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Comparison of the body outline of Mauriciosaurus fernandezi and Dermochelys coriacea. A) Schematic outline reconstruction of Mauriciosaurus fernandezi CPC RFG 2544 P.F.1. based on soft tissue evidence in ventral aspect. Note that trunk and tail form a functional unit with a drop-shaped outline with the thickest diameter lying anterior to the mid-section of the body. B) Outline sketch of a Leatherback Turtle (Dermochelys coriacea). Note that the drop-shaped outline of the carapace strikingly resembles the trunk-tail complex of Mauriciosaurus.
Source publication
A nearly complete skeleton of a polycotylid
plesiosaur is described from
the early Late Cretaceous laminated
limestones at Vallecillo, northeast
Mexico. It shows extensive soft tissue
preservation. In some exceedingly
well preserved areas there are transversely
elongate rectangular to trapezoid
millimetric scale-like structures
arranged in longitud...
Context in source publication
Context 1
... anatomical features, and the fact that the thickest part of the trunk and tail unit lies in its an- terior third, suggest swimming speeds comparable to that of modern sea turtles. Among these, the leatherback (Dermochelys coriacea), the fastest swim- ming sea turtle, travels at an average velocity of about 7 kph (Eckert, 2002) and shows a hydrody- namic carapace, the outline of which strikingly re- sembles the body outline of Mauriciosaurus ( Figure 20). This swimming speed falls within the range of swimming speeds reconstructed for Mesozoic marine reptiles (Massare, 1988). ...
Citations
... The presence of a short medial anterior process in such a large (likely adult) specimen suggests the lack of a girdle bar (in this reinterpretation, a pelvic bar). In addition, typical features present in polycotylid coracoids, such as the perforations on the symphyseal margin (Sato 2005;Albright et al. 2007;Schmeisser-McKean et al. 2012), although absent in Plesiopleurodon wellesi Carpenter, 1996and Mauriciosaurus fernandezi Frey, Mulder, Stinnesbeck, Rivera-Sylva, Padilla-Gutiérrez & González-González, 2017(Frey et al. 2017Fischer et al. 2018), are not present. Therefore, the specimen CD 457 is considered a plesiosaur pubis. ...
Polycotylidae Cope, 1869 is a clade of short-necked plesiosaurians that achieved a cosmopolitan distribution by the Late Cretaceous. Here, the material previously referred to Polycotylidae/Pliosauridae from the Upper Cretaceous of New Zealand is reviewed, concluding that only 2.4% and 7.7% respectively of the total plesiosaurians specimens recovered in these formations (late Campanian-early Maastrichtian Tahora Formation and Campanian-Maastrichtian Conway Formation) belong to Polycotylidae. This proportion is similar to that recorded in upper Campanian-Maastrichtian levels of the Allen, Los Alamitos and La Colonia formations, northern Patagonia (Argentina) and southernmost Chile, but contrasts with the coeval absence of polycotylids in Campanian-Santonian levels of Antarctica and central Chile. These new results improve our knowledge about the representation of Weddellian polycotylids and underline the relative scarcity of Campanian-Maastrichtian records in the Weddellian Province.
... Measurements (Table 1) Centra are short, length being~60% height (Table 1). Cervicals are about as long as tall in Nichollssaura (Druckenmiller and Russell, 2008) and Brancasaurus (Sachs et al., 2016), but shorter than long in Leptocleidus superstes (Kear and Barrett, 2011), L. capensis (Andrews, 1911), L. clemai (Cruickshank and Long, 1997), and in Polycotylidae (Frey et al., 2017). Centra are platycoelous. ...
