Paleoecology and Poop, a Perfect Pair

It’s time to stop feeling sheepish and discuss poop. That’s right. You may not know this, but both modern and fossil poop can tell us so much information about biology, ecology, and environments that I think we need to talk about it. Instead of saying poop one million times in this entry, I will use the more official terms us scientists use: fossil poop is called a coprolite, while modern (fresh) samples are typically called scats. Feel a little less embarrassed now?

You may be wondering how interesting a coprolite can be. After all, fossilized excrement may look funny but it surely cannot be useful, right? Well just two weeks ago in PLOS ONE we saw that a 270 million year old shark coprolite contains remains of tapeworm egg casings, which is the earliest example of vertebrate intestinal parasites (Dentzien-Dias et al. 2013). Also, fossil freshwater bivalve shells were discovered in vertebrate coprolites from the Karoo Basin in South Africa, making them the first record of any freshwater bivalve in the Early Triassic (Yates et al. 2012).

More traditionally though, coprolites are used to glean ecological information relating to the animal it came from and the environment it lived in. Knowledge about the diets of extinct animals can give us an indication of past vegetation structures and help us understand how climate change can alter landscapes and food webs. Researchers out of New Zealand were able to use extinct moa coprolites for radiocarbon dating and ancient DNA analysis (Wood et al. 2012). Moa were giant herbivorous birds (up to 250 kg) that went extinct shortly after the arrival of humans on the island. Moa coprolites can give us direct evidence of moa diet, and therefore the vegetation structure of their habitat, before the arrival of humans.

Pollen, along with DNA of both the moa and the plant remains in the coprolites were examined. 67 species of plants were identified in the coprolites, indicating the moa was a generalist browser ~6,500 BP.

In addition to diets, coprolites can also be used to obtain ancient genomes from extinct species, such as cave hyenas (Bon et al. 2012) and the first Americans (Jenkins et al. 2012). Under the right conditions, DNA will be preserved in coprolites and provide previously unknown information about genetic diversity of extinct populations and species.

Perhaps most importantly, coprolites can have a very important place in conservation paleobiology. Animal-plant (or any prey) interactions are often not preserved in the fossil record, and things like coprolites are the only record of these interactions. Conservation scientists want to know what these relationships were like before human colonization in many areas, and this is a useful proxy to determine the “natural state” of animal-environment interactions. Wood et al. 2012 describes a pollen analysis of a coprolite from a kakapo- a rare flightless parrot endemic to New Zealand. Evidence from the coprolite shows they used to feed on a cryptic root parasite, but now the ranges of these two species do not overlap, which can indicate a shifting position of the kakapo in the larger food web. Evidence from coprolites will not only help us understand biology of animals that was previously unknown, but also will allow us to see a snapshot in time of ancient environments, and this helps us learn more about what we should try and conserve. Looks like poop science might be more useful than you thought!

References:

Bon C, Berthonaud V, Maksud F, Labadie K, Poulain J, Artiguenave F, Wincker P, Aury JM, Elalouf JM. (2012) Coprolites as a source of information on the genome and diet of the cave hyena. Proceedings of the Royal Society B: Biological Sciences 279, (1739) 2825-2830.

Dentzien-Dias PC, Poinar G Jr, de Figueiredo AEQ, Pacheco ACL, Horn BLD, et al. (2013) Tapeworm Eggs in a 270 Million-Year-Old Shark Coprolite. PLoS ONE 8(1): e55007. doi:10.1371/journal.pone.0055007

Jenkins JL, et al. (2012) Clovis Age Western Stemmed Projectile Points and Human Coprolites at the Paisley Caves. Science 337 (6091), 223-228.

Wood, J. R., Wilmshurst, J. M., Worthy, T. H., Holzapfel, A. S. and Cooper, A. (2012), A Lost Link between a Flightless Parrot and a Parasitic Plant and the Potential Role of Coprolites in Conservation Paleobiology. Conservation Biology, 26: 1091–1099. doi: 10.1111/j.1523-1739.2012.01931.x

Wood JR, Wilmshurst JM, Wagstaff SJ, Worthy TH, Rawlence NJ, et al. (2012) High-Resolution Coproecology: Using Coprolites to Reconstruct the Habits and Habitats of New Zealand’s Extinct Upland Moa (Megalapteryx didinus). PLoS ONE 7(6): e40025. doi:10.1371/journal.pone.0040025

Yates AM, Neumann FH, Hancox PJ (2012) The Earliest Post-Paleozoic Freshwater Bivalves Preserved in Coprolites from the Karoo Basin, South Africa. PLoS ONE 7(2): e30228. doi:10.1371/journal.pone.0030228