Percy Jackson and the New Papers

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

Apesteguía, S., Gallina, P.A., and Haluza, A. 2010. Not just a pretty face:
anatomical peculiarities in the postcranium of rebbachisaurids (Sauropoda:
Diplodocoidea). Historical Biology. doi: 10.1080/08912960903411580.

ABSTRACT: Rebbachisauridae are poorly known 'bizarre' sauropods with two
nearly complete skeletons collected: Limaysaurus tessonei and Nigersaurus
taqueti. Whereas the latter taxon allowed the understanding of their cranial
novelties, other species show some peculiarities in the postcranium. L.
tessonei, Rebbachisaurus garasbae and a new form (MMCH-Pv-49) from Villa El
Chocoacuten, Patagonia, exhibit peculiar pectoral girdles and the loss of
the hyposphene-hypantrum accessory articulations in their amphyplathian
dorsal vertebrae. Actually, the postzygapophyses are not only devoid of
hyposphenal locks but also additionally show a curved postzygapophyseal eave
that allows a sliding over the corresponding structure of the anterior side
of the neural arch, a curved concave and elongated platform continuous along
both prezygapophyses: the prezygapophyseal shelf. As the 'ball and socket'
opisthocoelous centra in macronarians optimised mobility, the 'U-eaves and
shelf complex' of rebbachisaurids permitted wider movements between
successive vertebrae. While in titanosaurs the increased mobility occurred
related to the centrum shape, in rebbachisaurids it is related to a complex
system in the neural arch. Furthermore, whereas macronarians show large
centra, rebbachisaurids underwent a minimisation of the centrum. These
changes in both sauropod lineages probably had an outstanding relevance in
the diversity and ecological roles that sauropods experienced in Cretaceous
terrestrial ecosystems. 




Schoch, R.R., Nesbitt, S., Müller, J., Lucas, S.G., and Boy, J.A. 2010. The
reptile assemblage from the Moenkopi Formation (Middle Triassic) of New
Mexico. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. doi:
10.1127/0077-7749/2009/0030.

ABSTRACT: Focused collecting and excavation in the Moenkopi Formation (Anton
Chico Member) of north-central New Mexico yielded a large quantity of
tetrapod bones. Most of the finds were collected from intraformational
conglomerates, and consist of isolated bones or bone fragments. The most
abundant large members of the assemblage, the archosaurs, include at least
three taxa: (1) a primitive suchian or archosauriform, (2) a primitive
poposauroid (Arizonasaurus babbitti), and (3) a taxon similar to
shuvosaurids. Less abundant remains are tentatively referred to
archosauromorphs with rhynchosaur affinities. An analysis of the tetrapod
Lagerstatten reveals that primary deposits formed in lakes that were located
on floodplains. In these lakes, autochthonous conchostracans,
actinopterygians, coelacanths, and temnospondyls were evidently preserved.
Fluvial reworking of lacustrine deposits resulted in a secondary deposition
of bones, teeth, coprolites, and wood in channel-borne conglomerates.
However, the large amount of elements from terrestrial tetrapods indicates
that these conglomerates acquired bones from additional primary deposits
(?channels, paleosols?) that are still unknown.




Tatarinov, L.P. 2010. On the origin of the tympanic membrane in the middle
ear of mammals. Paleontological Journal 44(1):92-94. doi:
10.1134/S0031030110010120.

ABSTRACT: The tympanic membrane appeared in the evolution of archaic
mammals, when the articulare had already lost its function in the jaw
articulation. Even earlier the quadrate and, then, the articular bone had
acquired the role of additional auditory ossicles.





Alifanov, V.R., and Bolotsky, Y.L. 2010. Arkharavia heterocoelica gen. et
sp. nov., a new sauropod from the Upper Cretaceous of far eastern Russia.
Paleontological Journal 44(1):84-91. doi: 10.1134/S0031030110010119.

ABSTRACT: Arkharavia heterocoelica gen. et sp. nov., a new sauropod dinosaur
from the Maastrichtian deposits (Udurchukan svita) of Amur Region, Russia is
described on the findings of a tooth and the isolated proximal caudals. The
uniqual character of the new form is weakly heterocoelity of the caudals. It
is proposed the relationships of a new form with titanosauriforms like
Chubutisaurus insignis from the Upper Cretaceous of South America.

