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Basal dinosauriform and theropod dinosaurs from Late Triassic of Poland



From: Ben Creisler
bcreisler@gmail.com

A new online paper:


Grzegorz Niedźwiedzki, Stephen L. Brusatte, Tomasz Sulej, and Richard
J. Butler (2014)
Basal dinosauriform and theropod dinosaurs from the mid–late Norian
(Late Triassic) of Poland: implications for Triassic dinosaur
evolution and distribution.
Palaeontology (advance online publication)
DOI: 10.1111/pala.12107
http://onlinelibrary.wiley.com/doi/10.1111/pala.12107/abstract

The rise of dinosaurs during the Triassic is a widely studied
evolutionary radiation, but there are still many unanswered questions
about early dinosaur evolution and biogeography that are hampered by
an unevenly sampled Late Triassic fossil record. Although very common
in western North America and parts of South America, dinosaur (and
more basal dinosauriform) remains are relatively rare in the Upper
Triassic deposits of Europe, making any new discoveries critically
important. One of the most diverse dinosauriform assemblages from
Europe comes from the Poręba site in Poland, a recently described
locality with exposures of the Zbąszynek Beds, which have a
palynomorph assemblage characteristic for the mid–late Norian in the
biostratigraphic schemes of the Germanic Basin. Using a
synapomorphy-based approach, we evaluate several isolated
dinosauriform specimens from Poręba. This assemblage includes a
silesaurid, a herrerasaurid and remains of another type of theropod
(potentially a neotheropod). The Poręba herrerasaurid is the first
record of this rare group of primitive dinosaurs from Europe and one
of the youngest records worldwide, whereas the silesaurid is the
youngest record of a silesaurid from Europe. These findings indicate
that silesaurids persisted alongside true dinosaurs into the mid–late
Norian of Europe and that silesaurid–herrerasaurid–neotheropod
assemblages (which are also known from the Norian of North America, at
low latitudes) were more widespread geographically and latitudinally
than previously thought. Silesaurid–herrerasaurid–neotheropod
assemblages may have been a common ecological structuring of dinosaurs
during their early evolution, and their widespread distribution may
indicate weak palaeolatitudinal controls on early dinosaur
biogeography during the latest Triassic.
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