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Crocodyliformes evolutionary history (free pdf) + oldest therapsid + more papers



Ben Creisler
bcreisler@gmail.com

A number of recent (and not so recent) non-dino papers:


Mario Bronzati, Felipe C. Montefeltro & Max C. Langer (2015)
Diversification events and the effects of mass extinctions on
Crocodyliformes evolutionary history.
Royal Society Open Science 2015 2 140385
DOI: 10.1098/rsos.140385
http://rsos.royalsocietypublishing.org/content/2/5/140385

Free pdf:
http://rsos.royalsocietypublishing.org/content/royopensci/2/5/140385.full.pdf

The rich fossil record of Crocodyliformes shows a much greater
diversity in the past than today in terms of morphological disparity
and occupation of niches. We conducted topology-based analyses seeking
diversification shifts along the evolutionary history of the group.
Our results support previous studies, indicating an initial radiation
of the group following the Triassic/Jurassic mass extinction, here
assumed to be related to the diversification of terrestrial
protosuchians, marine thalattosuchians and semi-aquatic lineages
within Neosuchia. During the Cretaceous, notosuchians embodied a
second diversification event in terrestrial habitats and eusuchian
lineages started diversifying before the end of the Mesozoic. Our
results also support previous arguments for a minor impact of the
Cretaceous/Palaeogene mass extinction on the evolutionary history of
the group. This argument is not only based on the information from the
fossil record, which shows basal groups surviving the mass extinction
and the decline of other Mesozoic lineages before the event, but also
by the diversification event encompassing only the alligatoroids in
the earliest period after the extinction. Our results also indicate
that, instead of a continuous process through time, Crocodyliformes
diversification was patchy, with events restricted to specific
subgroups in particular environments and time intervals.
==


Lu Li, Haiyan Tong, Wei Gu & Jun Liu (2015)
A new trionychid turtle from the Early Cretaceous of Heilongjiang
Province, Northeastern China.
Cretaceous Research 56: 155–160
doi:10.1016/j.cretres.2015.04.013
http://www.sciencedirect.com/science/article/pii/S0195667115000658

A new soft-shelled turtle (“Trionyx” jixiensis sp. nov.) from the
Lower Cretaceous Chengzihe Formation, Jixi city, Heilongjiang
Province, China is described on the basis of a nearly complete
carapace. The new species is diagnosed by the absence of suprascapular
fontanelles and absence of a preneural; eight neurals, tetragonal
fifth neural; and eight pairs of costals, with the large eighth
costals meeting after the eighth neural. Due to the incompleteness of
the specimen and confused classification of the genera of trionychids,
the new species cannot be included in any genus of Trionychinae and is
temporarily assigned to “Trionyx” (sensu lato). “Trionyx” jixiensis is
one of the earliest trionychids, its discovery indicates that the
family was already diversified during the Early Cretaceous in Asia.


==

Frederik Spindler (2014)
Reviewing the question of the oldest therapsid.
Paläontologie, Stratigraphie, Fazies (22) Freiberger Forschungshefte C 548: 1–7
http://www.geo.tu-freiberg.de/psf/

Since the successful clade of therapsids occurs rather suddenly in the
fossil record of Guadalupian age, the reconstruction of their origin
is questionable and based on little data. Concerning the Artinskian
taxon Tetraceratops insignis, broadly accepted as the oldest and
basal-most member, no close relation to therapsids could be found
during the re-documentation. Instead, a fragmentarily preserved
vertebral sequence from the Desmoinesian assemblage of Florence, Nova
Scotia, is considered to be a new candidate for the oldest therapsid.
This pushes back their origin farther than required by phylogenetic
results. Moreover, it supports the ghost lineage of unknown
Carboniferous and Early Permian therapsids.

==

R. Mason, B. Rubidge, and J. Hancox (2015)
Terrestrial vertebrate colonisation and the Ecca-Beaufort boundary in
the southeastern main Karoo Basin, South Africa: implications for
Permian basin evolution.
South African Journal of Geology 118: 145-156
doi:10.2113/gssajg.118.2.145
http://sajg.geoscienceworld.org/content/118/2/145.abstract

Rocks of the Late Carboniferous to Early Jurassic aged Karoo
Supergroup of South Africa preserve a sedimentary succession,
deposited in a retro-arc foreland setting. This succession documents
environmental change from glacial-marine, through full marine to
continental fluvial and aeolian environments, culminating in rift
associated continental flood basalt extrusions. The Karoo Basin is
internationally renowned for its wealth of fossil tetrapods, enabling
the establishment of a reliable and useful biostratigraphic framework
which has international applicability for correlation of
Permian-Triassic tetrapod-bearing continental deposits. The transition
from marine to continental deposition in the Karoo has been the
subject of much recent research, particularly in regard to the
position of the Ecca-Beaufort contact. Our study indicates for the
first time that in the south-eastern part of the basin, as for the
rest of the basin, this transition comprises three separate facies
associations deposited respectively in the prodelta, subaqueous delta
plain and subaerial delta plain environments. The Tapinocephalus
Assemblage Zone is the lowermost vertebrate biozone in the Koonap
Formation indicating that the Ecca-Beaufort boundary is diachronous in
the southern part of the basin, younging towards the east. This
supports the easterly to northeasterly prograding shoreline model
previously proposed for the Ecca-Beaufort transition and provides new
insight on the distribution of the earliest land-living vertebrates in
the south-eastern Karoo Basin.