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Paronychodon and Richardoestesia teeth from Uzbekistan and other new Mesozoic papers



From: Ben Creisler
bcreisler@gmail.com

The new March issue of Canadian Journal of Earth Sciences is in honor
of Richard C. Fox and has a number of Mesozoic related articles, along
with Paleocene topics. Here are some of the Mesozoic papers:

http://www.nrcresearchpress.com/toc/cjes/current

==
Dinosaurs:

Hans-Dieter Sues & Alexander Averianov (2013)
Enigmatic teeth of small theropod dinosaurs from the Upper Cretaceous
(Cenomanian–Turonian) of Uzbekistan.
Canadian Journal of Earth Sciences 50(3): 306-314
doi: 10.1139/e2012-033
http://www.nrcresearchpress.com/doi/abs/10.1139/e2012-033#.UXCk7rXvtcQ

Upper Cretaceous (Cenomanian–Turonian) formations in the Kyzylkum
Desert of Uzbekistan, especially the Bissekty Formation at
Dzharakuduk, have yielded a great diversity of continental
vertebrates, including dinosaurs. Underwater screening of the sandy
matrix has recovered many dinosaurian teeth. Here we describe and
illustrate two types of enigmatic theropod teeth that are referable to
Paronychodon and Richardoestesia, respectively. Both of these tooth
taxa are well known from the Late Cretaceous of North America and
possibly represent stages in the development of the teeth of various
paravian theropods. Confirmation of this hypothesis awaits discovery
of more complete jaws.

===

Peter Dodson (2013)
Ceratopsia increase: history and trends.
Canadian Journal of Earth Sciences 50(3): 294-305
doi: 10.1139/cjes-2012-0085
http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2012-0085#.UXCkkLXvtcQ

The taxonomic history of the Ceratopsia began in 1876 with the
description of Monoclonius crassus Cope followed in 1889 by
Triceratops horridus Marsh. After a peak of discovery and description
in the 1910s and 1920s resulting from the Canadian dinosaur rush in
the province of Alberta and the Central Asiatic Expeditions to
Mongolia of the American Museum of Natural History, the study of
ceratopsians declined to a low level until the 1990s, when discoveries
in China, Montana, Utah, Alberta, and elsewhere, abetted by increased
biostratigraphic and phylogenetic precision, led to an unprecedented
resurgence of activity. Even Richard C. Fox, along with colleagues
from Peking University, joined in the activity, by naming
Psittacosaurus lujiatunensis. To place the activity in historical
perspective, half of all known ceratopsians have been described since
2003. Despite important finds of basal ceratopsians in China,
Mongolia, and Korea, North America continues to dominate ceratopsian,
especially ceratopsid, diversity.
==

Mammals


David W. Krause (2013)
Gondwanatheria and ?Multituberculata (Mammalia) from the Late
Cretaceous of Madagascar.
Canadian Journal of Earth Sciences 50(3): 324-340
doi: 10.1139/e2012-074
http://www.nrcresearchpress.com/doi/abs/10.1139/e2012-074#.UXCly7XvtcQ

In addition to four isolated mammalian teeth from the Late Cretaceous
(Maastrichtian) of Madagascar described previously and allocated to
Gondwanatheria, Marsupialia, and Mammalia incertae sedis, here I put
on record five more specimens. Four of these, a virtually complete
lower molariform cheek tooth, two fragmentary cheek teeth, and a
fragmentary lower incisor, are referred to the Sudamericidae
(Gondwanatheria). The internal structure of the hypsodont cheek teeth,
as revealed by micro-computed tomography scans to simulate different
stages of wear, is highly variable. Limited knowledge of
intra-individual morphological and size variability in the dentition
of sudamericids, which are known almost exclusively from isolated
teeth, precludes a conclusive assessment of whether some or all of the
new specimens belong to Lavanify miolaka, the only previously
described sudamericid from Madagascar, or to a new taxon.
Conservatively, therefore, pending the recovery of better material,
all four specimens are referred to Sudamericidae gen. et sp. indet.
The fifth specimen, a molar fragment, is tentatively allocated to the
Multituberculata, thereby adding to the controversial specimens that
comprise the very sparse and questionable record of this clade on the
southern supercontinent Gondwana. The new specimens do not provide any
profound insight into the origins of the highly endemic and imbalanced
extant mammalian fauna on Madagascar; rather, they provide only more
negative evidence. Like those previously described, they do not
represent the basal stocks of any of the five mammalian clades that
live on the island today and therefore further support the growing
consensus that representatives of the extant clades arrived in the
Cenozoic.