Plesiosaurs were a long-lived and widespread group of marine reptiles, with a worldwide distribution and a temporal range from the Late Triassic to the Late Cretaceous. Most occur in marine deposits, but some occur in low-salinity, brackish to freshwater environments. We report plesiosaurs from the freshwater fluvial deposits of the mid-Cretaceous (?Albian-Cenomanian) Kem Kem Group of Morocco. Remains include numerous shed teeth, vertebrae, and a humerus. The humerus represents a young juvenile; vertebrae likely belong to sub-adults. Teeth show heavy wear, similar to teeth of co-occurring spinosaurids. While coeval plesiosaurs from the Bahariya Formation of Egypt are members of Polycotylidae, the Kem Kem fossils show features of Leptocleididae, small-bodied plesiosaurs that were widely distributed in nearshore and non-marine settings in the Early Cretaceous. These fossils are the first freshwater plesiosaurs from Morocco, and are among the youngest representatives of Leptocleididae. The Kem Kem leptocleidids could have been infrequent visitors from the sea, freshwater-tolerant, or even freshwater-adapted, as in modern river dolphins. The abundance of shed teeth in the Kem Kem Group supports the hypothesis that they had some degree of freshwater tolerance. Furthermore, leptocleidids occur almost exclusively in shallow nearshore, brackish, or freshwater environments, suggesting adaptation to shallow, low-salinity environments. Other plesiosaur groups and other Mesozoic marine reptiles, including teleosaurids and mosasaurids, also occur in freshwater settings, suggesting plesiosaurs and other marine reptiles frequently exploited non-marine environments.
... These extremely rich deposits of well-preserved fossils, known as Lagerstätten, have enriched our view of evolution, revealing a plethora of new vertebrates (figures 1 and 2), invertebrates, plants and fungi [34][35][36][37]. These exposures yield tantalizing examples of fossil preservation, including several soft-tissue instances [25,[38][39][40][41]. Most of the published research output on fossils from these regions, however, has been led by foreign palaeontologists with the limited involvement of local researchers. ...
... Several published fossils lack contextual geographical and geological information, while many important specimens are in private or foreign collections, where they can be difficult to access. Recent publications describing new fossil species such as the plesiosaur Mauriciosaurus fernandezi [25] (figure 1e) and the shark Aquilolamna milarcae [32] (figure 1f ) from the Agua Nueva Formation (Sabinas Basin), Mexico as well as the snake-like reptile Tetrapodophis amplectus [27] (figure 2f ) and the dinosaur 'Ubirajara jubatus' [26] [25]. ( f ) Holotype of Aquilolamna milarcae [32]. ...
... Several published fossils lack contextual geographical and geological information, while many important specimens are in private or foreign collections, where they can be difficult to access. Recent publications describing new fossil species such as the plesiosaur Mauriciosaurus fernandezi [25] (figure 1e) and the shark Aquilolamna milarcae [32] (figure 1f ) from the Agua Nueva Formation (Sabinas Basin), Mexico as well as the snake-like reptile Tetrapodophis amplectus [27] (figure 2f ) and the dinosaur 'Ubirajara jubatus' [26] [25]. ( f ) Holotype of Aquilolamna milarcae [32]. ...
Scientific practices stemming from colonialism, whereby middle- and low-income countries supply data for high-income countries and the contributions of local expertise are devalued, are still prevalent today in the field of palaeontology. In response to these unjust practices, countries such as Mexico and Brazil adopted protective laws and regulations during the twentieth century to preserve their palaeontological heritage. However, scientific colonialism is still reflected in many publications describing fossil specimens recovered from these countries. Here, we present examples of ‘palaeontological colonialism’ from publications on Jurassic–Cretaceous fossils from NE Mexico and NE Brazil spanning the last three decades. Common issues that we identified in these publications are the absence of both fieldwork and export permit declarations and the lack of local experts among authorships. In Mexico, access to many fossil specimens is restricted on account of these specimens being housed in private collections, whereas a high number of studies on Brazilian fossils are based on specimens illegally reposited in foreign collections, particularly in Germany and Japan. Finally, we outline and discuss the wider academic and social impacts of these research practices, and propose exhaustive recommendations to scientists, journals, museums, research institutions and government and funding agencies in order to overcome these practices.
... Pliosaurier (Pliosauridae) stellen einen Hauptzweig der in Jura und Kreidezeit so bedeutsamen Plesiosaurier dar. Die völlige Anpassung an das Leben im Meer brachte eine weitgehende Reduktion des Schuppenkleids mit sich (Vincent et al. 2017;Frey et al. 2017). Urtümlichere Pliosaurier, die mit ihren langen Hälsen dem klassischen Bild eines Plesiosauriers gleichkommen, gerieten nach dem Mitteljura in eine Phase des Niedergangs (Benson & Druckenmiller 2013;Foffa et al. 2018). ...
