Resizing Lisowicia bojani: volumetric body mass estimate and 3D reconstruction of the giant Late Triassic dicynodont
TL;DR: Body size is one of the most crucial biological properties, with a major influence on ecology, metabolism and several physiological aspects as discussed by the authors, and the exceptionally large dicynodont Lisowicia bo...
Abstract: Body size is one of the most crucial biological properties, with a major influence on ecology, metabolism and several physiological aspects. Recently the exceptionally large dicynodont Lisowicia bo...
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TL;DR: A comparative quantitative framework to reciprocally illuminate and corroborate VD and ES approaches to body mass estimation in stem‐group taxa is provided and indicates a strong corroboration between recent iterations of the VD approach based on 3D specimen scans suggesting that the current understanding of size in dinosaurs, and hence its biological correlates, has improved over time.
Abstract: Inferring the body mass of fossil taxa, such as non-avian dinosaurs, provides a powerful tool for interpreting physiological and ecological properties, as well as the ability to study these traits through deep time and within a macroevolutionary context. As a result, over the past 100 years a number of studies advanced methods for estimating mass in dinosaurs and other extinct taxa. These methods can be categorized into two major approaches: volumetric-density (VD) and extant-scaling (ES). The former receives the most attention in non-avian dinosaurs and advanced appreciably over the last century: from initial physical scale models to three-dimensional (3D) virtual techniques that utilize scanned data obtained from entire skeletons. The ES approach is most commonly applied to extinct members of crown clades but some equations are proposed and utilized in non-avian dinosaurs. Because both approaches share a common goal, they are often viewed in opposition to one another. However, current palaeobiological research problems are often approach specific and, therefore, the decision to utilize a VD or ES approach is largely question dependent. In general, biomechanical and physiological studies benefit from the full-body reconstruction provided through a VD approach, whereas large-scale evolutionary and ecological studies require the extensive data sets afforded by an ES approach. This study summarizes both approaches to body mass estimation in stem-group taxa, specifically non-avian dinosaurs, and provides a comparative quantitative framework to reciprocally illuminate and corroborate VD and ES approaches. The results indicate that mass estimates are largely consistent between approaches: 73% of VD reconstructions occur within the expected 95% prediction intervals of the ES relationship. However, almost three quarters of outliers occur below the lower 95% prediction interval, indicating that VD mass estimates are, on average, lower than would be expected given their stylopodial circumferences. Inconsistencies (high residual and per cent prediction deviation values) are recovered to a varying degree among all major dinosaurian clades along with an overall tendency for larger deviations between approaches among small-bodied taxa. Nonetheless, our results indicate a strong corroboration between recent iterations of the VD approach based on 3D specimen scans suggesting that our current understanding of size in dinosaurs, and hence its biological correlates, has improved over time. We advance that VD and ES approaches have fundamentally (metrically) different advantages and, hence, the comparative framework used and advocated here combines the accuracy afforded by ES with the precision provided by VD and permits the rapid identification of discrepancies with the potential to open new areas of discussion.
30 citations
TL;DR: The gross morphology and internal architecture of muscles crossing the shoulder joint in two morphologically-conservative extant amniotes that form a phylogenetic and morpho-functional bracket for non-mammalian synapsids are characterized and striking similarities in muscle organization and architectural parameters are found.
Abstract: The evolution of upright limb posture in mammals may have enabled modifications of the forelimb for diverse locomotor ecologies. A rich fossil record of non-mammalian synapsids holds the key to unraveling the transition from "sprawling" to "erect" limb function in the precursors to mammals, but a detailed understanding of muscle functional anatomy is a necessary prerequisite to reconstructing postural evolution in fossils. Here we characterize the gross morphology and internal architecture of muscles crossing the shoulder joint in two morphologically-conservative extant amniotes that form a phylogenetic and morpho-functional bracket for non-mammalian synapsids: the Argentine black and white tegu Salvator merianae and the Virginia opossum Didelphis virginiana. By combining traditional physical dissection of cadavers with nondestructive three-dimensional digital dissection, we find striking similarities in muscle organization and architectural parameters. Despite the wide phylogenetic gap between our study species, distal muscle attachments are notably similar, while differences in proximal muscle attachments are driven by modifications to the skeletal anatomy of the pectoral girdle that are well-documented in transitional synapsid fossils. Further, correlates for force production, physiological cross-sectional area (PCSA), muscle gearing (pennation), and working range (fascicle length) are statistically indistinguishable for an unexpected number of muscles. Functional tradeoffs between force production and working range reveal muscle specializations that may facilitate increased girdle mobility, weight support, and active stabilization of the shoulder in the opossum-a possible signal of postural transformation. Together, these results create a foundation for reconstructing the musculoskeletal anatomy of the non-mammalian synapsid pectoral girdle with greater confidence, as we demonstrate by inferring shoulder muscle PCSAs in the fossil non-mammalian cynodont Massetognathus pascuali.
