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First 3D reconstruction and volumetric body mass estimate of the tapinocephalid dinocephalian Tapinocaninus pamelae (Synapsida: Therapsida)
Historical Biology
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 determinations are available for the clade. Here we present the first BM estimate for a dinocephalian on the basis of the remarkably well preserved and complete skeleton of the basal tapinocephalid Tapinocaninus pamelae from the lowermost Beaufort Group of South Africa. We reconstructed three 3D models of Tapinocaninus using mounted skeletons of the dinocephalians Moschops and Ulemosaurus to reconstruct the missing elements. Applying a density range between 0.9 and 1.15 Kg/1000 cm3 for living tissue to the model we reconstructed an average BM of 892.63 Kg for the taxon. Classic regression formulae, based on humerus and femur circumference, provide higher values of 1694.5 Kg and 2015.8 Kg, with an overestimation of 90% and 126% respectively. The study confirms that volumetric BM estimates are more precise, and are recommended if relatively complete skeletons are available. The ‘intermediate’ posture recognized for Tapinocaninus, more upright with respect to the sprawling condition characterizing sphenacodontid ‘pelycosaurs’, could represent a response to a large BM, which, for the first time in synapsids, reaches weights close to a tonne.
... There is consequently little consensus on when the erect locomotor behavior of extant therians first evolved. By current estimates, some taxa apparently used sprawled forelimb postures but more erect hindlimb postures (10,16,17,21,22,24,26,(27)(28)(29), a paradoxical configuration not observed among extant tetrapods. Moreover, anatomical and functional shifts in individual body systems often do not appear to phylogenetically coincide with those occurring in other systems (10-15, 22, 30-35), complicating interpretations of the sequence or mechanism of functional transformation. ...
... Additional functional analysis of fossil material, especially for stem therians, can provide improved clarity on the precise timing of this characteristically mammalian behavior. Irrespective of when asymmetric gaits evolved, our results for the hindlimb suggest that derived therapsids and cynodonts could well have used similar (and nonerect) fore-and hindlimb postures, offering a resolution to the apparent paradox of prior studies [e.g., (10,16,17,21,22,24,26,(27)(28)(29)] and reconciling the comparable mediolateral gauge typically observed in fossilized therapsid footprints [e.g., (87)]. Dynamic musculoskeletal simulations of whole-animal gait can further evaluate this [e.g., (88)]. ...
... log 10 m body + 0.24133 (3) log 10 ΣF max = −0.29993 log 10 m body + 0.91694 (4) circumferences may produce problematic estimates for some nonmammalian synapsids [e.g., (29)], our approach to expressing performance relative to muscle strength (see below) means that assessments of performance are largely unaffected by potential error in body mass. ...
The evolutionary transition from early synapsids to therian mammals involved profound reorganization in locomotor anatomy and function, centered around a shift from “sprawled” to “erect” limb postures. When and how this functional shift was accomplished has remained difficult to decipher from the fossil record alone. Through biomechanical modeling of hindlimb force-generating performance in eight exemplar fossil synapsids, we demonstrate that the erect locomotor regime typifying modern therians did not evolve until just before crown Theria. Modeling also identifies a transient phase of increased performance in therapsids and early cynodonts, before crown mammals. Further, quantifying the global actions of major hip muscle groups indicates a protracted juxtaposition of functional redeployment and conservatism, highlighting the intricate interplay between anatomical reorganization and function across postural transitions. We infer a complex history of synapsid locomotor evolution and suggest that major evolutionary transitions between contrasting locomotor behaviors may follow highly nonlinear trajectories.
... Pareiasaurs were among the world's first terrestrial tetrapods to evolve a large body size (up to 3 m long, weighing approximately 1 metric ton) having done so by the middle Permian (Lee 1994(Lee , 1997a, along with dinocephalian therapsids Romano and Rubidge 2019a;Day and Rubidge 2020;Rubidge and Day 2020) and caseid synapsids (Olson 1968;Reisz 1986;Reisz and Sues 2000;Ronchi et al. 2011;Nicosia 2014, 2015;Brocklehurst et al. 2016;Romano et al. 2017Romano et al. , 2018Romano 2017a). In the Karoo Basin of South Africa, they formed an abundant and significant component of the Tapinocephalus Assemblage Zone (AZ), accounting for approximately 25% of all vertebrate fossils found (Boonstra 1969;Smith and Keyser 1995;Nicolas 2007;Van Der Walt et al. 2011;Day and Rubidge 2020). ...
... Next, the photogrammetric models were exported as 'PLY' files and loaded in ZBrush, a software for digital sculpting and painting that enables isolation of individual bones in the skeleton, compensation for distortion and, where necessary, modifications of the posture of the animal (see Romano and Manucci 2019;Romano and Rubidge 2019a). ...
... We used ZBrush to add three different volumes of soft tissue around the reconstructed skeletons (slim, average and fat models) following the procedure proposed by Romano and Manucci (2019) and Romano and Rubidge (2019a), from which we derived a range of three mass estimates (Figures 3, 4). The slim model body reconstruction closely follows the contour of the skeleton; the average model, which we consider the most likely reconstruction of the animal in life, was sculpted using modern rhinoceros and proboscideans as a reference to create the most probable amount of fleshy material (Figures 7,8); and the fat reconstruction, which included an excess of soft tissue mass around the skeleton and a very wide, barrel-shaped rib cage. ...
Pareiasaurs were among the world’s first large terrestrial tetrapods, first appearing during the Guadalupian Epoch, and were later widespread across Pangea during the Lopingian where they formed a significant part of the large herbivore guild. The Bradysauria of the Lower Beaufort Group of the Karoo Basin of South Africa are among the oldest pareiasaurs, yet little is known of their palaeobiology. Here, we present the first volumetric body mass estimate and a new in vivo reconstruction of the earliest Karoo pareiasaur, and the phylogenetically basal-most pareiasaur, Bradysaurus baini, based on two almost complete adult mounted skeletons. Using 3D photogrammetric models of the two skeletons, we calculated a possible body mass range for B. baini by applying different densities for living tissue to reconstructions of differing soft tissue mass. Considering the larger adult Bradysaurus specimen, our volumetric body masses range from a minimum of 851.4 kg to a maximum of 1,276.5 kg, with an overall mean body mass of 1,022 kg, approximately the body weight of a large domestic cow. The study provides a more precise estimate of body mass in early members of Pareiasauridae, and we suggest that they were somewhat smaller than some late Permian taxa such as Scutosaurus karpinskii.
... They represent an early evolution of sizes over a ton and made up an important component of middle and late Permian biodiversity and ecosystems (Lee, 1997a;Day, 2013;Day et al., 2015Day et al., , 2018. Along with the Dinocephalia and caseids (Romano and Rubidge, 2019a;Rubidge et al., 2019;Day and Rubidge, 2020), pareiasaurs were the only other amniote group that attained massive size in the middle Permian (up to 3 m long). The pareiasaur clade achieved a high level of diversity and a world-wide distribution by the late Permian, before their ultimate demise at the Permo-Triassic boundary. ...
... High resolution Digital Photogrammetry is based on Multi View Stereo (MVS; Seitz et al., 2006) algorithms and structure from Motion (SfM) (Ullman, 1979); close-range photography results in an accuracy of up to 1 mm in the calculated models. The obtained photogrammetric model was exported as "Ply" files and uploaded in ZBrush, software for digital sculpting and painting, which enables isolation of individual bones in the skeleton, compensation for distortion and, when necessary, to modify the posture of the animal (Romano and Rubidge, 2019a; see Romano and Manucci, 2019). Following the procedure proposed by Romano and Manucci (2019) and Romano and Rubidge (2019a), to produce a realistic range of weight estimations we used the 3D sculpture software to obtain three different reconstructions of Scutosaurus, adding different masses of soft tissue around the reconstructed skeleton (Figures 2, 3). ...
... The obtained photogrammetric model was exported as "Ply" files and uploaded in ZBrush, software for digital sculpting and painting, which enables isolation of individual bones in the skeleton, compensation for distortion and, when necessary, to modify the posture of the animal (Romano and Rubidge, 2019a; see Romano and Manucci, 2019). Following the procedure proposed by Romano and Manucci (2019) and Romano and Rubidge (2019a), to produce a realistic range of weight estimations we used the 3D sculpture software to obtain three different reconstructions of Scutosaurus, adding different masses of soft tissue around the reconstructed skeleton (Figures 2, 3). The first is a body reconstruction following the contour of the skeleton, indicated as "slim model" (Figure 2B). ...
