Scientists say 310-million-year-old horseshoe crab fossil found in Illinois creek shows crustacean brains have barely evolved since then
- The intact brain anatomy of a 310-million-year-old horseshoe crab shows it has remained almost unchanged for most of its evolutionary history
- The fossil was compared to that of a contemporary juvenile horse show crabshow
- Experts found that the nervous system of the two almost… identical
- The arrangement of nerves to the eyes and appendages also corresponds
The delicate brain of a 310-million-year-old horseshoe crab, discovered in the famous Mazon Creek deposit in Illinois, shows that the aquatic arthropod’s brain anatomy has remained virtually unchanged for most of its evolutionary history.
The discovery is very rare in that soft tissue, such as the brain, is rarely preserved for hundreds of millions of years, and this specimen is the first brain anatomy ever found intact.
The specimen, known as Euproops danae, allowed scientists to see the ancient creature’s nervous system, which is “closely similar to that of living horseshoe crabs and matches their arrangement of nerves to the eyes and appendages,” Professor and Co. the University of England. study author John Paterson said in a pronunciation.
Along with revealing the evolutionary history of horseshoe crabs, the scientist also notes that this discovery shows that the brains of arthropods can be preserved in several ways.
The Euproops danae specimen was preserved in concretions made of iron carbonate mineral called siderite, and its brain is replicated by a white-colored clay mineral called kaolinite.
The delicate brain of a 310-million-year-old horseshoe crab shows that the aquatic arthropod’s brain anatomy has remained virtually unchanged for most of its evolutionary history
“This mineral cast would have formed later in the void left by the brain, long after it had decayed,” Paterson and his colleagues wrote in The conversation.
“Without this striking white mineral, we might never have seen the brain.”
The team compared the white mineral fossil to that of the brain of a modern juvenile horseshoe crab and found that the two are nearly identical in their arrangement of nerves to the eyes and appendages, along with the same central opening for the esophagus.
“We showed for the first time that the animals of the Mazon Creek were not only formed by the rapid formation of siderite that buried their entire bodies, but also that the siderite rapidly enveloped their internal soft tissues before they could decompose,” Paterson said. in the press release.
The team compared the white mineral fossil (A) with that of the brain of a modern juvenile horseshoe crab (D) and found that the two are nearly identical in their arrangement of nerves to the eyes and appendages, along with the same central opening for the esophagus.
Lead author, Dr. Bicknell, also explained what makes the discovery of a 310-million-year-old horseshoe crab with an intact brain so special.
“Most of our limited knowledge about prehistoric arthropod brains is derived from amber inclusions or Cambrian Burgess Shale-type fossil deposits,” Bicknell said.
‘Amber, or fossilized tree resin, often contains a variety of trapped organisms such as insects, while preserving the most intricate details. Using advanced imaging technology, scientists can study these buried creatures, including their cerebellum.
The fossil was discovered in Illinois’ famous Mazon Creek deposit
“We’ve gained a rare glimpse into the prehistoric past, which has given us a better understanding of the biology and evolution of these long-extinct animals.”
‘However, we are somewhat limited in studying these specific fossils, as the oldest arthropods in amber only date back to the Triassic, about 230 million years ago.’
Burgess Shale-like deposits from the Cambrian period — usually around 500 to 520 million years old — are much older than the amber and also preserve spectacular brain structures like carbon films in mud rock.
“These Burgess Shale-type fossils are very important because they represent some of the oldest animals on Earth and can inform us about their origins and earliest evolutionary history,” Bicknell said.