(this is the English version)





Bordy, E.M., Segwabe, T., and Makuke, B. 2010. Sedimentology of the Upper
Triassic-Lower Jurassic(?) Mosoltsane Formation (Karoo Supergroup), Kalahari
Karoo Basin, Botswana. Journal of African Earth Sciences. doi:
10.1016/j.jafrearsci.2010.02.006.

ABSTRACT: The Mosolotsane Formation (Lebung Group, Karoo Supergroup) in the
Kalahari Karoo Basin of Botswana is a scantly exposed, terrestrial red bed
succession which is lithologically correlated with the Late Triassic to
Early Jurassic Molteno and Elliot Formations (Karoo Supergroup) in South
Africa. New evidence derived from field observations and borehole data via
sedimentary facies analysis allowed the assessment of the facies
characteristics, distribution and thickness variation as well as
palaeo-current directions and sediment composition, and resulted in the
palaeo-environmental reconstruction of this poorly known unit. Our results
show that the Mosolotsane Formation was deposited in a relatively
low-sinuosity meandering river system that drained in a possibly semi-arid
environment. Sandstone petrography revealed mainly quartz-rich arenites that
were derived from a continental block provenance dominated by metamorphic
and/or igneous rocks. Palaeo-flow measurements indicate reasonably strong,
unidirectional current patterns with mean flow directions from southeast and
east-southeast to northwest and west-northwest. Regional thickness and
facies distributions as well as palaeo-drainage indicators suggest that the
main depocenter of the Mosolotsane Formation was in the central part of the
Kalahari Karoo Basin. Separated from this main depocenter by a
west-northwest - east-southeast trending elevated area, an additional
depocenter was situated in the north-northeast part of the basin and
probably formed part of the Mid-Zambezi Karoo Basin. In addition, data also
suggests that further northeast-southwest trending uplands probably existed
in the northwest and east, the latter separating the main Kalahari Karoo
depocenter from the Tuli Basin.





Genin, J.J., Willems, P.A., Cavagna, G.A., Lair, R., and Heglund, N.C. 2010.
Biomechanics of locomotion in Asian elephants. Journal of Experimental
Biology 213(5):694-706. doi: 10.1242/jeb.035436.

ABSTRACT: Elephants are the biggest living terrestrial animal, weighing up
to five tons and measuring up to three metres at the withers. These
exceptional dimensions provide certain advantages (e.g. the mass-specific
energetic cost of locomotion is decreased) but also disadvantages (e.g.
forces are proportional to body volume while supportive tissue strength
depends on their cross-sectional area, which makes elephants relatively more
fragile than smaller animals). In order to understand better how body size
affects gait mechanics the movement of the centre of mass (COM) of 34 Asian
elephants (Elephas maximus) was studied over their entire speed range of
0.4-5.0 m s?1 with force platforms. The mass-specific mechanical work
required to maintain the movements of the COM per unit distance is ~0.2 J
kg?1 m?1 (about 1/3 of the average of other animals ranging in size from a
35 g kangaroo rat to a 70 kg human). At low speeds this work is reduced by a
pendulum-like exchange between the kinetic and potential energies of the
COM, with a maximum energy exchange of ~60% at 1.4 m s?1. At high speeds,
elephants use a bouncing mechanism with little exchange between kinetic and
potential energies of the COM, although without an aerial phase. Elephants
increase speed while reducing the vertical oscillation of the COM from about
3 cm to 1 cm.






Deenen, M.H.L., Ruhl, M., Bonis, N.R., Krijgsman, W., Kuerschner, W.M.,
Reitsma, M., and van Bergen, M.J. 2010. A new chronology for the
end-Triassic mass extinction. Earth and Planetary Science Letters
291(1-4):113-125. doi: 10.1016/j.epsl.2010.01.003.