... Such remains are sparse for other groups. However, a few significant fossils, like the holotype of the polycotylid Mauriciosaurus fernandezi (Frey et al., 2017) and a specimen of the mosasaur Prognathodon (Lindgren, Kaddumi & Polcyn, 2013) strongly indicate that plesiosaurs and mosasaurs were also highly streamlined. Blubber (i.e. ...
... fatty hypodermal deposits) is present in many living aquatic tetrapods (Parry, 1949;Davenport, Holland & East, 1990), sculpting the body contour for drag reduction and providing thermal insulation (Hashimoto et al., 2015). The soft tissue distribution around the body and tail of M. fernandezi led Frey et al. (2017) to suggest the presence of blubber-like deposits in plesiosaurs and, more recently, histochemical and biochemical evidence of blubber has been identified in the ichthyosaur Stenopterygius (Lindgren et al., 2018). ...
... The reduction of integumentary structures occurred in a few very specialised aquatic reptiles. For example, a loss of osteoderms has been reported for thalattosuchians (Chiarenza et al., 2015), and in ichthyosaurs and plesiosaurs, current evidence suggests that scales were absent (Lindgren et al., 2018) or had simplified designs (Frey et al., 2017). Skin compliance and elasticity can potentially reduce drag by absorbing energy perturbations of the flow field, however these properties are very difficult to infer from fossils. ...
The colonisation of freshwater and marine ecosystems by land vertebrates has repeatedly occurred in amphibians, reptiles, birds and mammals over the course of 300 million years. Functional interpretations of the fossil record are crucial to understanding the forces shaping these evolutionary transitions. Secondarily aquatic tetrapods have acquired a suite of anatomical, physiological and behavioural adaptations to locomotion in water. However, much of this information is lost for extinct clades, with fossil evidence often restricted to osteological data and a few extraordinary specimens with soft tissue preservation. Traditionally, functional morphology in fossil secondarily aquatic tetrapods was investigated through comparative anatomy and correlation with living functional analogues. However, in the last two decades, biomechanics in palaeobiology has experienced a remarkable methodological shift. Anatomy-based approaches are increasingly rigorous, informed by quantitative techniques for analysing shape. Moreover, the incorporation of physics-based methods has enabled objective tests of functional hypotheses, revealing the importance of hydrodynamic forces as drivers of evolutionary innovation and adaptation. Here, we present an overview of the latest research on the locomotion of extinct secondarily aquatic tetrapods, with a focus on amniotes, highlighting the state-of-the-art experimental approaches used in this field. We discuss the suitability of these techniques for exploring different aspects of locomotory adaptation, analysing their advantages and limitations and laying out recommendations for their application, with the aim to inform future experimental strategies. Furthermore, we outline some unexplored research avenues that have been successfully deployed in other areas of palaeobiomechanical research, such as the use of dynamic models in feeding mechanics and terrestrial locomotion, thus providing a new methodological synthesis for the field of locomotory biomechanics in extinct secondarily aquatic vertebrates. Advances in imaging technology and three-dimensional modelling software, new developments in robotics, and increased availability and awareness of numerical methods like computational fluid dynamics make this an exciting time for analysing form and function in ancient vertebrates.
... Fossils are abundant in this sediment and marine reptiles (e.g. Buchy et al., 2005Buchy et al., , 2007Frey et al., 2017) but especially fishes (e.g. Giersch, 2014;Stinnesbeck et al., 2019Stinnesbeck et al., , 2020Vullo et al., 2021) are regularly found by quarry workers and yield an excellent preservation of soft tissues. ...
The Turonian plattenkalk of Vallecillo (Mexico) yielded two large-sized gladiuses of octobrachian coleoids. The specimens determined as Boreopeltis ifrimae sp. nov. are both classified as members of the suborder Prototeuthina and represent the first coleoids from the Turonian of Mexico. Belemnoid coleoids are still unknown from Late Cretaceous localities in Mexico. Boreopeltis ifrimae sp. nov. is the youngest representative of its genus. The occurrence of Boreopeltis in the northwestern Gulf of Mexico suggests a worldwide distribution in cold to warm temperate waters. The gladius (mantle) length of both specimens is remarkable and measures 470mm, respectively. A general trend towards large and very large-sized coleoids is identified during the Late Cretaceous and began in the Turonian, as indicated by taxa from the southern Western Interior and the northern Gulf of Mexico. This gradual increase in octobrachian body sizes may reflect a commencing escalation in the arms race between coleoids, fishes, and marine reptilians.
