06/20/2020 - 9:12
- Clarín.com
- international
The araucaria, also called pehuén, is the sacred tree of the Mapuche peoples. For centuries they worshiped him with offerings, they prayed in his shadow and his tribes always settled in the areas where those sturdy trunks were that restrained the strong winds of Patagonia.
It tells the legend that during a year of famine, tribal chiefs send to a forest to a group of children looking for food to keep them occupied on something. But when he returned from his tour, only one of them brought in his leather bag many araucaria pine nuts, saying that an old man had given them to him, and had told him that they were a very nutritious food, but that to eat it it was necessary to boil or cook them. on fire for a long time. They did, and that saved them all from starvation. Since then, this Pehuén fruit was born to the Pehuenche Indians. and the araucaria myth grew to veneration.
The Patagonian Indians would never have wondered what the origin of this wonderful tree was. But now science brings something else about them: New well-preserved coniferous fossils from Patagonia, in Argentina, show that a group of endangered tropical trees has roots in the ancient supercontinent that once comprised Australia, Antarctica, and America. from the south.
The araucaria leaves were part of the study led by Dr. Gabriela Rosseto Harris, from Penn State University, and staff from the Egidio Feruglio Museum in Chubut, specialized in paleontology.
"The genus Araucaria, which includes the well-known Norfolk Island pine , is unique because it is so abundant in the fossil record and still lives today," said Gabriella Rossetto-Harris, a geoscience PhD student at Penn State and lead author. "Although they can grow up to 60 meters in height, Norfolk Island pine is also a popular houseplant that you can recognize in a dentist's office or restaurant," he said in a statement.
In 2005, the same team of researchers found important samples in the Laguna del Hunco deposit, in Chubut, and the Pichileufú river, in Río Negro.
The araucaria grew around the world from about 170 million years ago, in the Jurassic period. Around the time of the dinosaurs' extinction 66 million years ago, the conifer was restricted to certain parts of the southern hemisphere, said co-author Peter Wilf, a professor of geosciences and associate at the Institute of Earth and Environmental Systems (EESI) .
Today there are four main groups of Araucaria, and the time of when and where these living lineages evolved is still debated, Rossetto-Harris said. One grows in South America, and the other three span New Caledonia, New Guinea, and Australia, including Norfolk Island. Many are now endangered or vulnerable species. The Norfolk group of pines, the most diverse with 16 species, is generally believed to have evolved near its modern range in the western Pacific long after the Gondwan supercontinent separated from about 50 million years ago. of years, Rossetto-Harris added.
Now, researchers from Penn State and the Egidio Feruglio Paleontological Museum in Trelew, Chubut province, in Argentina, have found the fossils in two sites in Patagonia where they have been investigated since 2002: the Pichileufú River , which has a geological age of approximately 47.7 million years, and Laguna del Hunco , with a geological age of approximately 52.2 million years. They analyzed fossil characteristics and compared them to modern species to determine which living group the fossils belonged to. They then developed a phylogenetic tree to show the relationships between fossils and living species. They reported their findings in a recent issue of the American Journal of Botany.
Unlike the living South American group of Araucaria, which have large, sharp leaves, the Patagonian conifer fossils have small needle-shaped leaves and cone debris that closely resemble the group of pines on Australia's Norfolk Island, according to the researchers. . They also found a fossil from a pollen cone attached to the end of a branch, which is also characteristic of the group.
The needle-shaped leaves would be traces communicating with the araucarias of the island of Norfolk, in Australia.
"The new discovery of a fossil pollen cone still attached to a branch is rare and spectacular, " said Rossetto-Harris, who is also an EESI environmental scholar. "It allows us to create a more complete picture of what the ancestors of these trees were like." Researchers used 56 new fossils from the Rio Pichileufú to expand the taxonomic description of Araucaria pichileufensis, a species first described in 1938 using only a handful of specimens. "Historically, scientists have grouped together the fossils of Araucaria found in Rio Pichileufú and Laguna of the Hunco as the same species, "said Rossetto-Harris. "The study shows, for the first time, that while both species belong to the Araucaria group of Norfolk pines, there is a difference in conifer species between the two sites ."
The araucaria forests are very common in Chubut and Río Negro, in Argentina.
The researchers named the new species of Laguna del Hunco - a region located between the towns of Paso de Sapo and Gastre - as Araucaria huncoensis. According to Rossetto-Harris, the fossils are about 30 million years older than many estimates by when the Australasian lineage evolved.
The findings suggest that 52 million years ago, before South America fully separated from Antarctica, and for the first million years after separation began, relatives of the Norfolk Island pine trees were part from a rain forest that stretched across Australasia and Antarctica and into Patagonia , Rossetto-Harris said.
The change in Araucaria species from the oldest site in Laguna del Hunco to the younger site in Río Pichileufú may be a response to the climate cooling and drying that occurred after South America was first isolated.
A 360 ° photo of a monkey puzzle forest in Conguillio, Chile.
"We are looking at the last chunks of these forests before the Drake Passage, between Patagonia and Antarctica, really began to widen and deepen and featured a host of major climate changes that would eventually cause this version of araucaria to become extinct in America South, but survive in the Australian rain forest and then spread and thrive in New Caledonia, "said Rossetto-Harris.