Vampire+Bat+(Ancient)

**Icaronycteris Index** //The Extinct Vampire Bat by Jacqui Chiu// **Modern Day Animal:** Vampire Bat **Future Animal:** Mixed Bat

** Introduction ** The fossil of the 50 million year old Icaronycteris index was found in Wyoming, USA. It has been proven that the remains belong to a microchiropteran bat who is a part of the microbat family – just like the vampire bat. The exact relationship between them is not known, however it can be confirmed that the Icaronycteris is an extinct ancestor of the vampire bat. Although the fossil has a primitive structure and resembles a very early form of bat, many scientists believe that the Icaronycteris was the transition between the primitive bat form and today’s vampire bat.

**Habitat ** The Icaronycteris was alive around 55.4 to 50.3 million years ago. It is most likely that they appeared during the Early Eocene Epoch, the second of the Tertiary Period. The Eocene Period began roughly 55 million years ago and ended 21 million years later, around34 million years ago. This time period was well known for its rise in the Earth’s temperature, which assisted the evolution of modern mammals replacing their more primitive form. The Eocene was considered by many scientists as the “age of the mammalian rise and domination of terrestrial mammals”; land mammals threatened the Icaronycteris ability to survive leading them to develop the ability of flight. The arrangement of the Earth’s land masses was not remotely different to that of today’s (see fig.1). Seeing as that the Icaronycteris was found in the Green River Formation located in Wyoming, USA, scientists have reason to believe that they would have lived around this area. Their homes would mostly be located in the area that spans across modern-day northeast Utah to the northwest border of Colorado, but would also be found a couple of kilometers within this area. These living conditions were ideal for the Icaronycteris as this was a sub-tropical region, with large areas of woodlands. It is believed that Icaronycteris had once lived in North America, but over time migrated into South America due to its favorable climate. The warm temperature of the Icaronycteris’ habitat would have been around 15°C to 20°C. Therefore the era which they lived in was perfect as the Eocene was a warm duration, in fact, there was even an overall rise in temperature of 7°C.This type of climate was important for the Icaronycteris’ survival as they could only survive in sub-tropical and temperate regions, where the area was humid and moist. Both these criterias were fulfilled in North America during the Eocene.

Much of the wildlife found in North America today had come into existence during the times when the Icaronycteris was alive. They shared their environment with numerous animal and plants such as various insect species, fish and other land mammals. As previously stated, the rise in global temperature led to the emergence of many land mammals like the lemurs**,** which competed for living spaces with the Icaronycteris. The vegetation that appeared during this time are still found today in vampire bat’s habitat. These trees include the birch, cedar, chestnut, elm and beech. The appearance of grass encouraged grazing animals to appear, and they will eventually be ones preyed on by the Icaronycteris’ descendant. Overall, their habitat was rich and luscious and would slightly resemble a rainforest.

** Labelled Photograph of an Icaronycteris Index Fossil **

**1. Teeth** The Icaronycteris had teeth unlike the ones found in vampire bats. Their teeth were less sharp, resembled spikes and could be described by many scientists as being “shrew-like”. These features allowed the Icaronycteris to survive on their insectivorous diet, which consisted of various insects found in their habitat - particularly those that appeared during the Eocene, like moths and [|dragonflies]. This adaptation was important for its survival because if they did not have flat incisors, they would have an extremely hard time grinding food as sharp teeth are not suitable for the type of diet they were living on. This may have caused them to spend a longer time "chewing" up food and would lose time the precious night hours which could have been used for hunting and feeding or they would be forced to swallow insects whole which would make it hard for their digestive system to break it down easily. In addition, if they could not properly eat their food it would affect their survival as they would be unable to consume enough nutrients to maintain normal body functions, which means that they will die sooner and be unable to reproduce.
 * Adaptations of the Icaronycteris Index **

The environmental pressure that would have caused this adaptation would be the various animal species in their habitat. Due to the abundance of insects during the Eocene, the Icaronycteris would have chosen to prey on these animals as they are a very easy-to-find food source. It would have been better to prey on insects instead of competing for food with other mammals as that would risk their chances of survival.

Scientists have found remains of a moth inside the fossil of an Icaronycteris. This proved that they already had the ability to echolocate. Other animals that could echolocate includes mammals like dolphins and whales. By vibrating air in their vocal cords, vampire bats can emit high frequency waves through its nose and mouth while it flies. These sound waves will bounce off any object and return to them in the form of echoes, carrying information on the food source. Being able to echolocate allows Icaronycteris to easily catch insects at night, who would have otherwise been too small and hard to see. Again, if the Icaronycteris could not take in enough food, they will die of starvation and be less likely to pass on their genes. Echolocation also heightens their senses and allows them to become more aware of their surroundings, such as any possible threats nearby and possible food sources. This alertness allowed Icaronycteris avoid dangers and their predators.
 * [[image:artist_impression_icaronycteris.jpg width="289" height="202" align="left" caption="Artist's impression of the Icaronycteris"]]2. Echolocation**

The environmental pressure that led to this adaptation was the overall rise in temperature. This created a warmer environment which saw the appearance of many insects in the Icaronycteris’ habitat. Since they consistently need to capture insects (as they are its main food source), they had to develop some sort of adaptation which would increase their chances of finding food. Additionally, the rise in temperature caused more trees to grow. Without the ability to echolocate, it would be very hard to navigate at night without bumping into trees.


