Evidence of a preservational gradient in the skeletal taphonomy of Ichthyopterygia (Reptilia) from Europe

Beardmore, Susan R.; Furrer, Heinz

doi:10.1016/j.palaeo.2015.11.049

Cited by 20 publications

(13 citation statements)

References 33 publications

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“…To compare our observations obtained from the Temnodontosaurus sample with data compiled from the literature [ 9 ], we categorized the skeleton of each specimen into six anatomical units, modified from [ 13 ]: (1) skull, (2) anterior (cervical+dorsal) vertebral column, (3) posterior (sacral+caudal) vertebral column, (4) thoracic ribs, (5) pectoral girdle and forefin, (6) pelvic girdle and hind fin. We compared the relative frequency of pathologies per anatomical unit, in order to obtain an estimate of frequency of pathologies relative to the number of individuals preserved, as well as the type of pathology most represented in Temnodontosaurus .…”

Section: Methodsmentioning

confidence: 99%

Pathological survey on Temnodontosaurus from the Early Jurassic of southern Germany

et al. 2018

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Paleopathologies document skeletal damage in extinct organisms and can be used to infer the causes of injury, as well as aspects of related biology, ecology and behavior. To date, few studies have been undertaken on Jurassic marine reptiles, while ichthyosaur pathologies in particular have never been systematically evaluated. Here we survey 41 specimens of the apex predator ichthyosaur Temnodontosaurus from the Early Jurassic of southern Germany in order to document the range and absolute frequency of pathologies observed in this taxon as a function of the number of specimens examined. According to our analysis, most observed pathologies in Temnodontosaurus are force-induced traumas with signs of healing, possibly inflicted during aggressive interactions with conspecifics. When the material is preserved, broken ribs are correlated in most of the cases with traumas elsewhere in the skeleton such as cranial injuries. The range of cranial pathologies in Temnodontosaurus is similar to those reported for extinct cetaceans and mosasaurs, which were interpreted as traces of aggressive encounters. Nevertheless, Temnodontosaurus differs from these other marine amniotes in the absence of pathologies in the vertebral column, consistent with the pattern previously documented in ichthyosaurs. We did not detect any instances of avascular necrosis in Temnodontosaurus from southern Germany, which may reflect a shallow diving life style. This study is intended to provide baseline data for the various types of observed pathologies in large ichthyosaurs occupying the ‘apex predator’ niche, and potentially clarifies aspects of species-specific behavior relative to other ichthyosaurs and marine amniotes.

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Section: Methodsmentioning

confidence: 99%

Pathological survey on Temnodontosaurus from the Early Jurassic of southern Germany

et al. 2018

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“…Many reviews of Triassic (Camp, 1980;Hogler, 1992;Motani et al, 2008;Hu et al, 2011;Liu et al, 2014) and Early Jurassic marine reptiles (Benton and Taylor, 1984) report good preservation and a high degree of completeness and articulation of skeletal material. This record might be partially controlled by prevailing anoxic or dysoxic conditions in the bottom waters of many Mesozoic fossiliferous deposits (e.g., Middle Triassic Besano and Guangling Formations, Lower Jurassic Blue Lias and Posidonia Shale Formations), which precluded organism activity within the sediment, and prevented predation or scavenging of the carcasses on the sea bottom (Beardmore and Furrer, 2016). Evidence of advanced levels of disarticulation or bone degradation (Martill, 1985; sauropterygians, crocodilians, ichthyosaurs and fishes from the Middle Jurassic Oxford Clay Formation) is mostly attributed to physical factors (e.g., weathering on the seafloor).…”

Section: Biotic Factorsmentioning

confidence: 99%

Pliocene stratigraphic paleobiology in Tuscany and the fossil record of marine megafauna