Pareiasaurs (Amniota, Parareptilia) were characterized by a global distribution during the Permian period, forming an important component of middle (Capitanian) and late Permian (Lopingian) terrestrial tetrapod biodiversity. This clade represents an early evolution of sizes over a ton, playing a fundamental role in the structure of middle and late Permian biodiversity and ecosystems. Despite their important ecological role and relative abundance around the world, our general knowledge of the biology of these extinct tetrapods is still quite limited. In this contribution we provide a possible in vivo reconstruction of the largest individual of the species Scutosaurus karpinskii and a volumetric body mass estimate for the taxon, considering that body size is one of the most important biological aspects of organisms. The body mass of Scutosaurus was calculated using a 3D photogrammetric model of the complete mounted skeleton PIN 2005/1537 from the Sokolki locality, Arkhangelsk Region, Russia, on exhibit at the Borissiak Paleontological Institute, Russian Academy of Sciences (Moscow). By applying three different densities for living tissues of 0.99, 1, and 1.15 kg/1,000 cm³ to reconstructed “slim,” “average” and “fat” 3D models we obtain average body masses, respectively, of 1,060, 1,160, and 1,330 kg, with a total range varying from a minimum of one ton to a maximum of 1.46 tons. Choosing the average model as the most plausible reconstruction and close to the natural condition, we consider a body mass estimate of 1,160 kg as the most robust value for Scutosaurus, a value compatible with that of a large terrestrial adult black rhino and domestic cow. This contribution demonstrates that barrel-shaped herbivores, subsisting on a high-fiber diet and with a body mass exceeding a ton, had already evolved in the upper Palaeozoic among parareptiles, shedding new light on the structure of the first modern terrestrial ecosystems.
... Although regression methods allow for estimating the BM of extinct tetrapods even from fragmentary skeletons or single bones, several studies have shown that the results obtained with such formulae can be highly misleading (e.g. Sellers et al. 2012;Bates et al. 2015;Brassey and Gardiner 2015;Larramendi 2016;Romano and Manucci 2019;Romano and Rubidge 2019a;Romano et al. , 2022Romano et al. , 2023Van den Brandt et al. 2023), leading to far-fetched estimates of little use for palaeo-biological studies. Differently, although it is often necessary to have mostly complete skeletons available, volumetric methods provide more limited estimate ranges and more plausible BM values which, being based on the general dimensions and shapes of the body plan of the tetrapods under study, are less influenced by issues related to the preservation, taphonomy, sexual dimorphism, and peculiar conformation of the selected individual bones. ...
... The photos were then processed with photogrammetry software Agisoft Metashape Standard Edition, version 1.5.0 (Educational License, 64 bits) leading to a highresolution 3D reconstruction of the skeleton that preserves the original colour and texture ( Figure 2). Once cleaned and isolated, the model was exported in 'PLY' format, and imported into the digital sculpting and painting software ZBrush, a tool that also allows to retrodeform compressed or distorted bones or correct incorrect postures of mounted skeletons (see Romano and Manucci 2019;Romano and Rubidge 2019a;Romano et al. 2023). Using the software, a mass of soft tissue was digitally sculpted around the 3D skeleton, using as a reference the anatomical proportions in different norms in extant hippos (Figure 3). ...
Hippopotamus antiquus was an extinct semiaquatic megaherbivore foraging mainly on aquatic vegetation, with a biochronological range in the Italian peninsula spanning from around 2.2 to 0.4 Ma. Considering its large body size, and its lifestyle considered to be more aquatic than the current form H. amphibius, a correct estimate of the body mass is interesting to correctly interpret various biological aspects of this extinct megaherbivore. In this contribution, we propose an estimate of the body mass of H. antiquus by comparing the results obtained with classical regression formulae with the values obtained through a new 3D volumetric approach. For both approaches, we used the mounted specimen on display at the Museum of Geology and Palaeontology of the University of Florence. As already found in recent contributions, the estimates obtained with the regression methods provide very high ranges compared to the volumetric approach, with minimum estimates of 200 kg and maximum estimates of over 6 tons, completely incompatible with a tetrapod of this size. The new volumetric estimate provides an average value for the BM in H. antiquus of approximately 3170 tons, thus confirming a body weight approximately double compared to the average values in the extant species H. amphibius.
... Next, the software ZBrush was used to digitally sculpt the soft tissue around the 3D models of the corrected skeletons in order to obtain an in vivo restoration of A. arvernensis. In previous studies on tetrapods for which no current analogues are available, three models, slim, average and fat, have been proposed (Romano and Manucci, 2019;Romano and Rubidge, 2019b;Romano et al., 2012b;Van den Brandt et al., 2023), suggesting three different body masses around the skeletons. In this way, it was possible to provide a range of soft tissue volumes and therefore a range of possible final BMs. ...
... In particular, as in previous contributions (Romano et al., 2022b), the work by Morfeld et al. (2016) was used as a reference for fleshy masses in elephants in natural conditions (therefore avoiding obese or starving individuals) (Figures 6 and 7). Following a procedure recently applied in several clades of terrestrial tetrapods (Romano and Manucci, 2019;Romano and Rubidge, 2019b;Romano et al., 2021aRomano et al., , 2021bRomano et al., , 2022a) the sculpted models were uploaded to the software 3D Studio Max which allows the models to be scaled to real sizes and both the surface and the volume of the reconstructions to be calculated. The models were scaled by using as a reference the best preserved long-bone elements. ...
In this contribution, we estimate the possible living body mass (BM) of the anancine gomphotheriid Anancus arvernensis, by testing a recently proposed volumetric method based on hyper-realistic in vivo 3D reconstructions and comparing the results with the BM obtained by using regression formulas. The analysis, conducted starting from two articulated skeletons, showed that the performance of regression formulas varies considerably from taxon to taxon, with plausible estimates obtained only when the mean of all the formulas on the individual bones is available and considered. Differently, formulas applied to single bones can lead to underestimations or overestimations of up to 300%, with BM ranging from 54 kg to 26 metric tonnes. By using the volumetric method, the in vivo reconstruction of Anancus arvernensis made it possible to estimate a BM between 5.2 and 6 t, a figure close to that of an extant adult male African elephant. The obtained results show that estimating BM in terrestrial tetrapods from single or fragmented bones might lead to highly improbable and misleading conclusions. Thus, in the presence of adequately complete mounted skeletons, it is always preferable and recommended to estimate the BM using the volumetric approach, which is based on an in vivo 3D reconstruction.
... The estimates obtained with the regression methods provide very high ranges compared to the volumetric approach, with minimum estimates of 200 kg and maximum estimates of over 6 tons, completely incompatible with a tetrapod of this size. Similar contrasting results have been recently obtained in a broad range of fossil tetrapods (e.g.,Romano & Manucci, 2019;Romano & Rubidge, 2019). The new volumetric estimate in H. antiquus provides an average BM of approximately 3170 tons, thus confirming a body weight approximately double compared to the average values in the extant species H. amphibius. ...
In this contribution we present an in-vivo reconstruction and a body mass (BM) estimate of Hippopotamus antiquus comparing and discussing the results calculated with classic regression formulas with the values obtained through a new 3D volumetric approach. H. antiquus, with a biochronological range in the Italian peninsula from around 2.2 to 0.4 Ma, was an extinct semiaquatic megaherbivore foraging mainly on aquatic vegetation. Taking into consideration its lifestyle, considered to be more aquatic than the extant H. amphibius, and its very large body size, a correct estimate of the BM is crucial to correctly interpret several biological aspects of this fossil tetrapod. The mounted specimen on display at the Museum of Geology and Paleontology of the University of Florence was used for both the classical regression method and for the new 3D volumetric approach. The estimates obtained with the regression methods provide very high ranges compared to the volumetric approach, with minimum estimates of 200 kg and maximum estimates of over 6 tons, completely incompatible with a tetrapod of this size. Similar contrasting results have been recently obtained in a broad range of fossil tetrapods (e.g., Romano & Manucci, 2019; Romano & Rubidge, 2019). The new volumetric estimate in H. antiquus provides an average BM of approximately 3170 tons, thus confirming a body weight approximately double compared to the average values in the extant species H. amphibius.
... Our transitional 'sprawling-parasagittal' landscape strongly supports monotreme-like sprawling postures in dinocephalian and anomodont therapsids (Figures 4 and 5), with these clades showing increased optimization for strength and muscle leverage at the expense of humerus length (Figures 2 and 3, Supplementary Figures 4, 5). This combination of functional traits is potentially related to fossorial behaviors in smaller dicynodonts [45][46][47] , as seen in modern monotremes and talpid moles 32,33,48 , and the acquisition of larger body sizes in both groups 49,50 . Similar ecomorphological convergence in the forelimb has been previously noted between fossorial and large-bodied mammals 13 . ...
