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Albertosuchus (Eusuchia), Kimurachelys (turtle), Tyrrellbatrachus (frog), new Cretaceous taxa
Other non-dino papers in the new special issue of Canadian Journal of
Xiao-Chun Wu & Donald B. Brinkman (2015)
A new crocodylian (Eusuchia) from the uppermost Cretaceous of Alberta, Canada.
Canadian Journal of Earth Sciences 52(8): 590-607
Albertosuchus knudsenii gen. et sp. nov. is described on the basis of
an incomplete skeleton from the lower part (uppermost Cretaceous) of
the Scollard Formation, southern Alberta, Canada. It is probably a
crocodyloid, the only Canadian representative of the group and also
the sole crocodylian known during the latest Cretaceous in Canada.
Within the Crocodyloidea, A. knudsenii is one of the most basal forms
and shares a sister-group relationship with the European genus
Arenysuchus. However, it needs to be emphasized that because of its
incompleteness, phylogenetic relationships proposed here for A.
knudsenii may change when better-preserved specimens are found.
Albertosuchus knudsenii differs from other crocodyloids in having no
premaxilla-maxillary notch, a very short mandibular symphysis with the
involvement of the splenial, and an extremely deep hypapophysis on the
last cervical and anterior dorsal vertebrae. The discovery of A.
knudsenii may expand the geographical range of the Crocodyloidea into
Canada during the Cretaceous. Crocodylians in the lower part of the
Scollard Formation are of low diversity compared with that of the
corresponding Hell Creek Formation of Montana and Lance Formation of
Wyoming, both farther to the south in the USA.
Donald B. Brinkman, Michael Densmore, Márton Rabi, Michael J. Ryan &
David C. Evans (2015)
Marine turtles from the Late Cretaceous of Alberta, Canada.
Canadian Journal of Earth Sciences 52(8): 581-589
Previously reported and new specimens of marine turtles from the late
Campanian of Alberta, Canada, provide additional information on the
diversity and distribution of chelonioid turtles at this time. An
articulated carapace from the Bearpaw Formation previously interpreted
as Lophochelys niobrarae is considered to be a juvenile of a
specifically indeterminate chelonioid and is referred to Lophochelys
sp. Isolated neurals and a hyoplastron from nonmarine estuarine
deposits in the uppermost beds of the Dinosaur Park Formation are
tentatively referred to Lophochelys sp. These specimens suggest that
this chelonioid could enter freshwater environments. A new chelonioid,
Kimurachelys slobodae gen. et sp. nov., is recognized on the basis of
two mandibles and a maxilla from the uppermost beds of the Dinosaur
Park Formation of southeastern Alberta. A partial postcranial skeleton
of an indeterminate chelonioid from the Bearpaw Formation provides
additional evidence that chelonioids of this formation included taxa
that were phylogenetically intermediate between chelonioids of the
late Santonian and members of the crown group.
James D. Gardner (2015)
An edentulous frog (Lissamphibia; Anura) from the Upper Cretaceous
(Campanian) Dinosaur Park Formation of southeastern Alberta, Canada.
Canadian Journal of Earth Sciences 52(8): 569-580
The frog Tyrrellbatrachus brinkmani, gen. et sp. nov., is described on
the basis of seven incomplete maxillae from vertebrate microfossil
localities in the Upper Cretaceous (Campanian) Dinosaur Park
Formation, in the Dinosaur Provincial Park area, southeastern Alberta,
Canada. The maxillae are distinctive in a unique suite of features
related to size, shape, and proportions of the bone, texture of the
labial surface, form of the surface for inferred contact with the
squamosal, form of the lamina horizontalis and the processus
pterygoideus, relative depth of the crista dentalis, and in being
edentulous (i.e., lacking teeth). The higher level affinities of
Tyrrellbatrachus are uncertain, although certain features exclude it
from several known families; for example, the presence of a processus
pterygoideus excludes it from Gobiatidae (Late Cretaceous, Asia),
whereas the presence of a crista dentalis and of a relatively
unreduced pars facialis exclude it from Pipidae (Cretaceous–Recent,
Africa and South America). The lack of teeth in Tyrrellbatrachus is
notable because although tooth loss is widespread among extant anurans
and has arisen independently multiple times, it has rarely been
documented among Mesozoic anurans. Comparisons with the only other
edentulous anuran from the Mesozoic of the Northern Hemisphere, namely
Theatonius (late Campanian – late Maastrichtian, western USA), reveal
no compelling similarities to support a close relationship between the
two genera. Those taxa represent an early (Campanian) instance of
independent tooth loss in anurans and, potentially, the oldest record
of tooth loss in nonpipid anurans.
Craig S. Scott & Richard C. Fox (2015)
Review of Stagodontidae (Mammalia, Marsupialia) from the Judithian
(Late Cretaceous) Belly River Group of southeastern Alberta, Canada.
Canadian Journal of Earth Sciences 52(8): 682-695
Although stagodontid marsupials are among the most distinctive mammals
of Late Cretaceous age in North America, there remain significant gaps
in knowledge of their dental anatomy, particularly that of the
stratigraphically oldest genus, Eodelphis Matthew, 1916. We report
here on stagodontid specimens from the Judithian Belly River Group of
southeastern Alberta, Canada, that document what was until now
previously unknown parts of the upper and lower premolar dentition of
Eodelphis browni Matthew, 1916 and Eodelphis cutleri (Smith Woodward,
1916). The new information further confirms the distinctiveness of
both nominal species of Eodelphis, and bolsters previous hypotheses
suggesting a close phylogenetic relationship between E. cutleri and
the advanced stagodontid Didelphodon Marsh, 1889. Although the new
specimens from Alberta suggest that the problematic holotype of
“Boreodon matutinus” Lambe, 1902 is an upper third premolar, a
referral to Eodelphis cannot be made with confidence and the name
should continue to be treated as a nomen dubium. Lastly, we report the
first occurrence of Didelphodon in strata of the Belly River Group,
extending the geological age of the genus into the Judithian, co-eval
with species of Eodelphis, and suggesting a significant prior and as
yet undiscovered evolutionary history.