Repo New Papers

["Jerry D. Harris" <jharris@dixie.edu>]

Cerda, I.A., and Powell, J.E. 2010. Dermal armor histology of Saltasaurus
loricatus, an Upper Cretaceous sauropod dinosaur from northwest Argentina.
Acta Palaeontologica Polonica.

ABSTRACT: The first unambiguous evidence of the presence of osteoderms in
sauropod dinosaurs came from the discovery of Saltasaurus loricatus, a
titanosaur from the Upper Cretaceous of Argentina. The dermal armor of
Saltasaurus is composed of bony plates and small dermal ossicles. Here, we
analyze the bone microstructure of these elements and provide information
regarding its origin and development. The bony plates are composed almost
entirely of reconstructed cancellous bone. Remains of primary bone consist
of coarse bundles of mineralized collagenous fibers towards the external
surface. Also, woven fibered bone tissue appears in the basal and lateral
regions. Dermal ossicles lack secondary remodeling, and their matrix is
formed by three orthogonal systems of collagenous fiber bundles. Growth
lines are present in both bony plates and ossicles. Bone histology reveals
that osteoderms mainly originated through direct mineralization (metaplasia)
of the dermis, although other mechanisms are also involved (at least in the
origin of dermal plates). The common features of development and
integumental location of the osteoderms of Saltasaurus and other non-related
vertebrates (e.g., lepidosaurs, crocodylomorphs) are linked to the intrinsic
skeletogenic properties of the dermis.




Senter, P. 2010. Evidence for a sauropod-like metacarpal configuration in
stegosaurian dinosaurs. Acta Palaeontologica Polonica.

ABSTRACT: The stegosaurian forelimb is usually portrayed with the
metacarpals slanted and distally spread. However, manual manipulation of
stegosaurian metacarpals reveals that in that configuration they do not
articulate with each other nor with the rest of the forelimb. Rather, they
do articulate with each other and with the rest of the forelimb when posed
vertically and arranged in a compact, semi-tubular configuration, as in
sauropods. This configuration agrees with data from articulated specimens
and trackways. As with sauropods, this metacarpal configuration makes
retention of phalanges awkward for locomotion and may be functionally
related to the vestigiality of the manual phalanges of the outer digits.





Mallison, H. 2010. The digital Plateosaurus II: an assessment of the range
of motion of the limbs and vertebral column and of previous reconstructions
using a digital skeletal mount. Acta Palaeontologica Polonica.

ABSTRACT: Scientific literature and museum exhibits are full of explicit and
implicit claims about the possible postures and motion ranges of dinosaurs.
For the example of the prosauropod Plateosaurus engelhardti Meyer, 1837 I
assessed the motion range of limbs and vertebral column in a CAD program
using a 3D virtual skeletal mount. The range of motion of the forelimb is
very limited, allowing the grasping of objects placed directly ventrally and
ventrolaterally of the anterior torso. The manus is adapted for grasping.
The powerful fore limb can barely reach in front of the shoulder, making a
quadrupedal walking cycle impractical. Only a digitigrade pose of the pes
with a steeply held metatarsus is feasible, and the morphology of the
stylopodium and zeugopodium indicates a slightly flexed limb posture. Hind
limb protraction and retraction are limited by the pelvic architecture. The
neck has significant mobility both dorsoventrally and laterally, but blocks
torsion. The dorsal vertebral column is flexible to a degree similar to the
neck, mainly in the anterior half, but blocks torsion totally in the
anterior and posterior thirds. The anterior dorsals are similar in shape to
the posterior cervicals and significantly increase the motion range of the
neck. The tail is highly flexible due to its large number of elements,
showing more lateral than dorsoventral mobility. These results are compared
to reconstruction drawings and museum skeletal mounts, highlighting a
pattern of errors specific to certain widely used reconstruction methods.






Dias-da-Silva, S., and Milner, A.R. 2010. The pustulated temnospondyl
revisited, a plagiosternine plagiosaurid from the Lower Triassic of Brazil.
Acta Palaeontologica Polonica. 

