Sunday, February 3, 2013

New Insights on Old Worms

As we've seen with past work, it's not easy to find parasites in coprolites that date back to 270 million years ago.  However, a team of researchers has found such diamonds in the rough...if you think of tapeworm eggs as tiny diamonds, and fossilized shark poop as the rough.

Shark coprolite containing 270 million year old tapeworm eggs.
These researchers published their work in PLoS One in January of this year (2013). From a Brazilian coprolite dating back to the Paleozoic era, this team found a group of 93 tapeworm eggs.  Like modern fish tapeworm eggs, these possessed a single operculum, and one even looked to contain a developing larva.  The oval-shaped eggs were beautifully preserved inside the coprolite encased within what appears to have been a proglottid. 

#1, this is awesome because it is the first time that tapeworm eggs have been recovered from anything that is this old.  We are talking older by FAR...these eggs predate parasites found in the fossil record dating back to dinosaurs. In fact, these eggs predate known instances of any form of vertebrate parasites by about 140 million years.  This sets the evolutionary time stamp much further back for intestinal parasites than we ever thought they had existed. (This is why biology is awesome! What we think we know today, could be completely wrong with the discoveries of tomorrow!)

This discovery will hopefully spur the interest of other researchers into doing paleoparasitology work.  It is absolutely amazing to have the definitive proof of the existence of something as soft-bodied as a tapeworm preserved for 270 million years.  This discovery was made from just one of over 500 similar coprolites located in a single area where researchers believe fish may have been trapped due to a dry spell.

270-million-year-old tapeworm eggs from a section taken from a shark coprolite.  In "A" you can see the proglottid surrounding the eggs.  In "B" you can see the eggs up close...the arrows indicate the opercula.

The state of preservation was astounding.  There was quiet a bit of pyrite (fool's gold) found in the coprolites, which tells us that the environment must have been pretty well depleted of oxygen.  Even though these coprolites can tell us a lot about the environmental conditions at the time of deposition, the exact species that deposited the coprolite will remain a mystery since all shark poop looks the same.

The tapeworm species is yet to be determined, but is similar to extant species found within Tetraphyllidea (which contains 540 extant species that parasitize Elasmobranchs).

I can't wait to see just how much more we discover about these little dudes in the coming year! :)

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