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Taphonomy of Upper Triassic prosauropod dinosaur beds at Trossingen, Germany



Ben Creisler
bcreisler@gmail.com


A new online paper:



Rainer R. Schoch & Dieter Seegis (2014)
Taphonomy, deposition and pedogenesis in the Upper Triassic dinosaur
beds of Trossingen.
Palaeobiodiversity and Palaeoenvironments (advance online publication)

DOI: 10.1007/s12549-014-0166-8
http://link.springer.com/article/10.1007/s12549-014-0166-8

The Upper Norian (Late Triassic) red-beds of the Knollenmergel
(Trossingen-Formation) are famous for their richness in prosauropod
dinosaurs. Among the most productive localities, the Obere Mühle
(Rutschete) at Trossingen (SW Germany) stands out for the large number
of skeletons found in the early 20th century and the wide
stratigraphic range of finds within a 12-m sequence of monotonous
floodplain mudstones. New excavations at the original site have been
carried out since 2007, aimed at securing taphonomic, sedimentological
and palaeopedological data on the formation of the deposit. Based on
the findings of the present and earlier excavations, the following
conclusions can be drawn. (1) The Obere Mühle yields at least two
different types of vertebrate lagerstaetten: (1) miring deposits,
preserving numerous articulated skeletons in “life-like” postures and
all stages of subsequent decomposition and (2) more regular sheet
flood deposits, producing only a few skeletons (e.g. turtles), which
were disarticulated into body parts and single elements, or in
bonebeds. (2) The deposits were laid down in numerous successive
cycles of sedimentation, interrupted by pedogenic phases. A broad
range of pedologic features is recognised, leading to the
interpretation of the deposits as paleo-vertisols and aridisols. This
indicates a long depositional history for the whole section,
interrupted by arid phases in which few vertebrates were preserved and
life was probably less rich. (3) The occurrence of vertebrate
skeletons correlates with more humid periods and traces of intense
vegetation. (4) Weathering played a significant role in some beds of
the Trossingen section. The absence of smaller tetrapods could be
caused by intense weathering.

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Another recent paper about Triassic in Germany that may be of interest:



Gregor Barth, Matthias Franz, Carmen Heunisch, Evelyn Kustatscher,
Detlev Thies, Jürgen Vespermann & Markus Wolfgramm (2014)
Late Triassic (Norian-Rhaetian) brackish to freshwater habitats at a
fluvial-dominated delta plain (Seinstedt, Lower Saxony, Germany).
Palaeobiodiversity and Palaeoenvironments (advance online publication)
DOI: 10.1007/s12549-014-0168-6
http://link.springer.com/article/10.1007/s12549-014-0168-6


The historic Late Triassic outcrops at Fuchsberg and Langenberg near
Seinstedt (Lower Saxony, Germany) are constrained to the
Norian/Rhaetian boundary interval by means of conchostracan and
palynomorph biostratigraphy. A comprehensive revision revealed a
fluvial-dominated delta plain that formed in response to the
successive transgression of the ‘Rhaetian Sea’ and received
siliciclastics from southern source areas. At Fuchsberg and
Langenberg, the distal lower delta plain is exposed and brackish
subaqueous delta plain wetlands, mouthbar/distributary channel
complexes and interdistributary bay subenvironments are reconstructed.
Delta formation was controlled by bifurcation of distributary channels
and avulsion of delta lobes. A diverse ecosystem is documented: a rich
invertebrate fauna of limulids (1 taxon), insects (at least 20 taxa of
9 orders), malacostracans and conchostracans (several taxa) and a
vertebrate fauna of amphibians (at least 1 taxon), sharks (9 taxa) and
osteichthyan fishes (at least 6 taxa). In particular, fossiliferous
interdistributary bay lithologies detail trophic systems of
autochthonous subaqueous and parautochthonous riparian habitats.
Abundant remnants of cycadophytes, ferns, horsetails and large
vertebrates from Fuchsberg and adjacent outcrops of the Seinstedt area
enable the reconstruction of vegetated upstream environments at the
upper delta plain and floodplain.