Brain Fossils Uncover How Animals Developed into Having Brains

Many of us failed to know that most animals millions of years ago didn’t have heads.

Scientists assess that the beginning of the evolution of animal brains happened during the Cambrian period, about 500 million years ago. Majority of the animals originated from the squishy-bodies animals like the penis worm to hard-bodied arthropods, which have body segments where the head/body alignment could be evaluated to the smallest degree. Nonetheless, the incidence of the evolution is still unknown to the scientists until today.

Experts studied ancient brain fossils in order to find clues about the transition of heads.

The samplings used were trilobite with a spongy body and an animal that looks like a submarine, the Odaraia alata. Both animals existed during the Cambrian period and it’s fascinating that there are still remnants of the brain after 500 years.

Javier Ortega-Hernández, lead author and post-doctoral researcher from Cambridge’s Department of Earth Sciences said, the front parts of the brains of both animals have nerve connections related to the animals’ eye stalks, and an anterior sclerite- which is a solid plate. Present day arthropods have brains that control its eyes.

Ortega-Hernández reported, “The anterior sclerite has been lost in modern arthropods, as it most likely fused with other parts of the head during the evolutionary history of the group.” He also added, “What we’re seeing in these fossils is one of the major transitional steps between soft-bodied worm-like creatures and arthropods with hard exoskeletons and jointed limbs – this is a period of crucial transformation.”

The anterior sclerite functioned as the bridge between the early and present arthropods in layman’s term.

During the same period, other creatures called Anomalocaridids, had very dissimilar body features with the other creatures but had a similar plate which they assume to have come from the same ancestral framework. This could be the rationalization on how dominant animals on earth developed head and bodies.

He added, “Heads have become more complex over time. But what we’re seeing here is an answer to the question of how arthropods changed their bodies from soft to hard. It gives us an improved understanding of the origins and complex evolutionary history of this highly successful group.”





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