ABSTRACT: A recent contribution published in this journal (Dias-da-Silva and
Ilha 2009) reported a dermal skull fragment indicating the presence of a
putative plagiosauroid temnospondyl in the Lower Triassic Sanga do Cabral
Formation of the Paraná Basin, Southern Brazil. The taxonomic assignation of
this specimen was necessarily tentative as it was based on circumstantial
evidence, specifically the presence of a dense pustular ornamentation over
four partial dermal skull bones, consideration of the described taxa known
to bear such ornamentation, and the stratigraphic and paleobiogeographic
range of such taxa. Therefore, Dias-da-Silva and Ilha (2009) could not be
totally certain about the plagiosauroid affinities of the new specimen and
ascribed it to ?Plagiosauridae. It was particularly difficult to make a
precise osteological identification of the specimen and six alternative
osteological interpretations were made in comparison to both Gerrothorax and
Peltobatrachus (see Dias-da-Silva and Ilha 2009: fig. 2). In spite of the
poor taxonomic resolution, the new specimen raised interesting questions
regarding the presence of plagiosauroid stereospondyls in western Gondwana,
as well as their evolutionary patterns, biostratigraphic and
paleobiogeographic implications. After Dias-da-Silva and Ilha´s (2009)
contribution was published, new data from Damiani et al. (2009) raised the
possibility of narrowing down the taxonomic identity of the plagiosauroid
from Brazil. Accordingly, this brief report provides a more precise
taxonomic assignation for this material.





Vitek, N.S., and Danilov, I.G. 2010. New material and a reassessment of
soft-shelled turtles (Trionychidae) from the Late Cretaceous of middle Asia
and Kazakhstan. Journal of Vertebrate Paleontology 30(2):383-393. doi:
10.1080/02724631003617548.

ABSTRACT: In this paper we describe previously unpublished trionychid turtle
material, consisting of numerous shell fragments, from two Late Cretaceous
(Santonian-early Campanian) localities from Middle Asia and Kazakhstan
(Central Asia in the U.S. tradition): Kansai (Tadjikistan) and Shakh-Shakh
(Kazakhstan). This material can be attributed to two forms of trionychids
present in both localities. One of them is the named species Trionyx
riabinini Kuznetsov and Chkhikvadze, 1987, described from Shakh-Shakh. New
data on its shell morphology provided by our study allow attribution to the
genus Aspideretoides Gardner et al., 1995, known previously only from the
Campanian-Maastrichtian of North America. The presence of this taxon in both
Middle Asia and North America provides the first clear evidence for the
relationship between Cretaceous Asian and North American trionychids. The
second form is established as a new species, ?Trionyx? kansaiensis, sp.
nov., with unclear systematic position within Trionychinae. We lastly
present a brief review of other named taxa of Cretaceous trionychids of
Middle Asia and Kazakhstan. 





Lyson, T.R., and Joyce, W.G. 2010. A new baenid turtle from the Upper
Cretaceous (Maastrichtian) Hell Creek Formation of North Dakota and a
preliminary taxonomic review of Cretaceous Baenidae. Journal of Vertebrate
Paleontology 30(2):394-402. doi: 10.1080/02724631003618389.

ABSTRACT: A fragmentary skull from the Hell Creek Formation (Maastrichtian)
of southwestern North Dakota represents a new taxon of baenid turtle named
herein Gamerabaena sonsalla. The length of the frontals, jugal contribution
to the labial ridge, and convex contact between the vomer and the pterygoids
indicate its affinities with the clade Palatobaena, but the new taxon
clearly lacks the great posterior expansion of the triturating surface,
complete absence of a lingual ridge, subrectangular skull, and wide angle
between the maxillae that diagnose Palatobaena  spp. A maximum parsimony
analysis provides strong support for G. sonsalla as sister taxon to
Palatobaena spp. Gamerabaena sonsalla has several morphological features
that are intermediate between Plesiobaena antiqua and the morphologically
disparate Palatobaena  spp., including orbits that are oriented slightly
dorsally and moderately expanded posterior triturating surfaces. Our
phylogenetic analysis, combined with stratigraphic arguments, indicates that
our skull-based taxon G. sonsalla could belong to the shell-based taxon
?Baena? hayi. Similarly, the skull taxa Hayemys latifrons and Eubaena
cephalica may be synonymous with the shell taxa Thescelus insiliens and
?Baena? hatcheri, respectively. 