The 'sprawling-parasagittal' postural transition is a key part of mammalian evolution, associated with sweeping reorganization of the postcranial skeleton in mammals compared to their forebears, the non-mammalian synapsids. However, disputes over forelimb function in fossil synapsids render the precise nature of the 'sprawling-parasagittal' transition controversial. We shed new light on the origins of mammalian posture, using evolutionary adaptive landscapes to integrate 3D humerus shape and functional performance data across a taxonomically comprehensive sample of fossil synapsids and extant comparators. We find that the earliest pelycosaur-grade synapsids had a unique mode of sprawling, intermediate between extant reptiles and monotremes. Subsequent evolution of synapsid humerus form and function showed little evidence of a direct progression from sprawling pelycosaurs to parasagittal mammals. Instead, posture was evolutionarily labile, and the ecological diversification of successive synapsid radiations was accompanied by variation in humerus morphofunctional traits. Further, synapsids frequently evolve towards parasagittal postures, diverging from the reconstructed optimal evolutionary path; the optimal path only aligns with becoming increasingly mammalian in derived cynodonts. We find the earliest support for habitual parasagittal postures in stem therians, implying that synapsids evolved and radiated with distinct forelimb trait combinations for most of their recorded history.
... The uses are varied, with many possibilities yet to be explored, and range from 3D bone scanning to biomechanics, locomotor capabilities, retrodeformation of fossils, muscle reconstruction and body mass estimate (e.g. Gunga et al. 2007Gunga et al. , 2008Bates et al. 2009Bates et al. , 2015Mallison 2010aMallison , 2010bMallison , 2010cHutchinson et al. 2011;Bates and Falkingham 2012;Sellers et al. 2012Sellers et al. , 2017Stevens 2013;Reiss and Mallison 2014;Brassey et al. 2015;Brassey 2016;Vidal and Diaz 2017;Romano and Manucci 2021;Bishop et al. 2021;Romano and Rubidge 2021;Romano et al. 2021aRomano et al. , 2021b. This virtual revolution, even with regard to the most common digital illustration, has not, however, hindered those who continue to use the traditional artistic tools, from painting to manual sculpture, with authors who continue the great paleoartistic tradition that has always accompanied this genre from its origins. ...
Between the fifteenth and sixteenth centuries, the first naturalistic illustrations appeared in texts and treatises, marking the true and proper passage from simple literary works to real scientific contributions. Since that time, the geo-palaeontological literature and the world of scientific illustrations developed together. For a long time initially the scientist and artist coincided in the same person, until the emergence of the ‘paleoartist’, as a professional devoted to naturalistic representations. Here, we review the fundamental
steps of ‘co-evolution’ between advances in scientific knowledge and their representation in ‘paleoart’. The study led to the identification of six principal ‘Genres’; in addition, a subdivision of the history and evolution of ‘paleoart’ into six periods or major ‘eras’ is proposed. The analysis is based on a dataset with a total of 605 authors, considering a time range between the first half of the 18th century up to 2020, with paleoartists from 42 different countries. The relationship between scientist and ‘paleoartist’ has been, and
will be in the future, a constructive interaction of ‘reciprocal illumination’, where the questions asked by the artist represent a genuine propellant for the advancement of knowledge and the research itself.
... Given the versatility and ongoing development of micro-drones, in this study we tested the use of unmanned aerial vehicles in palaeontology for the 3D acquisition of large skeletons mounted on exhibit in museum structures. In fact, 3D reconstruction of articulated vertebrate skeletons is a very useful tool in palaeontology, allowing, thanks to the help of modern image and video editing technologies, advanced studies in several fields such as locomotion, posture, and biomechanics (e.g., Mallison Bishop et al. 2021), body mass estimation and in vivo restoration of extinct tetrapods (e.g., Gunga et al. 2007Gunga et al. , 2008Bates et al. 2009Bates et al. , 2015Sellers et al. 2012;Brassey et al. 2015;Brassey 2016;Romano and Manucci 2019;Romano and Rubidge 2021;Romano et al. 2021aRomano et al. , 2021b, just to name a few. ...
Unmanned aerial vehicles (UAVs), have seen tremendous development in the last decade, with numerous applications in civil and research fields. Drones' success, particularly in the field of research, is due to a number of factors, including rapid technological advancement, tool versatility, and prices that are becoming increasingly affordable even for small research groups or individuals. Given the versatility and ongoing development of micro drones, we tested the use of micro-drones in vertebrate palaeontology to reconstruct mounted skeletons using the photogrammetry method. The experiment was carried out on a massive specimen of Mammuthus meridionalis (Nesti 1825) from Madonna della Strada, which is on display at the east bastion of the Spanish Fortress in L'Aquila (Abruzzo, Central Italy), comparing the results with those obtained using the traditional method using a digital camera. Even though both the traditional digital camera and the drone methods produced a high-resolution 3D model of the skeleton, the results obtained, indeed, lead us to consider the use of micro-drones in museum structures as a very interesting and promising new field of application. Drones provide a simple, fast, and non-invasive system for the study, monitoring, and enhancement of cultural heritage in all of its possible manifestations.
... In the Karoo Basin, the Capitanian mass extinction is characterized by a change from a dinocephalian-to a dicynodont-dominated tetrapod fauna. The primary extinction phase reduces diversity across most tetrapod clades except rhinesuchid temnospondyls but it is the larger components of the ecosystem that are worst affected: the only taxa that became completely extinct were dinocephalians and bradysaurian pareiasaurs, of which all species from the Tapinocephalus AZ grew to over 2.5 m and may have weighed between 700 to 1100 Kg (Lee, 1997;Romano and Rubidge, 2019). The vastly different dental adaptations of pareiasaurs and herbivorous dinocephalians suggests they had different diets, so body size remains the main common attribute. ...
The Beaufort Group of the main Karoo Basin of South Africa records two major extinction events of terrestrial vertebrates in the late Palaeozoic. The oldest of these has been dated to the late Capitanian and is characterized by the extinction of dinocephalian therapsids and bradysaurian pareiasaurs near the top of Tapinocephalus Assemblage Zone. Faunal turnover associated with the extinction of dinocephalians is evident in vertebrate faunas from elsewhere in Pangaea but it can be best studied in the Karoo Basin, where exposures of the upper Abrahamskraal and lower Teekloof formations allow continuous sampling across the whole extinction interval. Here we present field data for several sections spanning the Capitanian extinction interval in the southwestern Karoo and discuss recent work to establish its timing, severity, and causes. A large collections database informed by fieldwork demonstrates an increase in extinction rates associated with ecological instability that approach that of the end-Permian mass extinction, and shows significant turnover followed by a period of low diversity. Extinctions and recovery appear phased and show similarities to diversity patterns reported for the end-Permian mass extinction higher in the Beaufort sequence. In the Karoo, the late Capitanian mass extinction coincides with volcanism in the Emeishan Large Igneous Province and may have been partly driven by short-term aridification, but clear causal mechanisms and robust links to global environmental phenomena remain elusive.
Size has an impact on various aspects of an animal's biology including physiology, biomechanics, and ecology. Accurately and precisely estimating size, in particular body mass, is therefore a core objective of paleobiologists. Two approaches for estimating body mass are common: whole-body volumetric models and individual element-scaling (e.g., bones, teeth). The latter has been argued to be more accurate, while the former more precise. Here, we use minimum convex hulls (MCH) to generate a predictive volumetric model for estimating body mass across a broad taxonomic and size range (127 g to 2,735 kg). We compare our MCH model to stylopodial-scaling, incorporating data from the literature, and find that MCH body mass estimation is both more accurate and more precise than stylopodial estimation. An explanation for the difference between methods is that reptile and mammal stylopod circumference and length dimensions scale differentially (slope 1.179 ± 0.102 vs. 1.038 ± 0.031, respectively), such that reptiles have more robust bones for a given size. Consequently, a mammalian-weighted stylopodial-scaling sample overestimates the body mass of larger reptiles and this error increases with size. We apply both estimation equations to a sample of 12 Permo-Triassic tetrapods and find that stylopodial-scaling consistently estimates a higher body mass than MCH estimation, due to even more robust bones in extinct species (slope = 1.319 ± 0.213). Finally, we take advantage of our MCH models to explore constraints regarding the position of the center of mass (CoM) and find that relative body proportions (i.e., skull: tail ratio) influence CoM position differently in mammals, crocodylians, and Permo-Triassic tetrapods. Further, we find that clade-specific body segment expansion factors do not affect group comparisons but may be important for individual specimens with rather disproportionate bodies (e.g., the small-headed and large-tailed Edaphosaurus). Our findings suggest that the whole-body volumetric approach is better suited for estimating body mass than element-scaling when anatomies are beyond the scope of the sample used to generate the scaling equations and provides added benefits such as the ability to measure inertial properties.
