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Triassic tetrapod fossils from Spain and Poland + Triassic climate



Ben Creisler
bcreisler@gmail.com


A number of recent (and not so recent) papers about Triassic
vertebrate fossils and Triassic climate



Carlos de Miguel Chaves, Adán Pérez García, Alberto Cobos, Rafael
Royo-Torres, Francisco Ortega & Luis Alcalá (2015)
A diverse Late Triassic tetrapod fauna from Manzanera (Teruel, Spain).
Geobios (advance online publication)
doi:10.1016/j.geobios.2015.09.002
http://www.sciencedirect.com/science/article/pii/S0016699515000777


Several outcrops with vertebrate tetrapod remains have been located in
the Keuper levels (Carnian, Upper Triassic) of the Spanish
municipality of Manzanera (Teruel Province). The Manzanera remains
include ribs and vertebrae of the sauropterygian nothosauroid
Simosaurus, isolated osteoderms of cyamodontoid placodonts, partial
vertebral centra of ichthyosaurs, and fragmentary dermal bones of
temnospondyls. Therefore, a relatively high diversity is recognized in
the Late Triassic of this region. The Simosaurus identification may
represent the only occurrence of this genus in the Iberian Peninsula;
it is one of the youngest in the fossil record. Several morphotypes of
cyamodontoid placodont osteoderms are identified. The ichthyosaur
elements from Manzanera represent the first record of this clade in
the Iberian Keuper, constituting the second reference to this group in
the Iberian Triassic after those from the Ladinian of Catalonia.

==============


Monika Kowal-Linka (2015)
Analysis of marrow cavity fillings as a tool to recognise diverse
taphonomic histories of fossil reptile bones: Implications for the
genesis of the Lower Muschelkalk marine bone-bearing bed (Middle
Triassic, Żyglin, S Poland).
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2015.06.040
http://www.sciencedirect.com/science/article/pii/S0031018215003533

Highlights

Petrographic analysis of the marrow cavity fillings is a highly valuable tool.
It is useful to reveal complex taphonomic pathways of vertebrate bioclasts.
Some vertebrate bioclasts were inhabited by minute or juvenile invertebrates.
The Lower Anisian bone-bearing bed from Żyglin is recognised as
proximal tempestite.
Crinoid ossicles and bones included in deposit were derived from
various settings.

Abstract

The bone-bearing bed from Żyglin (S Poland), which likely represents
the oldest Lower Muschelkalk accumulation of reptile remains in the SE
part of the Germanic Basin, has been investigated in order to
determine its genesis. The basic methods were supported by
petrographic analysis of the marrow cavity and large inter-trabecular
pore space fillings of fossil bones, which was used to check its
usefulness to identify the environments where the bones were initially
deposited and to decipher taphonomic histories of the remains. The
bone-bearing bed is a composite deposit, which consists of three
distinct layers (from bottom to top): micritic limestone (mudstone,
bioturbated autochthonous mud), crinoidal limestone (grainstone to
packstone, calcirudite), and shell-rich limestone (packstone to
wackstone, calcirudite). The crinoidal limestone layer, the main
bone-bearing bed, is recognised as the proximal tempestite deposited
in the mid-ramp zone. The petrographic analysis of the fillings
reveals the prevalence of minute ostracod carapaces, accompanied by
other grains, embedded together with micrite to microspar. Such
compositions suggest that these sediments may have been inserted into
the bone pore spaces in lagoons and tidal-flat ponds. Features of some
bones record their early diagenetic burial and lithification before
the final redeposition. The isopachous spar, blocky spar and weathered
pyrite document changes in the chemical composition of fluids that
flowed into the bone interiors. The burrow found in the marrow cavity
of specimen IGUAM-ZOV-7 provides evidence that some remains were
inhabited by minute or juvenile invertebrates. All recognised features
indicate that both invertebrate and vertebrate bioclasts, included in
the tempestite, were initially deposited in various settings of the
carbonate ramp and in the end redeposited as a result of a heavy storm
or a hurricane. The examined bone-bearing bed represents time-averaged
assemblage, which originated due to hydraulic concentration of the
vertebrate bioclasts. The petrographic analysis of the fillings is a
valuable tool to identify complex taphonomic pathways of vertebrate
bioclasts.

