The deserts of Egypt contains some of the best preserved paleontological sites in the world one of which is Wadi al-Hitan or the Valley of Whales. This remote valley in the Western Desert, some 150 km southwest of Cairo, contains valuable collection of fossils and bones of a now extinct, suborder of whales, called the archaeoceti. These fossils explains one of the greatest mysteries of the evolution of whales: the emergence of the whale as an ocean-going mammal from a previous life as a land-based animal
The fossils of Wadi Al-Hitan dating back to 50 million years show the youngest archaeocetes, in the last stages of evolution from land animals to a marine existence. They already display the typical streamlined body form of modern whales, whilst retaining certain primitive aspects of skull and tooth structure, as well as hind legs. Many of the whale skeletons are in good condition as they have been well preserved in the rock formations. Semi-complete skeletons are found in the valley and in some cases, even stomach contents are preserved. Fossil of other early animals such as those of sharks, crocodiles, sawfish, turtles and rays found at Wadi al-Hitan makes it possible to reconstruct the surrounding environmental and ecological conditions of the time.
There is considerable evidence which indicates that the basin of Wadi Hitan was submerged in water some 40 to 50 million years ago. At that time, the so-called Tethys Sea reached far south of the existing Mediterranean. The Tethys Sea is assumed to have retreated north and over the years deposited thick sediments of sandstone and limestone visible in rock formations in Wadi Hitan.
Geological studies have been carried out in the area since the 1800’s, and the first skeletons were found around 1830 but were never collected due to the difficult accessibility to the site at that time. At first, it was thought to be a huge marine reptile. It was only later in 1902, that the species were identified as whales. For the next 80 years they attracted relatively little interest, largely due to the difficulty of reaching the area. In the 1980s interest in the site resumed as four wheel drive vehicles became more readily available..
Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively.
A fish eye from a primitive time when Earth was but one single continent has yielded evidence of color vision dating back at least 300 million years. Analyzing the fossilized remains of a fish called Acanthodes bridgei that lived long before the dinosaurs, scientists discovered light-sensing “rod” and “cone” eye cells — the oldest ever found. being the first discovery of vertebrate retinal fossils. The remains had been preserved under a thin coating of phosphate, analysis of the tissue provides the first record of mineralised rods and cones in a fossil. YAY!!!
Optical photographs of the Carboniferous fish A. bridgei: Complete dorsoventrally compressed specimen; the head, including a pair of black/dark brown eyes, is lower left. (b,c) Details of the head region and the right eye.
There are thousands upon thousands of layers in the earth’s crust. However, scientists have grouped the layers into major groups. The most recent three layers are the Paleozoic, Mesozoic, and Cenozoic. These layers represent the last 500 million years of life on earth.
In the Paleozoic, you find fish, amphibian, and reptile fossils (in that order), but never dinosaurs, birds, modern mammals, or even flowering plants.
Think of that: despite the billions of plant fossils in the Paleozoic layer, nobody has ever found one fossil of a flower, including any kind of deciduous tree or even a single blade of grass. Why not? The obvious explaination is flowers had not evolved yet.
The next layer, the Mesozoic, is often called the age of dinosaurs. The Mesozoic has dinosaurs like crazy. Of course, dinosaurs are reptiles and that’s why you won’t find any until after the Paleozoic which contains the first reptiles. The Mesozoic also has the first flowering plants, birds, and mammals, though few if any birds or mammals that we know of today.
On top of the Paleozoic and Mesozoic is the Cenozoic. This is the current layer that is still being deposited in oceans, deserts and swamps all around the earth today. The Cenozoic is the first major layer where we find modern mammal fossils like cats, dogs, monkeys and humans. This layer, or “era” is often referred to as the age of mammals.
These three layers make up a sort of 3-layer cake. Just like a cake, the bottom layer went down first, followed by the middle and the top. Since fossils progress from fish at the bottom to humans at the top, we have clear evidence that life evolved through time.
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Mary Anning (1799-1847) - A life long fossil hunter, Anning got her start at only 11 years old when she discovered the skull and 60 vertebrae of what would later be named
Despite a lack of formal education, Anning taught herself anatomy, geology, paleontology and scientific illustration. Scientists traveled from as far away as NYC to her home in Lyme Regis, England to consult and hunt for fossils with Anning. (Smithsonian Mag)
Earth-like soils on Mars? Ancient fossilized soils potentially found deep inside impact crater suggest microbial life | ScienceDaily
NASA rovers have shown Martian landscapes littered with loose rocks from impacts or layered by catastrophic floods, rather than the smooth contours of soils that soften landscapes on Earth. However, recent images from Curiosity from the impact Gale Crater, Retallack said, reveal Earth-like soil profiles with cracked surfaces lined with sulfate, ellipsoidal hollows and concentrations of sulfate comparable with soils in Antarctic Dry Valleys and Chile’s Atacama Desert.
His analyses appear in a paper placed online this week by the journal Geology in advance of print in the September issue of the world’s top-ranked journal in the field. Retallack, the paper’s lone author, studied mineral and chemical data published by researchers closely tied with the Curiosity mission. Retallack, professor of geological sciences and co-director of paleontology research at the UO Museum of Natural and Cultural History, is an internationally known expert on the recognition of paleosols – ancient fossilized soils contained in rocks.