April 5 () –
The discovery of ghost mosquito fossils suggests the existence of an extreme climate event in the past in New Zealand, according to a scientific team led by the Doñana Biological Station – CSIC, which has confirmed for the first time the presence of these species in fossil records. 23 million years old.
As reported this Friday by the CSIC, these species are the main predators of plankton and important engineers in freshwater ecosystems, and are currently present on all continents of the world except Antarctica and New Zealand, where their presence It was not confirmed until now.
With this new discovery, researchers point to the existence of a radical change in the climate of these islands, which would have led these species to extinction.
The CSIC has detailed that scientists have documented 30 specimens of immature individuals of these mosquitoes in fossils from Foulden Maar in New Zealand. This fossil lake, currently dry, originated in the crater of an inactive volcano and was 2 km in diameter and 350 meters deep. When they died, the abundant microscopic algae, called diatoms, formed a layer at the bottom of the lake that made possible the unique conservation of fossils for millions of years.
“This unique lake is our window to a southern hemisphere from 23 million years ago,” says Viktor Baranov, first author of the study and CSIC researcher at the Doñana Biological Station. “The Foulden Maar preserves in immense detail, fossils of plants and animals that perished in the lake, surrounded by a tropical humid forest.”
The specimens have been photographed and stored in the Geology Department Museum at the University of Otago, New Zealand. During the study, at least five different morphotypes were found, a term designated when the species cannot be determined precisely.
“It is very curious that they were present in New Zealand in the past, but not today. New Zealand is the only large continental mass where they do not exist, apart from Antarctica,” explains Baranov. There is no indication yet of what could have caused the extinction of these mosquitoes in New Zealand.
The CSIC has also explained that the extinction of certain groups of animals in New Zealand is usually explained by a hypothesis that states that the islands were submerged during the Oligocene, or by the cooling of the continental masses during the Pleistocene. However, these fossils are more recent and these mosquitoes did not become extinct even in regions affected by ice ages.
“The extinction of Chaoboridae in New Zealand may be indicative of some event that negatively affected aquatic fauna, such as a drought,” explains Baranov, who adds: “In fact, there are some studies with plant fossils that suggest a sustained drought in New Zealand. Zealand, from the Miocene, the period in which these fossils are dated.”
Another possibility is that its extinction is related to a potential immersion of New Zealand in the Oligocene, but there are still no studies to understand the specific link between these two events, he added.