Dominici

Danise

Benvenuti

2018

Earth-Science Reviews

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Tuscany has a rich Pliocene record of marine megafauna (MM), including mysticetes, odontocetes, sirenians and seals among the mammals, and six orders of sharks among the elasmobranchs. This is reviewed with respect to paleogeography and sequence-stratigraphy in six different basins. Conditions at the ancient seafloor are explored by means of sedimentary facies analysis, taphonomy and multivariate techniques applied to a large quantitative dataset of benthic molluscs. MM is rare or absent in most basins during the Zanclean, except in one basin, and most abundant in Piacenzian deposits in all six basins. MM occurs preferentially in fine-grained, shelfal highstand-deposits of small-scale depositional sequences, or at condensed horizons of the maximum flooding interval. It is rare in shallow marine paleonvironments and nearly absent in bathyal paleosettings. Paleogeographic and paleoecological evidence and a comparison with modern patterns of marine upwelling suggest that a wedge of nutrient-rich waters sustained in the offshore during the Pliocene a high biomass of primary producers and a community of apex consumers and mesopredators, similarly to the modern northwestern Mediterranean Sea, with a species-richness higher than the modern and a more complex trophic structure. The highest MM diversity coincides with the mid-Piacenzian warm period, suggesting that facies control does not obscure a link between climate and diversity. We underline however that not all marine environments were suitable for marine mammal preservation. Buoyant carcasses were preferentially dismembered and destroyed in high-energy shallow waters, with the possible exception of delta front deposits, where sudden sediment input occasionally buried pristine carcasses. We hypothesise that carcasses sunken on the seafloor below the shelf break underwent destruction through the activity of a whale-fall biota of modern type, specialised in the consumption of decomposing tissues, both soft and mineralised. A taphonomic window was left between storm wave base and the shelf break. Here water pressure is high enough to prevent the formation of decomposing gases and the resurfacing of carcasses, while the lack of a specialised whale-fall biota slows down bone degradation with respect to deeper settings. Sedimentation rate was high enough to cover skeletal material before its complete destruction. An estimate of paleobathymetries based on multivariate techniques suggests that the preferential depth for the inclusion of MM in the fossil record was 30-300 m. The results are compared with major Mesozoic and Cenozoic MM records worldwide. Available evidence suggests that the late Neogene radiation of large whales, true ecosystem engineers, and their size increase, triggered the radiation of a bone-eating fauna that hampered, and hampers, MM preservation in the deep sea. Stratigraphic paleobiology and an ecosystem-level approach deliver useful insights to the nature of the fossil record.

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“…Likewise, attrition attributable to weathering seems unlikely due to the low percentage of weathered elements (Table 4) and the similarity in preservation quality between large and small elements. If the carcasses experienced a bloat and float scenario, distal elements would be removed first, as seen in turtles [57], crocodiles [58], Ichthyopterygia [59], and Serpianosaurus [60]. This could account for the low recovery rate of distal appendage elements, but not for the low axial element recovery rate since the body core is assumed to be still intact.…”

Section: Plos Onementioning

confidence: 99%

Over 13,000 elements from a single bonebed help elucidate disarticulation and transport of an Edmontosaurus thanatocoenosis

Snyder¹,

McLain²,

Wood³

et al. 2020

PLoS ONE

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Over twenty years of work on the Hanson Ranch (HR) Bonebed in the Lance Formation of eastern Wyoming has yielded over 13,000 individual elements primarily of the hadrosaurid dinosaur Edmontosaurus annectens. The fossil bones are found normally-graded within a fine-grained (claystone to siltstone) bed that varies from one to two meters in thickness. Almost all specimens exhibit exquisite preservation (i.e., little to no abrasion, weathering, and breakage), but they are disarticulated which, combined with our sedimentological observations, suggests that the bones were remobilized and buried after a period of initial decay and disarticulation of Edmontosaurus carcasses. Because of the large number of recovered fossil elements, we have been able to gain deeper insight into Edmontosaurus biostratigraphy including disarticulation and transport of skeletal elements. The most common postcranial elements in the bonebed are pubes, ischia, scapulae, ribs, and limb bones. By contrast, vertebrae, ilia, and chevrons are rare. The most common craniomandibular bones include dentaries, nasals, quadrates, and jugals, whereas the premaxillae, predentaries, and braincase bones are underrepresented. Thus, overall, chondrocranial and axial elements, as well as distal elements of the limbs, are distinctly underrepresented. We hypothesize that following decay and disarticulation, hydraulic winnowing removed the articulated sections (e.g., vertebral columns) and the small, distal-most elements before, or at the same time, the remaining bones were swept up in a subaqueous debris flow that generated the deposit. Comparison of the HR Bonebed with other widely dispersed Upper Cretaceous hadrosaurid-dominated bonebeds reveals many shared attributes, which suggests similar processes at work in the formation of these bonebeds across space and time. This in turn reflects similar behavior by populations of these species around the world resulting in similar modes of death, becoming interred in similar depositional settings.

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Evidence of a preservational gradient in the skeletal taphonomy of Ichthyopterygia (Reptilia) from Europe

Cited by 20 publications

References 33 publications

Pathological survey on Temnodontosaurus from the Early Jurassic of southern Germany

Pathological survey on Temnodontosaurus from the Early Jurassic of southern Germany

Pliocene stratigraphic paleobiology in Tuscany and the fossil record of marine megafauna

Over 13,000 elements from a single bonebed help elucidate disarticulation and transport of an Edmontosaurus thanatocoenosis

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