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Late Cretaceous reptilian biota of La Colonia Formation + non-dino papers



Ben Creisler
bcreisler@gmail.com

A number of recent non-dino papers that may be of interest:

Zulma Gasparini, Juliana Sterli, Ana Parras, José Patricio O'Gorman,
Leonardo Salgado, Julio Varela & Diego Pol (2015)
Late Cretaceous reptilian biota of the La Colonia Formation, central
Patagonia, Argentina: Occurrences, preservation and paleoenvironments.
Cretaceous Research 54: 154–168
doi:10.1016/j.cretres.2014.11.010
http://www.sciencedirect.com/science/article/pii/S0195667114002225

Cropping out on the southeastern margin of the Somún Curá Plateau, the
La Colonia Formation (Campanian–Maastrichtian) has yielded, over the
last several decades, a varied fossil tetrapod fauna (mammals,
ophidians, turtles, dinosaurs, plesiosaurs, anurans). For this study
several field trips were carried out specifically to recover reptile
remains. Three sections, located on the southeastern slope of the
Sierra de La Colonia and in the vicinity of Cerro Bayo, Chubut
Province (Argentina), were selected for particular attention. The
prospected sections are composed of massive, laminated or heterolithic
siltstones and claystones, with scarce and thin intercalations of
massive, heterolithic o cross-bedded fine sandstones and of
fossiliferous conglomerates. The most abundantly recovered reptiles
are terrestrial and freshwater turtles, followed by plesiosaurs and
dinosaurs. Among the chelonians, more than 16 specimens of
Patagoniaemys gasparinae (Meiolaniformes), three specimens of
Yaminuechelys aff. Y. gasparinii (Chelidae), and the remains of a new
genus of Chelidae were identified. Among the dinosaurs, theropod
metatarsal fragments, an incomplete abelisaurid theropod skeleton,
sauropod vertebrae, ankylosaur osteoderms and appendicular fragments
of hadrosaurs were found. Among the plesiosaurs there are several well
preserved elasmosaurids (including two with associated gastroliths)
and a polycotylid (Sulcusuchus erraini). Except for the plesiosaurs,
all the reptiles are terrestrial or freshwater taxa. However, analysis
of the elasmosaurids indicates they are adult specimens of small body
size, which could be related to forms that lived in restricted aquatic
environments. Likewise, the polycotylid possesses deep rostral and
mandibular grooves, and a conspicuous vascularization and/or
innervation, that is consistent with the presence of some associated
special sensory structures similar to those known in some cetaceans
that inhabit modern rivers and estuaries. Sedimentological analysis
suggests that deposition would have been mostly in low-energy
restricted environments, like muddy plains, marshes and ponds cut by
meandering channels, probably in the central mixed-energy zone within
an estuary. This interpretation is consistent with the habitat
inferred for the recovered reptiles, as well as with associated
foraminifers and with the probable origin of gastroliths found
associate with the plesiosaurs.

==


Mirian Costa Menegazzo, Reinaldo José Bertini & Flávio Fernando Manzini (2015)
A new turtle from the Upper Cretaceous Bauru Group of Brazil, updated
phylogeny and implications for age of the Santo Anastácio Formation
Journal of South American Earth Sciences (advance online publication)
doi:10.1016/j.jsames.2014.12.008
http://www.sciencedirect.com/science/article/pii/S0895981114001734


Highlights
Phylogenetic analysis and morphological comparisons allow revision of
the Bauru Group turtle taxa.
First turtle fossil described from the Santo Anastácio Formation (Paraná Basin).
Late Cretaceous age estimated to new specimen.


Abstract
A new Podocnemidinura specimen from the Upper Cretaceous Bauru Group
(Paraná Basin) of southeastern Brazil was described. The Bauru Group
provided an important portrait of the Brazilian Mesozoic terrestrial
biota, which boasts a vertebrate fauna formed from fishes, frogs,
lacertilians, crocodyliforms, dinosaurs and mammals; records of
palinomorphs; and invertebrate fauna consisted of gastropods,
bivalves, ostracods and conchostracans. Nevertheless, the age of these
continental deposits is not precisely estimated, which prevents global
correlations, and its fauna is argued to be endemic. The new specimen
described is the first turtle from the Santo Anastácio Formation, and
its morphological comparison with other South American forms provided
a significant advancement in the understanding of the age of this unit
(Late Cretaceous). This study permitted a revision of the turtle taxa
of the Bauru Group. As a result, some taxa were considered synonym,
including the new Santo Anastácio form. The specimen is still unnamed
due to the absence of skull characters that preclude its accurate
positioning within the Bauru Group skull-based taxa. In addition, the
phylogenetic affinities of this taxon was analyzed into
Podocnemidinura clade.

