Skeletons Of Reptiles Research Articles

Palynological and sedimentological implications of the sauropterygian Upper Triassic site of El Atance (Central Iberian Peninsula)

This study presents new palynological and sedimentological data concerning the Upper Triassic outcrop El Atance (Guadalajara province, Spain). This fossil site has provided a unique and unprecedented concentration of reptile skeletons from the Late Triassic in the Iberian Peninsula, which are almost complete, articulated and preserved in three dimensions. It is the type locality of the simosaurid nothosauroid Paludidraco multidentatus and the henodontid placodont Parahenodus atancensis, being the only species of these clades represented with some certainty in the Iberian record.Although these reptiles are often linked to shallow marine environments, little is known about the sedimentary environment where they became fossilized. Furthermore, to compare these remains with those from other areas of Europe, greater precision in their age assignment is necessary.The new palynological data provided in this study allows us to assign a precise age, in addition to other data such as a probable plant community, palaeoecology, and palaeoclimatic conditions. This information together with the geological and sedimentological data and the new isolated sauropterygian remains studied, allow a better understanding of the local palaeogeography and the evolutionary history of the vertebrates found in the El Atance fossil site.

The uniquely diverse taphonomy of the marine reptile skeletons (Sauropterygia) from the Lower Muschelkalk (Anisian) of Winterswijk, The Netherlands

Having provided dozens of articulated, and even more disarticulated skeletons of marine reptiles with varying degrees of completeness, the Middle Triassic fossil deposit of Winterswijk, The Netherlands, might be considered the richest within the entire Germanic Basin concerning associated and partially articulated remains. Aside from these remains, a high number of isolated bones are also found. Among the various marine reptile taxa, the pachypleurosaur Anarosaurus and the nothosaur Nothosaurus are the most common. The skeletons and remains show diverse disarticulation patterns. These patterns range from mostly complete articulated skeletons to clustered and isolated bones. Interestingly, a large number of isolated articulated limbs is found, a pattern which is not known from other marine localities. Although numerous reports have been made on the taxa from Winterswijk, the taphonomy of the locality still remains poorly understood. Here, a series of methods are used to describe the taphonomy of 327 marine reptile specimens from the locality of Winterswijk in a qualitative manner. Furthermore, it is tested whether biofilms such as microbial mats could have had an influence on the preferential preservation of several body regions. Upon investigation, it is concluded that the taphonomy of Winterswijk is very complex and indeed depends on various factors such as: current activity, microbial activity, and anatomical differences between taxa. Finally, a total of 12 recurring patterns were identified within the dataset, which could largely be explained by the aforementioned factors.

Mesozoic marine reptiles from Spitsbergen and their ecosystems

In the Mesozoic seas, the apex predators were reptiles. From the Arctic archipelago of Svalbard, the Spitsbergen Mesozoic Research Group has excavated numerous well preserved marine reptile skeletons in order to understand the biology of these animals and the environment they lived in. The work of eleven field seasons has made this one of the largest and most productive palaeontological research projects in the high Arctic world‐wide. The initial eight seasons focused on one of the richest occurrences of Late Jurassic—earliest Cretaceous (c. 150–139 Ma) marine reptiles in the world, and nearly sixty specimens have been collected, together with a diverse assemblage of invertebrates, some of which are associated with methane seeps. The last three seasons were spent investigating events further back in time, as Spitsbergen preserves the remains from some of the first marine reptile radiations in the wake of the most devastating extinction in the history of the Earth, at the Permian–Triassic boundary (c. 252 Ma).

THE FEATURES OF THE GEOLOGICAL STRUCTURE AND SEDIMENTATION OF THE EARLY CRETACEOUS SITE OF THE TERRESTRIAL VERTEBRATES OF SHESTAKOVO (KEMEROVO REGION, RUSSIA)

A new data on the geological structure, conditions of formation and faunal composition of the Early Cretaceous site of the terrestrial vertebrates by Shestakovo village (Kemerovo Region, Western Siberia) has been presented.The consolidated geological section has been constructed along the line Shestakovo-1 — Shestakovo-4 — Shestakovo-3 in which five lithologic members have been identified. A distribution of the vertebrates fauna taxons has been carried out along the selected lithologic members composing the Shestakovo series of the Ilek formation. A new data obtained during fieldwork in 2017 has made it possible to distinguish two main bony levels (lithologic members 3 and 5), which contain whole skeletons of reptiles. Lithofacies analysis has shown that the formation of the sites occurred under the conditions of the fluviolacustrine plain, where the channel, delta and floodplain facies were replaced by lake and lake-marshy facies, forming a series of sedimentation cycles. The latter are the evidence of the increase in the aridization of the climate upwards along the section. The given data calls into question previously expressed point of view about the coastal-marine or lagoon genesis of the Shestakovo series.

