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Dinosaur and crocodilian isotope analyses for Lo Hueco (Upper Cretaceous, Spain)



From: Ben Creisler
bcreisler@gmail.com


A new paper:

Laura Domingo, Fernando Barroso-Barcenilla and Oscar Cambra-Moo (2013)
Paleoenvironmental reconstruction of the “Lo Hueco” fossil site (Upper
Cretaceous, Cuenca, Spain): preliminary stable isotope analyses on
crocodilians and dinosaurs.
Palaios 28(3): 195-202
doi: 10.2110/palo.2012.p12-097r
http://palaios.geoscienceworld.org/content/28/3/195.abstract


Stable isotope analyses (δ18OPO4, δ18OCO3, and δ13C) are reported for
the first time on crocodilian, theropod, and sauropod teeth from two
stratigraphic levels (G1 and G2) from the late Campanian–early
Maastrichtian “Lo Hueco” fossil site (Cuenca, Spain) in order to
better understand paleoclimatic and paleoenvironmental conditions
existing in the Iberian Peninsula during the Late Cretaceous.
Diagenetic alteration was evaluated using three tests: (1) consistent
differences in enamel and dentine δ18OPO4 values, (2) crocodilian
δ18OPO4 values consistently lower than dinosaur δ18OPO4 values in
agreement with the proposed latitudinal distribution between
ectotherms and endotherms, and (3) a Δδ18OCO3-PO4 value of 9.1 ± 1.7‰
for dinosaurs in accordance with the expected equilibrium
fractionation between carbonate and phosphate in unaltered modern
mammalian bioapatite. Calculated δ18OH2O values are slightly higher in
crocodilians compared to dinosaurs since semiaquatic ectothermic taxa
δ18OH2O represents local meteoric waters in a brief window of time
when the conditions are favorable for apatite synthesis, whereas
terrestrial endothermic taxa δ18OH2O records ingested water
year-round. Mean air temperature calculated using crocodilian and
dinosaur δ18OH2O values shows an increase between G1 and G2, which may
be related to differences in the sedimentological setting and/or to a
shift toward warmer conditions over time. Finally, the sauropod mean
δ13C value (−11.1 ± 0.2‰, VPDB) is in the predicted range for C3
vegetation.