Dicynodontia was an abundant, globally widespread clade of Permo-Triassic synapsids on the stem lineage of mammals. Although there is an extensive body of literature on dicynodont craniomandibular anatomy, only recently has the power of computed tomographic (CT) scanning been applied to this system. CT-assisted research on dicynodonts has focused on the smallest members of the clade, while larger dicynodonts (particularly the members of the diverse, long-ranging subclade Bidentalia) have received comparatively little attention. Here, we work towards filling that gap by presenting a µCT-assisted reconstruction of ‘The Elgin Marvel’, a bidentalian specimen consisting of a complete cranium and mandible from late Permian deposits near Elgin, Scotland, which historically has been difficult to study because of its unusual preservation as void space in sandstone. This specimen can be referred to Gordonia, which is solely represented by moulds of void specimens. The µCT data reveal new information on the palate and endocranium of this taxon that could not previously be gleaned from physical moulds made from the void specimens. A phylogenetic analysis indicates that Gordonia and the Chinese Jimusaria form a clade of bidentalians characterized by narrow pterygoid medial plates, expanding our understanding of late Permian biogeography. The endocast of Gordonia is similar to that of other non-cynodont therapsids, and has a remarkably enlarged pineal body, probably related to exaggeration of the sagittal crest. Comparisons of encephalization quotients (EQ), a measure of brain size relative to body size, reveal Gordonia has a similar EQ to most other non-cynodont therapsids.
This article deals with some debatable issues in the field of geology that can be resolved within the framework of the expanding and pulsating Earth hypothesis. It is assumed that cosmic factors, including the rotation of the Solar System around the center of the Galaxy, may cause periodic fluctuations in some parameters of the Earth, including its size. As proof of the concept of rhythmic pulsations of the Earth, statistical evidence is given for the confinement of various mineral deposits to different intervals of the planet’s history. Pulsations in the size of the Earth are a secondary phenomenon in relation to its general expansion, which can be evidenced by both geological and paleontological data. The concept of the expansion and pulsations of the planet is proposed as the basis of a new geotectonic theory, in which certain provisions of all the previously proposed hypotheses of the evolution of the Earth will also find a place.
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.
A proto-mammalian giant
Early terrestrial amniotes evolved into two groups: the sauropsids, which led to the bird and dinosaur lineages, and the synapsids, which led to mammals. Synapsids were diverse during the Permian but were greatly reduced after the end-Permian extinction (about 252 million years ago). The few groups that survived into the Triassic were mostly small and retained a sprawling gait. Sulej and Niedźwiedzki, however, describe a dicynodont from the Late Triassic of Poland that is as large as some coexisting dinosaurs and appears to have had an erect gait—like modern mammals. Thus, megaherbivores in the Triassic were not only dinosaurs.
Science , this issue p. 78
Accurate mapping and three-dimensional models are crucial for studying tracks
and tracksites at different scales. The use of small Unmanned Aerial Vehicles (UAVs)
for mapping and three-dimensional modelling is becoming increasingly common,
allowing the capture of high-resolution images comparable to those obtained by terrestrial
laser scanners and manned aerial photogrammetry, but with reduced working
costs and rapid execution times. The Lower Cretaceous (upper Aptian/lower Albian)
Molfetta dinosaur tracksite (Apulia, southern Italy), was used as a test area to evaluate
the results of UAV based photogrammetry. We used two different drones having different
technical features and for which we set different flight parameters. Ground-based
photogrammetry on single footprints was also performed, in the light of the recent introduction
of high-resolution digital cameras and powerful processing software, with the
aim to evaluate its impact on ichnological, ichnotaxonomical, and ichnosystematic
analyses. The accuracy of three-dimensional models, digital elevation models, and
orthophotos generated by UAV images is extremely high and allows for rapid mapping
and description of vast and/or hardly accessible tracksites with higher accuracy than
that obtained from traditional field data or from digital airphotos. By coupling groundand
aerial-based photogrammetry, ichnologists can rapidly obtain consistent and
affordable digital models useful to study dinosaur tracksites both at the meso- (track)
and macroscale (ichnosite). The adoption of aerial and close-range photogrammetry
will allow for the rapid production of data with sustainable costs that can be used both
by specialists and as a means of conservation and dissemination of knowledge to the
public.
The postcranial material referable to the Russian caseid Ennatosaurus tecton from the middle Permian is described. Although the cranium has been recently restudied in detail, the descriptions currently available for the postcranial skeleton are essentially limited to the original short account on the holotype provided by Efremov in 1956. The postcranium of Ennatosaurus is informative with respect to both taxonomy and phylogeny, with autapomorphic characters present particularly in the vertebral column. In addition to the anatomical description of the elements presented here, eight principal component analyses were conducted to investigate the position of the various osteological elements of Ennatosaurus within caseid morphospace. The inclusion of members of all major groups of ‘pelycosaurs’ and selected outgroup taxa allowed us to make more extensive preliminary inferences regarding postcranial morphospace occupation of these basal synapsids for each individually considered bone. The analysis revealed a major decoupling among the morphospaces of stylopodial and zeugopodial elements, with femora and humeri showing a shared common pattern, and a wider overlap in their respective morphospace. Conversely, the ulnae, radii, tibiae and fibulae show well-separated regions of morphospace in the different clades, indicating their potential importance, not only for functional and biomechanical studies, but also for taxonomic differentiation. Finally, a 3D photogrammetric model of the mounted specimen at the Paleontological Institute in Moscow forms the basis for the first in vivo reconstruction of Ennatosaurus tecton, providing a potentially realistic picture of the Russian caseid in life. © The Trustees of the Natural History Museum, London 2017. All rights reserved.
New characters of the giant caseid Alierasaurus ronchii are described here based on material recovered from the type locality in the Permian deposits of Cala del Vino Formation (Sardinia NW) and additional preparation of the previously collected material. All new described osteological elements are characterized by the same state of preservation and, given the absence of double elements and the total compatibility in absolute size, the new material can be attributed without doubt to the holotypic individual of A. ronchii. Highly diagnostic material includes a caudal neural spine with a broad bifid distal termination. This represents a synapomorphy characterizing the more derived caseids, thus fully confirming the attribution of the Sardinian specimen to Caseidae. Also the other vertebral material and newly collected ribs show a typical caseid structure, fully consistent with the previously published material. Despite the highly partial nature of Alierasaurus, the taxon was included in a recent phylogenetic analysis of caseids to investigate its phylogenetic position within the monophyletic Caseasauria. Alierasaurus falls as the sister taxon of Cotylorhynchus, and is autapomorphic in the general construction of MT-IV and proximal phalanx IV-I. The absolute size of the newly recovered material confirms a gigantic body size for Alierasaurus, comparable, if not greater, to that of the huge North American species Cotylorhynchus hancocki (up to 6 m in length). Such gigantic adult body size, closely correlated to its herbivorous lifestyle, must have been selected during evolution of caseids, leading to substantial advantages in terms of fitness.
According to a traditional view, the specific diet in vertebrates is one of the key factors structuring the composition of the gut microbiota. In this interpretation, the microbiota assumes a subordinate position, where the larger host shapes, through evolution and its fitness, the taxonomical composition of the hosted microbiota. The present contribution shows how the evolution of herbivory, framed within the new concept of holobiont, the possibility of inter-kingdom crosstalk and its epigenetic effects, could pave the way to a completely reversed interpretation: instead of being passively shaped, the microbiota can mold and shape the general host body structure to increase its fitness. Central elements to consider in this context are the inter-kingdom crosstalk, the possibility of transporting RNAs through nanovesicles in feces from parents to offspring, and the activation of epigenetic processes passed on vertically from generation to generation. The new hypothesis is that the gut microbiota could play a great role in the macroevolutionary dynamics of herbivorous vertebrates, causing directly through host-microbiota dialog of epigenetic nature (i.e., methylation, histone acetylation, etc.), major changes in the organisms phenotype. The vertical exchange of the same microbial communities from parents to offspring, the interaction of these microbes with fairly uniform genotypes, and the socially restricted groups where these processes take place, could all explain the reasons why herbivory has appeared several time (and independently) during the evolution of vertebrates. The new interpretation could also represent a key factor in understanding the convergent evolution of analogous body structures in very distant lineages.
