Vertical sections through dinosaur tracks (Late Triassic lake deposits, East Greenland) - undertracks and other subsurface deformation structures revealed

Lethaia ◽  
2004 ◽  
Vol 37 (3) ◽  
pp. 285-296 ◽  
Author(s):  
JESPER MILÀN ◽  
LARS CLEMMENSEN ◽  
NIELS BONDE
2014 ◽  
Vol 35 (4) ◽  
pp. 541-552 ◽  
Author(s):  
Tomasz Sulej ◽  
Andrzej Wolniewicz ◽  
Niels Bonde ◽  
Błażej Błażejowski ◽  
Grzegorz Niedźwiedzki ◽  
...  

Abstract The Fleming Fjord Formation (Jameson Land, East Greenland) documents a diverse assemblage of terrestrial vertebrates of Late Triassic age. Expeditions from the turn of the 21st century have discovered many important fossils that form the basis of our current knowledge of Late Triassic Greenlandic faunas. However, due to the scarcity and incompleteness of the fossils and their insufficient study, our understanding of the taxonomic diversity of the Fleming Fjord Formation is hindered. Here, we report the preliminary findings of a Polish-Danish expedition to the Fleming Fjord Formation that took place in 2014. Three areas were visited – the fairly well known MacKnight Bjerg and Wood Bjerg and the virtually unexplored Liasryggen. MacKnigth Bjerg and Liasryggen yielded fossils which promise to significantly broaden our knowledge of vertebrate evolution in the Late Triassic. Stem-mammal remains were discovered at Liasryggen. Other fossils found at both sites include remains of actinopterygians, sarcopterygians, temnospondyl amphibians and various archosaurs (including early dinosaurs). Numerous vertebrate trace fossils, including coprolites, pseudosuchian footprints, theropod and sauropodomorph dinosaur tracks, were also discovered. Newly discovered skeletal remains as well as abundant trace fossils indicate higher tetrapod diversity in the Late Triassic of Greenland than previously thought. Trace fossils also allow inferences of early theropod and sauropodomorph dinosaur behaviour.


2018 ◽  
Vol 66 ◽  
pp. 21-46 ◽  
Author(s):  
Marco Marzola ◽  
Octávio Mateus ◽  
Jesper Milàn ◽  
Lars B. Clemmensen

This article presents a synthesis of Palaeozoic and Mesozoic fossil tetrapods from Greenland, including an updated review of the holotypes and a new photographic record of the main specimens. All fossil tetrapods found are from East Greenland, with at least 30 different known taxa: five stem tetrapods (Acanthostega gunnari, Ichthyostega eigili, I. stensioi, I. watsoni, and Ymeria denticulata) from the Late Devonian of the Aina Dal and Britta Dal Formations; four temnospondyl amphibians (Aquiloniferus kochi, Selenocara groenlandica, Stoschiosaurus nielseni, and Tupilakosaurus heilmani) from the Early Triassic of the Wordie Creek Group; two temnospondyls (Cyclotosaurus naraserluki and Gerrothorax cf. pulcherrimus), one testudinatan (cf. Proganochelys), two stagonolepids (Aetosaurus ferratus and Paratypothorax andressorum), the eudimorphodontid Arcticodactylus, undetermined archosaurs (phytosaurs and both sauropodomorph and theropod dinosaurs), the cynodont Mitredon cromptoni, and three mammals (Haramiyavia clemmenseni, Kuehneotherium, and cf. ?Brachyzostrodon), from the Late Triassic of the Fleming Fjord Formation; one plesiosaur from the Early Jurassic of the Kap Stewart Formation; one plesiosaur and one ichthyosaur from the Late Jurassic of the Kap Leslie Formation, plus a previously unreported Late Jurassic plesiosaur from Kronprins Christian Land. Moreover, fossil tetrapod trackways are known from the Late Carboniferous (morphotype Limnopus) of the Mesters Vig Formation and at least four different morphologies (such as the crocodylomorph Brachychirotherium, the auropodomorph Eosauropus and Evazoum, and the theropodian Grallator) associated to archosaurian trackmakers are known from the Late Triassic of the Fleming Fjord Formation. The presence of rich fossiliferous tetrapod sites in East Greenland is linked to the presence of well-exposed continental and shallow marine deposits with most finds in terrestrial deposits from the Late Devonian and the Late Triassic.


Science ◽  
2009 ◽  
Vol 324 (5934) ◽  
pp. 1554-1556 ◽  
Author(s):  
J. C. McElwain ◽  
P. J. Wagner ◽  
S. P. Hesselbo

Geologos ◽  
2016 ◽  
Vol 22 (3) ◽  
pp. 201-211 ◽  
Author(s):  
Renchao Yang ◽  
A.J. (Tom) van Loon ◽  
Wei Yin ◽  
Aiping Fan ◽  
Zuozhen Han

Abstract The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China). The flows and the resulting SSDS were probably triggered by earthquakes, volcanic eruptions, shear stress of gravity flows, and/or the sudden release of overburden-induced excess pore-fluid pressure. The tectonically active setting, the depositional slope and the high sedimentation rate facilitated the development of soft-sediment deformations, which consist mainly of load casts and associated structures such as pseudonodules and flame structures. Sediments with such deformations were occasionally eroded by slurries and became embedded in their deposits.


2021 ◽  
pp. 1-12
Author(s):  
Peter L. Falkingham ◽  
Susannah C. R. Maidment ◽  
Jens N. Lallensack ◽  
Jeremy E. Martin ◽  
Guillaume Suan ◽  
...  

