Although geographically widespread, the genus Pelecanus has only 7 or 8 species extant (depending on the classification system used). A similar number of fossil species have been identified, although the morphological differences are quite small. Until recently, the earliest fossil form was dated as Early Miocene. Newly published work pushed the first appearance back to the Early Oligocene, considered to be about 30 million years old. The point of interest for us is that the fossil, and specifically the beak, is said to be "morphologically identical to modern pelicans".
"All these characteristics of the fossil are identical to those of the species in Pelecanus, the single extant genus in the family. [. . .] Therefore, [the specimen] can be considered a morphologically modern pelican of the genus Pelecanus, but it is not closer to any particular extant species."
"It is so similar to modern pelicans, despite its 30 million years" (image: A. Louchart, source here)
The beak is of particular interest, because it is "highly derived" and unique when compared with all other birds. Since the component parts are both unusual and inter-dependent, convergent evolution is not perceived as a viable hypothesis.
"Thus, the evolution of this advanced feeding apparatus, one of the most distinctive arrangements among birds, had already been achieved by the early Oligocene and its morphology is found unchanged in extant pelicans after ca. 30 million years, which can be considered a stasis of long duration."
The authors set out some thoughts to explain this stasis. The first hypothesis is that the beak is functionally optimal over 30 million years, and there has been no selection for change. The whole family can be considered to occupy an adaptive peak on their sector of the adaptive landscape. Another hypothesis is that flying ability is a constraint on morphological adaptation. However, neither of these options are found satisfying and the authors indicate their preference for keeping an open mind:
"The remarkable stasis in the beak of pelicans remains intriguing, and is probably in need of new explanations."
They are undoubtedly right: the stasis is intriguing and new explanations are needed. What we are seeing here is a particular type of stasis, and it concerns complexity. Much diversification has little or no effect on complexity and examples of diversification therefore have little or no bearing on the origin of complexity. The pelican beak, however, is not just a big beak! There are numerous coordinated elements that have to be present for the beak to function at all. The fossil find is important because the earliest fossil of a pelican exhibits the full functionality of the modern birds. As far as the known fossil record is concerned, complexity was present - before the radiation of the Pelecanidae. Yes, this makes stasis in the pelican beak intriguing and it means that Darwinism has nothing to offer by way of an explanation. New explanations should include the options opened up by intelligent design.
The earliest known pelican reveals 30 million years of evolutionary stasis in beak morphology
Antoine Louchart, Nicolas Tourment and Julie Carrier
Journal of Ornithology, advanced publication June 2010 | DOI: 10.1007/s10336-010-0537-5
Abstract: The feeding apparatus of Paleogene birds is rarely well-preserved. Here, we describe the earliest known pelican (early Oligocene, Luberon, southeastern France), with its almost complete beak. Morphologically identical to modern pelicans, the new fossil already shows several advanced features unique to extant species of the genus Pelecanus. It probably belongs to the lineage ancestral to all or some of these pelican species. This fossil reveals a remarkable evolutionary stasis in the morphology of such an advanced avian feeding apparatus through ca. 30 million years. Several hypotheses are proposed to suggest explanations for such examples of long stases in volant homeothermic vertebrates.
Hecht, J. Pelican fossil poses evolutionary puzzle, New Scientist (22 June 2010)
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