Announcement

this is a bad news prehistory lovers and fans because I won't  gonna post any daily dinosaur on weekdays any more. But I will always post daily dinosaur on weekends and national holidays. I also got good news prehistory lovers and fans. The monthly mammal will turn weekly mammal. I will begin on 26 September 2011. Thank you.

weekly fossil: Lucy

Discovered by Donald Johanson and Tom Gray in 1974 at Hadar in Ethiopia (Johanson and Edey 1981; Johanson and Taieb 1976). Its age is about 3.2 million years. Lucy was an adult female of about 25 years and was assigned to the species Australopithecus afarensis. About 40% of her skeleton was found, and her pelvis, femur (the upper leg bone) and tibia show her to have been bipedal, although there is evidence that afarensis was also partly arboreal (tree-dwelling). She was about 107 cm (3'6") tall (small for her species) and about 28 kg (62 lbs) in weight.
The humerofemoral ratio, or length of humerus divided by length of femur, is 84.6 for Lucy, compared to 71.8 for humans, and 97.8 and 101.6 for the two species of chimpanzee (all these figures have a standard deviation of between 2.0 and 3.0). In other words, humans have much shorter arms compared to their legs than chimpanzees do, and Lucy falls roughly in the middle. (Korey 1990)


http://www.talkorigins.org/faqs/homs/lucy.html

weekly video

Diplodocus

Diplodocus ( /dɪˈplɒdəkəs/,^[1][2] /daɪˈplɒdəkəs/,^[2] or / repeat: initial initial; color: #0645ad; text-decoration: none;" title="Wikipedia:IPA for English">ˌdɪploʊˈdoʊkəs/^[1]) is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 byS. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλόος (diploos) "double" and δοκός (dokos) "beam",^[1] in reference to its double-beamed chevron bones located in the underside of the tail. These bones were initially believed to be unique to Diplodocus; however, they have since then been discovered in other members of the diplodocid family and in non-diplodocid sauropods such as Mamenchisaurus.

It lived in what is now western North America at the end of the Jurassic Period. Diplodocus is one of the more common dinosaur fossils found in the Upper Morrison Formation, a sequence of shallow marine and alluvial sediments deposited about 155 to 148 million years ago, in what is now termed the Kimmeridgian and Tithonianstages (Diplodocus itself ranged from about 154 to 150 million years ago^[3]). The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs such as Camarasaurus, Barosaurus, Apatosaurus and Brachiosaurus.^[4]

Diplodocus is among the most easily identifiable dinosaurs, with its classic dinosaur shape, long neck and tail and four sturdy legs. For many years, it was the longest dinosaur known. Its great size may have been a deterrent to the predators Allosaurus and Ceratosaurus: their remains have been found in the same strata, which suggests they coexisted with Diplodocus.

http://en.wikipedia.org/wiki/Diplodocus

Monthly mammal: Doedicurus

Doedicurus clavicaudatus was a prehistoric glyptodont, living during the Pleistocene until the end of the last glacial period, some 11,000 years ago. This was the largest known glyptodontid, and one of the better known members of the New World Pleistocene megafauna, with a height of 1.5 meters (5 ft) and an overall length of around 4 meters. It had a huge domed carapace that was made of many tightly fitted scutes, somewhat similar to that of its modern-day relative, the armadillos. Its tail was surrounded by a flexible sheath of bone and had long spikes or knobs on the end, at least in male individuals (McNeill Alexander et al. 1999).

D. clavicaudatus inhabited woodlands and grasslands and was herbivorous. Its tail club was probably used in intraspecific conflict rather than defense against predators like Smilodon unlike the superficially similar club of theAnkylosaurs. For one thing, the latter use would have been hard since the animal's field of vision was so limited that it would essentially have had to blindly thrash the tail club about. In addition, carapaces have been found which show fractures that were produced by roughly the same amount of energy as could be produced by the tail muscles (McNeill Alexander et al. 1999).

Its name means "Pestle Tail", referring to how, if the spikes were removed, it would resemble a pestle.

The carapace was firmly anchored to the pelvis, but loose around the shoulder. Its front bore an additional, smaller dome. This has been interpreted as a fat-filled space, similar to a camel's hump, which would have stored energy for the dry season and cushioned blows of the tail of rival animals (McNeill Alexander et al. 1999).

Fossils of D. clavicaudatus are found in North America and South America, especially the Ensenada Formation inArgentina. Given the late date of its disappearance, it was encountered and probably also hunted by the first human settlers of South America.

http://en.wikipedia.org/wiki/Doedicurus

Daily dinosaur: Archaeopteryx

Archaeopteryx ( /ˌɑrkiːˈɒptərɨks/ ar-kee-op-tər-iks), sometimes referred to by its German name Urvogel ("original bird" or "first bird"), is a genus of theropod dinosaur. The name derives from the Ancient Greek ἀρχαῖος (archaīos) meaning "ancient", and πτέρυξ (ptéryx), meaning "feather" or "wing". Since the late 19th century, it has been generally accepted by palaeontologists, and celebrated in lay reference works, as being the oldest known bird (more precisely, a close relative of the direct ancestor of modern birds), although there have been occasional dissenters in the research community. The dissenting view has been bolstered by a research article published in July 2011, based on the reported discovery of a new species, Xiaotingia zhengi, to which Archaeopteryx and other fossil species are compared. The claims in the 2011 paper are being reviewed by palaeontologists.^[1]

Archaeopteryx lived in the Late Jurassic Period around 150 million years ago, in what is now southern Germany during a time whenEurope was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in shape to aEuropean Magpie, with the largest individuals possibly attaining the size of a raven,^[2] Archaeopteryx could grow to about 0.5 metres (1.6 ft) in length. Despite its small size, broad wings, and inferred ability to fly or glide, Archaeopteryx has more in common with other small Mesozoic dinosaurs than it does with modern birds. In particular, it shares the following features with the deinonychosaurs(dromaeosaurs and troodontids): jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest homeothermy), and various skeletal features.^[3][4]

The features above make Archaeopteryx a clear candidate for a transitional fossil between dinosaurs and birds.^[5][6] Thus, Archaeopteryxplays an important role not only in the study of the origin of birds but in the study of dinosaurs. It was named from a feather in 1861. That same year, the first complete specimen of Archaeopteryx was announced; this was only two years after Charles Darwin published On the Origin of Species, and it became a key piece of evidence in the debate over evolution. Over the years, nine more fossils of Archaeopteryxhave surfaced. Despite variation among these fossils, most experts regard all the remains that have been discovered as belonging to a single species, though this is still debated.

Most of these eleven fossils include impressions of feathers—among the oldest direct evidence of such structures. Moreover, because these feathers are of an advanced form (flight feathers), these fossils are evidence that the evolution of feathers began before the Late Jurassic.^[7] The first remains of Archaeopteryx were discovered just two years after Charles Darwin published On the Origin of Species.Archaeopteryx seemed to confirm Darwin's theories and has since become a key piece of evidence for the origin of birds, the transitional fossils debate, and confirmation of evolution.

http://en.wikipedia.org/wiki/Archaeopteryx