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Ichthyosaur skeletal taphonomy from locations in Europe



Ben Creisler
bcreisler@gmail.com

A new paper:

Susan R. Beardmore &  Heinz Furrer (2015)
Evidence of a preservational gradient in the skeletal taphonomy of
Ichthyopterygia (Reptilia) from Europe.
Palaeogeography, Palaeoclimatology, Palaeoecology (advacne online publication)
doi:10.1016/j.palaeo.2015.11.049
http://www.sciencedirect.com/science/article/pii/S0031018215007191


Highlights

Ichthyopterygian carcasses were delivered to the sediment surface soon
after death where external processes impacted on carcass condition.
The extent of disarticulation and loss of completeness are indicators
of the presence and intensity of environmental processes.
Water circulation and current activity are considered a main influence
on ichthyopterygian preservation.
Preservational variation among three European localities suggests the
presence and intensity of water movement varied with proximity to
land.
The study is a demonstration of the importance of the geographic and
stratigraphic information context of a specimen over specimen number.

Abstract

Studies of preservation have allowed environmental conditions at
numerous localities in space and time to be inferred. However, in the
search for sufficient vertebrate specimens to provide a large dataset,
details of specimen taxonomy, geographic origin and stratigraphic
level are often ignored or not collected. Any preservational variation
identified as a result is therefore from a broad range rather than a
specific group, locality or time. The effect of this limitation,
mainly regarding the loss of crucial information on environmental
processes in ancient settings and the biology of long extinct
organisms, is demonstrated using specimens of Ichthyopterygia
(Reptilia). Taphonomic analysis of a dataset of 173 specimens infers a
consistent reduction of skeletal condition from peripheral to medial
within a carcass and a taphonomic pathway involving minimal floating
and prolonged residence on the sediment surface. The same dataset
divided into three sub-datasets, from the Middle Triassic Besano
Formation, Lower Jurassic Blue Lias Formation and Lower Jurassic
Posidonia Shale Formation, highlight preservational variation, in the
extent of loss of articulation and completeness that follows an
environmental gradient related to proximity to major landmasses.