viernes, 3 de febrero de 2017

Whale watching in the Egyptian desert...

Imagine swimming in the ocean with an over 20 meter long whale, looking rather like both an alligator and a snake. 
Now imagine being afraid to even take a bath ever again.

The modern ocean is a scary place, filled with barracuda, sharks, giant-squids, and what possibly else. However, no matter what we find in the depths these days, none of it seems to come close to the giant terrors that roamed the seas in the Earth’s past. Megalodon being probably the best-known creature in the list, this included giant sea-lizards, monster sharks and even “hyper-carnivorous” whales, for most of which, humans would barely qualify as a snack.

The Tethys sea

Birthplace of the whales, the ancient Mediterranean Sea is called the Tethys Sea. Its shoreline ran across northern Egypt. Throughout the Eocene, this sea, which had then reached as far south as to where Luxor is now located, began to retreat northward. In the meantime, continental river deposits effected the long-term regression of sea level. By the end of the Eocene, deep marine water was restricted to lagoons and eventually deltaic and riverine conditions in northern Egypt. 

Wadi el Hitan whales

Some 50 million years ago, in the Eocene, land mammals started to evolve to a fully aquatic life, through some remarkable intermediate stages in which they became “walking whales”, living on the abundant food there, until they eventually left the land altogether. A tropical forest and mangroves existed in Oligocene time in the presently Egyptian Fayun desert… which witnessed a flourishing of biological diversity and the emergence of species which descended from the preceding Eocene.

Heavy rains formed seasonal rivers bringing rich nutrients to the shallow seas. This attracted an abundance of marine life and organisms, including carnivorous whales, especially the large Basilosaurus and its smaller prey Dorudon. Despite its name and appearance, Basilosaurus was not a reptile, but actually a fearsome predatory whale and an ancestor of modern whales. 15 to 20 meter long, it is described as being the closest a whale has ever come to being a snake because of how long and sinuous it was. 

Dorudon and Basilosaurus evolved around 40 million years ago. Skeletal adaptations allowed them to adopt a fully aquatic lifestyle and permitted their limbs to be used more for steering than for paddling. Their hind limbs are important in verifying the evolutionary process from primitive whales witch had them fully developed, to recent whales that lack external hind limbs. 

Basilosaurus and Dorudon whales 

Basilosaurus was present in Wadi el Hitan some 37 million years ago. Its name means “King lizard” and it was chosen when people first thought that its bones belonged to some sort of reptilian sea monster. 

Wadi el Hitan was at the time also inhabited by Dorudon, whose name means ”spear tooth”. As fierce as they may have appeared, Dorudon were preyed upon by much larger Basilosaurus. Dorudon, or a species of an early whale like it, was probably the ancestor of all the modern whales. 

Basilosaurus and Dorudon rear feet, a small one for such a big animal, hasn’t got its pelvic bone attached to its vertebrae, as in land mammals. There is no way they could use them for walking, but were possibly used as claspers to help them mate in the water. These hind limbs are very important in verifying the evolutionary process as an intermediate between primitive whales with large hind limbs and recent whales that lack hind limbs altogether.

UNESCO Wold Heritage

A unique landscape of huge boulders of varying sizes, shapes and textures provide a striking background for the Wadi el Hitan fossils. 

A geological survey of Egypt visited the valley in 1902 and recorded the existence of fossil remains. In 1912, the first national team to work in the field of Vertebrate Paleon- tology was able to make new discoveries of previously unknown species, and efforts were crown with the discovery of the largest complete Basilosaurus fossil in the world. 

Still, it wasn’t until 1983 that an early whale displaying the remains of hind limbs and feet was discovered. This discovery triggered intense interest in the valley and especially in the evolution of whales.

Designing and building facilities for this sensitive site of global importance presented several challenges, as how to be least intrusive on such a unique landscape, counter the hot climate, benefit the local people and also take advantage from their local knowledge and skill. The result was a World Heritage facilities which were inspired by nature through mimicking the earth tone colors, textures and shapes of the landscapes.

Wadi el-Hitan o Valle de las ballenas es una región de la gobernación de El Fayún, en el desierto occidental de Egipto que contiene importantes restos fósiles del suborden de los arqueocetos (antepasados de los cetáceos modernos). Fue incluido en la lista de Patrimonio de la Humanidad de la Unesco en julio 2005.

Esos restos paleontológicos representan uno de los principales registros de la historia de la evolución de las especies: la transformación de animal terrestre en uno acuático sufrido por las ballenas. El Valle es el sitio más importante del mundo para demostrar esta evolución. 

Se retrata con precisión la forma de vida de esos mamíferos durante su evolución. El número, la concentración y la calidad de los fósiles son únicos. Los restos muestran a los animales perdiendo sus miembros traseros, los cuerpos hidrodinámicos, como los de las ballenas modernas, al mismo tiempo que presentan aspectos primitivos de estructura ósea. Otros materiales fósiles encontrados en la localidad permiten reconstruir el ambiente y condiciones ecológicas de la época.

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