=======


Hamid Haddoumi, Ronan Allain, Said Meslouh, Grégoire Metais, Michel
Monbaron, Denise Pons, Jean-Claude Rage, Romain Vullo, Samir Zouhri &
Emmanuel Gheerbrant (2015)
Guelb el Ahmar (Bathonian, Anoual Syncline, eastern Morocco): First
continental flora and fauna including mammals from the Middle Jurassic
of Africa.
Gondwana Research (advance online publication)
doi:10.1016/j.gr.2014.12.004
http://www.sciencedirect.com/science/article/pii/S1342937X14003694

Highlights
First discovered Middle Jurassic flora and fauna with microvertebrates
from Africa.
It yields the first Middle Jurassic mammals from Africa (stem Cladotheria).
The fauna has either Laurasian or Pangean affinities.

Abstract
We report the discovery in Mesozoic continental “red beds” of Anoual
Syncline, Morocco, of the new Guelb el Ahmar (GEA) fossiliferous sites
in the Bathonian Anoual Formation. They produced one of the richest
continental biotic assemblages from the Jurassic of Gondwana,
including plants, invertebrates and vertebrates. Both the
sedimentological facies and the biotic assemblage indicate a
lacustrine depositional environment. The flora is represented by tree
trunks (three families), pollen (13 species, five major clades) and
charophytes. It suggests local forests and humid (non-arid)
conditions. The vertebrate fauna is dominated by microvertebrates
recovered by screening-washing. It is rich and diverse, with at least
29 species of all major groups (osteichthyans, lissamphibians,
chelonians, diapsids, mammals), except chondrichthyans. It includes
the first mammals discovered in the Middle Jurassic of Arabo-Africa.
The GEA sites yielded some of the earliest known representatives of
osteoglossiform fishes, albanerpetontid and caudate amphibians,
squamates (scincomorphans, anguimorphan), cladotherian mammals, and
likely choristoderes. The choristoderes, if confirmed, are the first
found in Gondwana, the albanerpetontid and caudatan amphibians are
among the very few known in Gondwana, and the anguimorph lizard is the
first known from the Mesozoic of Gondwana. Mammals (Amphitheriida, cf.
Dryolestida) remain poorly known, but are the earliest cladotherians
known in Gondwana.The GEA biotic assemblage is characterized by the
presence of Pangean and Laurasian (especially European) taxa, and
quasi absence of Gondwanan taxa. The paleobiogeographical analysis
suggests either a major fossil bias in Gondwana during the Middle
Jurassic, and an overall vicariant Pangean context for the GEA
assemblage, or alternatively, noticeable Laurasian (European)
affinities and North-South dispersals. The close resemblance between
the Bathonian faunas of GEA and Britain is remarkable, even in a
Pangean context. The similarity between the local Anoual Syncline
Guelb el Ahmar and Ksar Metlili faunas raises questions on the
?Berriasian age of the latter.

===

Free pdf:

Mark A. Sephton, Dan Jiao, Michael H. Engel, Cindy V. Looy and Henk
Visscher (2015)
Terrestrial acidification during the end-Permian biosphere crisis?
Geology (advance online publication)
doi: 10.1130/G36227.1
http://geology.gsapubs.org/content/early/2015/01/07/G36227.1.abstract
http://geology.gsapubs.org/content/early/2015/01/07/G36227.1.full.pdf+html



Excessive acid rainfall associated with emplacement of the Siberian
Traps magmatic province is increasingly accepted as a major
contributing factor to the end-Permian biosphere crisis. However,
direct proxy evidence of terrestrial acidification is so far not
available. In this paper, we seek to determine the probability that
relative proportions of extractable monophenolic components from
soil-derived organic matter in marine sediments provide a molecular
proxy for estimating soil acidity. Intermittently low and high ratios
of vanillic acid to vanillin detected in latest Permian and earliest
Triassic deposits of the southern Alps, Italy, support concepts of
pulses of severe acidification (pH <4) during the main phase of the
biosphere crisis.