==

Violeta Borruel-Abadía, José López-Gómez, Raúl De la Horra, Belén
Galán-Aballán, José F. Barrenechea, Alfredo Arche, Ausonio Ronchi,
Nicola Gretter & Mariano Marzo (2015)
Climate changes during the Early–Middle Triassic transition in the E.
Iberian plate and their palaeogeographic significance in the western
Tethys continental domain.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2015.09.043
http://www.sciencedirect.com/science/article/pii/S0031018215005532

Highlights

Olenekian alternating arid to semi-arid climates in near equator
continental areas.
Two main arid periods located at the end of the Smithian and middle of
the Spathian.
Olenekian alternating arid to semi-arid climates in periods shorter
than 0.4 m.a.
A late Spathian first subhumid period coincides with the beginning of
fauna and flora recovery
South of the Iberian Basin a generalized wetter climate extended
towards the equator during the Olenekian-Anisian.

Abstract

Until recently the climate of the Early–Middle Triassic at low
latitudes was broadly considered as generally temperate-warm with no
major climate oscillations. This work examines the climate of this
period through a detailed study of the sedimentary, plant, soil and
mineral records of continental rocks (Buntsandstein facies) in eastern
Iberian basins. Our findings indicate temporal climate variations for
these near equator (10°–14°N) regions and unveil the significance of
such variations in the southern Laurasian domain.

The climate of Iberia's Early Triassic was mainly dominated by
alternating brief (< 0.4 ma) arid and semi-arid climate periods, with
two main arid periods documented at the end of the Smithian and middle
Spathian. However, an initial short subhumid to semi-arid period was
also observed in the late Spathian. Remarkably, this latter period
appears just after an unconformity related to the tectonically induced
Hardegsen Event in western Europe. It is also of interest that this
short subhumid climate period is concurrent with the beginning of
faunal and floral recovery in the basins examined. The Early Triassic
ended again with a short very arid period.

Although the beginning of the Anisian (Aegean) was represented by
alternating arid and semi-arid to subhumid intervals, during the
Bithynian and Pelsonian clearly wetter climates are recorded by the
succession consisting of alternating semi–arid to semi-humid
intervals. This general tendency was interrupted by three short but
marked intervals, two humid intervals in the late Bithynian, and one
arid period near the Bithynian/Pelsonian boundary.

Iberia was crossed by prominent irregular highs separating marked
corridors or isolated areas. This palaeogeography, prevailing since
Variscan tectonics, clearly conditioned dominant climates and their
geographical distribution. No clear climate belts developed in these
conditions. However, isolated internal climate zones separated by
elevated areas are identified. This palaeogeographic configuration and
the low latitudinal position of Iberia determined central Iberia highs
in the southernmost border of Laurasia, beyond which more humid
conditions clearly extended towards the equator reaching the
present-day Moroccan Meseta and Argana Basin.

===

Sofie Lindström (2015)
Palynofloral patterns of terrestrial ecosystem change during the
end-Triassic event – a review.
Geological Magazine (advance online publication)
DOI: http://dx.doi.org/10.1017/S0016756815000552
http://128.232.233.5/action/displayAbstract?fromPage=online&aid=9937498&fulltextType=RV&fileId=S0016756815000552


A review of the palynofloral succession at the well-documented
Triassic–Jurassic boundary sites – Kuhjoch (Austria), St Audrie's Bay
(UK), Stenlille (Denmark), Astartekløft (Greenland), Sverdrup Basin
(Arctic Canada), Northern Carnarvon Basin (Western Australia),
Southeast Queensland (eastern Australia) and New Zealand – show all
sites experienced major to moderate re-organization of the terrestrial
vegetation during the end-Triassic event. The changes led to
subsequent taxonomic losses of between 17% and 73% of the Rhaetian
pre-extinction palynoflora. The majority of the typical Rhaetian taxa
that disappear are so far not known from in situ occurrences in
reproductive structures of macrofossil plant taxa. From an ecological
perspective, the most dramatic changes occurred in the Sverdrup Basin,
Stenlille, Kuhjoch and Carnarvon Basin, where the pre- and
post-extinction palynofloras were fundamentally different in both
composition and dominance. These changes correspond to ecological
severity Category I of McGhee et al. (2004), while the remaining sites
are placed in their Subcategory IIa because there the pre-extinction
ecosystems are disrupted, but recover and are not replaced
post-extinction. Increased total abundances of spores on both
hemispheres during the extinction and recovery intervals may indicate
that environmental and/or climatic conditions became less favourable
for seed plants. Such conditions may include expected effects of
volcanism in the Central Atlantic Magmatic Province, such as acid
rain, terrestrial soil and freshwater acidification due to volcanic
sulfur dioxide emissions, fluctuating ultraviolet flux due to ozone
depletion caused by halogens and halocarbon compounds, and drastic
changes in climatic conditions due to greenhouse gas emissions.