Ancient brain fossils hint at body evolution of creepy-crawlies

Odaraia alata

The fossilized brain of Odaraia alata, an arthropod ancestor found in western Canada’s Burgess Shale, had a hard plate that may have had nerves connecting its eyes and brain.

Jean Bernard Caron/Royal Ontario Museum

Fossilized brains of the ancient ancestors of spiders, insects and crustaceans are giving hints about how those creatures evolved from soft- to hard-bodied.

Javier Ortega-Hernández from the University of Cambridge studied 500-million-year-old brain remnants from two types of arthropod ancestors, including the submarine-like Odaraia alata. In these creatures, traces of nerves appear to connect the front of the brain to eyelike features and a hard plate, called the anterior sclerite, Ortega-Hernández reports May 7 in Current Biology.

Modern arthropods don’t have these hard plates. Finding them in arthropod ancestors suggests the plates acted as a transitional element that helped the animals evolve from soft, jellylike organisms to the hard-bodied creatures of today, Ortega-Hernández argues.

Use up and down arrow keys to explore.Use right arrow key to move into the list.Use left arrow key to move back to the parent list.Use tab key to enter the current list item.Use escape to exit the menu.Use the Shift key with the Tab key to tab back to the search input.