Protoavis

• Dockum Group (Texas, USA)

• Protoavis texensis

The term Protoavis ( " First Bird " - composed of ancient Greek πρῶτος protos " first " and Latin avis " bird" ) was awarded fossil bone assemblages, which are found in 1984 with post in the U.S. state of Texas in strata of the Dockum group from the Upper Triassic were. It was Archosauria - ruins, which were described as a primitive bird species - this would set back the origin of birds, with proper assignment for another 60 to 75 million years.

Protoavis has reportedly reached a size of 35 centimeters, his age is given as 225-210 million years BP. Although Protoavis is so much older than Archaeopteryx, will be much birdlike his skeleton construction yet. Reconstructions show him as a carnivorous bird whose teeth were sitting at the border of the mandible and its eyes were placed far forward on the skull - which points to a crepuscular or nocturnal lifestyle. The skeletal remains are located but in a very bad state of preservation, it can thus no further statements about his flight fortunes are made. Although reconstructions show him mostly feathered, so there is no clear evidence for a thorough study of the fossil material for this purpose.

The first description assumes that Protoavis really existed and the reconstruction was carried out correctly. Almost all paleontologists doubt that it is at Protoavis to a bird or a unique species - for them the remains are too fragmentary and typical for birds synapomorphies not convincing enough. The circumstances of the discovery are not necessarily rely awakening - the remains were within a tangled accumulation of dinosaur bones and bones of other species scattered. The archaeological site itself points to a problem caused by a flash flood mass death in a river delta.

Controversial Fund

Sankar Chatterjee of Texas Tech University was convinced that some of the broken pieces of bone belonged to two individuals of the same species, a young and an older animal. There were but few fragments found ( a skull and several bones belonging to limbs ) that also did not want to fit together so well in their proportions. For this reason, many specialists believe that it is Protoavis is a chimerical fossil, which is composed of several organisms. The skull pieces are likely to come from a Coelurosaurier, most of the limbs fragments indicate Cerato dinosaurs and at least some of the vertebrae resemble those of a Megalancosaurus - the latter is actually not a dinosaur, but a avicephaler Diapside.

"No matter how you want to look at it and turn, even the Protoavis assigned fossil fragments represent his real existence in question. The minimum final requirement is therefore that Chatterjee's provocative Fund represents only a chimera, a huddle of long-dead archosaurs ".

If Protoavis ever should it have existed, he would raise interesting questions about the timing of cleaving the birds from dinosaurs. The status of the animal must remain in the dark but as long as before no better evidence comes to light. Moreover, studies indicate palaeobiogeographic to realize that the Americas were first colonized from the Cretaceous of birds. The oldest and most primitive evolutionary lines of undisputed birds have been discovered in all Eurasia. Certainly, the discovered fossil remains were as already stated above assigned according to the Ockham's principle of economy primitive dinosaurs and other reptiles, but are Coelurosaurier and Cerato dinosaurs of the ancestors of the first birds kinship terms really so far away? In some ways, their skeletons are quite similar - this also explains why these dinosaurs could be confused with bird -like. Thus, for example, Archaeopteryx also originally thought to be a small theropod dinosaur. Zhonghe Zhou concludes:

" Protoavis never met with broad support and was never seriously recognized as a Triassic bird [ ... Witmer, who examined the material and one of the few Chatterjee's theory seriously considered, came to the conclusion that the bird status of P. texensis not as controversial as it is usually presented by Chatterjee. He recommended further give Protoavis in the discussion about the origin of birds in the future less attention to ".

Disputes in evolutionary questions

It is sometimes claimed that Protoavis would refute the hypothesis of the origin of birds from dinosaurs. However, this is not true. The only consequence is that the timing of the splitting of the two lines further recedes into the past and that the Dromaeosauridae must be included in the Vogelklade with. Let this also be noted that at the time of the arguments about Protoavis the now generally favored among ornithologists and recognized evolution induced proximity between birds and theropod maniraptorischen was far more controversial - is the fact that most of the birds from the Mesozoic era have been discovered until later. Even Chatterjee has Protoavis used to support the close relationship between dinosaurs and birds.

" Since there is no compelling evidence for the bird status of Protoavis and its taxonomic scope are more left, it may seem a little strange that this issue is so controversial. The author agrees with Chiappe agreement to the effect that Protoavis has become irrelevant at the present time for the reconstruction of the bird family tree. Other findings in the Dockum Group can this strange archosaurs may retablieren, at the moment the case Protoavis is certainly shelved for now. "