How Tortoises and Alligators Survived on Ellesmere Island 50 Million Years Ago

One of the topics we have discussed in lab recently is the different ages that occur in Geologic time. The beginning period that contained life is the Cambrian Age. This had shelled animals and Trilobites. The dinosaurs came into existence in the Triassic period, almost 185 million before humans set foot on the geologic time scale.  Amphibians, reptiles, and fish existed long before the dinosaurs existed.  The progression of life on the earth is extremely interesting, especially when we see where they ended up living as the tectonic plates shifted the continents.

Scientists at the University of Colorado at Boulder conducted a new study that looked at temperature in the Eocene time period, about 50 to 52 million years ago, in the High Artic region.  This study helped explain how giant turtles and alligators were able to live in the freezing cold temperatures.  Using oxygen isotopes from the tooth enamel of fish, mammals, and reptiles during the period, scientists were able to deduce the average temperature during this time period in the area.  What was discovered was quite shocking.  The average temperature in the warmest months were from 66-68 degrees F while the coldest months ranged only from 32-38 degrees F.   With this new information, scientists are able to estimate the species diversity and richness in the area.  The main place researched in the High Artic was Ellesmere Island.  This data was the most comprehensive so far collected.

According to the scientists, the geography in the Eocene time was similar to swampy cypress forests in the southeastern United States today.  Not only did alligators and giant tortoises live in the area but also a wide variety of other species including flying lemurs, tapers, rhino-like mammals, aquatic turtles, and large snakes.  This is certainly very different from the species that exist there today, a few of which include various species of fish, polar bears, seals, and seal lions.

As was previously stated, in order to deduce the temperature in the area, oxygen isotopes were analyzed from the tooth enamel of different species in the area.  Since teeth grow year round, they can take oxygen isotope ratios from the teeth and estimate the warm and cold months during the year.  They used the water that the animals drank during the period in order to do this.  Scientists also studied where animals of the same species exist today in order to help them estimate the temperature in which they lived back in the Eocene time frame.

The most interesting part of this study is the implications it will have for the future.  By gathering this information, we will be able to forecast what the climate, temperature, and biosphere may be like in the High Arctic in the future due to the increasing temperatures in that region.  If we are able to accurately gather this information we might also be able to estimate what other region’s climates may be as well. This will make us better prepared for a future unlike we have ever known.

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