 2022a , 2022b ; Henderson, 2018 ; Hone & Holtz Jr, 2019 , 2021 ; Ibrahim et al, 2014 , 2020 ; Myhrvold et al, 2022 ; Sereno et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Modified skulls but conservative brains? The palaeoneurology and endocranial anatomy of baryonychine dinosaurs (Theropoda: Spinosauridae)

et al. 2023

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The digital reconstruction of neurocranial endocasts has elucidated the gross brain structure and potential ecological attributes of many fossil taxa, including Irritator, a spinosaurine spinosaurid from the "mid" Cretaceous (Aptian) of Brazil. With unexceptional hearing capabilities, this taxon was inferred to integrate rapid and controlled pitch-down movements of the head that perhaps aided in the predation of small and agile prey such as fish. However, the neuroanatomy of baryonychine spinosaurids remains to be described, and potentially informs on the condition of early spinosaurids.Using micro-computed tomographic scanning (μCT), we reconstruct the braincase endocasts of Baryonyx walkeri and Ceratosuchops inferodios from the Wealden Supergroup (Lower Cretaceous) of England. We show that the gross endocranial morphology is similar to other non-maniraptoriform theropods, and corroborates previous observations of overall endocranial conservatism amongst more basal theropods. Several differences of unknown taxonomic utility are noted between the pair. Baryonychine neurosensory capabilities include low-frequency hearing and unexceptional olfaction, whilst the differing morphology of the floccular lobe tentatively suggests less developed gaze stabilisation mechanisms relative to spinosaurines. Given the morphological similarities observed with other basal tetanurans, baryonychines likely possessed comparable behavioural sophistication, suggesting that the transition from terrestrial hypercarnivorous ancestors to semi-aquatic "generalists" during the | 1125 BARKER et al.

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Sinking a giant: quantitative macroevolutionary comparative methods debunk qualitative assumptions

Cited by 5 publications

References 12 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

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

Modified skulls but conservative brains? The palaeoneurology and endocranial anatomy of baryonychine dinosaurs (Theropoda: Spinosauridae)

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