... Distally, both bones are increasingly dorsoventrally flattened and pre-axially to post-axially expanded (Andrews 1910) (Fig. 4c, d, g, h). How humeri and femora expand distally may vary across taxa: Sometimes the pre-axial margin is rather straight and the post-axial margin is expanded and curved post-axially (Druckenmiller and Russell 2008;Schumacher and Martin 2015;Delsett et al. 2016;Sachs et al. 2016) (Fig. 6a, d), sometimes the both the pre-and post-axial margin are expanded and curved pre-axially and post-axially (Hawkins 1840;Andrews 1910;Großmann 2006;Frey et al. 2017). The degree of expansion may also vary (Hawkins 1840;Andrews 1910;Großmann 2006;Druckenmiller and Russell 2008;Schumacher and Martin 2015;Delsett et al. 2016;Sachs et al. 2016;Frey et al. 2017) (Fig. 6b, c, e, g). ...
... How humeri and femora expand distally may vary across taxa: Sometimes the pre-axial margin is rather straight and the post-axial margin is expanded and curved post-axially (Druckenmiller and Russell 2008;Schumacher and Martin 2015;Delsett et al. 2016;Sachs et al. 2016) (Fig. 6a, d), sometimes the both the pre-and post-axial margin are expanded and curved pre-axially and post-axially (Hawkins 1840;Andrews 1910;Großmann 2006;Frey et al. 2017). The degree of expansion may also vary (Hawkins 1840;Andrews 1910;Großmann 2006;Druckenmiller and Russell 2008;Schumacher and Martin 2015;Delsett et al. 2016;Sachs et al. 2016;Frey et al. 2017) (Fig. 6b, c, e, g). Further, it is possible that the femur and humerus have approximately the same shape or they may differ (Hawkins 1840;Großmann 2006;Schumacher and Martin 2015;Sachs et al. 2016) (e.g., Fig. 6a, e). ...
... Radius, ulna, tibia, and fibula are shortened and may diverge from the hourglass long-bone shape they have in basal Eosauropterygia (Rieppel 2000) becoming more rounded and disc-like (Andrews 1910;O'Keefe 2002;Großmann 2006;Sato et al. 2006;Druckenmiller and Russell 2008;Schumacher and Martin 2015;Sachs et al. 2016;Frey et al. 2017) (Fig. 5b, c). Often, accessory ossicles are present at the level of the zeugopodium or carpus/tarsus on the side of humerus or femur which is flared (Andrews 1910;Sato and Storrs 2000;Großmann 2006;Sato et al. 2006;Smith 2007;Druckenmiller and Russell 2008;Schumacher and Martin 2015;Sachs et al. 2016;Frey et al. 2017) (Fig. 6a-g). ...
The terrestrial origins of the diapsid Sauropterygia and Testudines are uncertain, with the latter being highly controversially discussed to this day. For only 15 Ma, Nothosauroidea lived in shallow-marine seas of the Triassic. Contrastingly, the pelagic Plesiosauria evolved in the Late Triassic, dispersed globally, and inhabited the oceans of the Jurassic and Cretaceous for approximately 135 Ma. Since the Cretaceous (~ 100 Ma), Chelonioidea, the modern sea turtles, have populated the oceans. All three groups evolved aquatic paraxial locomotion. Nothosaurs swam with their foreflippers, supported by the swimming tail. Plesiosaurs are the only tetrapods to have ever evolved four hydrofoil-like flippers. The plesiosaur flipper beat cycle has been debated for nearly two centuries. The different proposed locomotory styles (rowing, rowing-flight, underwater flight) are discussed in this review. A fourth gait that is employed by Carettochelys insculpta , which combines rowing and flying, is introduced. The osteology of the locomotory apparatus of nothosaurs and plesiosaurs is reviewed and compared to that of extant underwater-flying Chelonioidea. In conclusion, underwater flight remains the favoured locomotory style for plesiosaurs. Also, the review reveals that nothosaur locomotion has largely remained unstudied. Further, our understanding of joint morphologies and mobilities of the foreflipper in nothosaurs, plesiosaurs, and even recent sea turtles, and of the hindflipper in plesiosaurs, is very limited. It is crucial to the discussion of locomotion, to find out, if certain limb cycles were even possible, as evidence seems to point to the improbability of a rowing motion because of limited humerus and femur long axis rotation in plesiosaurs.
