Fossil Arthropod Brains Shed Light On Lobster Evolution

You never know what you might learn by studying a fossilized brain. According to a study published Thursday in Current Biology, 500 million-year-old fossilized brains of ancient marine arthropods have provided useful insights into the evolution of modern lobsters and scorpions.

Fossil Arthropod Brains

Fossil arthropod brains led to breakthrough

The new study examined a structure called the anterior sclerite found in the heads of ancient arthropods. The anterior sclerite has long baffled paleontologists, mainly because some prehistoric arthropods have it, but others don’t. Moreover, the exact location of the anterior sclerite in the head also seems to vary from fossil to fossil.

The newly found fossil arthropod brains have led to an apparent solution to  the mystery. The analysis of the more than 500 million years old indicated that the structures were related to the creatures’ bulbous eyes. The new research provide evidence that these oval structures were associated with nerves feeding in from the anterior region of the brain.

Statement from study researcher

“[Now] we can say, ‘Ah-ha, where does anterior sclerite come from? It comes from the anterior most part of the brain — the forebrain,'” explained researcher Javier Ortega-Hernández, a research fellow in paleobiology at the University of Cambridge.

More on fossilized brains

Experts say fossilized brains are quite rare, but they are found occasionally. Researchers have published several studies over the last few years detailing  specimens containing fossilized neural tissue, including a more than 500-million-year-old Chinese arthropod.

Soft tissue like brains and organs will only fossilize only if the conditions are ideal. If a creature is suddenly buried in low-oxygen conditions with minerals such as carbon present, then there’s a good chance neural tissue could fossilize.

In the research published this week, Ortega-Hernández studied two fossils that were discovered in British Columbia’s Burgess Shale during the early 20th century. The specimens are 500 million to 510 million years old.

The first fossil specimen, Helmetia expansa, is a trilobite-type arthropod that had a soft body. The other fossil arthropod, Odaraia alata, had a body more like a submarine.

“We know from the fossil record that the earliest ancestors of arthropods are soft bodied. They look a little bit like worms with legs,” Ortega-Hernández pointed out. “But then, at some point in time, we start seeing arthropods that look a lot more familiar. They have this jointed skeleton. The question here is how do we go from something that looks nothing like an arthropod to something that looks completely like an arthropod?”