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Azhdarchid pterosaur paleoenvironments in Late Cretaceous of Kazakhstan (free pdf)

Ben Creisler

A recent paper not yet mentioned, in open-access Zookeys:

Alexander Averianov, Gareth Dyke, Igor Danilov & Pavel Skutschas (2015)
The paleoenvironments of azhdarchid pterosaurs localities in the Late
Cretaceous of Kazakhstan.
Zookeys 483: 59–80
doi: 10.3897/zookeys.483.9058

Five pterosaur localities are currently known from the Late Cretaceous
in the northeastern Aral Sea region of Kazakhstan. Of these, one is
Turonian-Coniacian in age, the Zhirkindek Formation (Tyulkili), and
four are Santonian in age, all from the early Campanian Bostobe
Formation (Baibishe, Akkurgan, Buroinak, and Shakh Shakh). All so far
collected and identifiable Late Cretaceous pterosaur bones from
Kazakhstan likely belong to Azhdarchidae: Azhdarcho sp. (Tyulkili);
Aralazhdarcho bostobensis (Shakh Shakh); and Samrukia nessovi
(Akkurgan). These latter two taxa, both from the Bostobe Formation
might be synonyms. Azhdarcho sp. from the Zhirkindek Formation lived
in a tropical-to-subtropical relatively humid climate on the shore of
an estuarine basin connected to the Turgai Sea. Known fossils were
collected in association with brackish-water bivalves and so the
overall paleoenvironment of this pterosaur was likely an estuarine
marsh as indicated by the dominance of conifers and low relative
counts of ferns and angiosperms. Aralazhdarcho bostobensis, from the
Bostobe Formation, lived on a coastal fluvial plain along the Turgai
Sea. This paleoenvironment was either floodplain (Akkurgan, Buroinak,
and Shakh Shakh) or estuarine (Baibishe). In the Santonian – early
Campanian, shallow waters near this coastal plain were sites for the
intensive accumulation of phosphates under upwelling conditions caused
by strong winds from the ancient Asian landmass. These winds also
caused significant aridization of the climate during this time. We
speculate that pterosaurs may have been attracted to this area by the
abundant resources in the bio-productive estuaries and nearshore
upwelling waters.