... Porém, em todos esses trabalhos não foi possível identificar se tais tecidos realmente continham moléculas orgânicas. Estruturas dérmicas de plesiossauros são raramente preservadas porque tais animais provavelmente tinham um tecido adiposo subdérmico e uma epiderme muito fina (Frey et al., 2017); o processo de putrefação do tecido adiposo subdérmico levaria rapidamente a uma delaminação e perturbação da epiderme fina. ...
... Médio-Superior, no arquipélago ártico da Noruega (Kihle et al., 2012). A presença em plesiossauros de biomoléculas orgânicas originais tem sido explicada a partir do processo de mineralização diagenética precoce no qual o fechamento imediato da carcaça fresca por sedimentos macios e embebidos em água funcionaria como uma câmara selada (Frey et al., 2017). Neste microambiente, o tecido associado a uma camada adiposa promoveria reação química por meio da qual o tecido adiposo poderia se saponificar em cera mortuária ou adipócito, que por sua vez auxiliaria na conservação da epiderme fina da pele do animal. ...
... Discussões recentes sobre sua história evolutiva têm sugerido que seus corpos planos parecem ter evoluído independentemente múltiplas vezes(Delsett et al., 2019).Apesar de numerosos esqueletos completos e totalmente articulados terem sido descobertos ao longo dos anos, permitindo aos pesquisadores compreenderem mais sobre seu estilo de vida, pouco se sabe sobre sua biologia, por exemplo, cor, fisiologia e metabolismo (O'Keefe e Carrano, 2005; O'Keefe e Chiappe, 2011). Isso porque são raros os achados de tecidos moles e biomoléculas no registro fóssil da Plesiosauria(Frey et al., 2017).A literatura relata descobertas, na pedreira de Holzmaden, Alemanha, de uma substância negra com borda delgada flexível, que parecia ser remanescente de tecidos moles originais, localizada em nadadeiras anteriores da espécie Hydrorion ...
In the last few decades, several studies have found exceptional preservation of different original biomolecules in dinosaurs. However, distinct groups of reptiles that dominated airs, seas and oceans in the Mesozoic Era, such as pterosaurs, ichthyosaurs, mosasaurs, notosaurs and plesiosaurs, present scarce data regarding nonmineralized biomaterialsfindings and those that have already been identified are dispersed in the literature, associating the idea of discoveries with isolated phenomena. Thus, this article presents a review of the literature published in the last twodecades, in order to better understand the frequency of claimed non-mineralized biomaterialsfindings in fossils of reptiles from the Pterosauria clade and marine reptiles from the Lepidosauromorpha clade of the Mesozoic Era, often mistaken for dinosaurs by the popular imaginary. The results identified 3 studies describing preserved organic material for representatives of Pterosauria. For marine reptiles of the Lepidosauromorpha clade, were found 8studies, with findings distributed amongthe Ichthyosauria, Mosasauria, Nothosauroidea and Plesiosauria. In general, the data for such groups were not geographically and taxonomically comprehensive in Mesozoic rocks. However, it is believed that the frequency is underreported, and from the emergence of new technologies, the forecast is that fossil biochemistry will be more frequently characterized.
... The anterior surface of each ramus has a broad, shallow groove which receives the posteromedial surface of each first lateral element. We interpret the median element as likely belonging to the anterior gastral rib sequence, as the angle between the rami is typically smaller in more posterior median elements (Frey et al., 2017). The angle between the rami of another, partial median gastralium (Fig. 7H) is more acute, suggesting that it may have been situated posteriorly. ...