Maxwell, E.E. 2010. Generic reassignment of an ichthyosaur from the Queen
Elizabeth Islands, Northwest Territories, Canada. Journal of Vertebrate
Paleontology 30(2):403-415. doi: 10.1080/02724631003617944.

ABSTRACT: An ichthyosaur from the Oxfordian-Kimmeridgian of Melville Island,
Northwest Territories, Canada, is redescribed. This specimen was previously
referred to as Ophthalmosaurus chrisorum Russell, 1993, but exhibits several
features incompatible with this generic assignment. Here, I refer this
specimen to a new genus, Arthropterygius, characterized by a basioccipital
with an extremely reduced extracondylar area, a foramen for the internal
carotid artery located on the posterior surface of the basisphenoid, a
humerus with a well-developed distal facet for the articulation of a
preaxial accessory element, and a radius and ulna with highly angular
proximal surfaces for articulation with the humerus. Arthropterygius can be
referred to the Ophthalmosauria based on the presence of a preaxial element
anterior to the radius and ulna. This referral is supported by a
phylogenetic analysis, in which a sister-group relationship between
Arthropterygius  and the South American genus Caypullisaurus is recovered.
This specimen represents the most complete ichthyosaur from the Canadian
Arctic, and has important implications for marine reptile diversity at high
latitudes during the Jurassic. 






Bullard, T.S., and Caldwell, M.W. 2010. Redescription and rediagnosis of the
tylosaurine mosasaur Hainosaurus pembinensis Nicholls, 1988, as Tylosaurus
pembinensis (Nicholls, 1988). Journal of Vertebrate Paleontology
30(2):416-426. doi: 10.1080/02724631003621870.

ABSTRACT: Tylosaurus pembinensis (Mosasauridae; Tylosaurini), from the
middle Campanian Pembina Member of the Pierre Shale, exposed near Morden,
Manitoba, Canada, is redescribed and removed from the genus Hainosaurus. In
support of our reassignment, we highlight incorrect diagnostic features in
the original description that were used as support for the assignment of the
new species to Hainosaurus (e.g., small suprastapedial process of the
quadrate and the presence of 54 vertebrae in the dorsal and pygal series [33
dorsals and 21 pygals]). In contrast, we note that the fully prepared
quadrate possesses key Tylosaurus  features such as a moderately large-sized
suprastapedial process. We also report that of the original 54
'pre-chevron'-bearing vertebrae, that 26 are from a second, unrelated
species of mosasaur. Of the 29 remaining vertebrae, it is difficult, due to
poor preservation, to identify which of these elements are pygals. Although
the exact pre-chevron count is unclear, the preserved remains clearly do not
support a diagnosis of a high pygal count consistent with Hainosaurus. In
recharacterizing Tylosaurus pembinensis, we discuss a number of problematic
characters used to diagnose Hainosaurus, in the context of diagnosing
Tylosaurus and not for the purpose of revising the European taxon
Hainosaurus bernardi.




Whitlock, J.A., Wilson, J.A., and Lamanna, M.C. 2010. Description of a
nearly complete juvenile skull of Diplodocus (Sauropoda: Diplodocoidea) from
the Late Jurassic of North America. Journal of Vertebrate Paleontology
30(2):447-452. doi: 10.1080/02724631003617647.

ABSTRACT: More than any other sauropod dinosaur group, the long-necked
herbivores belonging to Diplodocoidea have been defined by their skulls.
Their unique skull shape, which is extremely elongate antorbitally, with a
transversely broad, square snout packed at its anterior extreme with
narrow-crowned, pencil-like teeth, has served as a touchstone for describing
the biology of these animals ever since the discovery of the first skull in
the late 19th century. In particular, the unusual diplodocoid skull has been
discussed frequently in the context of examining feeding behavior, spawning
hypotheses ranging from branch stripping, propalinal shearing, and aquatic
plant 'grazing.' Here, we describe a juvenile skull of Diplodocus (Carnegie
Museum 11255) that does not share the unusually blunted snout and anteriorly
sequestered teeth seen in adult specimens, suggesting that adults and
juveniles may have differed greatly in their feeding behavior, an
ontogenetic distinction that may be unique among sauropodomorphs.




