| Sunflower or daisy emerged about 50 million years |
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The discovery of intact fossil of a flower on a rock called Patagonia suggests that Asteraceae, among which is the sunflower or daisy, there were about 50 million years ago (much earlier than previously thought) as today is South America, as enshrined in the journal Science.
The sunflower ('Helianthus annuus') belongs to the botanical family
'Asteraceae', one of the most abundant and diverse in the world. Also
called 'composite' in colloquial, brings together more than 23,000
species distributed worldwide, except Antarctica, among which are
chrysanthemums, daisies, dahlias, thistles and artichokes. Members of
this cosmopolitan family are distributed from the Polar Regions to the
tropics, conquering all available habitats.
However, determining where did and how it spread throughout the world
has been a mystery until now, partly because researchers have found
relatively few fossils, and most were only grains of pollen.
According to a previous study by the Botanical Society of Argentina, the
oldest pollen record of the fossil Asteraceae are Patagonia. This,
together with the subfamily 'Barnadesioideae' (with strong
representation in this area) is considered the most basal in the
evolutionary tree of the Asteraceae, led investigators to hypothesize
that the origin of the family was in the southern South America with
further expansion into Africa, thus giving rise to most of the species
we know today.
Thanks to the good state of preservation of fossil found, Viviana
Barreda and other science team members have observed several features of
the family 'Asteraceae', including the structure of the leaves
surrounding the flowers and pappus or a set of simple or feathery hairs
distributed around the flowers (such as dandelion).
The fossil was found in rocks from 47.5 million years ago along the
river Pichileufu in the arid steppe of northwestern Patagonia. The
authors propose that a reservation could have arisen from ancestral
Asteraceae in southern super continent of Gondwana before it split into
South America, Africa, India, Australia and Antarctica.
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