Queen Ant Fossil the Size of a Humming Bird Sheds Light on Eocene Climate Change

The fossilised remains of a giant ant which grew to over 5 centimetres long is helping researchers to understand how the climate changed in northern latitudes during the Eocene Epoch.  The fossil suggests that giant ants were able to cross continents via the Arctic and this was probably only possible due to global warming.

A North American team of palaeontologists have discovered the fossil of a huge ant, whose presence sheds light on the spread of such insects after the demise of the dinosaurs.  The distribution of fossils of these large members of the Hymenoptera and providing scientists with valuable data on times of global warming over the last fifty million years or so.

Fossils of gigantic ants have been found elsewhere in the world, perhaps most notably in the Messel shales and Eckfeld Maar Eocene aged strata of Germany (Formicium giganteum).  However, writing in the British based, Proceedings of the Royal Society B (Biology) the four scientists have linked these fossil finds to a climate change study deducing that since large extant species of ants are only found in the tropics today, then the fossil species must also have lived in tropical environments.  Charting the spread and distribution of these fossils with a cross reference to their geological age would provide scientists with a better understanding of periods of global warming during the Palaeogene Period.

In a paper entitled “Intercontinental dispersal of giant thermophilic ants across the Arctic during early Eocene hyperthermals“, the authors Bruce Archibald and Rolf Mathewes from the Simon Fraser University (British Columbia, Canada), David Greenwood from Brandon University (Manitoba, Canada) and Kirk Johnson from the Denver Museum of Nature & Science in Colorado (USA) describe a new species of giant ant.

The species has been formally described and named Titanomyrma lubei. This winged queen ant lived in the Eocene Epoch about 50 million years old.  It had a body just over five centimetres long — comparable to a hummingbird — a size only rivalled today by the enormously large queens of an ant species found in tropical Africa.

As Big as a Humming Bird – T. lubei

Picture Credit: SFU

Dr. Archibald found the ant fossil in a drawer when visiting Johnson at the Denver Museum.

He commented:

“What is surprising is that this ant scurried about an ancient forest in what is now Wyoming when the climate there was hot like the modern tropics. In fact, all of the closely related fossil giant ants have been found in Europe and North America at sites that had hot climates.”

The North American research team looked at the habitats of the largest modern ants, and found that almost all live in the tropics, indicating that there might be something about being big that requires ants to live in hot climates.

During the Eocene Epoch, many plants and animal species migrated between Europe and North America via continuous land across the Arctic, bridging the two continents.  Scientists have puzzled over the mystery of how did these ancient members of the Hymenoptera cross through a temperate Arctic climate which is believed would have been simply to cold for them.

The researchers suspect that the key is in the brief, but intense episodes of global warming that happened around this time.  These events appear to have created periodic opportunities for life forms more suited to a warmer climate to pass between continents through the Arctic.  Dr. Archibald calls them brief openings of a physiological gate to cross the physical land bridge.

After the mass extinction of the Dinosauria, the Earth experienced a prolonged period of global warming with global temperatures steadily rising and this led to extensive tropical rain-forest forming in latitudes as high as Canada and northern Europe.  For much of this period, even the Poles were free from ice, instead they were covered by dense conifer forests.

Dr. Archibald added that these findings will help scientists gain a better grasp of the impacts of global warming on life. He concluded:

“As the Earth’s climate changes, we are seeing tropical pest species extend their ranges into mid-latitudes and dragonflies appear in the Arctic.  Understanding the details of how life forms adapted to global warming in the past will be of increasing importance in the future.”

Reproduced from Simon Fraser University source.

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