ABSTRACT: The transition from the Triassic to Jurassic Period, initiating
the ?Age of the dinosaurs?, approximately 200 Ma, is marked by a profound
mass extinction with more than 50% genus loss in both marine and continental
realms. This event closely coincides with a period of extensive volcanism in
the Central Atlantic Magmatic Province (CAMP) associated with the initial
break-up of Pangaea but a causal relationship is still debated. The
Triassic?Jurassic (T?J) boundary is recently proposed in the marine record
at the first occurrence datum of Jurassic ammonites, post-dating the
extinction interval that concurs with two distinct perturbations in the
carbon isotope record. The continental record shows a major palynological
turnover together with a prominent change in tetrapod taxa, but a direct
link to the marine events is still equivocal. Here we develop an accurate
chronostratigraphic framework for the T?J boundary interval and establish
detailed trans-Atlantic and marine?continental correlations by integrating
astrochronology, paleomagnetism, basalt geochemistry and geobiology. We show
that the oldest CAMP basalts are diachronous by 20 kyr across the Atlantic
Ocean, and that these two volcanic pulses coincide with the end-Triassic
extinction interval in the marine realm. Our results support the hypotheses
of Phanerozoic mass extinctions resulting from emplacement of Large Igneous
Provinces (LIPs) and provide crucial time constraints for numerical
modelling of Triassic?Jurassic climate change and global carbon-cycle
perturbations.






Lucas, S.G., Minter, N.J., and Hunt, A.P. 2010. Re-evaluation of alleged
bees' nests from the Upper Triassic of Arizona. Palaeogeography,
Palaeoclimatology, Palaeoecology 286(1-4):194-201. doi:
10.1016/j.palaeo.2010.01.010.

ABSTRACT: Published records of supposed Triassic bees' nests are based on
trace fossils in silicified wood and in sandstone in Upper Triassic strata
of the Chinle Group in Petrified Forest National Park, Arizona. A critical,
firsthand restudy of these trace fossils indicates that they lack diagnostic
features of bees' nests, such as cells with smooth linings and spiral
closure caps. Indeed, many of the observations claimed to identify these
traces as bees' nests cannot be replicated. Instead, the putative Triassic
bees' nests can be classified as: 1. Clavate borings in petrified wood,
somewhat similar to Teredolites; these borings preferentially penetrate
heart-rot fungus (Polyporites) and are mostly likely larval chambers of
wood-boring beetles. 2. Cylindrical, vertical burrows in sandstone
assignable to Skolithos; these are almost certainly arthropod produced. The
recognition that the Chinle Group trace fossils are not bees' nests
eliminates them as evidence that decouples bee origins from the Cretaceous
origin of angiosperms. The Triassic trace fossils in silicified wood are
also a new and unique record of likely beetle borings in Triassic wood.







Allen, V., Elsey, R.M., Jones, N., Wright, J., and Hutchinson, J.R. 2010.
Functional specialization and ontogenetic scaling of limb anatomy in
Alligator mississippiensis. Journal of Anatomy. doi:
10.1111/j.1469-7580.2009.01202.x.

ABSTRACT: Crocodylians exhibit a fascinating diversity of terrestrial gaits
and limb motions that remain poorly described and are of great importance to
understanding their natural history and evolution. Their musculoskeletal
anatomy is pivotal to this diversity and yet only qualitative studies of
muscle-tendon unit anatomy exist. The relative masses and internal
architecture (fascicle lengths and physiological cross-sectional areas) of
muscles of the pectoral and pelvic limbs of American alligators (Alligator
mississippiensis Daudin 1801) were recorded for an ontogenetic series of
wild specimens (n = 15, body masses from 0.5 to 60 kg). The data were
analysed by reduced major axis regression to determine scaling relationships
with body mass. Physiological cross-sectional areas and therefore muscle
force-generating capacity were found to be greater in the extensor
(anti-gravity) muscles of the pelvic limb than in the pectoral limb,
reflecting how crocodylians differ from mammals in having greater loading of
the hindlimbs than the forelimbs. Muscle masses and architecture were
generally found to scale isometrically with body mass, suggesting an
ontogenetic decrease in terrestrial athleticism. This concurs with the
findings of previous studies showing ontogenetic decreases in limb bone
length and the general scaling principle of a decline of strength : weight
ratios with increasing size in animals. Exceptions to isometric scaling
found included positive allometry in fascicle length for extensor
musculature of both limbs, suggesting an ontogenetic increase in working
range interpreted as increasing postural variability ? in particular the
major hip extensors ? the interpretation of which is complicated by previous
described ontogenetic increase of moment arms for these muscles.







~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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