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Dinosaur papers in new special issue of Canadian Journal of Earth Sciences (with 2 free pdfs)



Ben Creisler
bcreisler@gmail.com

A new special issue of the Canadian Journal of Earth Sciences
celebrating 30 years of the Royal Tyrrell Museum is now out online.

http://www.nrcresearchpress.com/toc/cjes/52/8

https://royaltyrrellmuseum.wordpress.com/2015/08/05/special-edition-of-canadian-journal-of-earth-sciences-celebrates-royal-tyrrell-museums-thirty-years-of-contributions-to-science/


The issue includes a number of papers on dinosaur-related topics (two are free):

Philip J. Currie & Eva B. Koppelhus (2015)
The significance of the theropod collections of the Royal Tyrrell
Museum of Palaeontology to our understanding of Late Cretaceous
theropod diversity.
Canadian Journal of Earth Sciences 52(8): 620-629
doi: 10.1139/cjes-2014-0173
http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2014-0173#.VcJCPflVhHw


Significant specimens of theropod dinosaurs were part of the
collections that were transferred to the Royal Tyrrell Museum of
Palaeontology when it split off from the Provincial Museum of Alberta
in 1981. Collecting activity of the institution increased dramatically
in the period leading up to the opening of the building and displays
in 1985, and resulted in the recovery and preparation of many fine
theropod skeletons. New specimens have been added to the collection
every year since the museum opened. Several (mostly small) taxa are
only represented by isolated bones, partial skeletons, and (or) teeth.
Theropod specimens also include footprints, coprolites, eggs, and
feathers in amber. Although theropods are relatively rare in
comparison with herbivorous dinosaurs, the Tyrrell has managed to
build one of the finest research collections of Late Cretaceous forms.
Thirty-seven species of theropods in the Tyrrell are currently
accepted as being valid, of which 30 are from the Upper Cretaceous
deposits of Alberta.



===

David C. Evans, David A. Eberth & Michael J. Ryan (2015)
Hadrosaurid (Edmontosaurus) bonebeds from the Horseshoe Canyon
Formation (Horsethief Member) at Drumheller, Alberta, Canada: geology,
preliminary taphonomy, and significance.
Canadian Journal of Earth Sciences 52(8): 642-654
doi: 10.1139/cjes-2014-0184
http://www.nrcresearchpress.com/doi/full/10.1139/cjes-2014-0184#.VcJBl_lVhHw

Free pdf:

http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2014-0184

Three monodominant hadrosaurid bonebeds in the Horsethief Member of
the Horseshoe Canyon Formation (uppermost Campanian) in southern
Alberta, Canada, are documented. Each bonebed is hosted by a
decimetre-thick deposit of poorly sorted and graded
organic-fragment-rich mudstone. These fossil deposits are interpreted
as having been carried and deposited by debris flows or
hyperconcentrated mass sediment flows initiated by overbank flooding
from local channels. Each bonebed is dominated (>50% of identifiable
elements) by the disarticulated to occasionally associated remains of
hadrosaurine hadrosaurids, inferred to be Edmontosaurus regalis. The
majority of hadrosaurid elements at two of the sites (Bleriot Ferry
and Prehistoric Park) are from large, presumably adult-sized
individuals, whereas the majority of elements from the Fox Coulee site
are from subadults and juveniles. Fossil elements from all the sites
exhibit similar taphonomic signatures suggestive of a high degree of
biostratinomic modification including: (i) thorough disarticulation of
carcasses, (ii) a large amount of breakage, (iii) modest amounts of
size sorting, and (iv) minimum to modest occurrences of abrasion, and
scratch and tooth marks. These signatures indicate that carcasses were
exposed for significant amounts of time on the floodplain, where they
rotted, were scavenged and trampled, and were exposed to moving water
prior to final burial. The size of each bonebed together with the
density of bones suggest that the biocoenoses comprised large groups
of hadrosaurids, and bone size distributions suggest the possibility
of age-segregated populations. The monodominant nature of the
assemblages combined with homogenous taphonomic signatures within and
between sites suggests that these bonebed assemblages are best
interpreted as the result of mass kills rather than attrition, with
recurring tropical storm-induced coastal-plain flooding postulated as
a likely mechanism for what killed and eventually buried these
dinosaurs.

==

François Therrien, Darla K. Zelenitsky, Annie Quinney & Kohei Tanaka (2015)
Dinosaur trackways from the Upper Cretaceous Oldman and Dinosaur Park
formations (Belly River Group) of southern Alberta, Canada, reveal
novel ichnofossil preservation style.
Canadian Journal of Earth Sciences, 2015, 52(8): 630-641
doi: 10.1139/cjes-2014-0168
http://www.nrcresearchpress.com/doi/full/10.1139/cjes-2014-0168#.VcJB7PlVhHw