The vertebrae of sauropod dinosaurs are characterized by complex architecture involving laminae, fossae, and internal chambers of various shapes and sizes. These structures are interpreted as osteological correlates of a system of air sacs and pneumatic diverticula similar to that of birds. In extant birds, diverticula of the cervical air sacs pneumatize the cervical and anterior thoracic vertebrae. Diverticula of the abdominal air sacs pneumatize the posterior thoracic vertebrae and synsacrum later in ontogeny. This ontogenetic sequence in birds parallels the evolution of vertebral pneumaticity in sauropods. In basal sauropods, only the presacral vertebrae were pneumatized, presumably by diverticula of cervical air sacs similar to those of birds. The sacrum was also pneumatized in most neosauropods, and pneumatization of the proximal caudal vertebrae was achieved independently in Diplodocidae and Titanosauria. Pneumatization of the sacral and caudal vertebrae in neosauropods may indicate the presence of abdominal air sacs. Air sacs and skeletal pneumaticity probably facilitated the evolution of extremely long necks in some sauropod lineages by overcoming respiratory dead space and reducing mass. In addition, pulmonary air sacs may have conveyed to sauropods some of the respiratory and thermoregulatory advantages enjoyed by birds, a possibility that is consistent with the observed rapid growth rates of sauropods.
We compare theropod footprints with elongate metatarsal prints from central Italy with known autopod structures in major theropod groups, in order to more accurately define the trackmaker attribution. Our work, using morphometric analysis, shows the considerable potential of explorative methods such as PCA (principal component analysis) and cluster analysis when describing important characters for a given taxonomic group (body and ichnofossils) and identifying important anatomical regions. Moreover, the results of the analysis suggest that the putative trackmaker is likely a member of Ornithomimosauria, with significant affinities in the posterior autopod structure with the genus Struthiomimus . The fundamental importance of integrating both osteological and ichnological data, when investigating locomotor and behavioural hypotheses, is highlighted. This approach could also contribute positively to the complex cognitive process of trackmaker identification and be favourable for the attainment of a more natural definition of ichnotaxa.
New dinosaur footprints were recently discovered in southern Latium (Italy). The
tracks all appear slightly differently preserved and are characterized by elongated
metatarsal impressions, recording the complex locomotor behaviour of a medium-sized
theropod. The spatial distribution and the features of the footprints indicate that the
trackmaker adopted a “crouched” position as part of an activity as well as a resting
phase suggested by sub-parallel, calcigrade tracks. These new data once again highlight
the great potential of ichnological evidence in the study of the biology and
behaviour of extinct tetrapods.
In recent decades there has been a growing interest in proboscideans’ body size, given that mass is highly correlated with biological functions. Different allometric equations have been proposed in the recent decades to estimate their body masses, based on a large number of living examples. However, the results obtained by these formulae are not accurate because extinct animals often had different body proportions and some were outside the size range of extant samples. Here the body mass of a large number of extinct proboscideans has been calculated by the Graphic Double Integration volumetric method which is based on technical restorations from graphical reconstructions of fossils employing photos, measurements and comparative anatomy of extant forms. The method has been tested on extant elephants with highly accurate results. The reconstructions necessary to apply this method give important information such as body proportions. On the other hand, equations to calculate the skeletal shoulder height have been developed, with a large number of published shoulder heights being recalculated. From the shoulder heights, several equations were created to find out the body mass of a series of extant and extinct species. A few of the largest proboscideans, namely Mammut borsoni and Palaeoloxodon namadicus, were found out to have reached and surpassed the body size of the largest indricotheres. Bearing this in mind, the largest land mammal that ever existed seems to be within the order of Proboscidea, contrary to previous understanding.
Literature concerning dinosaur footprints or trackways exhibiting abnormal gait or morphology reflecting pathology (ichnopathology) is rare. We report on a number of Jurassic and Cretaceous occurrences of theropod footprints from western North America with unusual morphologies interpreted herein as examples of inferred pathologies, or ichnopathologies. The majority of ichnopathologies are primarily manifested in the digit impressions and include examples of swelling, extreme curvature, dislocation or fracture, and amputation. A number of occurrences are single tracks on ex situ blocks with substantial deformation (inferred dislocation or fracture), or absence of a single digit impression. Two occurrences are from in situ natural mould trackways, one of which is a lengthy trackway of a presumed allosauroid with no noticeable deformation of the digits or feet but with strong inward rotation of the left footprint toward the midline and a pronounced, waddling limp. The other is a tyrannosaurid trackway consisting of three footprints (one right, two left) with the two left prints exhibiting repetitive ichnopathology of a partially missing Digit II impression.
Estimates of body mass often represent the founding assumption on which bio-mechanical and macroevolutionary hypotheses are based. Recently, a scaling equation was applied to a newly discovered titanosaurian sauropod dinosaur (Dreadnoughtus), yielding a 59 300 kg body mass estimate for this animal. Herein, we use a modelling approach to examine the plausibility of this mass estimate for Dreadnoughtus. We find that 59 300 kg for Dreadnoughtus is highly implausible and demonstrate that masses above 40 000 kg require high body densities and expansions of soft tissue volume outside the skeleton several times greater than found in living quadrupedal mammals. Similar results from a small sample of other archosaurs suggests that lower-end mass estimates derived from scaling equations are most plausible for Dreadnoughtus, based on existing volumetric and density data from extant animals. Although volumetric models appear to more tightly constrain dinosaur body mass, there remains a clear need to further support these models with more exhaustive data from living animals. The relative and absolute discrepancies in mass predictions between volumetric models and scaling equations also indicate a need to systematically compare predictions across a wide size and taxonomic range to better inform studies of dinosaur body size.
Body mass is a key biological variable, but difficult to assess from fossils. Various techniques exist for estimating body mass from skeletal parameters, but few studies have compared outputs from different methods. Here, we apply several mass estimation methods to an exceptionally complete skeleton of the dinosaur Stegosaurus. Applying a volumetric convex-hulling technique to a digital model of Stegosaurus, we estimate a mass of 1560 kg (95% prediction interval 1082-2256 kg) for this individual. By contrast, bivariate equations based on limb dimensions predict values between 2355 and 3751 kg and require implausible amounts of soft tissue and/or high body densities. When corrected for ontogenetic scaling, however, volumetric and linear equations are brought into close agreement. Our results raise concerns regarding the application of predictive equations to extinct taxa with no living analogues in terms of overall morphology and highlight the sensitivity of bivariate predictive equations to the ontogenetic status of the specimen. We emphasize the significance of rare, complete fossil skeletons in validating widely applied mass estimation equations based on incomplete skeletal material and stress the importance of accurately determining specimen age prior to further analyses.
This chapter explores the axial skeleton from the perspective of pneumaticity and “efficiency of design.” It estimates that eusauropod vertebrae are in most cases between 50% and 60% air. Pneumatic ribs are part of a growing list of pneumatic characters that evolved in parallel in diplodocids and titanosauriforms, along with complex vertebral chambers and pneumatic caudal vertebrae. Furthermore, the characteristics of a single pneumatic bone are covered. The problem of estimating the masses of sauropods is used as an example of how information about postcranial skeletal pneumaticity (PSP) may be applied to a paleobiological question. Pneumatic diverticula were present in the vertebrae of most sauropods and in the ribs of some. Vertebral laminae and fossae were clearly associated with pneumatic diverticula in most eusauropods, but it is not clear whether this was the case in more basal forms.
Recent work on the Jurassic-Cretaceous transition of the Iberian Range (Spain) has opened a new window onto the interpretation of the trackmakers of some medium-sized tridactyl tracks. The ichnotaxon Therangospodus oncalensis has been described in the Huérteles Formation (Berriasian) and is one of the classical tracks from the area assigned to medium-sized theropods.
A review of the type locality of Therangospodus oncalensis (Fuentesalvo tracksite) and other tracksites from the Huérteles Formation (Berriasian) has yielded new information on the morphology, gait and trackmaker identity of the aforementioned ichnospecies. The new data suggest that the trackmaker is an ornithopod rather than a theropod on the basis of the length/width ratio, the anterior triangle length-width ratio, the short steps, the round to quadrangular heel pad impression and the probable manus impressions.