... One of the right elements appears to have been situated posterior to the left elements, suggesting that at least seven rows of gastralia were originally present. This gastral rib count compares with that of the rhomaleosaurid Macroplata (Ketchum & Smith, 2010), but exceeds that of the polycotylid Mauriciosaurus (six; Frey et al., 2017), the leptocleidid Nichollsaura (six; Druckenmiller & Russell, 2008a), and the pliosaurid Peloneustes (six; Andrews, 1913). Increased gastral rib rows are known in the pliosaurid Thalassiodracon (eight; Smith, 2007), the cryptoclidid Cryptoclidus oxoniensis (eight; Brown, 1981), the pliosaurid Hauffiosaurus zanoni (eight to 10; Vincent, 2011), the rhomaleosaurid Atychodracon (Smith, 2007(Smith, , 2015, Plesiosaurus dolichodeirus (at least nine; Storrs, 1997), the rhomaleosaurid Meyerasaurus (10; Smith & Vincent, 2010), Callawayasaurus (11;Welles, 1962), the rhomaleosaurid Rhomaleosaurus thorntoni (estimated to be 11 or 12; Smith, 2007), and Pachycostasaurus (23; Cruickshank, Martill & Noè, 1996). ...
... We reconstructed the holotype skeleton of Fluvionectes sloanae (Fig. 2B) by situating the first pectoral vertebra dorsal to the anterior half of the scapula based on comparisons with the articulated remains of Albertonectes (Kubo, Mitchell & Henderson, 2012), Hydrotherosaurus (Welles, 1943), and Mauriciosaurus (Frey et al., 2017). The acetabulum was located at the dorsal-sacral vertebral transition as in Mauriciosaurus (Frey et al., 2017). ...
Elasmosaurid plesiosaurian remains have been documented from non-marine to paralic (fluvial to estuarine) sediments of the upper Campanian Dinosaur Park Formation (DPF) of southern Alberta since 1898. Despite this long collection history, this material has received relatively little research attention, largely due to the highly fragmentary nature of most recovered specimens. However, this assemblage is significant, as it constitutes a rare occurrence of plesiosaurian remains in a non-marine depositional environment. This study reports on a recently collected and prepared specimen, which represents the most complete elasmosaurid yet collected from the DPF. This specimen preserves the trunk region, the base of the neck and tail, a partial fore and hind limb, and tooth, and is sufficiently complete to be assigned as the holotype of a new genus and species. This new taxon is diagnosed by a distinctive character state combination including a boomerang-shaped clavicular arch with acute anterior process, convex anterolateral margin, deeply embayed posterior margin, and pronounced ventral keel, together with the presence of 22 dorsal vertebrae, and the anterior dorsal centra bearing a ventral notch. The DPF plesiosaurian fossils were recovered from both estuarine/bay and fluvial palaeochannel sediments. The holotype skeleton represents an osteologically mature individual with an estimated body length of around 5 m, although the largest referred DPF elasmosaurid might have been closer to 7 m, which is considerably larger than other plesiosaurians reported from non-marine deposits. This suggests small-body lengths relative to typical elasmosaurids from marine settings, but is consistent with other plesiosaurians recovered from non-marine sediments. The identification of a distinct elasmosaurid taxon in the DPF might be evidence of niche-partitioning among the predominantly oceanic members of the ubiquitous plesiosaurian clade.
... Cenozoic mammals, most dramatically cetaceans, lost their fur and evolved a smooth, highly streamlined skin (Themudo et al., 2020). This adaptation was somewhat paralleled by the Mesozoic ichthyosaurs (Fraas, 1888;Lingham-Soliar and Plodowski, 2007;Renesto et al., 2020) and plesiosaurus (Frey et al., 2017;Vincent et al., 2017), which lost the scaly integument of their terrestrial reptile ancestors in favor of smooth skin. Not all marine reptile groups became scaleless, however. ...
... Given horizontal undulation in the ancestors of metriorhynchids, we predict the prevalent plane of motion for the fluke in this group to be dorsal/frontal. Frey et al. (2017) reported a new plesiosaurian specimen (holotype of Mauriciosaurus fernandezi) with extensive soft tissue preservation including a very broad horizontal soft tissue apron around the proximal tail. Further observations included: soft tissue aprons also occurring at the rear edge of the flippers, which may not have been fully covered with scales; skin surface characterized by crossed lines of small scales (square coordination); trunk integument exhibiting longitudinal rows of fine, transversely rectangular units, interpreted as scales; hip region including some larger scales; and adipocere deposition. ...