Free pdf:

http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2014-0168


Dinosaur tracksites recently discovered in exposures of the Belly
River Group in the Milk River Natural Area (MRNA) and Dinosaur
Provincial Park (DPP) of southern Alberta represent a novel type of
ichnofossils. The tracks, all referable to hadrosaurs, occur as
sideritic or calcareous concretions protruding above fine-grained
deposits and are here termed concretionary tracks. Detailed
sedimentological, petrographic, and geochemical analyses reveal that,
although the MRNA and DPP tracks are of different mineralogical
compositions (calcium carbonate versus siderite, respectively), they
display similar internal structures (microscopic convoluted
laminations) and occur in depositional settings indicative of wet
paleoenvironments, where the ground was soft and water saturated.
These characteristics suggest that concretionary tracks are footprint
casts that formed as groundwater rich in dissolved carbonates flooded
depressions left in the soft substrate. As the ponded water
evaporated, minerals began to precipitate and mix with clastic
material transported into the depressions, settling as finely
laminated mud within the tracks and filling them either completely or
partially. The geochemical composition of the precipitate would depend
on the prevalent groundwater conditions (e.g., pH, dissolved carbonate
and sulphate concrentrations). Cementation of the tracks occurred
relatively soon after burial (<100 years), possibly in response to
microbial activity and saturation by mineral-rich groundwater, and
modern erosion exposed the concretionary tracks by removing the softer
host unit. Recognition of this novel type of ichnofossils suggests
dinosaur tracks may be more common than previously thought.
Unfortunately, concretionary tracks tend to break apart rapidly when
the encasing and underlying substrate erodes away, altering their
diagnostic shape and rendering them indistinguishable from
nonichnogenic concretions. As such, concretionary tracks may be
transient ichnofossils in the badlands, explaining why they are rarely
recognized.


======

Takuya Konishi (2015)
Redescription of UALVP 40, an unusual specimen of Chasmosaurus Lambe,
1914 (Ceratopsidae: Chasmosaurinae) bearing long postorbital horns,
and its implications for ontogeny and alpha taxonomy of the genus.
Canadian Journal of Earth Sciences 52(8): 608-619
doi: 10.1139/cjes-2014-0167
http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2014-0167#.VcJC3vlVhHw



UALVP 40, an articulated and reasonably complete skull of a small
chasmosaurine dinosaur collected in 1920 by George F. Sternberg from
the lower unit of the Dinosaur Park Formation, Dinosaur Provincial
Park, Alberta, Canada, is here redescribed. The focus of the study is
on the newly prepared right side of the skull and the hitherto
undescribed mandible. There are substantial differences between the
right and the left side of the skull, most notably the right
postorbital horncore exhibits a greater angle of inclination at 60°
from horizontal, which is approximately 15° greater than that of the
left. The right side of the skull also shows many unfused cranial
sutures that are obliterated on the left side. These unfused sutures
and the short predentary lacking an anterior elongation, indicate that
UALVP 40 likely represents a subadult individual. UALVP 40 is
diagnosed to the genus Chasmosaurus by its possession of the
following: (i) premaxillary flange along entire anterior margin of
external naris; (ii) supraorbital horns curving posteriorly along
their length; and (iii) squamosal dorsal border laterally adjacent to
supratemporal fenestra straight in profile, sloping posteroventrally
at a shallow angle before ascending farther posteriorly to form
lateral border of parietal fenestra. The last character is newly
proposed. A bivariate correlation in UALVP 40 and other Canadian
specimens of Chasmosaurus bearing long postorbital horncores (>150 mm
long) reveals a near isometric relationship between interorbital width
and horn length. This may indicate those specimens represent an
ontogenetic series of a single species diagnosed by long postorbital
horncores.

===


David A. Eberth (2015)
Origins of dinosaur bonebeds in the Cretaceous of Alberta, Canada.
Canadian Journal of Earth Sciences 52(8): 655-681
doi: 10.1139/cjes-2014-0200
http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2014-0200#.VcJDCvlVhHw



Upper Cretaceous dinosaur bonebeds are common in Alberta, Canada, and
have attracted continuous scientific attention since the 1960s. Since
its inception, the Royal Tyrrell Museum of Palaeontology has
documented the presence of hundreds of these sites and has been
involved directly in the scientific study of many tens. Because many
of these bonebeds have been used to address questions about the
paleobiology and paleoecology of dinosaurs, questions have arisen
about bonebed origins and preservation in the Cretaceous of Alberta.
This study of 260 bonebeds delineates broad paleoenvironmental
settings and associations, and taphonomic signatures of assemblages as
a first step in assessing patterns of dinosaur bonebed origins in the
Upper Cretaceous of Alberta. Bonebeds are known predominantly from the
Belly River Group and the Horseshoe Canyon, lower St. Mary River,
Wapiti, and Scollard formations. In these units, bonebeds are mostly
associated with river channel and alluvial wetland settings that were
influenced by a subtropical to warm-temperate, monsoonal climate. Most
bonebeds formed in response to flooding events capable of killing
dinosaurs, reworking and modifying skeletal remains, and burying
taphocoenoses. The “coastal-plain-flooding hypothesis,” proposed in
2005, suggested that many bonebeds in the Dinosaur Park Formation
formed in response to the effects of recurring coastal-plain floods
that submerged vast areas of ancient southern Alberta on a seasonal
basis. It remains the best mechanism to explain how many of the
bonebeds were formed and preserved at Dinosaur Provincial Park, and
here, is proposed as the mechanism that best explains bonebed origins
in other Upper Cretaceous formations across central and southern
Alberta.