T. oncalensis shows similarities with various tracks from the Berriasian of Europe assigned to Iguanodontipus. The ichnotaxonomical status of this ichnospecies is here considered as Iguanodontipus? oncalensis due to the current state of knowledge of the ichnotaxonomy of medium-sized ornithopod tracks. This reassessment of I? oncalensis also has two significant implications for the palaeoecology of the faunas during the deposition of the Huérteles Formation: 1- the high number and percentage of theropod tracks would be lower than previous papers have suggested. 2- the gregarious behaviour described in the type locality (Fuentesalvo) would be among ornithopods instead of theropods.
Fossil discoveries from South Africa have greatly expanded knowledge of the development of life on Earth. In particular, the
enormous palaeontological wealth of the Karoo, covering a period of almost 100 million years from the Permian to the Jurassic,
has enhanced understanding of the evolution of important tetrapod lineages, including mammals and dinosaurs. These fossils
provide the best record of continental Permian to Jurassic faunal biodiversity, and have been crucial to studies of the global
Permo-Triassic mass extinction in the continental realm, as well as giving insight into other extinction events. Recent collaborative
interdisciplinary studies of stratigraphic and geographic distribution patterns of Karoo fossils have enhanced biostratigraphic
resolution and global correlation of vertebrate faunas from the Permian to the Jurassic. This in turn has led to a better
understanding of the biodiversity across Pangaea, and the places of origin and initial diversity of early tetrapod evolutionary
lineages. Many of these originated in the southern African portion of the Gondwanan super-continent. The combination of palaeontological
and sedimentological studies has led to new basin development models and solved problems which each discipline in isolation
could not have achieved.
The postcranial morphology of the early scylacosaurid therocephalian Glanosuchus macrops from the Pristerognathus Assemblage Zone of the Beaufort Group is described and compared with that of later therocephalians. This database is used as a basis to identify postcranial differences between therocephalians, gorgonopsians and cynodonts in an attempt to increase understanding of the postcranial anatomy of theriodont therapsids. It is demonstrated that some postcranial elements can be used to identify particular theriodont groups. The T-shaped interclavicle, absence of ossified sternum, humerus without shaft area, and large pubic foramen are characteristics of therocephalians from the Tapinocephalus Assemblage Zone of the Beaufort Group of South Africa.
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 bojani from the Late Triassic of Poland has been described. Using a regression formula based on long bone circumferences, an impressive body mass of 9.33 tons was reconstructed in the original description for this new and largest member of dicynodonts. The taxon is characterized by particularly robust long bones with very massive and stout shafts, thus raising the theoretical possibility that the regression
formulae may have led to a substantial overestimate of the body mass. Here we present a new body mass estimate for Lisowicia based on 3D digital volumetric models, aiming to provide a more reliable and conservative estimate. The new body mass ranges from 4.87 tons to 7.02 tons for the adult taxon, with an average body mass of 5.88 tons; thus, the original value of 9.33 tons overestimates the weight of about 60%. Our study confirms empirically that volumetric methods for body mass estimates should be preferred and implemented whenever possible. Synapsids still had to wait until the Eocene to reach
the enormous body mass of 9 tons.
In the present paper we provide a new estimate of the body mass (BM) of the dwarf elephant Palaeoloxodon ex gr. P. falconeri from Spinagallo cave (Sicily) at three different ontogenetic stages. The new estimates are based on 3D in-vivo restorations, digitally sculpted on anatomically updated photogrammetric models of the skeletons mounted at the Museo Universitario di Scienze della Terra (MUST), University of Rome (Italy). The new method provided an average BM of 249.98 Kg for the adult male, 150.47 Kg for the adult female, 38.81 Kg for the juvenile male, and 7.83 Kg for the new-born male. Assuming as reliable these estimates, the values previously obtained by applying the regression formulae based on pad circumferences, shoulder height and long bone circumferences substantially would underestimate or overestimate the Spinagallo elephant BM up to 103%. The results obtained indicate that the volumetric methods can be regarded as the most solid and reliable to estimate the BM in those extinct vertebrates for which accurate mounted skeletons are available. This new method is therefore of critical importance for inferring the BM of taxa characterised by peculiar osteological proportions, such as those shown by the insular dwarf elephant analysed in the present work.
Dinocephalians form an important component of the Guadalupian basal therapsid faunas of Pangaea. Most research undertaken on this clade has focused on the skull while postcranial research has lagged, largely because of the rarity of sufficiently complete specimens. The discovery of an almost complete skeleton of the basal tapinocephalid dinocephalian Tapinocaninus from the rocks of the lowermost Beaufort Group of South Africa for the first time provides an accurate vertebral count for a dinocephalian as well as morphological information on the appendicular skeleton. The long bones of Tapinocaninus pamelae are autapomorphic in several features within the dinocephalians, and the results enable discussion of some more general aspects of the appendicular skeleton of basal synapsids. Combined, the new data enable a new reconstruction of the posture of tapinocephalids. Although demonstrating several apomorphic characters, the skeleton retains pleisomorphic anatomical features previously known only in pelycosaur-grade synapsids, especially in the axial skeleton. The discovery greatly advances understanding of the postcranial morphology of tapinocephalid dinocephalians and will provide input on the enigmatic phylogenetic relationships of early therapsids.
Captorhinids are a speciose clade of sauropsids that are crucial to understand several aspects of basal amniote general biology. Members of the Captorhinidae explored different diets and, amongst basal amniotes, were one of the first groups to demonstrate high-fibre herbivory. Several papers have been published on the cranial anatomy of captorhinids, but there are relatively few studies which focus on the post-cranium, especially on the appendicular skeleton and long bones. This contribution presents the first quantitative long bone scaling in Captorhinidae performed through morphometric analyses. From classical biomechanical research, it is well-established that to accommodate an increase in size, gravity will result in elastic deformation of long bones. This outcome is especially significant in terrestrial tetrapods with a sprawling limb posture such as captorhinids, where great torsional stresses are applied to long bones, both during locomotion and in the resting phase. In this paper, we test whether the consistent evolutionary size increase in captorhinids led to major re-patterning in long bone structure as theoretically expected, based on the theory of elastic similarity. Morpho-metric analysis shows that, apart from a small positive allometry in the humerus, cap-torhinid long bones scale geometrically as body size increases. Thus, the predicted elastic similarity to maintain similar levels in peak stress with an increase in dimensions does not seem not to apply to long bone evolution in captorhinids. We propose that, as already observed experimentally in larger-bodied varanid lizards, large cap-torhinids could also mitigate size-related increases in stress by reducing femur rotation and increasing the percentage of the stride cycle during which the right hindfoot was on the ground (i.e. the duty factor). In this way, large captorhinids could avoid reaching peak stress thresholds by sacrificing speed during locomotion and without a substantial long bone re-patterning or postural change. □ Allometry, duty factor, locomotion, long bone scaling, Palaeozoic. Marco Romano ✉ [marco.romano@uniroma1.it], and Bruce Rubidge [bruce.rubidge@ wits.ac.za], Evolutionary Studies Institute (
The Torre del Porticciolo palaeontological locality (Alghero, northwest Sardinia, Italy) is important for having provided the skeletal remains of the first Permian basal synapsid from Italy, Alierasaurus ronchii, the largest late early Permian to early middle Permian non-therapsid synapsid known to date. Recently, other skeletal remains preliminarily attributed to a carnivorous non-therapsid synapsid were described from a second site, approximately from the same stratigraphic level within the Cala del Vino Fm. During the excavation of this second site, tetrapod tracks were found near Cala Viola, about 1 km from the first two sites. The new find represents the first ichnological record from the Permian of Sardinia. The ichnological analysis allowed the recognition of tetrapods presently not recognized, just on the base of skeletal remains. This new evidence sheds more light on the faunal diversity within the Cala del Vino Fm., which is one of the few examples in the Permian of Europe of a combined ichno-and body-fossil record. The tracks have been referred to as Merifontichnus, an ichnotaxon established from the uppermost portion of the Permian succession of the Lodève Basin in southern France. The new material is the first reliable occurrence of this ichnotaxon from Italy and would represent, to date, the oldest occurrence of the ichnogenus.
Here we describe a number of articulated teeth of a hybodont shark from Upper Jurassic
deposits of the Monte Nerone Pelagic Carbonate Platform, in the Umbria‐Marche‐Sabina
Palaeogeographic Domain (Northern Apennines, Central Italy). The material has been referred
to as Asteracanthus cf. A. magnus, a quite well‐known taxon already reported from Middle to
Upper Jurassic deposits of Europe. Teeth indicate an extreme crushing feeding behaviour,
suggesting as putative prey both infaunal and epifaunal hard‐shelled invertebrates dwelling
the sea‐floor, such as large bivalves, brachiopods, gastropods as well as vagile crustaceans.
