An international team of paleontologists has described a remarkable fossilized poop that shows evidence of a prehistoric fish mistakenly biting on what turned out to be crocodile poop. The fossilized coprolite includes tooth raking marks made by the gar fish, which is believed to have misidentified the poop as prey.
The incident happened about 16 million years ago in what is now the State of Virginia, U.S.A. The gar fish, which is a ram feeder that stalks its prey before suddenly striking, maneuvered into biting range and snapped at the poop. The glancing bite was enough to register in the gar’s brain as “inedible,” and it did not attempt to eat any more of the fossilized poop.
The fossilized poop is a trace fossil, which is the preserved evidence of the activity of a once-living organism. The fish bite marks are also trace fossils, making this an exceedingly rare example of a trace fossil on a trace fossil known as a composite trace fossil.
The crocodile coprolite is estimated to have come from an extinct crocodile that was around 11 feet long. Carnivore poop, such as that of a crocodile, can fossilize due to the minerals in the bones of their prey. The fossilized poop is an example of a valuable process that has been happening for millions of years, as organisms eat and recycle poop.
The research team described the fossilized poop and the gar bite marks in an open-access paper published recently in Ichnos.