Another Alleged Transitional Form: Archæopteryx



Evolutionists pronounce the name of one single creature in response. This is the fossil of a bird called Archæopteryx, one of the most widely-known so-called transitional forms among the very few that evolutionists still defend. Archæopteryx, the so-called ancestor of modern birds according to evolutionists, lived approximately 150 million years ago. The theory holds that some small dinosaurs, such as Velociraptors or Dromeosaurs, evolved by acquiring wings and then starting to fly. Thus, Archæopteryx is assumed to be a transitional form that branched off from its dinosaur ancestors and started to fly for the first time.SPECIAL LUNGS FOR BIRDSThe anatomy of birds is very different from that of reptiles, their supposed ancestors. Bird lungs function in a totally different way from those of land-dwelling animals. Land-dwelling animals breathe in and out from the same air vessel. In birds, while the air enters into the lung from the front, it goes out from the back. This distinct "design" is specially made for birds, which need great amounts of oxygen during flight. It is impossible for such a structure to evolve from the reptile lung.However, the latest studies of Archæopteryx fossils indicate that this creature is absolutely not a transitional form, but an extinct species of bird, having some insignificant differences from modern birds.The thesis that Archæopteryx was a "half-bird" that could not fly perfectly was popular among evolutionist circles until not long ago. The absence of a sternum (breastbone) in this creature was held up as the most important evidence that this bird could not fly properly. (The sternum is a bone found under the thorax to which the muscles required for flight are attached. In our day, this breastbone is observed in all flying and non-flying birds, and even in bats, a flying mammal which belongs to a very different family.)However, the seventh Archæopteryx fossil, which was found in 1992, caused great astonishment among evolutionists. The reason was that in this recently discovered fossil, the breastbone that was long assumed by evolutionists to be missing was discovered to have existed after all. This fossil was described in Nature magazine as follows:The recently discovered seventh specimen of the Archaeopteryx preserves a partial, rectangular sternum, long suspected but never previously documented. This attests to its strong flight muscles.46This discovery invalidated the mainstay of the claims that Archæopteryx was a half-bird that could not fly properly.Moreover, the structure of the bird's feathers became one of the most important pieces of evidence confirming that Archæopteryx was a flying bird in the real sense. The asymmetric feather structure of Archæopteryx is indistinguishable from that of modern birds, and indicates that it could fly perfectly well. As the eminent paleontologist Carl O. Dunbar states, "because of its feathers [Archæopteryx is] distinctly to be classed as a bird." 47Another fact that was revealed by the structure of Archæopteryx's feathers was its warm-blooded metabolism. As was discussed above, reptiles and dinosaurs are cold-blooded animals whose body heat fluctuates with the temperature of their environment, rather than being homeostatically regulated. A very important function of the feathers on birds is the maintenance of a constant body temperature. The fact that Archæopteryx had feathers showed that it was a real, warm-blooded bird that needed to regulate its body heat, in contrast to dinosaurs.....continues....

[admin edit: link remove - we're not a link dump site for invasive ideologies, thanks]

Kindest Regards, jasonparker! Welcome to CR!

We actually had a long running discussion that addressed this and a great deal more:

