Scientists find daisy fossils from dinosaur times


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The dinosaurs of Gondwana may have wandered around and died in fields of flowers that were the ancestors of daisies, suggests new research.

Scientists find daisy fossils from dinosaur times
Fossil pollen grains from the Asteraceae or daisy family have been discovered
 in Antarctica by scientists from the Royal Botanic Gardens, Kew and colleagues 
in Argentina and New Zealand, drastically pushing back the assumed origin 
of this flowering plant lineage by twenty million years 
[Credit: afhunta/iStockphoto]

Findings published in this week’s Proceedings of the National Academy of Sciences, show that the Asteraceae family of flowering plants is much older than previously thought.

“It’s one of the few modern families of flowering plants that can be traced back to the Cretaceous,” says co-author and palynologist, Dr Ian Raine, of GNS Science in New Zealand.

Flowers of the Asteraceae family — such as daisies, sunflowers, chrysanthemums, dandelions, gerberas and lettuce — are characterised by inflorescences, or clusters of small tightly packed flower heads, which often form a larger composite flower.

“The Asteraceae were thought to be a rather highly evolved family and not to have appeared until well along the evolution of the flowering plants,” says Raine.

While the earliest flowering plants evolved 130 million years ago, to date the earliest known member of the Asteraceae family, was thought to have lived in Patagonia 47.5 million years ago.

As part of ongoing research into the family, lead author Dr Viviana Barreda of the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires, and colleagues, have now pushed that timeline back by at least 20 million years.

They examined pollen grains extracted from 76 to 66 million-year-old sediments on the eastern side of the Antarctic Peninsula.

Based on the shape and surface sculpture of the pollen grains the researchers identified the grains as being from the species Tubulifloridites lillei.

This extinct species had previously been found in New Zealand and southern Australia in sediments of the same age, but researchers have only now confirmed it is an early member of the Asteraceae family.

The team show the pollen grains are similar to those from members of the Barnadesioideae subfamily of Asteraceae in South America. However they don’t yet know exactly what the flower would have looked like.

Barreda and colleagues argue that once this latest find is included in the family tree of flowering plants, this places the earliest Asteraceae as living at least 80 million years ago.

While today, there are only two flowering plants native to Antarctica, back in the Cretaceous the continent was part of Gondwana and would have been covered with temperate forests and roaming dinosaurs, says Raine.

Indeed, the sediments containing the pollen grains also contained dinosaur bones.

Asteraceae are thought to have played an important role in the evolution of certain insect and bird pollinators such as bees, hummingbirds and wasps.

Apart from Asteraceae, the family that contains the Nothofagus, which includes the Antarctic or southern beech — can also be traced back to the Cretaceous.

Author: Anna Salleh | Source: ABC News Website [August 12, 2015]



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