The finding represents, to date, the first formal report of hybodont shark in the Umbria‐
Marche‐Sabina Domain, throwing further light on the ecology within Pelagic Carbonate Platform
settings, and on the occurrence of Asteracanthus in the Late Jurassic of the Western Tethys.
In this contribution we present the first material referable to hybodont shark from the Rosso
Ammonitico Formation (Umbria-Marche-Sabina Palaeogeographic Domain). Two teeth were
recovered isolated within Toarcian red marly-limestone (Bifrons Zone). The best-preserved tooth is
characterized by a general structure well in accord with the classic crushing dentition typical of
hybodont sharks within the Subfamily Acrodontinae. The gently domed occlusal surface of the
tooth does not show any trace of occlusal crest and of wrinkles, and is characterized by densely
pitted, finely reticulated ornamentation. The available characters allow a conservative classification
of the material at the genus level as Asteracanthus sp. The best-preserved tooth can be referred to
the most mesial area of the first row of lateral teeth, using as a reference the holotype of
Asteracanthus medius. The new material represents the earliest evidence of Asteracanthus and the
second one from the whole Northern Apennines (Central Italy), throwing new light on the dispersal
of the genus on the Jurassic Tethys.
Abstract About thirty human footprints made approximately 12,000 years B.P. inside the ‘Sala dei Misteri’ Cave of Básura near Toirano, Liguria, northern Italy, were studied by standard ichnological analysis. Eleven of the best-preserved tracks were examined further using morpho-classificatory and morphometric approaches, in order to estimate the minimum number of trackmakers; biometric measurements were also used to tentatively determine their physical characteristics (e.g., height and age). Results indicate at least three different producers, two youths and the third of tender age. Analysis of the data demonstrate the power of 3D, of landmark-based morphometrics, and the utility of methods of forensic anthropology in the determination of human footprints. The study of the number of trackmakers using the principal component analysis (PCA) on 'multi-trampling' surfaces could represent a model in the ichnological study of cave sites.
Body mass is a key parameter for understanding the physiology, biomechanics, and ecology of an organism. Within paleontology, body mass is a fundamental prerequisite for many studies considering body-size evolution, survivorship patterns, and the occurrence of dwarfism and gigantism. The conventional method for estimating fossil body mass relies on allometric scaling relationships derived from skeletal metrics of extant taxa, but the recent application of three-dimensional imaging techniques to paleontology (e.g., surface laser scanning, computed tomography, and photogrammetry) has allowed for the rapid digitization of fossil specimens. Volumetric body-mass estimation methods based on whole articulated skeletons are therefore becoming increasingly popular. Volume-based approaches offer several advantages, including the ability to reconstruct body-mass distribution around the body, and their relative insensitivity to particularly robust or gracile elements, i.e., the so-called ‘one bone effect.’ Yet their application to the fossil record will always be limited by the paucity of well-preserved specimens. Furthermore, uncertainties with regards to skeletal articulation, body density, and soft-tissue distribution must be acknowledged and their effects quantified. Future work should focus on extant taxa to improve our understanding of body composition and increase confidence in volumetric model input parameters.
Mediterranean dwarf elephants represent some of the most striking examples of phyletic bodysize
change observed in mammals and are emblematic of the ‘island rule’, where small mammals become
larger and large mammals dwarf on islands. The repeated dwarfing of mainland elephant taxa
(Palaeoloxodon antiquus and Mammuthus meridionalis) on Mediterranean islands provide a ‘natural
experiment’ in parallel evolution, and a unique opportunity to investigate the causes, correlates and
mechanisms of island evolution and body-size change. This thesis provides the first pan-Mediterranean
study that incorporates taxonomic and allometric approaches to the evolution of dwarf elephants,
establishing a framework for the investigation of parallel evolution and key morphological correlates of
insular dwarfism.
I show that insular dwarfism has evolved independently in Mediterranean elephants at least six
times, resulting in at least seven dwarf species. These species group into three, broad size-classes: ‘smallsized’
(P. falconeri, P. cypriotes and M. creticus), ‘medium-sized’ (P. mnaidriensis and P. tiliensis) and
‘large-sized’ (Palaeoloxodon sp. nov. and ‘P. antiquus’ from Crete). Size-shape similarities between
independent lineages from the east and central Mediterranean indicate that homoplasy is likely among
similar-sized taxa, with implications for the existence of meta-taxa. These homoplasies appear to result
from the exploitation of ontogenetic trajectories common to the Elephantidae, underpinning the evolution
of small size. Interspecific allometry between dwarf and full-sized species can be seen to result from
these common, but grade-shifted ontogenetic trajectories, and this may also be true of broader
macroevolutionary trends in the Proboscidea. These size-related grade-shifts suggest that similar, but
increasingly extreme, modifications of pre-natal development underpin the evolution of insular dwarfism
in elephants. By incorporating research into the morphology and ontogeny of teeth and post-crania in fullsized
extant and extinct elephants, this thesis provides new insights into insular dwarfism, elephant
systematics and elephant functional morphology and adaptation.
The endemic Pleistocene dwarf elephants from Sicily and Malta display numerous anatomical changes with respect to their putative mainland ancestor and contemporary Palaeoloxodon antiquus, including significant differences in the functional morphology of the astragalus-calcaneus. Here we describe the functional morphology of dwarf elephants from the Siculo-Maltese palaeo-archipelago, with a particular emphasis on Palaeoloxodon ex gr. P. falconeri from Spinagallo Cave (Hyblean plateau, Sicily). Interspecific comparisons across a wide spectrum of body mass indicate that a decrease in the mass of dwarf elephants was accompanied by a shift from mass being transmitted between the tibia-astragalus to relatively more mass being transmitted by the tibia-calcaneus. This is most evident in the calcaneus of small-bodied Palaeoloxodon ex gr. P. falconeri, which have a large and continuous tibio-fibular facet suggesting increased flexion in the ankle-joint. Synostosis between the distal tibia-fibula and the calcaneus' wide articular facet for the fibula in this species limited medio-lateral displacement of the astragalus-calcaneus relative to the tibia, suggesting possible evidence of 'low-gear' locomotion related to the very hilly topography of Sicily. Furthermore, differences in the functional morphology of the calcaneus between the similar-sized Palaeoloxodon sp. from Luparello Fissure (Palermo, Sicily), and Benghisa Gap (southern Malta) are possibly ecophenotypic, as a result of differing insular environments, or alternatively warrant a taxonomic revision of the material from Luparello Fissure.
A mathematical-computational method for determining the volume, mass, and center of mass of any bilaterally symmetric organism is presented. Cavities within the body of an organism such as lungs are easily accommodated by this method. Sagittal and frontal profiles, obtained from tracings of 'fleshed-out' skeletal reconstructions, are used to provide limits for defining transverse slices of the body. Any internal cavities are defined by their own sagittal and frontal profiles. The computations consist of mathematically slicing the body and any cavities into independent sets of transverse laminae and computing their masses, centroids, and moments with respect to the three coordinate axes. Further calculations produce the masses and the (x,y,z) coordinates for the centers of mass of the body, any cavities, and the body + cavities. Predicted body masses of large, extant mammals (elephant, giraffe, hippopotamus, and rhinoceros) are in close agreement with actual body masses. New, lower estimates for body masses of selected large dinosaurs, based on modern skeletal reconstructions, are also presented, along with numerical estimates of their centers of mass. This method is an improvement over earlier ones that relied on measuring displaced volumes of water or sand by scale models to estimate the masses, and suspending models by threads to estimate their centers of mass.
When the car ferry “Rethymnon” sails from Piraeus towards Crete one can already feel the strong endemic atmosphere of the island. Rethymnon itself is a beautiful historical town on Crete in an area containing many Pleistocene fossil mammal localities which have yielded endemic deer, elephants and murids. A striking thing on board the ferry are notices written in Japanese which suggest that the ship was probably not launched under the name Rethymnon and served in her earlier days on the Japanese islands. For a paleontologist this is a remarkable coincidence since the Pleistocene of Japan has also yielded unbalanced endemic faunas with a very uniform composition of elephant and deer like the fauna of Crete.
Arguments based on elastic stability and flexure, as opposed to the more conventional ones based on yield strength, require that living organisms adopt forms whereby lengths increase as the ⅔ power of diameter. The somatic dimensions of several species of animals and of a wide variety of trees fit this rule well.