The vertebrates of the Anisian/Ladinian boundary (Middle Triassic) from Bissendorf (NW Germany) and their contribution to the anatomy, palaeoecology, and palaeobiogeography of the Germanic Basin reptiles

Systematically excavated bones are described from Bissendorf (Osnabrücker Bergland, north-western Germany). The bone bed in the compressus zone of the Ceratitenschichten (Meißner Fm, Upper Muschelkalk, Anisian/Ladinian boundary, Middle Triassic) was dated by ceratites. Sedimentologically, it is a bioclastic rudstone built mainly from Coenothyris vulgaris brachiopods, which were heavily compressed into a 3 mm thin layer. Parts of the bone bed and the following 15 cm of autochthonous mud were partially eroded synsedimentary by the compressus storm event. The material of the not-rich bone bed in the Germanic Upper Muschelkalk consists of isolated teeth or fin spines from five well-known shark species: Hybodus longiconus Agassiz, 1843, Acrodus lateralis Agassiz, 1837, Acrodus gaillardoti Agassiz, 1837, Palaeobates angustissimus Agassiz, 1838 and Polyacrodus polycyphus Agassiz, 1837. Teeth and scales from the teleosteans Gyrolepis sp, Dollopterus sp., Colobodus maximus, Quenstedt, 1835, C. frequens, Dames [Dames, W., 1888. Die Ganoiden des Deutschen Muschelkalkes. Palaeontologische Abhandlungen 4, 133–180] and Saurichthys sp. have been proved. Found were mostly vertebra centra and ribs, but also teeth and some other postcranial bones from the small pachypleurosaurs Anarosaurus sp. as well as mostly Neusticosaurus sp. These originated from adult and juvenile animals which indicates the primary habitat and populations of this region. Large marine nothosaur reptiles found include Nothosaurus cf. mirabilis Münster, 1834, and N. giganteus Münster, 1834. Proof of two placodonts is given thanks to Placodus gigas Agassiz, 1833 and Cyamodus sp. Finally, a tooth from the terrestrial lepidosaur Tanystrophaeus longibardicus (Bassani, 1866) is the northerly most sample found. The recorded fauna is well-known with complete skeletons of the described species from the northern Tethys (Mte. San Giorgio, Switzerland). The reptile skeletons are presented here in reconstruction. The bone bed composition in Bissendorf shows differences in the younger and more terrestrial mixed as well as the age difference in bone beds of northern ( enodis/posseckeri zone) and southern Germany ( dorsoplanus zone). At Bissendorf, only nearly complete marine vertebrates occur within the maximum high stand. High marine ichthyosaurs seem to be absent, indicating a shallow marine position in the western Germanic Basin.

Oxygen isotopes in phosphatic fish remains from Israel: Paleothermometry of tropical cretaceous and tertiary shelf waters

The isotopic composition of oxygen in phosphate was measured on 24 fossil fishes from Israel and Jordan ranging in age from Cretaceous to Eocene. From these, the first paleotemperatures were calculated for shallow water Cretaceous Paleotropics. The results were compared to those of fish from other Mediterranean localities and to Late Cretaceous marine reptiles from Israel. δ 18O in the fish average 18.0‰ in the Early Cretaceous, 17.8‰ in the Cenomanian, 18.3‰ in the Coniacian, 18.2‰ in the Santonian, 19.4‰ in the Campanian, 20.1‰ in the Maastrichtian and 18.4‰ in the Early Eocene. Such variations suggest a warm Cenomanian-Turonian, cooling towards the end of the Cretaceous, and warming up again in the Eocene. The deduced temperatures for the Cretaceous range between 20°C and 34°C, which is about 10° higher than Cretaceous water surface temperatures in Northern Europe. Apatite from marine reptile skeletons yields similar δ 18O to coexisting fish. The good agreement between these and previously known paleotemperature data give further credence to the validity of paleotemperatures obtained by isotopic analysis of oxygen in phosphates. The relatively large thermal gradient between middle and low paleolatitudes favors Barron's (1983) “coolest” Cretaceous model.

Further Evidence of the Affinity between the Dinosaurian Reptiles and Birds

O n my way to Birmingham, in October 1867, I chanced to meet with Prof. Phillips; and mentioning some palæontological inquiries, chiefly relating to the Ichthyosauria (with which I then happened to be occupied), he very kindly urged me, as I returned to London, to pay a visit to the collection under his charge in the University Museum at Oxford. I did so; but as we were traversing the museum towards the Ichthyosaurian cases, we stopped at that containing the Megalosaurian remains, and I may say with Francesca— It is indeed a wonderful collection, ample enough to occupy the working hours of many a day; and it was particularly attractive to me, as some difficulties in the organization of Megalosaurus and its allies had long perplexed me. As Prof. Phillips directed my attention to one after the other of the precious relics, my eye was suddenly caught by what I had never before seen, namely the complete pectoral arch of the great reptile, consisting of a scapula and a coracoid ankylosed together. Here was a tangle at once unravelled. The coracoid was totally different from the bone described by Cuvier, and by all subsequent anatomists, under that name. What then was the latter bone? Clearly, if it did not belong to the shoulder-girdle it must form a part of the pelvis; and, in the pelvis, the ilium at once suggested itself as the only possible homologue. Comparison with skeletons of reptiles and of birds, close at hand, showed it to be.