Caught off guard and buried alive by an approaching deadly mudslide some 465 million years ago, this marine scavenger spent its final moments feasting on a vast and varied diet of seafood, now allowing people to see such detail in the best-preserved fossils of its kind.
Researchers at Charles University in the Czech Republic have used synchrotron radiation X-ray microtomography to piece together the last supper of the Ordovician trilobite Bohemolichasincola. What they found in the trilobite's digestive tract was quite a feast: densely packed calcareous shells and their fragments that once belonged to invertebrates such as ostracods, bivalves and echinoderms, some of which even had identifiable species.
"The non-selective feeding behavior of this trilobite suggests that it was primarily an opportunistic scavenger. It can be considered a light crusher and opportunistic eater, hoarding carcasses or live animals that are easily decomposed or are small enough to be swallowed whole," the researchers noted.
This is the first time we've been able to peer into the guts of this prolific trilobite, one of about 20,000 species described to date. They have lived on the earth for about 270 million years and are an important part of the marine ecosystem.
This particular fossil was discovered in 1908 and is housed in a museum in the town of Czechoslovakia. It was preserved in a silicified clot nicknamed a "Rokycany ball," which proved to be a lucky fossil storage system for paleontologists studying specimens from this period.
Lead author Petr Kraft, from the Faculty of Science at Charles University, said: "I remember this specimen from my childhood. It was my grandfather's favorite fossil. That's why a picture of it used to hang in the palaeontology office of the Rocky Carney Museum, where he volunteered."
"Obtaining sliced images is just the first step, similar to what most people know from hospital CT scans," said paper co-author Valéria Vaškaninová. "The next step is to manually segment the individual structures using reconstruction software. A three-dimensional model of the fossil is then rendered in a virtual photo studio, which adds depth to the image and makes it extremely informative."
The researchers not only presented the animal's last opportunistic feeding in great detail, but also how it allowed other animals to take on the role of scavenger after death. However, these unlucky diners were eventually imprisoned in this earthy tomb, where they would stay for nearly 500 million years.
They also noticed that the shape of the arthropod's exoskeleton suggested it was about to undergo a routine molt, much like today's arthropods. "We believe that the feeding behavior of trilobites may be similar to the corresponding life cycle of modern crustaceans," the researchers noted.
The research was published in the journal Nature.