Fossilized shark poop, called a coprolite (shown here), was found to contain ancient tapeworm eggs.
Researchers found a cluster of 270-million-year-old tapeworm eggs (shown here) in fossilized shark poop.
The eggs were perfect oval shapes, with each spanning only about 150 microns long, or about one-and-a-half times the average width of a human hair. The researchers discovered the eggs by cutting coprolites into thin slices.
One of the tapeworm eggs even contained a probable developing larva (E), which held a cluster of fiberlike objects that may have been the beginnings of hooklets used to attach to a host's intestines as adults.
Here a schematic of the tapeworm egg showing: the shell (C), embryo or larva (E), developing hooklets (H), inner envelope (I) and outer envelope (O).
Like today's tapeworms, these ancient parasites would have clung to the intestines of the shark or other vertebrate (animal with a backbone). When the parasite reached adulthood, it would unleash its eggs on the world via the feces of its host. Here, a tapeworm attached to a human intestine.
Here, a scanning electron micrograph of the scolex (anterior attachment organ) of Rhinebothrium sp., an extant tapeworm.