Still More New Papers

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

Jeez, finding non-boring subject lines for these messages is a pain in the 
patookus...

Another from the Early Sauropodomorph volume:

Fedak, T.J., and Galton, P.M. 2007. New information on the braincase and 
skull of Anchisaurus polyzelus (Lower Jurassic, Connecticut, USA; 
Saurischia: Sauropodomorpha): implications for sauropodomorph systematics; 
pp. 245-260 in Barrett, P.M. and Batten, D.J. (eds.), Evolution and 
Palaeobiology of Early Sauropodomorph Dinosaurs. Special Papers in 
Palaeontology 77. Palaeontological Association, London.

ABSTRACT: A skull of Anchisaurus polyzelus (YPM 1883) has been 
misinterpreted for over 120 years as a result of deformation during 
preservation and loss of a small piece of the skull block shortly after 
collection in 1884. The only other skull of this taxon (YPM 209), from a 
smaller individual, has been largely ignored in previous studies owing to 
distortion and incomplete preparation. Additional preparation of the latter 
specimen has exposed several new elements, including the nearly complete 
parabasisphenoid, a region that is damaged and incomplete in YPM 1883. Based 
on this new information, a phylogenetic analysis supports the recent 
hypothesis that Anchisaurus was a basal sauropod. However, the strength of 
this hypothesis has been greatly reduced, and is also undermined further by 
the possibility that the specimens of Anchisaurus are skeletally immature. 
In general, the skull and braincase of Anchisaurus resembles those of 
'prosauropods' more closely than those of derived sauropods.


Also:

Phillips, P.L., Jr., Ludvigson, G.A., Joeckel, R.M., González, L.A., 
Brenner, R.L., and Witzke, B.J. 2007. Sequence stratigraphic controls on 
synsedimentary cementation and preservation of dinosaur tracks: Example from 
the lower Cretaceous, (Upper Albian) Dakota Formation, Southeastern 
Nebraska, U.S.A. Palaeogeography, Palaeoclimatology, Palaeoecology 
246(2-4):367-389. doi: 10.1016/j.palaeo.2006.10.013.

ABSTRACT: A thin cemented sandstone bed in the Upper Albian Dakota Formation 
of southeastern Nebraska contains the first dinosaur tracks to be described 
from the state. Of equal importance to the tracks are stable-isotope (C, O) 
analyses of cements in the track bed, especially in the context of data 
derived from generally correlative strata (sandstones and 
sphaerosiderite-bearing paleosols) in the region. These data provide the 
framework for interpretations of paleoenvironmental conditions, as well as a 
novel approach to understanding mechanisms of terrestrial vertebrate track 
preservation.
  High minus-cement-porosity (> 47%) and low grain-to-grain contacts (2.5) 
in the track bed indicate early (pre-compaction) lithification. Although 
phreatic cements dominate, the history of cementation within this 
stratigraphic interval is complex. Cathodoluminescence petrography reveals 
two distinct calcite zones in the track-bearing horizon and four cement 
zones in stratigraphically equivalent strata from a nearby section. The 
earliest calcite cements from both localities are likely coeval because they 
exhibit identical positive covariant trends (d18O values of - 9.89 to - 
6.32? and d13C values of - 28.01 to - 19.33? VPDB) and record mixing of 
brackish and meteoric groundwaters. All other calcite cements define 
meteoric calcite lines with d18O values clustering around - 9.42? and - 
8.21? VPDB from the track-bearing horizon, and - 7.74?, - 5.81?, and - 3.95? 
VPDB from the neighboring section. Distinct meteoric sphaerosiderite lines 
from roughly correlative paleosols serve as a proxy for locally recharged 
groundwaters. Back-calculated paleogroundwater d18O estimates from paleosol 
sphaerosiderites range from - 7.4 to - 4.2? SMOW; whereas, meteoric calcite 
lines from the track horizon are generally more depleted.
  Differences in cement d18O values record changes in paleogroundwater 
recharge areas over time. Early calcite cements indicate mixing of fresh and 
brackish groundwaters during the syndepositional lithification of the track 
horizon. Later calcite cements, however, indicate recharge from a larger 
catchment basin that extended far inland. Therefore, the cements likely 
record a rise and subsequent fall in relative sea level. We conclude that 
scrutiny of the cement isotope geochemistry of genetically significant 
surfaces, especially track beds, can provide new data for interpreting sea 
level change.


A slew from the newest _Acta Palaeontologica Polonica_:

Wings, O. 2007. A review of gastrolith function with implications for fossil 
vertebrates and a revised classification. Acta Palaeontologica Polonica 
52(1):1-16.

ABSTRACT: Misleading interpretations of "gastroliths" in fossil taxa have 
complicated the use of this term in palaeontology. This paper reviews the 
definitions and ascribed functions of gastroliths. According to the 
suggested definition, gastroliths are hard objects within the digestive 
tract of animals-without specification of the mechanisms that are 
responsible for their accumulation. To further improve definitions, the 
origin-based terms "bio-gastrolith", "patho-gastrolith", and 
"geo-gastrolith" are introduced. The term "exolith" is introduced for 
isolated clasts with a possible history as geo-gastroliths. Hypotheses about 
the function of stomach stones in fossil and extant taxa are reviewed, 
discussed and supplemented with new research. Trituration and mixing of 
foodstuff are the generally accepted functions of gastroliths in many 
vertebrates, including birds. In contrast, ballast provided by swallowed 
stones is considered to be of limited importance for buoyancy in aquatic 
animals. Other functional hypotheses include mineral supply and storage, 
stomach cleaning, maintenance of a beneficial microbial gut flora, 
destruction of parasites and alleviation of hunger. Accidental ingestion of 
sediment, either by being mistaken for prey, by being attached to it, during 
playing or due to pathological behaviour, is considered to be common. 
Different functions may overlap in various taxa.


