25th International Meeting on Organic Geochemistry IMOG 2011

P-205
Lipid biomarker analysis of faeces from modern and ancient
herbivores
Fiona Gill 1 , Richard Pancost 2 , Richard Dewhurst 3 , Emma McGeough 3 , Padraig O'Kiely 3 ,
Ian Bull 2
1 University of Leeds, Leeds, United Kingdom, 2 University of Bristol, Bristol, United Kingdom, 3 Animal &
Grassland Research and Innovation Centre,, Dunsany, Ireland (corresponding author:F.Gill@leeds.ac.uk)
Coprolites (fossilised faeces) are an underutilised
source of palaeoecological information. The
potential for lipid biomarkers preserved in coprolites to
reveal unique details of the diet, digestive processes
and digestive tract microbiota of extinct animals has
already been demonstrated [1]. However, in order to
fully exploit the benefits of this new approach it is
necessary to investigate further the controls on faecal
biomarkers in modern animals and on preservation of
lipids in coprolites.
Previous studies [2] found the methanogen
biomarker archaeol to be present in the faeces of
foregut-fermenting herbivores, but not hindgut
fermenters, suggesting that archaeol found in
coprolites therefore could be interpreted as evidence
that the producer was a foregut fermenter. More
recent research [3] has shown a correlation between
the concentration of archaeol in the faeces of modern
cattle and their methane emissions (Fig. 1). Archaeol
has also been detected in a 2500 year old ovi-caprid
dung pellet, raising the possibility that this method
may be used to estimate methane emissions from
ancient fauna. This could be used to test recent
suggestions of a causal link between megaherbivore
extinctions and global cooling in the Pleistocene [4].
However, a recent survey of over 20
coprolites from Cretaceous to Pleistocene in age has
shown that the preservation of lipids in herbivore
coprolites is highly variable and is related to factors
including age, mode of preservation and diagenetic
history of the material. Ancient faeces preserved by
desiccation have been found to contain
concentrations of lipids order of magnitude higher
than those recovered from lithified coprolites. This
suggests that further research efforts should focus on
desiccated coprolites or exceptionally well preserved
lithfied coprolites with high organic carbon content.
References
[1] Gill et al. (2009) Quaternary Research 72, 284-288
[2] Gill et al. (2010) Organic Geochemistry 41, 467-
472
Methane g -1 kg DMI
Archaeol μg -1 g dry weight faeces
individual animals
Silage diet
Concentate
diet
individual animals
Figure 1 Methane emissions and faecal archaeol
concentration in cattle (DMI = dry matter intake)
[3] Gill et al. Animal Feed Science and Technology, in
press
[4] Smith et al. (2010) Nature Geoscience 3 374-375
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