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Triassic ichthyosaurs from Svalbard in Arctic



From: Ben Creisler
bcreisler@gmail.com


A recent paper not yet mentioned on the DML:

Erin E. Maxwell & Benjamin P. Kear (2013)
Triassic ichthyopterygian assemblages of the Svalbard archipelago: a
reassessment of taxonomy and distribution.
GFF (advance online publication)
DOI:10.1080/11035897.2012.759145
http://www.tandfonline.com/doi/full/10.1080/11035897.2012.759145#.Ubnpyfm1FcQ

Ichthyopterygians were amongst the most specialised lineages of
secondarily aquatic amniotes; however, their origin and initial
radiation remain obscure. The stratigraphically oldest and
phylogenetically most basal taxa have been found in Early–Middle
Triassic deposits throughout the northern hemisphere, but one of the
earliest documented and arguably most important localities is the High
Arctic Svalbard archipelago. Like many classic palaeontological sites,
the Svalbard Triassic fossil-bearing horizons are plagued by
inconsistent geological interpretations and taxonomic classifications.
To resolve these conflicts, a comprehensive revision of the various
ichthyopterygian assemblages was undertaken. The fossils were found to
be distributed through three sequential rock units: the Olenekian
Vikinghøgda Formation (six discernible taxa distributed over two
distinct horizons), Anisian lower Botneheia Formation (two taxa) and
the Ladinian–Carnian Blanknuten Member of the Botneheia
Formation–Tschermakfjellet Formation (five taxa). Unfortunately, many
of the specimens are non-diagnostic at species-level, although they do
contribute a cohesive picture of marine faunal successions during the
Early–earliest Late Triassic. Indeed, the Svalbard archipelago has
produced one of the most diverse Early Triassic ichthyopterygian
assemblages known worldwide, but is comparatively species poor
throughout the early Middle Triassic, perhaps due to sampling biases.