Science Literature

The first specimen of Archaeopteryx was discovered in 1861 in Bavaria, Germany, and it quickly made its way into Darwin's Origin of Species as an example of a transitional form. The German name of the fossil was Urvogel ("original bird" or "first bird"), but the English speaking world adopted Archaeopteryx - from the Greek archaios meaning 'ancient' and pteryx meaning 'feather' or 'wing'. The sense of the German name, however, was universally received: this was the first known bird and it displayed sufficient reptilian features to encourage hypotheses about an evolutionary past. This summary is from the University of California Museum of Paleontology: "It has long been accepted that Archaeopteryx was a transitional form between birds and reptiles, and that it is the earliest known bird." The history of evolutionary theory could not be written without the name Archaeopteryx appearing prominently - this is from the National Center for Science Education:

"Archaeopteryx is frequently used for pedagogical purposes because it is easy to recognize its mixture of "bird" and "reptile" features and because it played an historical role in helping to cement Darwin's theory (it was discovered 2 years after publication of the Origin). Textbook authors like Archaeopteryx for these reasons and often illustrate their discussions with pictures of the Berlin specimen, one of the most beautiful fossils ever discovered, and remarkably complete. Textbooks also use Archaeopteryx as an example of how fossils are important for showing transitional features of evolution, and how the fossil record is good evidence that evolution has occurred."

An artist's impression of Xiaotingia zhengi, (credit: Copyright Xing Lida and Liu Yi, source: here)

In recent years, however, the story has become much more complicated, with the finding of the so-called 'feathered dinosaurs' in China, and several Archaeopteryx-like fossils. Lead researcher Xing Xu has reported recently a fossil with the name Xiaotingia zhengi, and published a new phylogenetic analysis which knocks Archaeopteryx off its perch and relocates the animal among a sub-group of dinosaurs. Nature has a news report here, and Discover Magazine here. The latter source has this summary of developments:

"By comparing Xiaotingia's features with those of Archaeopteryx and other related birds and dinosaurs, Xu has drawn up a new family tree. In it, Archaeopteryx sits with Xiaotingia among the deinonychosaurs, a celebrity-filled group of small, predatory dinosaurs that includes Deinonychus and Velociraptor. The lineage that led to modern birds perches on a different branch of the tree."

In view of the iconic status of Archaeopteryx, commentators have been anxious that "creationists" do not gain an advantage from this particular rewriting of the textbooks. When evidence used to prove evolution turns out to be incorrect, there is a danger that people will become disillusioned. Xing Xu knows this: "Because it has held the position as the most primitive bird for such a long time, I am kind of nervous about presenting this result" he said. Consequently, there has been a great deal of damage-limitation activity, pointing out that 'this is the way science works'. This activity is reviewed here, with much of it drawn from Witmer (here):

"In truth, this chapter of the scientific story is just beginning. Just as Xiaotingia moved Archaeopteryx out of the birds, the next find could move it back in - or to somewhere else within this fuzzy tangled knot that makes up the origins of birds and bird-like dinosaurs. That said, during this sesquicentennial anniversary of Archaeopteryx, which is being honoured with exhibits and commemorative coins, the bitter irony may be that it may not have been the bird we've always thought it was. But Archaeopteryx will remain an icon of evolution, perhaps even more so now, providing compelling evidence that, as we should expect, evolutionary origins are rather messy affairs."

One is tempted to say - if the next find could move Archaeopteryx back in, why are people getting so excited about it now? Why can't we treat Xu's approach as a hypothesis that needs to be tested by further analysis and forthcoming discoveries? The answer is that Xu et al. have not presented it like this. Although giving lip-service to tentativeness, they claim that their analysis makes far more sense of the fossil data and that, as Nature News says: "we are about to enter a new era in which Archaeopteryx is considered as distant from the ancestry of modern birds as dinosaurs such as Deinonychus."

The cladistic analysis is recognized as provisional in the abstract: the conclusion has only "tentative statistical support". Animals that deserve to be in the analysis, but are not, are Early Cretaceous birds: Dalianraptor, Jixiangornis, Zhongjianornis; late Jurassic or Early Cretaceous dinosaurs: Pedopenna, Shanag, Sinusonasus, Tianyuraptor, and the enigmatic Jinfengopteryx. Is it possible that the selection of species for inclusion in the cladistic analysis has influenced the outcome? The basal bird species chosen have a stubby snout morphology, and this may have led to those species with a more pointed snout to be shifted over to the deinonychosaurs: namely Archaeopteryx, Anchiornis and Xiaotingia. With additional clear Avialae species, the analysis may come out differently. Witmer writes:

"According to Xu and colleagues' analysis, the most basal fossil birds are forms such as Epidexipteryx, Jeholornis and Sapeornis, all of which were named in the past decade and so comprise new territory even for specialists. Clearly, without the safety net of good old Archaeopteryx at the base of the birds, we've got some fresh work to do."

There is scope also for a discussion of the parameters used within the analysis, although this will have to be pursued by the specialists. Unfortunately, cladistic analyses tend to produce 'black box' outcomes, and there is relatively little attention given to parameter trends within the cladogram and whether these are biologically meaningful. There is also scope for critiquing cladism itself, and whether the underpinning assumptions restrict the scope of the analysis. For more, go here.

According to many commentators, the evolutionary story of the origin of birds is going to be fuzzy:

"The researchers acknowledged that their reclassification was "only weakly supported by the available data," but they said this kind of fuzziness was to be expected when the fossils being analyzed are close to the common ancestor of now-extinct dinosaurs and modern birds. "This phenomenon is also seen in some other major transitions, including the origins of major mammalian groups," they wrote.
Witmer agreed: "We're looking at an origin, and consequently it's going to be messy." [also, he added] "It just shows what evolution is all about. A prediction of evolutionary theory is that it should be really hard for us to figure out what's going on in an origin.""

Interesting. In the past, evolutionists looked for an identifiable trajectory that documented evolution. Now, it is a confused mess which is hard to decipher. Perhaps the most realistic conclusion for the present is that the Late Jurassic-Early Creataceous fossil record shows many features that we do not properly understand, and the most appropriate response is to withhold judgment and await further discoveries and analysis. This applies to the whole of the Birds Are Dinosaurs (BAD) thesis, as is evident here, here, here, here and here.

An Archaeopteryx-like theropod from China and the origin of Avialae
Xing Xu, Hailu You, Kai Du & Fenglu Han
Nature, 475: 465-470 (28 July 2011) | doi:10.1038/nature10288

Abstract: Archaeopteryx is widely accepted as being the most basal bird, and accordingly it is regarded as central to understanding avialan origins; however, recent discoveries of derived maniraptorans have weakened the avialan status of Archaeopteryx. Here we report a new Archaeopteryx-like theropod from China. This find further demonstrates that many features formerly regarded as being diagnostic of Avialae, including long and robust forelimbs, actually characterize the more inclusive group Paraves (composed of the avialans and the deinonychosaurs). Notably, adding the new taxon into a comprehensive phylogenetic analysis shifts Archaeopteryx to the Deinonychosauria. Despite only tentative statistical support, this result challenges the centrality of Archaeopteryx in the transition to birds. If this new phylogenetic hypothesis can be confirmed by further investigation, current assumptions regarding the avialan ancestral condition will need to be re-evaluated.

See also:

Kaplan, M., Archaeopteryx no longer first bird, Nature News (27 July 2011) | doi:10.1038/news.2011.443

Witmer, L.M. An icon knocked from its perch, Nature, 475: 458-459 (28 July 2011) | doi:10.1038/475458a