It is a simple matter to show that energy metabolism during maximal sustained work depends on body cross-sectional area, not total body surface area as proposed by Rubner ( 1 ) and many after him. This result and the result requiring animal proportions to change with size amount to a derivation of Kleiber's law, a statement only empirical until now, correlating the metabolically related variables with body weight raised to the ¾ power. In the present model, biological frequencies are predicted to go inversely as body weight to the ¼; power, and total body surface areas should correlate with body weight to the ⅝ power. All predictions of the proposed model are tested by comparison with existing data, and the fit is considered satisfactory.
In The Fire of Life, Kleiber ( 5 ) wrote "When the concepts concerned with the relation of body size and metabolic rate are clarified, . . . then compartive physiology of metabolism will be of great help in solving one of the most intricate and interesting problems in biology, namely the regulation of the rate of cell metabolism." Although Hill ( 23 ) realized that "the essential point about a large animal is that its structure should be capable of bearing its own weight and this leaves less play for other factors," he was forced to use an oversimplified "geometric similarity" hypothesis in his important work on animal locomotion and muscular dynamics. It is my hope that the model proposed here promises useful answers in comparisons of living things on both the microscopic and the gross scale, as part of the growing science of form, which asks precisely how organisms are diverse and yet again how they are alike.
A giant caseid, Alierasaurus ronchii, gen. et sp. nov., is herein described, based on a partial postcranial skeleton
collected from the Permian Cala del Vino Formation (Alghero, Nurra, northwest Sardinia). Despite the highly conservative
morphology of ribs and vertebral material, typical of caseids, the very well-preserved foot elements show highly autapomorphic
features, warranting assignment of the specimen to a new genus. In particular, the fourth metatarsal is not short and
massive, as in other large caseids, and shows a distinct axial region. Finally, the claw-shaped ungual phalanges are autapomorphic
in being proportionately very short, with a strong double ventral flexor tubercle positioned very close to the proximal
phalangeal rim, and a distal end that is not spatulate, but rather subtriangular in transverse section. Principal component and
reduced major axis slope analyses, performed on 10 caseid specimens, suggest that the observed changes in overall shape of
metatarsal IV were mainly linked to the enormous body size reached by the Sardinian specimen.
Modern comparative methods allow the examination of the probable course of evolution in a lineage of lizards (family Varanidae, genus Varanus). Within this genus, body mass varies by nearly a full five orders of magnitude. The fossil record and present geographical distribution suggest that varanids arose over 65 million yr ago in Laurasia and subsequently dispersed to Africa and Australia. Two major lineages have undergone extensive adaptive radiations within Australia: one evolved dwarfism (subgenus Odatria, pygmy monitors), whereas the other Australian lineage (subgenus Varanus) remained large, and several of its members evolved gigantism. Body sizes of extant varanid species are plotted on a phylogeny, and probable sizes at ancestral nodes are inferred from those of their descendants. Felsenstein's method of phylogenetically independent contrasts, coupled with information on branch lengths, is exploited to identify several likely instances of relatively rapid evolution of body size, both between and within clades. Numerous questions about the evolution of size in this genus within a historical/geographical perspective remain to be answered.
Whether body size will increase or decrease in an evolving population depends on whether mean body size is larger or smaller than the optimum for the population. Cope's Rule, the generalization that most animal groups have evolved toward larger body size, cannot be explained by intrinsic advantages of large size. Rather, it is the tendency of groups to arise at small body size relative to their optima that produces the widely observed pattern of net size increase. The specialized nature of large species of a given body plan, required by problems of similitude, renders these forms unlikely potential ancestors for major new descendent taxa. The adaptive discontinuity that must be crossed for invasion of a new adaptive zone at large body size exists because of the need for descendent taxa to be specialized along new lines. These factors tend to restrict large-scale adaptive breakthroughs to small body sizes. Size changes probably tend to occur sporadically, during speciation events. Size increase is not inherently favored in speciation, but prevails during diversification because origin of a higher taxon at small body size concentrates many early species in the small size range. Nearly all diverse animal orders and classes, and many families and super-families, are composed of species whose body sizes are distributed as positively skewed histograms. The typical pattern of size change during diversification of such a group can be determined from time-series plots for fossil species of diversifying higher taxa. A major taxon normally arises at small body size relative to its potential size range, and a slightly skewed histogram is rapidly formed. The histogram may expand or contract slightly in the small size range as diversification proceeds, but spreads continually farther in a positive direction, to develop a strongly attenuated tail in the large size range. Skewing occurs very rapidly because possible increments of size change with speciation are not constant throughout a taxon's size range, but are a direct function of body size, so that early spreading of the range proceeds more rapidly in a positive direction than in a negative direction. Nearly always an increase in mean size results. Just as taxonomic and morphologic diversification approach limits as a group's potential adaptive zone is filled, the size-frequency plot approaches a limiting distribution. The attenuated right flank of a high-diversity distribution reflects not only well known ecological factors, but also the fact that structural specialization at large relative body size for a given higher taxon gradually limits the range of potential morphologies (and hence diversity). The left flank is often steeper even than that of a Gaussian distribution partly because the onset of factors determining minimum size limits tends to be abrupt. In the Aves and Mammalia, for example, the curve for metabolic rate versus size turns sharply upward in the 4-5 gram range. In both groups many species are only slightly larger than this size, but hardly any are smaller. For most highly diversified poikilothermous metazoan groups, the minimum space required for fundamental organ systems is abruptly limiting. The probabilistic explanation offered for Cope's Rule implies that the rule is more fruitfully viewed as describing evolution from small size rather than toward large size. Although his interpretation was erroneous, Cope himself adopted this viewpoint. Strangely, it has been abandoned by most modern workers who have analyzed Cope's Rule.
The Gonnesa Quaternary deposits have been cited since the end of the 19th century due to the discovery, during the construction of a railway, of an incomplete postcranial skeleton belonging to an endemic dwarfed elephant, afterward described by Major as a new species (“Elephas lamarmorae”Major, 1883). Although the remains have since been reported in the literature as coming from the aeolian deposits outcropping at Funtana Morimenta, the precise provenance of the findings and their chronostratigraphical setting remained uncertain. Taking into account the route of the now disused railway, the stratigraphical successions of the Morimenta area, and the fact that the elephant bones were actually collected during a number of excavations spanning several decades, the location of the fossiliferous site is most likely on the northeast end slope of Guardia Pisano hill (Gonnesa), where aeolianites correlate with the Funtana Morimenta Formation (FMF) outcrop. The FMF is supposed to predate the onset of the MIS 5e climatic event and the Tyrrhenian “Panchina” overlies equivalent deposits cropping out along the Gonnesa Gulf coast. Therefore, the hypothesis that the elephant remains found in the “Morimenta” area were retrieved from late Middle Pleistocene deposits cannot be ruled out. The anatomical features of the bones suggest they represent a single individual, perhaps partially exposed and damaged before the discovery. New evidence, including a thus far unpublished tusk fragment from the Guardia Pisano hill (Gonnesa), whose Schreger angles fall within the range of Mammuthus, supports the systematic attribution of the incomplete Morimenta skeleton to a dwarfed mammoth. The size reduction of this Sardinian dwarfed mammoth is discussed in light of body-mass changes undergone by insular endemic elephants.
Morphological features of the terminal phalanges of extinct tetrapods can be used to infer whether or not keratinous claws were present even though these structures are not preserved in the fossil record. Such features as dense vascularization grooves and foramina, and a general claw-like morphology, are present in some of the earliest fully terrestrial tetrapods, the Permo-Carboniferous synapsids. Early synapsids are represented by a rich fossil record that preserves the detailed anatomy of the terminal phalanges and allows for an examination of the early evolution of these structures in a well-resolved phylogenetic context. The pattern of change in the morphology of the terminal phalanges of five basal synapsids, Cotylorhynchus romeri, Varanops sp., Edaphosaurus boanerges, Haptodus garnettensis, and Dimetrodon limbatus, reveals a clear trend from a broad, flat, and spatulate morphology in the basal taxa to a tall, narrow, and curved structure. This trend in overall shape change does not reflect changes in feeding behaviour. The size and shape of the flexor tubercle appears to be a factor of size and function, rather than possessing a phylogenetically informative signal. The osteological features used to infer the presence of a keratinous sheath in the synapsids are also observed in the non-amniote taxon Diadectes absitus. This indicates that claws were not an amniote innovation and that they instead originated somewhere outside the crown group Amniota.