23 citations
TL;DR: 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, and it is cautioned against the use of the sideways canal as a proxy to infer precisely the horizontal plane on dry skulls and in extinct species.
Abstract: 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.
16 citations
TL;DR: New body mass estimates for 93 adult thylacines are presented, including two taxidermy specimens and four complete mounted skeletons, representing 40 known-sex specimens, using three-dimensional volumetric model-informed regressions and show that prior estimates substantially overestimated average adult thymacine body mass.
Abstract: The relative body masses of predators and their prey strongly affect the predators' ecology. An accurate estimate of the mass of an extinct predator is therefore key to revealing its biology and th...
12 citations
TL;DR: The study confirms that volumetric BM estimates are more precise, and are recommended if relatively complete skeletons are available, and the ‘intermediate’ posture recognized for Tapinocaninus could represent a response to a large BM, which, for the first time in synapsids, reaches weights close to a tonne.
Abstract: Dinocephalians were the earliest large terrestrial tetrapods from Gondwana, making this group crucial in understanding body mass (BM) evolution in basal synapsids, but no detailed weight de...
9 citations
Cites background or methods or result from "Resizing Lisowicia bojani: volumetr..."
...2019), and the large Late Triassic dicynodont Lisowicia bojani from Poland (Romano and Manucci 2019)....
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...In the case of the huge dicynodont Lisowicia bojani, Romano and Manucci (2019) propose three different models (‘slim’, ‘average’ and ‘fat’) following the same procedure applied here for Tapinocaninus, and obtained an average BM of 5.88 tons....
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...Similar results to those of Tapinocaninus have been obtained recently by estimating body mass in the dwarf elephant Palaeoloxodon ex gr. P. falconeri from Sicily (Romano et al. 2019), and the large Late Triassic dicynodont Lisowicia bojani from Poland (Romano and Manucci 2019)....
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...Also in this case, Romano and Manucci (2019) stressed how the discrepancy between the two methods is likely linked to the particularly robust long bones of Lisowicia, which are characterized by very massive and stout shafts when compared to the bone length....
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References
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01 Jan 1932
TL;DR: In spite of the theoretical weakness of the surface law, the computation of basal metabolism to the unit of the body surface seems at present the most satisfactory method available of equalizing experimental results for differences in the size of experimental animals.
Abstract: does not appear. First page follows.
The statement that the basal metabolism of animals differing in size is nearly proportional
to their respective body surfaces, is called the surface law.
Benedict has shown that this law is already over ninety years old, Robiquet and Tillaye
having formulated it quite clearly in 1839. The history of the surface law is given
in the paper of (Harris and Benedict (1919)). We may here only briefly mention the different ways in which it has been found.
The early writers derived the law from theoretical considerations on a rather small
experimental basis, as did Bergmann, who in 1847 had already written a book on the
subject. Respiration trials were carried out by Regnault and Reiset, and Rameaux based
the surface law on measurements of the amount of air respired per minute by two thousand
human beings of different sizes. (Rubner (1883)) demonstrated the law in accurate respiration trials on dogs and Richet rediscovered
it empirically on rabbits. The latter writes (p. 223): “C’est apree coup seulement que je me suis avise que la donnee surface etait plus interessante que la donnee poids.”
Although (Armsby, Fries, and Braman (1918), p. 55) found the surface law confirmed to a rather striking degree, this law is
not at all so clear today as it appeared to its early discoverers. (Carman and Mitchell (1926), p. 380) state the situation very well: “In spite of the theoretical weakness of
the surface law, the computation of basal metabolism to the unit of the body surface
seems at present the most satisfactory method available of equalizing experimental
results for differences in the size of experimental animals.”
1,950 citations
"Resizing Lisowicia bojani: volumetr..." refers background in this paper
...…ecology, growth rate, home range and trophic requirements, reproduction rate, life span, fecundity and several other physiological aspects (e.g. Kleiber 1932; Millar and Zammuto 1983; LaBarbera 1989; Martin and Palumbi 1993; Calder 1996; Hillebrand and Azovsky 2001; Angiletta et al. 2004;…...