 * 3. Ability to fly**Many scientists are convinced that the Icaronycteris was the first bat that could truly fly. The structure of their front limbs allows them to fly for quite some distance and not merely glide. By developing wings, the chances of survival for Icaronycteris increased as they became safer seeing as they are further away from their ground predators who could easily attack them. Also, flying to hunt for food was more efficient than the primitive bat’s method of hunting which was to run up and down trees, across the ground and up the next tree in search of food. It is more likely that they consume more energy to seek food than what they could actually gain from their hunt. This would have lead to starvation and decreases the chance for them to reproduce.

The environmental pressure that would have led to the ability to fly would have caused the evolution of land mammals, many of which were predators of the Icaronycteris. Through flight they are minimizing the time they spend on ground with these mammals. Additionally there were more mammals that began competing with the Icaronycteris for insects as food. To maximize their chances of survival the Icaronycteris had to increase the area of land which they travelled to hunt for food and also adapt to know how to fly.

The Icaronycteris’ bone structure was slender and light, it weighed roughly 2 to 3 grams less than today's vampire bat. The bone structure is always important because it would affect their balance and the speed at whch they are able to travel at. This would have made flying long distances easier as they were lighter in weight and did not require as much energy to carry themselves. By conserving energy, they would not need to feed as much in their next meal which would have been very advantageous if they have difficulties finding food on that particular night. It would reduce the chances of them dying from starvation which would prolong their lifespan and increase the chances for reproduction.
 * [[image:icaronycteris_bone.jpg width="350" height="494" align="right" caption="Fossil of the Icaronycteris"]]4. Lighter bones**

The environmental pressure that led to this adaptation would be the change in climate leading to the evolution of land animals, many of which were predators of the Icaronycteris. Without the ability to fly the Icaronycteris would easily become food. In order to escape from the land predators would have been forced to develop lighter bones enabling flight, where they are further away from such threats. Also the general rise in temperature during the Eocene caused sea levels to rise, flooding low lying areas. If the Icaronycteris could not fly, the size of their hunting ground would have been severely reduced as they were unable to swim and could easily drown. It would have cut them off from a lot of their food supply which would have easily killed off the Icaronycteris.

Just like vampire bats, Icaronycteris was a nocturnal creature just like many other animals in the wild. This means that they spend most of the day sleeping and was most active at night. This adaptation lets it survive as night time was the safest time for them to appear as many of the potential predators are asleep, thus reduces the chances of them being preyed upon. It was also essential for them to be active at night because during the Eocene period the humidity at night was much lower, this was the most ideal condition for the Icaronycteris as they had difficulties hunting in dry environments. If they were forced to hunt in dry conditions, the Icaronycteris could easily dehydrate and they would die much easier.
 * 5. Nocturnal**

The environmental pressure that caused this adaptation would have been the emergence of new species of mammals. Most of these mammals threatened the survival of Icaronycteris and since they were mainly diurnal, meaning that they slept at night and was most active during daytime, it would only make sense for Icaronycteris to avoid them by living a different lifestyle.

** Selection Pressure ** The Icaronycteris was very well adapted to the environment of the Eocene Era, unfortunately the Earth is constantly changing and that made it very difficult for the Icaronycteris to survive. The reason for the extinction would be due to natural selection. They may be extinct but their lineage continues and it has diverged into many bat species including the modern-day vampire bat.

Many believe that the sharp rise in temperature during the Eocene period wiped out many mammals, who were then replaced with more modern ones. This period of rising temperature was known as the Palaeocene-Eocene Thermal Maximum and happened around 50 million years ago. In just 20,000 years the global temperature rose by 7 degrees! The rise in temperature had made it difficult for the Icaronycteris to survive as well, this decreased their population size dramatically. Meanwhile there was an increased number of predators within their environment, which would have further reduced its population size. During this time there was a flourish in wildlife which also meant that new animals, who also fed on insects, emerged making the competition for food more intense. This would have forced the Icaronycteris to change their diet. Basically, the Icaronycteris would have become extinct because some would have been unable to survive in hotter conditions, and would have died off before they could reproduce. Those that did survive passed this gene on to its next generation. Overtime it began evolving into the extant microchiropteran bat species we know today and the original Icaronycteris became extinct.


 * Bibliography **
 * 1) BBC. (2011). //Eocene Epoch videos, news and more.// Retrieved June 18, 2011 from []
 * 2) Blakey, R. (2007). //Cenozoic Time and Paleogeography.// Retrieved June 18, 2011 from []
 * 3) Encyclopedia Britannica (Online). (2011). //Eocene Epoch.// Retrieved June 21, 2011 from []
 * 4) Strauss, B. (2008). //Icaronycteris.// Retrieved June 20, 2011 from []
 * 5) Unknown. (n.d.) //The Evolution of Chiroptera.// Retrieved June 19, 2011 from []
 * 6) World Of Earth Science Group. (2003). //Eocene Epoch.// Retrieved June 19, 2011 from []