==

Amphibians

Ke-Qin Gao, Jianye Chen, & Jia Jia (2013)
Taxonomic diversity, stratigraphic range, and exceptional preservation
of Juro-Cretaceous salamanders from northern China.
Canadian Journal of Earth Sciences 50(3): 255-267
doi: 10.1139/e2012-039
http://www.nrcresearchpress.com/doi/abs/10.1139/e2012-039#.UXCjtrXvtcQ


Since the late 1990s, eight localities in volcanic shale-rich
lacustrine deposits of Middle Jurassic through Early Cretaceous age in
northern China (western Liaoning Province, northern Hebei Province,
and southern Inner Mongolia) have yielded thousands of exceptionally
well-preserved salamander specimens. With 10 species published and
several new taxa yet to be named and described, the fossil samples
from northern China represent the most species-diverse, individually
abundant, and exquisitely preserved salamander fossil assemblage known
from the Mesozoic Era. The stratigraphic range of the fossil record
covers a geologic time span of roughly 40–45 million years from the
Middle Jurassic (Bathonian) through the Early Cretaceous (Aptian). In
contrast to the well-known stem-group salamanders Karaurus and
Kokartus from the Middle to Late Jurassic of Middle Asia, the Chinese
record contains the earliest known crown-group salamanders, including
Jurassic representatives of both Cryptobranchoidea and Salamandroidea.
The Chinese Mesozoic record includes numerous examples of virtually
complete larval, juvenile, young adult, and fully grown adult
individuals that collectively provide key information on the life
histories and developmental patterns of the earliest known crown-group
salamanders. Many specimens show preservation of soft tissue
structures, including body outline, eye, liver, and external gill
filaments. This kind of soft tissue preservation is unusual for fossil
salamanders, so the Chinese Mesozoic specimens are important for
furnishing otherwise unavailable information on the life history,
diversity, and ecological adaptations of early crown-group
salamanders.

==

Zoltán Szentesi, James D. Gardner & Márton Venczel (2013)
Albanerpetontid amphibians from the Late Cretaceous (Santonian) of
Iharkút, Hungary, with remarks on regional differences in Late
Cretaceous Laurasian amphibian assemblages.
Canadian Journal of Earth Sciences 50(3): 268-281
doi: 10.1139/e2012-024
http://www.nrcresearchpress.com/doi/abs/10.1139/e2012-024#.UXCkJ7XvtcQ

Since its discovery in 2000, the Iharkút fossil locality in the Upper
Cretaceous (Santonian) Csehbánya Formation of western Hungary has
yielded a taxonomically diverse assemblage of terrestrial and
freshwater vertebrates that continue to provide insights into the
diversity, paleobiogeography, and paleoecology of Late Cretaceous
vertebrates in Europe. Albanerpetontidae, an extinct group of
superficially salamander-like amphibians that were widespread across
Laurasia during the latter part of the Mesozoic, are represented at
Iharkút by 16 fragmentary jaws. Here we describe and figure these
specimens as Albanerpetontidae genus and species indeterminate. Based
on the age of the Iharkút locality, several premaxillary features, the
known distribution (late Early Cretaceous – late Pliocene) of the type
genus Albanerpeton, and an unusually large dentary specimen, we
suggest that the Iharkút albanerpetontid may pertain to a previously
unrecognized species of Albanerpeton, but verification of that must
await the recovery of more diagnostically informative specimens, such
as frontals and more nearly complete premaxillae. The Iharkút
lissamphibian assemblage contains a mixture of taxa with Laurasian
(the albanerpetontid and a discoglossid anuran) and Gondwanan (a
neobatrachian anuran) affinities. Intriguing higher level differences
are evident among Late Cretaceous Laurasian assemblages; for example,
urodeles are scarce or absent (as at Iharkút) in Europe, whereas
albanerpetontids are scarce in Middle Asia.