It is buried in the archives, so it is no wonder it was difficult for a new member to find. There should be plenty of enjoyable reading. If you have anything to further that discussion, perhaps it would be better to post on that thread. Unless you have a specific point to address yourself?
Jason's just a spammer, I'm afraid - come in and dumpy some ideological garbage in forums, in the hope that he can convert one poor lost soul to his way of thinking. Crude and invasive, and ultimately, not welcome.
You were right, Brian. I saw he had posted the same article in another forum, same day ! He got some answers, but he didn't reply.
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The avian flow-through lung
All tetrapods (mammals, reptiles, amphibians, crocodilians) apart from birds have a pair of lungs that operate on the bellows principle. That is, a pair of lungs that inhale and exhale air by volume changes associated with respiratory movements of the diaphragm and rib cage. The volume of the lungs are increased by inspiratory effort drawing oxygen-rich air into the lung; and are decreased to expel air partially depleted of oxygen and carrying waste carbon dioxide, from the lungs.
Birds, however, have an entirely different respiratory system. Birds breathe using a respiratory system that consists of a pair of lungs and a number of separate air sacs that take up some considerable space in the body cavity of the bird. Most birds have nine air sacs. The air sacs are connected to the lungs in such a way that when a bird breathes air is first drawn into the posterior air sacs. It then flows though the lungs in a single direction into the anterior air sacs through a fine set of 'air capillaries' (the parabronchi) in the lung. The air capillaries are closely surrounded by blood capillaries and this is where the exchange of oxygen and carbon dioxide takes place. The air sacs and lungs are arranged in such a way that air flows in the same direction through the lungs whether the bird is inhaling or exhaling (uni-directional flow-through). Unlike mammals and other tetrapods, the avian lungs remain the same volume during breathing - the air is pumped by changes in the volume of the air sacs not the lungs. The bird skeleton is highly pneumatized - that means that there are large air spaces in the bones and vertebrae of birds which connect with the air sacs.
Go to reference 10 for a detailed explanation of the avian respiratory system.
Recent finding
A recent paper in Nature (11), shows that theropod dinosaurs have vertebrae pneumatized in a way that is very similar to modern birds. The authors have investigated the well preserved fossil of a theropod dinosaur called Majungatholus atopus and have found that the vertebrae possess very close similaritiies in pneumaticity compared with an extant bird (the sarus crane). See fig 1 below.
Fig 1: After reference 11. Comparisons between a bird (a, b) and theropod dinosaur (c, d) in caudal (a, c) and right lateral (b, d) views, illustrating the topological similarity of pneumatic features. a, b, Cranial thoracic vertebra of a sarus crane (Grus antigone, SBU AV104063). c, d, Mid-cervical (c) and cervicothoracic (d) vertebra of an abelisauroid theropod (Majungatholus atopus, UA 8678). Scale bar, 1 cm (a, b) and 3 cm in (c, d). CeP, central pneumatic foramen; NaP, neural arch pneumatic foramen; Nc, neural canal; Ns, neural spine; Pp, parapophysis
However, the similarity between the pneumatic features of theropod dinosaurs and modern birds was already known through a number of studies (12). So what does this new study indicate that we didn't know before? Detailed analysis of the individual vertebrae and ribs reveal a pattern of pneumaticity that is entirely consistent with the pattern in living birds - that is, the cervical air sac connect to vertebrae and ribs in the neck region of the spine, and in the thoracic vertebrae nearest the head; the abdominal air sac connects with the tail and sacrum vertebrae and the thoracic vertebrae nearest the tail; and the lung itself connects with the mid-thoracic vertebrae. This pattern is the same in all birds and is exactly what is found by detailed analysis of the vertebrae of M atopus. So it is not the discovery of pneumatised vertebrae in this fossil that is new, but the fact the pattern of pneumatisation is found to be the same as in living birds and consistent with a uni-directional flow-through breathing system. This situation is consistent for all known non-avian theropods, suggesting that it is a derived characteristic of the first theropods and spread throughout the entire clad of theropods including modern birds
Furthermore, O'Connor and Claessens point out that in order for either uni-directional or bi-directional flow-through ventilation to work, the tail end of the abdominal cavity has to change volume more than the head of the cavity. Indeed that is the arrangement in birds, and analysis of the skeleton of theropods shows that they possess the appropriate characteristics in the articulation of the ribs with the vertebrae to show that the tail end of the trunk can change volume mure than the head end, just as in birds. Indeed air sacs and associated features at the tail end of the abdominal cavity are known to have developed in chameleons, snakes and certain types of lizard and this indicates that the tail end of the lung in the entire sauropsid (a group that includes birds and most reptiles and dinosaurs) is able to develop air sacs and invade the tail end of the skeleton.
So, this recent study has shown that non-avian theropod dinosaurs had the necessary anatomy for flow-through ventilation similar to extant birds and, that in the evolution of the flow-through system, the tail end air sacs likely developed before those at the head end of the trunk.