Archaeopteryx
To date, Archeopteryx (Archaeopteryx) is still the most primitive and oldest old birds, but also so that birds and dinosaurs of the chains connected to each other in a very critical link. Archeopteryx known specimens are all found in the Solnhofen Bavaria, Germany around the Upper Jurassic Solnhofen limestone layer. Solnhofen — any one of a little air jordan fusion knowledge of ancient people who are not their biological unfamiliar, which is nothing contingent is a world-renowned shrine of the fossils. Archeopteryx is so famous because of its beautifully preserved fossils of the feathers, this is precisely the Solnhofen limestone is unique in that it has to address soft-tissue preservation of magic. Far in the late Jurassic, Solnhofen located in the tropics, is a shallow lake surrounded by rocks, mud flats scattered around the ground. It is now central Germany on land north of the south is the vast Tethys (Ancient Mediterranean). This piece of sand from the coast and coastal lakes and the sea between the almost no communication, so a few million years since the bottom of the lake gradually deposited delicate mud, salt water is also growing, life is difficult stop. Once a storm or the animal’s body was washed into the lake or the overflow of water, they sink to the bottom of the lake with very low oxygen content, slurry seal the body, protecting it does not further decay damage, followed by a gradual infiltration of minerals and Instead, become fossils, fine carbonate matrix, such as resin preserved the structure of which is extremely detailed. So far, Solnhofen fossils have been discovered in 400-500 species, mostly marine animals are useful, such as fish, crustaceans, in addition to some live in the coastal region, insects, dinosaurs, wing lung.
1860-2008 years, 148 years, the Solnhofen gradually found a feather james lebron shoes and 10 archeopteryx fossils, and each time found to have so Solnhofen shine a household name. These alone is enough to make the place holy Solnhofen success.
I first became a human is a feather, it is a flight feathers. This is the root magic feathers in 1860 near a quarry in Solnhofen was discovered by the Museum of Natural History in Frankfurt sunken released at the end of Meyer. This is one of the feathers length 68 mm, width 11 mm, feather feathers dry neatly divided into two asymmetric pinna, feather shaft, feather sticks and feather sprig are very clear. This structure with the current health of primary flight feathers of birds is very similar, but it is 1.45 billion years ago from the Upper Jurassic of the bottom is really incredible. From this we can be sure that, as far away as 1.45 billion years ago, the Earth already had the birds on sight, in addition to not have a second to explain.
Away from the feathers of more than a month after the research paper published early in 1861, Meyer has announced the Solnhofen near Langen Yi Tehan, Jude Biao about 30 meters deep pit Altman found an addition to the first Department of absence are relatively complete fossils, fossils clearly shows that the species has a pair of feathered wings. Meyer named the fossil Archaeopteryx lithographica, signed meaning «ancient wing», species name means «printed version of Stone», the domestic is usually sound, meaning lithography Archeopteryx. Archeopteryx retained many features of reptiles, if by a long tail composed of 21 caudal vertebrae; forelimbs 3 metacarpal from each other, there is no carpal metacarpal and synthesis, the tip of finger with claws; bone within the nest and so do not gas. On the other hand, it already has feathers, and began to air jordan force differentiate, these are the characteristics of birds. In addition, it also in a number of bone morphogenetic show some bird features or transitional features. The second metacarpal as it has healed wrist, but the second and the first metacarpal has not yet healed and so on, we can see that birds probably evolved in the reptiles on the basis of the past.
Finally a archeopteryx fossils, which is the tenth in December 2005 in the «Science» magazine has been specifically described, this may not need to Berlin specimen less, and is the first non-European countries, an inflow archeopteryx fossils, and soon caused a sensation. Authors Meyer and Paul, the former is sunken in Frankfurt, Germany Museum of Natural History ornithologist. The latter is the United States a veterinarian, but also the owner of fossils. Paul is very complete specimen of its head bone, the front wing and tail feathers of the prints clearly visible, it is not clear enough to answer some of the problems. Interestingly, from the shape and composition of bone characteristics of point of view, Paul specimen closer to Deinonychus class, which directly supports the hypothesis that birds originated from dinosaurs.
First, from the skull of view, Paul has the most complete specimens jordan xi preserved skull, its jaw the right side of the head and all exposed, you can see a complete orbit before the hole, which is the orbital theropods before the hole is the same source structure, one of their evolution from the same ancestor, so there are similarities between the structure and function. The specimens of birds beak Paul bone (scapula, bird beak composition of bone and wishbone strap birds) form and theropods in class is very similar to Chi-lung, and the beak of bone and scapula are not healed. The most interesting is the well-preserved specimens from Paul’s feet can be seen Archeopteryx should be to habitat in nature, it may be difficult to a tree. We know that birds fly in order to meet its hind legs generated a great deal of change, its degradation into a thorn-shaped fibula, tarsal bones of the upper part of the merger into the tibia and tibial tarsal bone. Through this simplification nike dunks high and extension of tibial tarsal bone of birds has greatly increased the flexibility of take-off and landing. In addition, most birds have four toes (the fifth toe degradation), the first toe (thumb) back, the other three toes forward, the same as the structure of pliers can easily hold the branches when they are arboreal. Previously, due to the early Archeopteryx nike sb dunk low specimens to preserve these morphological characteristics are not the details, so paleontologists have speculated Archeopteryx should be in the trees of life. Now we have the opposite high-speed specimen Paul answers: it’s the first toe bone health first position of front extension and formation of bone attached to the second side, the first toe has not reversed, it is also a direct reflection of the Archeopteryx do not have the first toe and the toe of the grip and his 3-structure, to prove that it is no longer a tree of life.
Since there was no longer a tree of life, then Archeopteryx can jordan shoes only run of the ground. Paul also gave us samples of other habitats of evidence: extension of the second toe, second toe section near the top of the extremely swollen joints, were indicative of Archeopteryx good run on the ground, but by the second toe grip strength acquired . This is very similar to Deinonychus.
A lot of new information to the classification of birds in this big family, a change in position, the birth of a new academic point of view, put forward the origin and evolution of birds «multiple» theory. In the past, paleontologists have always thought that birds evolved from dinosaurs from a direct and thus developed into today’s large and complex family of birds. However, according to Paul Meyer specimens of property characteristics, its phylogenetic position were analyzed, a new phylogenetic tree tells us that Archeopteryx Deinonychus category with sister taxa, together with the composition of nearly birds, cheap jordan shoes this is not new, However, other paleontologists are surprised that Deinonychus class actually contains the Confucius bird, Confucius Bird Microraptor King-shing, in order to sister taxa. This result may be due as a character analysis of the result of ancient birds, less information, but an evolutionary sense, the new system the tree jumped out of the birds are monophyletic systems mode of thinking so that we can be more «unbridled «to assume that the origin of birds issue. Have paleontologists assumed that those who dressed in feathered dinosaurs there may be caused by loss of Archeopteryx flying abilities of birds such as the degradation made it?