Spanish
A fossil over 500 million years old found in Morocco may be key to understanding how some echinoderms evolved, as well as the enigmatic symmetry of some of these invertebrates, including starfish.
The finding corresponds to an international team of researchers, co-led by the Geological and Mining Institute of Spain (IGME-CSIC), which has named the fossil as Atlascystis acantha, remains that will help to understand how echinoderms went from having a bilateral body to the characteristic five-ray symmetry that distinguishes them today.
The study, whose results have been published in the journal Current Biology, presents Atlascystis acantha as the oldest known echinoderm with bilateral symmetry and the first documented in different stages of development, reported this Monday the IGME-CSIC in a press release.
This fossil, from Lower Cambrian deposits in the Moroccan Anti-Atlas, dates back about 510 million years, a key period in the early diversification of animal life.
The fossil shows a bilateral form, very different from the radial symmetry that characterizes current echinoderms, explained the CSIC in the note, which specified that bilateral symmetry, which humans and most animals share, refers to a basic scheme with a body axis that divides the body into two sides.
In fact, echinoderms themselves present this composition in their larval stage, but as they metamorphose and settle on the seabed, they develop pentaradial symmetry, a kind of head without a trunk that characterizes them in the adult stage.
According to the study, Atlascystis acantha seems to move between both symmetries, as it maintained bilateral symmetry during its adult stage while its anatomical structures anticipated the evolution towards a body with five rays.
