Zhalmouzia, new Late Cretaceous eutherian from Kazakhstan; Early Cretaceous mammals in US

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com


A couple of new advance articles about Mesozoic mammals:


Alexander Averianov, J. David Archibald, and Gareth J. Dyke (2012)
A new eutherian mammal from the Late Cretaceous of Kazakhstan.
Acta Palaeontologica Polonica (in press)
doi: http://dx.doi.org/10.4202/app.2011.0143
http://app.pan.pl/article/item/app20110143.html

A dentary fragment containing the last two molars (m2-3) from the Late
Cretaceous (Santonian-?Campanian) Bostobe Formation exposed at the
locality of Shakh Shakh, northeast Aral Sea region, Kazakhstan, is
attributed to a new taxon of Zhelestidae, Zhalmouzia bazhanovi, gen.
et sp. nov. This specimen is only the second mammal described from
Shakh Shakh, the unidentifiable eutherian Beleutinus orlovi Bazhanov,
1972, being the first, and it is only the fifth Mesozoic mammal named
from Kazakhstan. Zhalmouzia gen. nov. belongs to the endemic clade of
Middle Asian zhelestids (Zhelestinae), better known from the Turonian
of Uzbekistan.

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Richard L. Cifelli, Brian M. Davis, and Benjamin Sames (2012)
Earliest Cretaceous mammals from the western United States.
Acta Palaeontologica Polonica (in press)
doi: http://dx.doi.org/10.4202/app.2012.0089
http://app.pan.pl/article/item/app20120089.html

Mammalian diversity in North America shifted significantly during the
Early Cretaceous, from archaic groups dominant in the well-sampled
faunas of the Late Jurassic to advanced forms (including early members
of modern clades) by the Albian–Cenomanian. However, the dynamics of
this transition are poorly understood, since faunas of earliest
Cretaceous age are unknown. Here we describe the first fossil mammals
from exposures of the Lakota Formation in the Black Hills of South
Dakota, a unit correlated with the upper Berriasian–lower Barremian
and positioned stratigraphically between the underlying Morrison
Formation and Aptian–Albian units exposed elsewhere in North America.
The mammalian fauna from the Lakota Formation is transitional with
regard to the North American fossil record, representing a broad
spectrum of both Jurassic and Cretaceous lineages: present are
“plagiaulacidan” multituberculates allied with Late Jurassic
Allodontoidea and Early Cretaceous Plagiaulacoidea; the geologically
youngest dryolestoid(s) and “triconodontine” triconodontids
(characteristic Late Jurassic taxa from the Morrison Formation); the
oldest spalacotheriid “symmetrodont”; the first record of an
amphitheriid-like stem zatherian from North America (abundant in the
Middle Jurassic–earliest Cretaceous of Europe); and the oldest North
American tribosphenic mammal (abundant and diverse on the continent by
the end of the Early Cretaceous). Taxa making their first North
American appearance in the Lakota Formation (Plagiaulacoidea,
including a genus also known from the Purbeck of Britain;
Spalacotheriidae, stem Zatheria, Tribosphenida) are also known from
the Early Cretaceous of Western Europe, suggesting the possibility
that they represent immigrants.