Abstract Evidence of Late Triassic large tetrapods from the UK is rare. Here, we describe a track-bearing surface located on the shoreline near Penarth, south Wales, United Kingdom. The total exposed surface is c. 50 m long and c. 2 m wide, and is split into northern and southern sections by a small fault. We interpret these impressions as tracks, rather than abiogenic sedimentary structures, because of the possession of marked displacement rims and their relationship to each other with regularly spaced impressions forming putative trackways. The impressions are large (up to c. 50 cm in length), but poorly preserved, and retain little information about track-maker anatomy. We discuss alternative, plausible, abiotic mechanisms that might have been responsible for the formation of these features, but reject them in favour of these impressions being tetrapod tracks. We propose that the site is an additional occurrence of the ichnotaxon Eosauropus, representing a sauropodomorph trackmaker, thereby adding a useful new datum to their sparse Late Triassic record in the UK. We also used historical photogrammetry to digitally map the extent of site erosion during 2009–2020. More than 1 m of the surface exposure has been lost over this 11-year period, and the few tracks present in both models show significant smoothing, breakage and loss of detail. These tracks are an important datapoint for Late Triassic palaeontology in the UK, even if they cannot be confidently assigned to a specific trackmaker. The documented loss of the bedding surface highlights the transient and vulnerable nature of our fossil resources, particularly in coastal settings, and the need to gather data as quickly and effectively as possible.


1996 ◽  
Vol 42 ◽  
pp. 121-136
Author(s):  
D.V. Kent ◽  
L.B. Clemmensen

A 210 m section of Late Triassic Fleming Fjord Formation (the Malmros Klint Member and the lowermost 80m of the overlying Carlsberg Fjord beds of the Ørsted Dal Member) in the Tait Bjerg area of the Jameson Land Basin, East Greenland, was sampled for paleomagnetic study and measured for cycle stratigraphie analysis. Paleomagnetic samples were also taken from the underlying Gipsdalen Formation in the Gipsdalen area. A high stability characteristic magnetization carried by hematite was successfully isolated in 63 sampling levels in the Fleming Fjord Formation and 9 sampling sites in the Gipsdalen Formation using progressive thermal demagnetization. The mean characteristic directions for the Herning Fjord and the Gipsdalen Formations may be be biased by sedimentary inclination error but are consistent with a northward drift of East Greenland of about 10° from the arid (ca. 25° N) to semihumid (ca. 35° N) paleoclimatic belts in the Middle to Late Triassic. Seven normal and reversed polarity intervals are clearly delineated in the Fleming Fjord Formation section. A preferred correlation of the magnetostratigraphy to a cyclostratigraphically calibrated reference polarity sequence recently derived from drill cores in the Newark Basin of eastern North America suggests that the sampled interval represents about a 3.5 m.y. interval of the late Norian. The Malmros Klint Member and the overlying Carlsberg Fjord beds have composite sedimentary cycles that vary in thickness from 25 m to about 1 m and seem to match Milankovitch orbital climatic cyclicity with periods of ~400ky, ~100ky, ~40ky, and ~20ky. The composition and thickness ratio of the cycles suggest that the measured section of the Malmros Klint Member and the Carlsberg Fjord beds represents lacustrine accumulation over about 4 m.y., a duration consistent with the magnetostratigraphic correlations.


2016 ◽  
Vol 3 ◽  
pp. 1-32
Author(s):  
Brooks Britt ◽  
Daniel Chure

This field trip focuses on the Late Triassic-Early Jurassic transition in northeastern Utah. This transition records one of the most striking terrestrial environmental transformations in the history of North America, wherein the fluvio-lacustrine Chinle Formation is transgressed by the vast erg system of the Nugget (Wingate+Navajo)/Navajo/Aztec Sandstones. Exposures in northeastern Utah are ideal for studying this transition as they are closely spaced and accessible. The uppermost Chinle Formation beds are lacustrine/fluvial fine-grained sediments which are overlain by increasingly drier, sandy, transitional beds. The non-eolian basal beds of the Nugget Sandstone preserve a Late Triassic ichnofauna, with some sites including Brachychirotherium tracks. Large-scale dune deposits comprise most of the Nugget Sandstone and contain vertebrate (Brasilichnium) tracks and a diverse invertebrate ichnofauna. Interdunal, carbonate, spring mounds, as much as 3 m tall, fed carbonate freshwater lake deposits containing gastropod body fossils and invertebrate ichnofossils. Another lacustrine deposit, located at the Saints & Sinners Quarry, is on the shoreline of a non-carbonate interdunal lake/oasis. Over 11,500 bones have been collected from the site and represent two theropod dinosaur taxa, sphenodonts, sphenosuchians, a pterosaur, and drepanosaurs (with many complete, three-dimensional, articulated skeletons). In addition to bones, dinosaur trackways are also preserved in shoreline and other interdunal beds. The fauna shows that this interdunal area of the Nugget Sandstone was the site of intense biological activity. The drepanosaurs are chronologically significant in that they are restricted globally to the Late Triassic, indicating that at least the lower one-fourth to one-third of the formation is Late Triassic in age.


2018 ◽  
Vol 83 ◽  
pp. 194-206 ◽  
Author(s):  
David Javier Candia Halupczok ◽  
Maria Lidia Sánchez ◽  
Gonzalo Diego Veiga ◽  
Sebastián Apesteguía

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