Geoscience Reference
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out and cracked slightly before burial and fossilization, meaning they were origin-
ally deposited on dry land.
Ghosh and his colleagues detected vascular plant remains in the coprolites, as
well as fungal spores, algae, and plenty of bacteria. However, their most significant
findscamefromachemicalanalysisofthecoprolites,whichhelpedthemtonarrow
down which types of plants the titanosaurs ate. To figure this out, these scientists
calculated a couple of stable-isotope ratios in the coprolites—for carbon and nitro-
gen—and compared these ratios to those in the feces of modern animals, such as
deer, camels, buffalo, and big cats (leopards and tigers).
Justtobackupwithsomebasicdefinitions: isotopesarevariationsofthesame
element, but with different atomic weights. For example, the isotopes of carbon (C)
are
12
C,
13
C, and
14
C. Of those isotopes,
12
C and
13
C are stable, but
14
C is not,
as it undergoes radioactive decay and changes to another element. Nitrogen (N)
isotopes are
14
N and
15
N, and both of these are stable. Then what are stable-iso-
toperatios?Inthisinstance,thesescientistscalculated
12
C/
13
Cand
14
N/
15
N.Plants,
through different means of photosynthesis, take in carbon and nitrogen isotopes in
distinct ways, which is then reflected by their stable-isotope ratios. For instance,
C
3
and C
4
plants—so called because of the number of certain carbon compounds
they form—have dissimilar ratios, because C
4
plants absorb
13
C more easily than
C
3
plants. In short, these ratios are chemical signatures that, under ideal conditions,
persistinfossilplants,eveniftheywentthroughthegutofadinosaurandwerebur-
ied for about 70 million years.
As it turned out, the carbon-isotope ratios showed that the titanosaurs ate C
3
plants, nearly matching a value for birds, and they were much closer to ratios of
modern herbivores—goats, camels, and buffalo—than carnivores. Additionally, C
3
plantsmakeupnearly90%ofallmodernvegetation,andincludegrasses.However,
this did not mean these titanosaurs were eating grasses specifically; plant pieces in
the coprolites matched those of conifers and other non-flowering plants. But these
dinosaurs were certainly consuming plants with similar modes for photosynthesiz-
