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???ViewItemFull_lblSubject???:
Carbon and oxygen isotopes, enamel, paleoecology, Temnospondyli
???ViewItemFull_lblAbstract???:
The Middle Triassic (Ladinian) fossil assemblages from the Lower Keuper localities of Vellberg-
Eschenau and Kupferzell (Germany) are notable for their rich vertebrate fauna, including the ear-
liest stem-turtle Pappochelys rosinae and the oldest rhynchocephalian Wirtembergia hauboldae.
Among them, the largest temnospondyl known to date, Mastodonsaurus giganteus, is an iconic
apex predator in these swamp-like ecosystems. Stable isotopes (δ18 O CO3, δ13C) of Mastodonsaurus
tooth enamel were analysed in bulk samples using continuous-flow mass spectrometry for selected
teeth to characterize its habitat conditions and paleoecology at the two contemporaneous locali-
ties. To further assess similarities and differences in the paleoenvironmental settings of the fossilifer-
ous horizons, additional skeletal remains from associated aquatic and terrestrial fauna (Ceratodus,
Serrolepis, Nothosaurus, Batrachotomus, Pappochelys) were also analysed for comparison. High-
resolution secondary ion mass spectrometry (SIMS) in situ δ18 O analyses in the thin enamel were
performed to determine paleoenvironmental conditions such as salinity and temperature changes,
and thus niche occupation. Preliminary δ13C and δ18 O data from Mastodonsaurus tooth enamel
reveal differences in isotope compositions between Vellberg-Eschenau (δ13C VPDB = -8.7‰ [range:
-13.4 to -6.8‰], δ18 O CO3,VSMOW = 24.1‰ [range: 22.1–26.0‰]) and Kupferzell ( δ13C VPDB = -8.1‰
[range: -11.3 to -7.2‰], δ18 O CO3,VSMOW = 25.1‰ [range: 24.0–26.4‰]), despite their geographical
proximity. Complementary, comparative analysis of Mastodonsaurus fang teeth of different sizes
shows a slight variation in their intra-tooth δ13C and δ18 O signatures, hinting at potential ontoge-
netic differences. Additional 87Sr/86Sr analysis of Mastodonsaurus enamel will further refine paleo-
salinity reconstructions for these Middle Triassic Keuper swamp settings through combined Sr and
O isotope mixing models and provide insights into habitat use and potential migration
