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Chirothere (crurotarsan archosaur) tracks from Triassic in Sichuan, China + other non-dino papers



Ben Creisler
bcreisler@gmail.com

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

Lida Xing, Hendrik Klein, Martin G. Lockley, Zezhong Kan, Jianping
Zhang, Guangzhao Peng & Yong Ye (2014)
First chirothere and possible grallatorid footprint assemblage from
the Upper Triassic Baoding Formation of Sichuan Province, southwestern
China.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
DOI: 10.1016/j.palaeo.2014.07.032
http://www.sciencedirect.com/science/article/pii/S0031018214003873

Trackways of archosaurs have recently been discovered in sandstones of
the Upper Triassic (Norian-Rhaetian) Baoding Formation of Panzhihua
City in southern Sichuan Province, China. Based on their
overall-morphology, pes imprints are of characteristic chirotheriid
shape showing a compact and symmetrical anterior group of digit traces
II–IV with the trace of digit III being longest, and a
posterolaterally positioned, long and slender trace of digit V.
Imprints of digit I and the manus are not preserved. This could be
related to substrate conditions and the relatively shallow
impressions, even if peculiarities in the gait such as overstep of the
manus by the pes or bipedal movement cannot completely be excluded.
Ichnotaxonomically, the imprints are assigned tentatively to cf.
Chirotherium. There are some similarities with the type ichnospecies
C. barthii from the Middle Triassic that has a global distribution and
that was described also from the Guanling Formation (Middle Triassic)
of adjacent Guizhou Province. However, the long and slender digit V
that lacks a distinct large oval basal pad, the relatively short
stride/step length, the low pace angulation, and the slight inward
rotation of the imprints toward the midline are different. The
peculiar shape of digit V and the lack of digit I in all imprints also
precludes an assignment to the common Late Triassic ichnogenus
Brachychirotherium or similar ichnotaxa such as Pseudotetrasauropus.
An isolated tridactyl footprint on the same surface is different in
shape from the chirotheriid ones by the stronger mesaxony and narrower
digit divarication. It is considered here as a possible large
grallatorid. This is the first occurrence of tetrapod footprints in
the Baoding Formation of Sichuan Province and the second record of
chirotheriids in the Triassic of China. The Baoding Formation has also
yielded a characteristic Upper Triassic flora with cycads,
filicopsids, gingkos, and conifers as well as bivalve fossils. The
depositional environment can be designated as fluvial-lacustrine with
occasional opening to marine areas. Considering biostratigraphic and
palaeobiogeographic aspects, the late occurrence of chirotheriids cf.
Chirotherium in China supports the view that basal crown-group
archosaurs with a distinct tendency toward a functionally tridactyl
pes developed and dispersed in parallel to typical tridactyl
dinosaurs.

=====
Callapez, Pedro M.; Barroso-Barcenilla, Fernando; Cambra-Moo, Oscar;
Ortega, Francisco; Pérez-García, Adán; Segura, Manuel; Torices,
Angélica (2014)
Fossil assemblages and palaeoenvironments in the Cenomanian vertebrate
site of Nazaré (West Central Portugal).
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 273(2):  179-195
DOI: http://dx.doi.org/10.1127/0077-7749/2014/0422
http://www.ingentaconnect.com/content/schweiz/njbgeol/2014/00000273/00000002/art00004

A palaeontological site with early and middle Cenomanian vertebrate
remains has been located near Nazaré, a village on the west coast of
Central Portugal known for its large promontory with exposures of
Upper Cretaceous platform carbonates and "Garumnian" siliciclastic
beds. The sampled remains are rather well preserved biomineralized
skeletal elements, including bones, teeth and fish scales of
disarticulated and fragmented specimens. The vertebrate remains
preserve their volume without signs of distortion, and many of the
original biological characteristics are still visible. Their taxonomic
study allows the identification of several middle Cenomanian
osteichthyans, including isolated teeth of Coelodus sp., a few jaw
fragments and an almost complete tooth of cf. Enchodus, and a large
and articulated teleostean specimen (Teleostei indet.) with
well-formed and ossified vertebrae and cycloid scales. The turtle
remains are late early Cenomanian in age, and include several
indeterminate fragments, besides a costal plate fragment and a
complete peripheral plate corresponding to the oldest occurrence of a
probable member of the clade Pan-Chelonioidea in the Iberian record.
The crocodyliform specimens are represented by three osteoderms of
Mesoeucrocodylia indet. and a dorsal vertebra collected from middle
Cenomanian beds. This last element is attributed to Eusuchia, a clade
poorly known in the European Cenomanian. The late early Cenomanian
assemblage with sea turtles and associated benthic faunas have been
interpreted as the record of an open inner shelf environment with
bivalve biostromes of Ilymatogyra pseudoafricana and Ceratostreon
flabellatum located close to an intertidal flat with mixed
carbonate-sand sedimentation. The inner shelf episode was followed by
the development of a lagoonal environment during the middle
Cenomanian, with oyster communities of Gyrostrea ouremensis and a
diverse vertebrate assemblage with several fish and crocodyliform
species adapted to more restricted ecological conditions. These new
discoveries increase the limited number of European locations with
Cenomanian vertebrate assemblage records, and provide additional data
for several less well known taxa.

==
Ádám T. Kocsis, Wolfgang Kiessling, and József Pálfy (2014)
Radiolarian biodiversity dynamics through the Triassic and Jurassic:
implications for proximate causes of the end-Triassic mass extinction.
Paleobiology 40(4):625-639. 2014
doi: http://dx.doi.org/10.1666/14007
http://www.bioone.org/doi/abs/10.1666/14007

Within a ~60-Myr interval in the Late Triassic to Early Jurassic, a
major mass extinction took place at the end of Triassic, and several
biotic and environmental events of lesser magnitude have been
recognized. Climate warming, ocean acidification, and a
biocalcification crisis figure prominently in scenarios for the
end-Triassic event and have been also suggested for the early
Toarcian. Radiolarians, as the most abundant silica-secreting marine
microfossils of the time, provide a control group against marine
calcareous taxa in testing selectivity and responses to changing
environmental parameters. We analyzed the origination and extinction
rates of radiolarians, using data from the Paleobiology Database and
employing sampling standardization, the recently developed gap-filler
equations and an improved stratigraphic resolution at the substage
level. The major end-Triassic event is well-supported by a late
Rhaetian peak in extinction rates. Because calcifying and siliceous
organisms appear similarly affected, we consider global warming a more
likely proximate trigger of the extinctions than ocean acidification.
The previously reported smaller events of radiolarian turnover fail to
register above background levels in our analyses. The apparent early
Norian extinction peak is not significant compared to the long-term
trajectory, and is probably a sampling artifact. The Toarcian Oceanic
Anoxic Event, previously also thought to have caused a significant
radiolarian turnover, did not significantly affect the group.
Radiolarian diversity history appears unique and complexly forced, as
its trajectory parallels major calcareous fossil groups at some events
and deviates at others.