trilobite are a diverse group of marine animals that lived between 540 and 250 million years ago. They were some of the oldest and longest-lived arthropods known. Trilobites are named for the shape of their bodies, which are characterized by a hard exoskeleton divided into three lobes.

Paleontologists have described more than 20,000 different species of trilobites. Lifestyle and eating behavior. Some burrowed into the ocean floor, while others floated or swam freely in the ocean. But everything scientists know (or think they know) about what trilobites ate; indirect evidencelike them Intestinal shape and size. Researchers have never before discovered a fully-fed trilobite fossil. until now…

A group of researchers from the Czech Republic and Sweden recently reported a complete fossil of a trilobite. Bohemorichas Incora The intestinal contents remain intact. They discovered this unique specimen in the Šárka Formation in the Prague Basin of the Czech Republic. It died 465 million years ago lying on its belly on the ocean floor, rapidly becoming encased in a mass of silica. nodules. The researchers explained that the silica nodules prevented the carcass from being crushed during burial, preserving the entire fossil in three dimensions for millions of years.

The research team used a 3D imaging technique called . micro tomography Let's take a look inside the intestines of trilobites. They used this method to create a series of superimposed slice-by-slice images of the fossil's interior, which a computer program knitted into his three-dimensional shape. Scientists traditionally used his X-rays for microscopic tomography, but this team used a special energy source. synchrotron radiation, increase image resolution and contrast. Synchrotron radiation is high-intensity light produced by electrons traveling at nearly the speed of light in a circular accelerator. synchrotron. They combined this method with another type of imaging known as . Propagation phase contrast imagingwhich further enhances the contrast between normal light-absorbing soft tissues as well.

The researchers discovered that the trilobite's intestines were completely filled with shell fragments made of calcium carbonate. They determined that most of the shells belonged to small crustaceans, about the size of ants. ostracod. Some of the shell fragments were from larger, two-shelled organisms, similar to bivalves or bivalves, while others were from a single organism, similar to starfish. All of these creatures lived in the mud on the ocean floor, suggesting that the trilobites were feeding on them as they ran along the ocean floor. Because the trilobite ate several types of shelled creatures, the researchers hypothesized that it was a scavenger that scavenged indiscriminately on whatever it encountered, rather than a selective predator.

The researchers also noted that the trilobite's intestinal shell had sharp edges and no signs of etching. The researchers interpreted this to mean that the pH of the trilobite's digestive tract was neutral or alkaline, since if the intestine is acidic, like humans and most mammals, the shell will begin to dissolve. The researchers explained that enzymes that help animals digest food are very sensitive to pH. Therefore, this evidence suggests that trilobites had enzymes similar to other organisms with neutral or alkaline digestive systems. Living examples of these organisms include crustaceans such as shrimp and lobsters, and chelicerae such as spiders and scorpions.

Finally, the researchers found a series of small tunnels dug into the trilobite's remains. This indicates that the trilobites fell prey to their own scavengers after death, before becoming encased in silica. They found the most concentrated set of burrows near the trilobite's head, which appeared to be the area of ​​most intense feeding. They also found several burrows in the lower part of the trilobite's body, but none of them entered the digestive tract. In other words, the scavengers avoided the trilobite's intestines entirely. The researchers suggested that if intestinal enzymes continued to digest the animal's last meal after it died, the intestine could have remained toxic for some time.

The researchers concluded that the 3D specimen was: Bohemorichas Incola They said this provides the best knowledge to date of the feeding habits of trilobites, including what they eat and how they digest it. They also suggested that the physiological properties of this particular trilobite may mean that a near-neutral pH gut is a feature of most primitive arthropods. However, they also noted that few scientists have studied how gut pH affects digestion in living arthropods, so further research is needed to test this hypothesis. .

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