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[dinosaur] Dinosaur footprints from Mt. Pelmo in Italy + vertebrate tracks from Lesotho + Triassic fauna dates





Ben Creisler
bcreisler@gmail.com


Some recent papers for the Triassic and Early Jurassic:


Belvedere M., Franceschi M., Sauro F. & Mietto P. (2017)
Dinosaur footprints from the top of Mt. Pelmo: new data for Early Jurassic palaeogeography of the Dolomites (NE Italy). 
Bollettino della Società Paleontologica Italiana 56: in press.
http://paleoitalia.org/archives/bollettino-spi/92/vol-56-2-2017/


Dinosaur footprints from the Lower Jurassic of northeastern Italy are well known and, since the first discoveries in the early 1990s, many sites have been described. Tracks are mostly found in the peritidal limestones of the Calcari Grigi Group, deposited on the Trento carbonate platform, now cropping out in the Southern Alps. In 2011, a group of speleologists discovered a new tracksite in the Lower Jurassic Calcari Grigi Group exposed almost at the top of Mt. Pelmo (Dolomites), 3037 m above sea level. Footprints are generally poorly preserved, but it proved possible to recognise some tridactyl footprints with theropodian features (i.e., elongated digit III and narrow interdigital angle) and some possible quadruped tracks whose configuration resembles that of a sauropodomorph trackmaker. Careful examination of the depressions excludes their inorganic origin (chemical weathering). Despite the poor quality of the traces, the Pelmo site is significant because it is the most easterly site ever found on the Trento Platform and the only one which is located north of the Valsugana Fault. This fault system is a major alpine tectonic lineament that separates the classical successions of the Calcari Grigi Group in the Italian Prealps from those located in the Dolomites. Moreover, the discovery of the Pelmo tracks considerably expands the documented area of movement of Early Jurassic terrestrial vertebrates in the northern part of the Trento Platform, extending the size of the Early Jurassic megatracksites of the Southern Alps.


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Bordy E.M., Abrahams M. & Sciscio L. (2017)
The Subeng vertebrate tracks: stratigraphy, sedimentology and a digital archive of a historic Upper Triassic palaeosurface (lower Elliot Formation), Leribe, Lesotho (southern Africa). 
Bollettino della Società Paleontologica Italiana 56: in press.
http://paleoitalia.org/archives/bollettino-spi/92/vol-56-2-2017/


Dinosaur vertebrate body and ichnofossils are relatively abundant in the Upper Triassic-Lower Jurassic Elliot Formation (Stormberg Group, Karoo Supergroup) in the main Karoo Basin in southern Africa. Herein we present the results of our sedimentological, stratigraphical and ichnological investigations at a historic ichnosite in NE Lesotho that is among the first documented vertebrate track-bearing palaeosurfaces in southern Gondwana. After decades of neglect, the Subeng ichnosite is restudied in this paper in light of the advances in ichnological methods and the formalised stratigraphy of the Stormberg Group. Documentation of this ichnosite was conducted using a mix of field-based sedimentological and ichnological methods and photogrammetry, which collectively allowed us to place the site within the lowermost Elliot Formation (Upper Triassic). Our detailed palaeoenvironmental reconstruction, based on palaeocurrent measurements and sedimentary facies analysis of the host rocks, suggests that this diverse Upper Triassic assemblage of vertebrate ichnofossils, which is an integral part of the history of life on land just before the end-Triassic mass extinction event, formed near a shallow oxbow lake or drying up watering hole on the floodplain of a meandering river system. This water source attracted numerous bipedal and quadrupedal animals as attested by the presence of tridactyl, tetradactyl and pentadactyl tracks on the palaeosurface. We have also produced a photogrammetric digital 3D model (available online) of the Subeng ichnosite to serve as a digital replica and archive for further ichnological study. This digital documentation is important not only for the preservation of this rapidly eroding palaeosurface (situated in an active streambed), but also for the provision of a visually stimulating tool for community outreach and science education in rural African communities.