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TL;DR: Reconsideration of the generation time hypothesis to include physiological effects such as metabolic rate improves the theoretical underpinnings of molecular evolution.
Abstract: There is increasing evidence for variation in rates of nucleotide substitution among divergent taxonomic groups. Here, we summarize published rate data and show a strong relationship between substitution rate and body size. For instance, rates of nuclear and mtDNA evolution are slow in whales, intermediate in primates, and fast in rodents. A similar relationship exists for poikilothermic vertebrates. However, these taxa have slower mtDNA substitution rates overall than do homeotherms of similar size. A number of physiological and life history variables are highly correlated with body size. Of these, generation time and metabolic rate explain some patterns of rate heterogeneity equally well. In many cases, however, differences in metabolic rate explain important exceptions to the generation time model. Correlation between metabolic rate and nucleotide substitution may be mediated by (i) the mutagenic effects of oxygen radicals that are abundant by-products of aerobic respiration, and (ii) increased rates of DNA synthesis and nucleotide replacement in organisms with higher metabolic rates. Both of these factors increase mutation rate by decreasing the "nucleotide generation time," the average length of time before a nucleotide is copied either through replication or repair. Reconsideration of the generation time hypothesis to include physiological effects such as metabolic rate improves the theoretical underpinnings of molecular evolution.
1,151 citations
"Resizing Lisowicia bojani: volumetr..." refers background in this paper
...…reproduction rate, life span, fecundity and several other physiological aspects (e.g. Kleiber 1932; Millar and Zammuto 1983; LaBarbera 1989; Martin and Palumbi 1993; Calder 1996; Hillebrand and Azovsky 2001; Angiletta et al. 2004; Davidowitz and Nijhout 2004; Nagy 2005; Gillooly et al.…...
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TL;DR: A multivariate theory that focuses on the coevolution of thermal reaction norms for growth rate and size at maturity is recommended, which should incorporate functional constraints on thermal Reaction norms, as well as the natural covariation between temperature and other environmental variables.
Abstract: SYNOPSIS. The majority of ectotherms grow slower but mature at a larger body size in colder environments. This phenomenon has puzzled biologists because classic theories of life-history evolution predict smaller sizes at maturity in environments that retard growth. During the last decade, intensive theoretical and empirical research has generated some plausible explanations based on nonadaptive or adaptive plasticity. Nonadaptive plasticity of body size is hypothesized to result from thermal constraints on cellular growth that cause smaller cells at higher temperatures, but the generality of this theory is poorly supported. Adaptive plasticity is hypothesized to result from greater benefits or lesser costs of delayed maturation in colder environments. These theories seem to apply well to some species but not others. Thus, no single theory has been able to explain the generality of temperature-size relationships in ectotherms. We recommend a multivariate theory that focuses on the coevolution of thermal reaction norms for growth rate and size at maturity. Such a theory should incorporate functional constraints on thermal reaction norms, as well as the natural covariation between temperature and other environmental variables.
843 citations
TL;DR: Etude des methodologies employees pour les mesures d'echelle en biologie, montree par 3 exemples tires de the litterature ecologique and evolutionniste pour illustrer les problemes communs a la plupart des controverses sur ce sujet.
Abstract: Etude des methodologies employees pour les mesures d'echelle en biologie, montree par 3 exemples tires de la litterature ecologique et evolutionniste pour illustrer les problemes communs a la plupart des controverses sur ce sujet
760 citations
"Resizing Lisowicia bojani: volumetr..." refers background in this paper
...Body size is one of the most crucial biological properties characterizing both extinct and extant organisms, with a dramatic influence on metabolism, ecology, growth rate, home range and trophic requirements, reproduction rate, life span, fecundity and several other physiological aspects (e.g. Kleiber 1932; Millar and Zammuto 1983; LaBarbera 1989; Martin and Palumbi 1993; Calder 1996; Hillebrand and Azovsky 2001; Angiletta et al. 2004; Davidowitz and Nijhout 2004; Nagy 2005; Gillooly et al. 2006; Fisher et al. 2011; Campione and Evans 2012; Clauss et al. 2013)....
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...…trophic requirements, reproduction rate, life span, fecundity and several other physiological aspects (e.g. Kleiber 1932; Millar and Zammuto 1983; LaBarbera 1989; Martin and Palumbi 1993; Calder 1996; Hillebrand and Azovsky 2001; Angiletta et al. 2004; Davidowitz and Nijhout 2004; Nagy 2005;…...
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