calcite was processed in the stable isotope labs of the Michigan University (USA) following the methods described in Gomez and Goy (2011).
VPDB is the corrected isotope delta value for 13C measured against the reference standard Vienna Pee Dee Belemnite
"FEA will hopefully allow us to see the effect of eating hard foods, such as the belemnites
with their bullet-shaped guards," Moon said.
The [[delta].sup.13]C values were expressed relative to Vienna-Pee Dee Belemnite
The squid-like belemnite
fossil shown at the bottom of the page, showing its internal shell, ink sac, and other internal structures, supposedly demonstrates the rare preservation of the soft body outline.
Here, next to the ammonite, is the darkbullet shaped mark of a belemnite
, which would have had squidlike tentacles emerging from it.
Hiking trails lead past floodplain forests, over the hills and ridges of the Tafeljura, where a practiced eye can still find many an ammonite or belemnite
Soon the girls learned how to tell an ammonite, belemnite
, or crinoid from a stone.
Stable carbon isotope composition ([delta][sup.13]C), that is, the ratio of [sup.13]C/[sup.12]C relative to that found in the PDB (Pee Dee belemnite
) standard, is measured by mass spectrometry.
where [sup.13]C/[sup.12]C refers to the isotope ratio in the sample or an international standard (a reference gas calibrated relative to Pee Dee Belemnite
The ratio of carbon isotopes in leaf tissue samples ([R.sub.sam]) relative to that of the PeeDee Belemnite
standard ([R.sub.std]) was used to express carbon isotope compositions on a parts per thousand (??) basis:
Where there is a discrepancy between the disposition of a structure and its anatomical origins, as in tortoise shells and belemnite
guards, we classify the structure on the basis of its actual geometry, for we are here concerned with the design elements animals actually employ, rather than their strict homologies and evolutionary derivations.
Isotope results were reported in the conventional delta ([delta]) notation, with units of per mil or parts per thousand ([per thousand]), relative to the international standards of Vienna-Pee Dee Belemnite
(V-PDB) for [[delta].sup.13]C and [N.sub.air] for [[delta].sup.15]N:
Converting the values to Vienna Pee Dee Belemnite
(VPDB) following Copien et al.