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LIU Jun, Jahandar RAMEZANI, LI Lu, SHANG Qing-Hua, XU Guang-Hui, WANG Yan-Yin, YANG Jia-Sheng (2017)
High-precision temporal calibration of Middle Triassic vertebrate biostratigraphy: U-Pb zircon constraints for the Sinokannemeyeria Fauna and Yonghesuchus.
Vertebrata PalAsiatica (advance  online publication)
http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201708/t20170808_4840462.html

Free pdf:
http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201708/P020170808385510262354.pdf

Tetrapod assemblages provide a useful means for global correlation of the terrestrial Triassic sedimentary deposits, but currently no reliable temporal framework has been achieved for the Middle Triassic tetrapod assemblages. Here we report U-Pb zircon chemical abrasion–thermal ionization mass spectrometry dates for five volcanic ashes interbedded with vertebrate fossils from the Ermaying and Tongchuan formations of China. Our results support a late Anisian age for the Sinokannemeyeria Fauna and an early Ladinian age for Yonghesuchus Fauna. It is now possible, through biostratigraphic correlation, to provide accurate ages to other Middle Triassic successions such as the Upper Cynognathus Assemblage Zone of the Karoo of South Africa, the Eryosuchus fauna of the Donguz Suite of Russia and the Karamayi Formation of Xinjiang, China. The base of Anisian (Lower/Middle Triassic boundary) should lie below the base of the Ermaying Formation in the Ordos Basin. 


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Mingsong Li, Yang Zhang, Chunju Huang, James Ogg, Linda Hinnov, Yongdong Wang, Zhuoyan Zou & Liqin Li (2017)
Astronomical tuning and magnetostratigraphy of the Upper Triassic Xujiahe Formation of South China and Newark Supergroup of North America: Implications for the Late Triassic time scale.
Earth and Planetary Science Letters (advance online publication)
doi: https://doi.org/10.1016/j.epsl.2017.07.015
http://www.sciencedirect.com/science/article/pii/S0012821X1730393X

Highlights

We report the first astronomically tuned magnetic polarity timescale (APTS) for the Xujiahe Formation of South China.
The Upper Triassic Xujiahe APTS verifies the Newark APTS of North America.
Age of the earliest dinosaur footprints in China is the middle Rhaetian (ca. 204 Ma).
Italian Rhaetian GSSP is projected to be within lower part of the Xujiahe Formation.

Abstract

The time scale of the Late Triassic Epoch has a divergence of age models, especially for the durations of competing definitions for its Rhaetian Stage (uppermost Triassic). The astrochronology derived from relative depth of lacustrine-bearing clastic successions and astronomically tuned geomagnetic polarity time scale (APTS) of the Newark Supergroup of eastern North America provides a basis for the Late Triassic time scale. However, the Newark APTS has been challenged regarding its age scale and completeness; therefore an independent astronomical-tuned magnetic polarity zonation is required to verify the upper Newark APTS reference scale. We compiled a 6.5 million year (myr) APTS with magnetic stratigraphy from four sections of the lacustrine-fluvial, dinosaur-track-bearing Xujiahe Formation in the Sichuan Basin of South China that also has dating from detrital zircons and regional biostratigraphy. Variations in natural gamma-ray and magnetic susceptibility that reflect variable continental weathering in the source regions of the Xujiahe Formation are paced by Milankovitch cycles, especially the 100-kyr short eccentricity and 405-kyr long eccentricity. The cycle-tuned magnetostratigraphy of the Xujiahe Formation is compared directly via the magnetic-polarity zones to the depth ranks of the Newark Supergroup that are indicative of relative depths of lacustrine facies. The Sichuan APTS indicates that there is no significant hiatus between the sedimentary succession and the basalt flows at the top of the Newark Supergroup. The Sichuan APTS is compatible with the magnetostratigraphy from the candidate Global Boundary Stratotype Section and Point (GSSP) for the Norian–Rhaetian boundary interval at the Pignola–Abriola of South Italy, but does not extend downward to the proposed GSSP in Austria associated with the longer Rhaetian option. The earliest dinosaur tracks in China are from the middle of this Xujiahe Formation, therefore are implied to be middle Rhaetian in age. This Sichuan APTS helps to resolve the controversy about the completeness and reliability of the Newark-APTS, and can be used in the future to verify if isotopic excursions in organic carbon recorded in the Italian sections that are proposed as possible secondary markers for a base-Rhaetian definition are global in nature.



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