Mayr, G., Rana, R.S., Rose, K.D., Sahni, A., Kumar, K., Singh, L., and
Smith, T. 2010. Quercypsitta-like birds from the Early Eocene of India
(Aves, ?Psittaciformes). Journal of Vertebrate Paleontology 30(2):467-478.
doi: 10.1080/02724631003617357.

ABSTRACT: We report new avian remains from the early Eocene Cambay Formation
of Vastan Lignite Mine in western India. Most of the bones belong to the as
yet poorly known taxon Vastanavis, of which a new species, V. cambayensis,
is described. For the first time, tarsometatarsi of Vastanavis  can be
identified, which show that this taxon had semi-zygodactyl feet. In overall
morphology, Vastanavis closely resembles the species of the Quercypsittidae,
which occur in the late Eocene of Europe and are considered stem group
representatives of the parrots (Psittaciformes). Several plesiomorphic
features indicate, however, that Vastanavis  is outside a clade including
Quercypsitta and crown group Psittaciformes, and we therefore assign it to a
new family, Vastanavidae. Vastanavis corresponds well with an as yet
undescribed avian species from the early Eocene London Clay in England, and
we conclude that, at least concerning the arboreal taxa, the early Eocene
avifauna of India shows some concordances with the much better known one
from the early Eocene of Europe. We further describe a distal
tarsometatarsus from Vastan Lignite Mine that superficially resembles that
of extant New World vultures (Cathartidae), but comes from a roller-sized
species.




Wilson, G.P., Dechesne, M., and Anderson, I.R. 2010. New latest Cretaceous
mammals from northeastern Colorado with biochronologic and biogeographic
implications. Journal of Vertebrate Paleontology 30(2):499-520. doi:
10.1080/02724631003620955.

ABSTRACT: Few latest Cretaceous mammalian faunas are known from the central
part of the Western Interior of North America. Here we report a collection
of 28 mammalian fossils (23 isolated teeth, 5 dentulous jaw fragments) from
five Upper Cretaceous localities in and around the Pawnee National Grassland
(Weld County) in the Cheyenne Basin, northeastern Colorado. At least 10 taxa
are represented, including two new multituberculates, a neoplagiaulacid
Parikimys carpenteri and a ?cimolomyid Paressonodon nelsoni, which has
greatest affinities to Essonodon browni. The new specimens combine with a
previously reported sample for a total of 40 mammalian specimens from the
area. Using a subsurface model based on geophysical log data, we
stratigraphically arranged the fossil localities relative to the top of the
Fox Hills Sandstone. Our stratigraphically lowest site is 95 m above the
datum and likely near the top of the Laramie Formation. Presence of
Meniscoessus collomensis at this site implies a late 'Edmontonian' or early
Lancian age. The remaining sites are 220, 330, and 410 m above the datum and
temporally equivalent to the Cretaceous part of the D1 sequence in the
Denver Basin; the stratigraphically highest site is near the predicted
Cretaceous-Tertiary boundary. The faunal samples from the latter sites
include mostly typical Lancian taxa, except for two new taxa that suggest
biogeographic differences with contemporaneous localities from farther
north. This stratigraphic succession of fossil localities from northeastern
Colorado may offer new perspectives on temporal and biogeographic changes of
mammalian faunas leading up to the Cretaceous-Tertiary boundary.




Shimada, K., Tsuihiji, T., and Hasegawa, H. 2010. A remarkable case of a
shark-bitten elasmosaurid plesiosaur. Journal of Vertebrate Paleontology
30(2):592-597. doi: 10.1080/02724631003621920.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770   USA
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
 and     dinogami@gmail.com
http://cactus.dixie.edu/jharris/


"I have noticed even people who
claim everything is predestined, and
that we can do nothing to change it,
look before they cross the road."

                   -- Stephen Hawking

"Prediction is very difficult,
especially of the future."

                   -- Niels Bohr