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Saurosuchus, dinosaur tracks and eggs in new Ameghiniana



From: Ben Creisler
bh480@scn.org

The new issue of Ameghiniana is available online at:
http://www.ameghiniana.org.ar/index.php/ameghiniana

New articles include:

María Jimena Trotteyn, Julia Desojo, & Oscar Alcober (2011)
New postcranial material of Saurosuchus galilei Reig (Archosauria:
Crurotarsi) from the Late Triassic of central-western Argentina. 
Ameghiniana 48 (1): 13-27.
http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/265

Abstract 
Saurosuchus galilei Reig is a ?rauisuchid? from the Ischigualasto Formation
(late Carnian, Late Triassic) located in central-western Argentina. This
paper is the first detailed description of the proatlas-atlas-axis complex
of this taxon, of a complete and articulated vertebral column, and of both
scapulae. Overall morphology of the proatlas-atlas-axis complex is similar
to that of other ?rauisuchids?. This complex and the post-axial cervical
vertebrae show the typical traits of an animal with a short and strong
neck. The cervical vertebrae are anteroposteriorly compressed and
dorsoventrally elongated. Vertebral laminae, interlaminar depressions, and
lateral depressions on the centra are present in the cervical and dorsal
vertebrae, as in other ?rauisuchids?. The presacral series bears ventrally
keeled centra and large transversal expansions of the distal ends of the
neural spines. The caudal series shows axially compressed centra with a
longitudinal ventral groove. The scapulae are very robust and have a brief
expansion and a slightly curved scapular blade. The remarkable diversity of
?rauisuchids? in general, makes a detailed analysis necessary in order to
approach morphofunctional and phylogenetic problems; this new material is
expected to contribute towards the solution of these problems.


Silvina de Valais (2011)
Ichnotaxonomic revision of the dinosaur ichnotaxa from the Middle Jurassic
La Matilde Formation, Santa Cruz Province, Argentina.
Ameghiniana 48 (1): 28-42.
http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/244

Abstract
An ichnological assemblage from the Middle Jurassic La Matilde Formation at
Estancia Laguna Manantiales, Santa Cruz Province, Argentina, is exceptional
both in diversity and abundance. It includes four dinosaurian ichnotaxa
(Wildeichnus, Grallator, and the endemic Delatorrichnus and
Sarmientichnus), the mammalian Ameghinichnus, several vertebrate tracks of
uncertain ichnogeneric assignation and invertebrate and root cavities.
Because of its importance, an updated ichnotaxonomic revision and a
detailed study are needed. In this contribution, the dinosaur ichnogenera
are revised and emended diagnoses of three of them are provided. Recorded
together with ichnogenera originally named by Casamiquela ?Delatorrichnus,
Sarmientichnus and Wildeichnus? is the cosmopolitan Grallator. A few tracks
of dubious assignation are described. Casamiquelichnus Coria and Paulina
Carabajal, 2004, from the same locality, is a junior synonym of
Sarmientichnus. The paleocommunity represented by the La Matilde ichnofauna
was dominated by small-bodied species with high regenerative and resettling
capacity.

Mariela Soledad Fernández (2011)
Late Cretaceous altered dinosaur eggshells from Río Negro Province,
Argentina.
Ameghiniana 48 (1): 43-52.
http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/272

Abstract 
Abnormal dinosaur eggshells are described from the Allen Formation (Late
Cretaceous) at Salitral de Santa Rosa (Río Negro Province). Two different
types of abnormalities were identified, i.e., (1) eggshells with altered
microstructure and heterogeneous ornamentation, among which can be
distinguished (1a) eggshells without rosettes (in megaloolithids and
faveoloolithids), and (1b) eggshells with rosettes (in faveoloolithids);
and (2) multilayered eggshells (only in megaloolithids). In the first group
(1a) the eggshells display a greater range of diameters than the normal
ones and the surface nodules are overgrown by recrystallization. Thin
sections show alterations of the normal eggshell structure of the units. In
the second group (1b) eggshells present groups of flower-shaped nodules (or
rossettes) on certain sectors of their surface. In thin sections it is
possible to observe that the outline of the eggshell units is completely
irregular, while the pore channels are corroded. Two identical layers were
identified in the double eggshell (2), the externalmost of which is the
thinnest and lacks growth nuclei. Cathodoluminescence analysis established
that double eggshells and eggshells with heterogeneous ornamentation with
rossettes have a pathological origin, while eggshells with heterogeneous
ornamentation without rossettes are only strongly altered diagenetically.



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