Image caption The fossil flower, related to sunflowers, was found in Patagonia

A fossilised flower found in Patagonia by an Argentinean team is shedding light on the origins of sunflowers.

The large flower is highly unusual because most plant fossils are just pollen grains.

The fossil is from the Asteraceae family, the relatives of daisies, sunflowers, and dandelions.

Until now, scientists have relied on genetic evidence to work out where this plant family originated.

Finding this very well-preserved flower confirms that the family came from the ancient southern landmass, Gondwana, about 50 million years ago.

The researchers, headed by Dr Viviana Barreda from the Museo Argentino de Ciencias Naturales, published their results in Science magazine.

The region that is modern-day Patagonia was at that time sub-tropical, with temperatures around 19C (66F).

Dr Tod Steussy, of the University of Vienna, commented on the finding: "Members of the family are found in every continent except Antarctica," he said, adding that they are now normally found in temperate areas.

This plant family includes not just flowers but lettuces, chicory, and artichokes.