The accuracy and precision of body mass estimation in non‐avian dinosaurs

Campione, Nicolás E.; Evans, David C.

doi:10.1111/brv.12638

Cited by 57 publications

(62 citation statements)

References 187 publications

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“…Body mass data were not available for most fossil taxa in our sample – especially ootaxa, i.e. fossil eggs with no associated skeletal material, for which body mass cannot be estimated (Campione and Evans 2020) – and were therefore not included in subsequent analyses. We found egg mass and body mass in modern birds (n = 57) to be highly correlated ( R 2 = 0.999, p < 0.001).…”

Section: Methodsmentioning

confidence: 99%

Shifts in eggshell thickness are related to changes in locomotor ecology in dinosaurs

Legendre

Clarke

2021

Evolution

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Birds share an array of unique characteristics among extant land vertebrates. Among these, external and microstructural characteristics of extant bird eggs have been linked to changes in reproductive strategy that arose among non‐avian theropod dinosaurs. More recently, differences in egg proportions recovered in crown birds relative to other dinosaurs were suggested as possibly linked to avian flight, but dense sampling close to its proposed origin was lacking. Here we assess the evolution of eggshell thickness in a targeted sample of 114 dinosaurs including birds, and test the relationship of eggshell thickness with potential life history correlates and locomotor mode using phylogenetic comparative methods. Only egg mass and flight are identified as significant predictors of eggshell thickness. While a high correlation between egg mass and eggshell thickness is expected, that relationship is much stronger in flying taxa, which show a significantly higher slope and lower residual variance than flightless species. This suggests stabilizing selection of eggshell thickness among theropods, as recovered for other traits in extant birds (e.g. genome size, metabolic rate). Within living birds, Eufalconimorphae present an apomorphic increase in relative eggshell thickness which remains unexplained, as few morphological synapomorphies of this clade have been identified.

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Section: Methodsmentioning

confidence: 99%

Shifts in eggshell thickness are related to changes in locomotor ecology in dinosaurs

Legendre

Clarke

2021

Evolution

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“…Considering the larger referred femur (EMF164), our estimated femur length of this individual 2,146 mm, which would confirm the limb element size of A. cooperensis close to Dr. schrani and F. dukei , but smaller than P. mayorum . Body mass estimates for these two titanosaurians vary considerably, from a minimum estimate for F. dukei of 23,601 kg to a maximum estimate for Dr. schrani of 74,487 kg ( Campione & Evans, 2020 ). This reflects the uncertainty discussed above and thus demonstrates the issues relating to body mass estimation in extremely large tetrapods.…”

Section: Discussionmentioning

confidence: 99%

“…Body mass estimation is a fraught exercise for fragmentary skeletons ( Bates et al, 2015 ; Bates et al, 2009 ; Bates et al, 2016 ; Campione & Evans, 2012 ; Campione & Evans, 2020 ; Paul, 2019 ). Recent body mass estimates of giant sauropods ( Carballido et al, 2017 ; Lacovara et al, 2014 ) using humeral and femoral circumferences ( Benson et al, 2014 ; Campione & Evans, 2012 ; Campione & Evans, 2020 ) have come under scrutiny and are shown to be implausible or inaccurate ( Bates et al, 2015 ; Otero, Carballido & Moreno, 2020 ; Paul, 2019 ). However, a recent review of these inaccuracies has suggested that the estimation methods themselves can be reconciled, albeit with reservations when dealing with particular groups of tetrapods, like giant sauropods ( Campione & Evans, 2020 ).…”

Section: Phylogenetic Assessmentmentioning

confidence: 99%

“…Recent body mass estimates of giant sauropods ( Carballido et al, 2017 ; Lacovara et al, 2014 ) using humeral and femoral circumferences ( Benson et al, 2014 ; Campione & Evans, 2012 ; Campione & Evans, 2020 ) have come under scrutiny and are shown to be implausible or inaccurate ( Bates et al, 2015 ; Otero, Carballido & Moreno, 2020 ; Paul, 2019 ). However, a recent review of these inaccuracies has suggested that the estimation methods themselves can be reconciled, albeit with reservations when dealing with particular groups of tetrapods, like giant sauropods ( Campione & Evans, 2020 ). Therefore, although it is tempting to produce an estimate of body mass for A. cooperensis based on the preserved and reconstructed stylopodial circumferences we consider that this will not add significant interpretative value to our main purpose of describing this taxon, and comparing it to other members of the Titanosauria from the Winton Formation and semi-contemporaneous faunas.…”

