Coryphodon

 
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Coryphodon

When the Arctic was a hot and tropical place, many large mammals roamed the land.  Although the Arctic was warmer in temperature than today, many mammals living north of the Arctic Circle experienced months of complete darkness and 24-hour summer days.

Image: A Coryphodon tooth.

 
3D View: Coryphodon
 
 
A reconstruction of Coryphodon in a forest.

Why this species is important

The Coryphodon (its scientific name) was a large mammal that roamed the Arctic from 51 to 59 million years ago, becoming one of the largest mammals to exist in the area since the extinction of the dinosaurs.  Living in warm swampy forests, this creature moved slowly and had very strong neck muscles, short tusks and short legs.

Scientists have excavated Coryphodon fossils on Ellesmere Island in the Canadian Arctic, including a Coryphodon tooth molar.   Through chemical studies of fossil bone, scientists have discovered that in the summer, Coryphodon ate flowers, leaves and swamp plants. In the winter dark, they munched on pine needles and fungi.

 

The Continental Drift

The Earth is constantly changing.  Over millions of years the planet's continents have shifted and continue to do so today.  This geological phenomenon is known as the Continential Drift.

Associated with these drifts are specific geological time periods when air temperature and life on Earth was very different than present day.

This interactive image shows how the Earth's continents have shifted over millions of years.  400 million years ago the Earth's land masses were close to one another and near the equator.  Around every 100 million years there were major landmass shifts. By 10 million years ago, the Earth's continents were located in their current positions.

A map of the world showing the continents shifting between 400 and 10 million years ago.
 
10 million years ago
400 million years ago
 
 

Brain to body ratio

 

Once the biggest mammal of its time, the Coryphodon was a large creature weighing about 500 kg, about the size of a modern-day hippopotamus.  Its brain size, however, only weighed around 90 grams, distinguishing it as having one of the smallest body-to-brain ratios of any mammal.

 

What is in a tooth?

 

Scientists have discovered a Coryphodon’s diet by studying its teeth.  This study not only reveals what the creature ate but also its behaviour.  Many animals migrate to warmer climates as the winter months approach.  The Coryphodon did not migrate and instead switched between two seasons and two types of food sources.

 

The last of its kind

 

All species on Earth evolve or become extinct.  Coryphodon is one mammal that became extinct and no other mammals are currently known to have evolved from it.

 

Video

 

Arctic palaeontology

Learn about the environment and various species that existed when Coryphodon roamed the Arctic region.

 

Transcript: Arctic palaeontology

Natalia Rybczynski
Vertebrate paleontologist, Canadian Museum of Nature:

Strathcona Fiord on Ellesmere Island is a key fossil site in Canada's High Arctic.
It preserves the remains of unique fossil mammal species and tells us what the Eocene looked like about 50 million years ago.
While today Ellesmere Island is a polar desert, this diorama illustrates what it would have looked like during the early Eocene.
I’m Natalia Rybczynski, a vertebrate paleontologist here at the Canadian Museum of Nature.
In the course of my research in the Arctic, I collaborate with other paleontologists including Mary Dawson, from the Carnegie Museum of Natural History.
Mary is a pioneer of Arctic paleontology. In 1975, she made the first scientific discoveries of Eocene land vertebrates on Ellesmere Island.
As you see in the diorama, 50 million years ago the Arctic was a wet, swampy place, similar to the modern cypress forests of the American South.

Mary Dawson
Palaeontologist, Carnegie Museum of Nature History:
The vertebrates - with alligators and a lot of turtles certainly indicate a different climate than the climate of today, from the austere high cold arctic. In addition
there is a certain light regime, the sun is up in the summer and the darkness all winter. And that is true in the Eocene also.

Natalia Rybczynski:
At that time, Ellesmere Island was mostly covered by lush deciduous forests. The Strathcona Fiord area was a valley that contained extensive river systems and swamps that drained into a shallow sea.
It was a rich ecosystem and provided unusually good conditions for preserving fossil remains and making coal.
The dinosaurs had gone extinct, and many of the modern groups of mammals appeared, including modern carnivores, bats and rodents.
Many fossil mammal species from Strathcona Fiord are unique. The fossils include evidence of some highly specialized early primate species. Many plagiomenid species also were found here.
Plagiomenids are an extinct group that thrived on Ellesmere. They probably lived in trees.
Some researchers considered them to be related to today’s flying lemurs.
The primate and plagiomenid species, as well others from Ellesmere Island, have not been discovered anywhere else in the world.

The appearance of unique species in the Eocene Arctic may be associated with the unique combination of warm temperatures, high rainfall, and the extreme seasonal light and dark cycle.
Today, vertebrate fossils are found throughout layers of compressed beds of sediment and coal -- the remnants of the lush Eocene forests.
Paleontologists use these exposed coal beds as “markers” to look for fossils. The beds themselves also provide insight into Arctic climate change.
These fossils are small and are often broken up by the freeze and thaw cycle of the permafrost, making them difficult to find and collect.
The fossils of Strathcona Fiord on Ellesmere Island include some of the first pre-ice age land vertebrates collected in the High Arctic.
Strathcona Fiord and other Arctic sites are scientifically important, unique in the world, and need to be protected.
Modern climate change, mining development and tourism in Nunavut could destroy this and other critical areas and their important fossil records.

The Canadian Museum of Nature, in cooperation with Nunavut, has the responsibility for caring for these fossils.
This commitment is part of the Museum’s long tradition of exploration and research in the Canadian High Arctic.
The continued study of these sites has implications for our understanding of evolution and climate change.
It provides our only glimpse into a rare moment in the earth’s history, when our planet was under extreme greenhouse conditions.

As global temperatures are again on the rise, we need to preserve this record to better understand our warming planet.

---End.