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Synapsids from Liassic of Germany; earliest rhynchosaur from Argentina; anomodont fossil record



From: Ben Creisler
bcreisler@gmail.com

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

William A. Clemens & Thomas Martin (2013)
Review of the non-tritylodontid synapsids from bone beds in the
Rhaetic Sandstone, southern Germany.
Paläontologische Zeitschrift (advance online publication)
DOI: 10.1007/s12542-013-0201-5
http://link.springer.com/article/10.1007/s12542-013-0201-5

Since the nineteenth century, bone beds in the Rhaetic Sandstone
(Rhätsandstein) exposed around Bebenhausen near Tübingen,
Baden-Württemberg, have been a source of small vertebrate fossils.
These bone beds were part of deltas formed during a stillstand in a
marine transgression from the western and northern parts of the
Germanic Basin. The fossils in these bone beds appear to be
time-averaged assemblages of Rhaeto-Liassic or older age. A collection
of fossils from excavations at Olgahain made in 1948 augmented those
reported by E. von Huene (Jahreshefte des Vereins vaterländische
Naturkunde in Württemberg 84:65–128, 1933). The synapsids, other than
tritylodonts, represented by fossils from the Olgahain locality
include Tricuspes, a non-mammaliaform eucynodont; the haramiyid
Thomasia antiqua is the most abundantly represented mammaliaform, and
a morganucodontid. Tricuspes tuebingensis was based on a tooth found
at the nearby Gaisbrunnen locality. Tricuspes tuebingensis, Thomasia
antiqua, and a probably different morganucodontid are known from the
Hallau bone bed (Switzerland), which apparently is older than the
Olgahain bone bed in Baden-Württemberg.

==

Martín D. Ezcurra, M. Jimena Trotteyn, Lucas E. Fiorelli, M. Belén von
Baczko, Jeremías R. A. Taborda, Maximiliano Iberlucea & Julia B.
Desojo (2013)
The oldest rhynchosaur from Argentina: a Middle Triassic rhynchosaurid
from the Chañares Formation (Ischigualasto–Villa Unión Basin, La Rioja
Province).
Paläontologische Zeitschrift (advance online publication)
DOI: 10.1007/s12542-013-0203-3
http://link.springer.com/article/10.1007/s12542-013-0203-3

Rhynchosaurs first appear in the Early Triassic fossil record and
flourished during the late Carnian as the dominant members of several
assemblages worldwide. In Argentina, the rhynchosaur record is
currently restricted to the Ischigualasto Formation of late
Carnian–earliest Norian age. Recent fieldwork in the new locality of
Brazo del Puma, in the lowermost levels of the Chañares Formation,
yielded three rhynchosaur tooth-bearing bones, which were collected
five metres above the contact with the underlying Tarjados Formation.
The most complete specimen is the posterior end of the alveolar region
of a left dentary. The dentary possesses densely packed tooth rows on
the lingual surface and medial half of the occlusal surface, showing
longitudinal Zahnreihen. The teeth of the occlusal surface are worn
flat and those of the lingual surface are organized in multiple rows,
supporting the referral of the specimen to Rhynchosauridae. In
addition, the dentary teeth are conical to mesiodistally compressed,
resembling the condition observed in hyperodapedontines. The
rhynchosaur remains reported here are the oldest collected in
Argentina and among the oldest in South America, together with an
unnamed form from Brazil. The new rhynchosaur specimens come from
levels in which dicynodonts are numerically dominant, whereas
cynodonts are considerably less abundant. Accordingly, the specimens
reported here bolster faunal differences within the Chañares Formation
and add a new faunal component to this already diverse vertebrate
assemblage.

===

Marcus Walther & Jörg Fröbisch (2013)
The quality of the fossil record of anomodonts (Synapsida, Therapsida).
Comptes Rendus Palevol (advance online publication)
doi: http://dx.doi.org/10.1016/j.crpv.2013.07.007
http://www.sciencedirect.com/science/article/pii/S1631068313001139


The quality of the fossil record of anomodont synapsids, one of the
major clades of Permian–Triassic terrestrial tetrapods, is assessed. A
Character Completeness Metric (CCM2) is calculated for each taxon and
consecutive time intervals at a global scale and in the South African
Karoo Basin. The mean completeness score is 66.80% (globally) and
77.37% (regionally) with completeness ranging between 60.12% and
91.33% per time interval. Up-to-date taxic, phylogenetic and residual
diversity estimates confirm the general biodiversity trends recovered
by recent analyses. The consistently high CCM2 scores throughout their
evolutionary history together with a lack of correlation with
biodiversity patterns and sampling proxies document a high quality of
the known anomodont fossil record. In fact, when compared to other
vertebrate groups, the completeness values for anomodonts are
exceptionally high. Yet, whether this pattern results from the
unrivalled record of the Karoo Basin or whether it is clade-specific
and unique to anomodonts remains to be tested.