Fanti, F., and Therrien, F. 2007. Theropod tooth assemblages from the Late 
Cretaceous Maevarano Formation and the possible presence of dromaeosaurids 
in Madagascar. Acta Palaeontologica Polonica 52(1):155-166.

ABSTRACT: The latest Cretaceous (Campanian?-Maastrichtian) Maevarano 
Formation of the Mahajanga Basin, Madagascar, preserves one of the most 
diverse fossil vertebrate faunas of the Gondwanan landmasses. Over 180 
isolated theropod teeth recovered from that formation were studied in order 
to document theropod diversity in the Madagascar insular setting. Tooth 
morphology and characteristics of the Maevarano teeth were compared to those 
of known theropod teeth for identification, including the Malagasy non-avian 
theropods Majungatholus atopus and Masiakasaurus knopfleri. Tooth and 
denticle morphologies permit the recognition of five tooth morphotypes: 
three morphotypes are referable to Majungatholus atopus based on variation 
in tooth morphology observed in teeth preserved in situ in the jaws of two 
specimens, and one morphotype is ascribable to Masiakasaurus knopfleri. 
Teeth pertaining to the fifth morphotype differ from other morphotypes in 
the size and orientation of the denticles, shape and orientation of blood 
grooves, and in general tooth morphology. Statistical analyses reveal that 
the fifth Maevarano tooth morphotype is similar to dromaeosaurid teeth, 
suggesting that a yet unknown theropod taxon inhabited Madagascar during the 
latest Cretaceous. This morphotype represents the first evidence of the 
possible presence of a dromaeosaurid in Madagascar and supports the theory 
that dromaeosaurids were present throughout Pangaea before the break-up of 
the supercontinent during the Late Jurassic and had colonized Madagascar 
before its separation from Africa during the Early Cretaceous.



Schwarz, D., Frey, E., and Meyer, C.A. 2007. Pneumaticity and soft-tissue 
reconstructions in the neck of diplodocid and dicraeosaurid sauropods. Acta 
Palaeontologica Polonica 52(1):167-188.

ABSTRACT: The axial soft-tissue system in the neck of Dicraeosauridae and 
Diplodocidae, including pneumatic diverticula, ligaments, and muscles, is 
reconstructed on the basis of phylogenetic and functional morphological 
comparisons with extant crocodylians and birds and compared with other 
soft-tissue reconstructions for sauropods. Bifurcation of the neural spines 
separated the paired supraspinal ligament into two sheets. A paired 
interspinal septum was attached to the cranial and caudal margins of the 
neural spines. The dorsal and the lateral portions of the cervical 
musculature must have been strongly segmented, whereas the laterocostal 
portion was divided with one myoseptum per vertebral segment. The hypaxial 
cervical muscle was most probably small and only poorly segmented. In 
Diplodocidae and Dicraeosauridae, the distribution of external pneumatic 
structures is similar, whereas only Diplodocidae possess intraosseous 
pneumatic structures. Supravertebral pneumatic diverticula are reconstructed 
for both groups, which, together with dorsal ligaments filled the gap 
between the metapophyses of bifurcate neural spines. Comparisons between the 
vertebrae of juvenile and adult diplodocids strongly indicate that 
pneumatisation proceeded from the supramedullary diverticula into the neural 
arch and the neural spine. The regular branching pattern of the pneumatic 
cavities as well as the vertical I-beam construction of the vertebral 
corpora is interpreted as a consequence of the biomechanical constraints of 
the vertebral corpora in diplodocids. These reconstructions form the ground 
for functional morphological considerations in Diplodocidae and 
Dicraeosauridae while addressing the possible mechanical consequences of 
pneumatic structures for the integrity of the support system of the neck.


And lastly:

Lü, J., Liu, J., Wang, X., Gao, C., Meng, Q., and Ji, Q. 2006. New material 
of pterosaur Sinopterus (Reptilia: Pterosauria) from the Early Cretaceous 
Jiufotang Formation, western Liaoning, China. Acta Geologica Sinica (English 
Edition) 80(6):783-789.

ABSTRACT: Based on a new nearly complete postcranial skeleton of an adult 
specimen of Sinopterus from the Early Cretaceous Jiufotang Formation of 
western Liaoning, China, the diagnosis of Sinopterus is amended. The revised 
diagnosis of Sinopterus includes skull relatively elongate with weakly 
developed cranial crest; ratio of the length of Ph2d4 to that of Ph1d4 is 
approximately 0.73; ratio of the length of wing metacarpal to that of 
metatarsal 3 is 4.5; ratio of the length of mt3 to that of tibia is 
approximately 0.21, and wing phalanges 1 and 2 are straight. Comparison 
between the ratios of the limb bones between non-adult and adult individuals 
of Sinopterus indicates that during the ontogenetic process,some ratios 
between bones are constant, such as the first wing phalanx to the second 
wing phalanx, the wing metacarpal to the metatarsal 3, metatarsal 3 to the 
tibia, but others are not, such as humerus to wing metacarpal and femur to 
tibia, in which the former grows faster than the latter.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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/

"Trying to estimate the divergence times
of fungal, algal or prokaryotic groups on
the basis of a partial reptilian fossil and
protein sequences from mice and humans
is like trying to decipher Demotic Egyptian with
the help of an odometer and the Oxford
English Dictionary."
              -- D. Graur & W. Martin (_Trends
                  in Genetics_ 20[2], 2004)