[dinosaur] Rise of dinosaurs linked to increasing oxygen levels + Estimation of Dinosaur Body Temperature From Sauropod Eggshell

Ben Creisler
[email protected]

Goldschmidt 2019 Conference abstracts

Rise of dinosaurs linked to increasing oxygen levels

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New constraints on ancient atmospheric oxygen concentrations and the Late
Triassic rise of the first North American dinosaurs
MORGAN F. SCHALLER, ELIZABETH PETTITT, TODD KNOBBE, DANIEL O. BREECKER

We have developed a new proxy for ancient atmospheric oxygen concentrations
based on the composition of soil carbonate-hosted fluid inclusions. Fluid
inclusions form in equilibrium with the soil pore space gas during
inclusion closure. Based on modern soil gas measurements, we show that the
atmospheric gases liberated from soil carbonate-hosted inclusions closely
reflect soil gas concentrations and contain all the major atmospheric
species. The concentration of O2 in soil pore space gas is controlled by
respiration and diffusion-mediated exchange with the atmosphere, and we
show that profiles of fluid inclusion compositions can be used along with
production-diffusion modeling to reconstruct atmospheric pO2. An inversion
of the diffusion model can be solved iteratively to predict atmospheric O2
from the gases hosted in modern soil carbonates and reproduces modern
atmospheric pO2. The model is then applied to Late Triassic paleosols from
cores taken through two contemporaneous sedimentary sequences that formed
>1000 km apart across the Pangean supercontinent: the Colorado Plateau and
Newark Basin Coring Projects (CPCP and NBCP). Combined results from the
Colorado Plateau and Newark Basin show a secular increase in pO2 that
corresponds to a decrease in pCO2, coinciding with the appearance of the
very first North American dinosaur, Chindesaurus.


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Estimation of Dinosaur Body Temperature From Late Cretaceous Sauropod
Eggshell From India Using Carbonate Clumped Isotopes
YOGARAJ BANERJEE, PROSENJIT GHOSH, RAJEEV PATNAIK, SYED A JAFAR, ASHOK
SAHNI


The thermal physiology of saurischian dinosaurs is a subject of research
interest over the years. Here in this study, we have carried out clumped
isotope investigation on well preserved late Cretaceous Sauropod eggshell
from India. Our preliminary investigation reveals a Δ47 based temperature
of 39 (±2)°C in CDES scale, similar to the Titanosurid eggshell
investigated by [1] and theoritically predicted value [2]. Clumped isotope
study on co eval Crocodile egg shell reveals a temperature of 28 (±4)°C. We
have also carried out similar investigation on the Australian Emu, Egyptian
Ostrich and Antarctic Penguin eggshells of recent to subrecent time frame,
which yielded temperatures around 42 (±2)°C. It is interesting to note that
the δ18Owater derived from the sauropod egg shell shows an enriched
signature of 4.59‰ in VSMOW scale similar Titanosurid eggshell investigated
by [1]. On contrary co eval Crocodile eggshell captures a freshwater
δ18Owater signature. Possible scenarios related to palaeo physiological
processes and disequillibrium isotope effect will be discussed during
presentation to explain the obtained temperature and δ18Owater information.


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