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Cretaceous Blackleaf Formation site in Montana and other refs and news



From: Ben Creisler
bh480@scn.org

First, let me welcome Dan back and wish him a speedy and complete recovery!
To celebrate, I've put together a  quick grab-bag of new refs, uncited
older refs, and news stories. Not as exciting a set as Dan deserves,
certainly, and maybe not the kind that will inspire great paleoart in every
case.

New Articles:

Paul V. Ullmann, David Varricchio & Michael J. Knell (2011)
Taphonomy and taxonomy of a vertebrate microsite in the mid-Cretaceous
(Albian?Cenomanian) Blackleaf Formation, southwest Montana.
Historical Biology (advance online publication)
DOI:10.1080/08912963.2011.602405
http://www.tandfonline.com/doi/abs/10.1080/08912963.2011.602405

Abstract
The vertebrate fauna of the Cretaceous Blackleaf Formation of southwest
Montana remains largely undocumented. A microsite (BL1) discovered in the
Flood Member in the Lima Peaks area, Montana, consists of a green siltstone
and yields taxa previously unreported from the formation, including several
dinosaurs: a hypsilophodont, dromaeosaurid, tyrannosauroid, hadrosaurid and
an ankylosaurian. Non-dinosaurian taxa include goniopholidid and
Bernissartia crocodilians; Glyptops, cf. chelydrid and other turtles and at
least two neopterygiian fish. This diversity corresponds well with the
fluvial-deltaic-estuarine environment interpreted for the uppermost unit of
the Flood Member. Taphonomic data and sedimentologic relationships suggest
that this assemblage represents a floodplain depression accumulation.
Comparisons with contemporaneous faunas from around the Western Interior of
the USA suggest a remarkably consistent faunal makeup, at least at the
family level, existed across western North America in the mid-Cretaceous.



Pan, Y., Sha, J., Fürsich, F.T., Wang, Y., Zhang, X. & Yao, X.  (2011).
Dynamics of the lacustrine fauna from the Early Cretaceous Yixian
Formation, China: implications of volcanic and climatic factors. 
Lethaia (advance online publication) 
doi: 10.1111/j.1502-3931.2011.00284.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1502-3931.2011.00284.x/abstract

Abstract
The taphonomy and palaeoecology of the famous Lower Cretaceous Jehol biota
of northeastern China are two of its least resolved aspects. The biota
occurs in lacustrine sediments characterized by abundant volcanic ash
layers. The general view is that these tuff layers correlate strongly with
vertebrate mass mortality events. However, though aquatic invertebrates
also suffered mass mortality, in the majority of cases individuals tend to
occur on bedding planes of finely laminated sediments, suggesting that each
mass mortality event is not related to volcanic activity. Based on data
collected in the course of two excavations at Zhangjiagou and Erdaougou,
the role of volcanic activity and other factors that could have controlled
the dynamics of the fauna were investigated. Cluster analyses of fossil
assemblages from both localities show similar results, and eight fossil
communities are recognized. In the lacustrine Yixian Formation, frequent
and often severe volcanic activity represented by the abundant tuff layers
influenced the water quality, causing repeated collapse of the aquatic
ecosystem. Bedding planes with remains of the eight different communities
were analysed, each recording the community dynamics of a shallow eutrophic
lake system that was most probably controlled by fluctuations of oxygen
level related to climate. A mortality model, in which oxygen-level
fluctuations play the decisive role, is proposed to explain the existence
and distribution of the fossil communities, as well as the unfossiliferous
layers.



A few older articles that apparently have not been mentioned on the DML
yet. Some do not have online links, unfortunately.

Yates, Adam M. & Barrett, Paul M (2010). 
Massospondylus carinatus Owen 1854 (Dinosauria: Sauropodomorpha) from the
Lower Jurassic of South Africa: proposed conservation of usage by
designation of a neotype.  
Palaeontologia Africana 45:  7-10 
(no online link for now)

Abstract: 
The purpose of this article is to preserve the usage of the binomen
Massospondylus carinatus by designating a neotype specimen. Massospondylus
is the most abundant basal sauropodomorph dinosaur from the Early Jurassic
strata of southern Africa. This taxon forms the basis for an extensive
palaeobiological literature and is the eponym of Massospondylidae and the
nominal taxon of a biostratigraphical unit in current usage, the
'Massospondylus Range Zone'. The syntype series of M. carinatus (five
disarticulated and broken vertebrae) was destroyed during World War II, but
plaster casts and illustrations of the material survive. Nonetheless, these
materials cannot act as type material for this taxon under the rules of the
ICZN Code. In order to avoid nomenclatural instability, we hereby designate
BP/1/4934 (a skull and largely complete postcranial skeleton) as the
neotype of Massospondylus carinatus. 

Buchy, Marie-Celine & Covarrubias Cervantes, Anabel (2011)
Large Ichthyosaurian remains from the La Casita type locality (Tithonian,
Upper Jurassic), Coahuila, Mexico.  
Paludicola 8(2): 100-105  

Abstract: 
The specimen described here (CPC 306) is the first and only vertebrate from
the Tithonian La Casita type locality in southern Coahuila, Mexico. The
specimen comprises at least 42 centra from the posterior trunk and anterior
tail, as well as neural arch and rib fragments, of an ophthalmosaurid
ichthyosaur. The size of the centra are comparable to Ophthalmosaurus
natans, but the pattern of variation in the centrum height/centrum length
ratio and the values of that ratio are more similar to O. icenicus. The
preservation prevents a more precise taxonomic identification.
Ophthalmosaurus has been reported from Gomez Farias, a site further south
in Coahuila. The Mexican Gulf ichthyosaurs show no signs of endemism and
have a lower diversity than elsewhere in the world at the time. Thus every
specimen from the Gulf at present is important, pending futhcr discoveries
in the region.

Mary Higby Schweitzer (2011)
Soft Tissue Preservation in Terrestrial Mesozoic Vertebrates.
Annual Review of Earth and Planetary Sciences 39: 187-216 
DOI: 10.1146/annurev-earth-040610-133502
http://www.annualreviews.org/doi/abs/10.1146/annurev-earth-040610-133502
 
Abstract:
Exceptionally preserved fossils--i.e., those that retain, in some manner,
labile components of organisms that are normally degraded far too quickly
to enter the fossil record--hold the greatest potential for understanding
aspects of the biology of long-extinct animals and are the best targets for
the search for endogenous biomolecules. Yet the modes of preservation of
these labile components, and exactly what remains of the original
composition, are not well understood. Here, I review a selection of cases
of soft tissue preservation in Mesozoic vertebrates, examine chemical and
environmental factors that may influence such preservation, explore the
potential of these fossils for high-resolution analytical studies, and
suggest clarification of terminologies and criteria for determining the
endogeneity of source and the degree of preservation of these
well-preserved tissues.


An international news story:

French-language news sources are reporting the world's longest set of
tracks from a single dinosaur (continuing for at least 155 meters), made by
a  giant sauropod that left foot impressions up to 1.1 meters (3.7 ft)
across, claimed to be the widest ever found. The trackmaker has been
nicknamed "Odysseus." Sources indicate a Jurassic age of about 150 million
years ago. The site is near Plagne in the Ain department of the Rhone-Alps
region in eastern France, near Switzerland. 

In French:
http://www.leprogres.fr/ain/2011/07/23/155-metres-d-empreintes-de-dinosaures
-devoiles-dans-l-ain


http://www.lefigaro.fr/flash-actu/2011/07/22/97001-20110722FILWWW00514-ain-r
ecord-de-traces-de-dinosaure.php



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