Section: Phylogenetic Assessmentmentioning

confidence: 99%

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A new giant sauropod,Australotitan cooperensisgen. et sp. nov., from the mid-Cretaceous of Australia

Hocknull

Wilkinson

Lawrence

et al. 2021

PeerJ

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A new giant sauropod, Australotitan cooperensis gen. et sp. nov., represents the first record of dinosaurs from the southern-central Winton Formation of the Eromanga Basin, Australia. We estimate the type locality to be 270–300 m from the base of the Winton Formation and compare this to the semi-contemporaneous sauropod taxa, Diamantinasaurus matildae Hocknull et al., 2009, Wintonotitan wattsi Hocknull et al., 2009 and Savannasaurus elliottorum Poropat et al., 2016. The new titanosaurian is the largest dinosaur from Australia as represented by osteological remains and based on limb-size comparisons it reached a size similar to that of the giant titanosaurians from South America. Using 3-D surface scan models we compare features of the appendicular skeleton that differentiate Australotitan cooperensis gen. et sp. nov. as a new taxon. A key limitation to the study of sauropods is the inability to easily and directly compare specimens. Therefore, 3-D cybertypes have become a more standard way to undertake direct comparative assessments. Uncoloured, low resolution, and uncharacterized 3-D surface models can lead to misinterpretations, in particular identification of pre-, syn- and post-depositional distortion. We propose a method for identifying, documenting and illustrating these distortions directly onto the 3-D geometric surface of the models using a colour reference scheme. This new method is repeatable for researchers when observing and documenting specimens including taphonomic alterations and geometric differences. A detailed comparative and preliminary computational phylogenetic assessment supports a shared ancestry for all four Winton Formation taxa, albeit with limited statistical support. Palaeobiogeographical interpretations from these resultant phylogenetic hypotheses remain equivocal due to contrary Asian and South American relationships with the Australian taxa. Temporal and palaeoenvironmental differences between the northern and southern-central sauropod locations are considered to explain the taxonomic and morphological diversity of sauropods from the Winton Formation. Interpretations for this diversity are explored, including an eco-morphocline and/or chronocline across newly developed terrestrial environments as the basin fills.

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“…(2). As estimating body mass in extinct species is always contentious [79][80][81][82] , the first of these equations may seem more practical to estimate the actual head posture of a given extinct ungulate species. In both cases, the variance of the residuals is high, which might indicate a low predictive power of these models (R 2 equals 0.26 and 0.33, respectively).…”

Section: Lsc Orientation Is Correlated With Head Posture But Is Not mentioning

confidence: 99%

A test of the lateral semicircular canal correlation to head posture, diet and other biological traits in “ungulate” mammals

Benoît

Legendre

Farke³

et al. 2020

Sci Rep

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For over a century, researchers have assumed that the plane of the lateral semicircular canal of the inner ear lies parallel to the horizon when the head is at rest, and used this assumption to reconstruct head posture in extinct species. Although this hypothesis has been repeatedly questioned, it has never been tested on a large sample size and at a broad taxonomic scale in mammals. This study presents a comprehensive test of this hypothesis in over one hundred “ungulate” species. Using CT scanning and manual segmentation, the orientation of the skull was reconstructed as if the lateral semicircular canal of the bony labyrinth was aligned horizontally. This reconstructed cranial orientation was statistically compared to the actual head posture of the corresponding species using a dataset of 10,000 photographs and phylogenetic regression analysis. A statistically significant correlation between the reconstructed cranial orientation and head posture is found, although the plane of the lateral semicircular canal departs significantly from horizontal. We thus caution against the use of the lateral semicircular canal as a proxy to infer precisely the horizontal plane on dry skulls and in extinct species. Diet (browsing or grazing) and head-butting behaviour are significantly correlated to the orientation of the lateral semicircular canal, but not to the actual head posture. Head posture and the orientation of the lateral semicircular canal are both strongly correlated with phylogenetic history.

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The accuracy and precision of body mass estimation in non‐avian dinosaurs

Cited by 57 publications

References 187 publications

Shifts in eggshell thickness are related to changes in locomotor ecology in dinosaurs

Shifts in eggshell thickness are related to changes in locomotor ecology in dinosaurs

A new giant sauropod,Australotitan cooperensisgen. et sp. nov., from the mid-Cretaceous of Australia

A test of the lateral semicircular canal correlation to head posture, diet and other biological traits in “ungulate” mammals

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