A Growing Paradigm

As if hurried by the process of discovery and the level of achievement gained through the recovery and description of Darwinopterus (details summarized here),researchers have uncovered yet another long-tailed, large-skulled “intermediate” between the rhamphorhynchoid and pterodactyloid grades of pterosaur, Wukongopterus lii.

Wang X.-l., A. W. A. Kellner, Jiang S.-x. and Meng J. 2009. An unusual long-tailed pterosaur with elongated neck from western Liaoning of China. Anais da Academia Brasileira de Ciências 81(4):793-812.

As this transistory grade of pterosaurs grows, first uncovered with Pterorhynchus and then earlier this year by Darwinopterus, the complex development of the origin of the pterodactyloid morphotype — including the potential for it to have developed convergently in two different groups — increases and belittles some of our understanding of the linearity of evolution.

Wukongopterus differs very little from Darwinopterus, but where it differs is primarily in the mandible and dentition (most of the cranium is missing in the only known specimen, IVPP V15113), which is unusual as this region is very similar to Pterorhynchus. The mandible is robust and deep compared to its length, although this may be little more than a preservational artefact as rotation of the bone and lack of crushing (potentially present in Darwinopterus and Wukongopterus) could result in the perceived differences.

A, Darwinopterus inexpectatus; B, Wukongopterux lii. Skull and teeth closeups.

Peculiarly, Wukongopterus is much like Pterorhynchus in that it produces a robust mandible and short teeth, but skeletally it is much more like Darwinopterus, and some may even suggest that they are synonymous.

As time goes on, it may become even more convoluted, depending on whether one scores these features in their analyses differently, or whether one reads any distinctiveness among specimens as skeletally unimportant save for the general features these two taxa seem to share. Nonetheless, an interesting pair of pterosaurs.

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5 Responses to A Growing Paradigm

  1. Christopher Collinson says:

    The anterior snout, relative to the NAOF, of Darwinopterus is proportionally longer than it is in Wukongopterus. Assuming the hint of the opening in Wukongopterus is in actual fact a NAOF, this is yet another significant crainial difference that cannot be explained through crushing.

  2. Jack says:

    What is the “growing paradigm”? Is it the non-linearity of evolution?
    If so, that topic interests me a great deal.

    • qilong says:

      Yes. It is argued that each module in an organism’s body is separately influencable by its environment. To date, we’ve hypothesized that locomotory, digestive, respiratory and masticatory modules were all linked in one way or another and directly influenced by singular events; however, we realize that some of these are influenced by cascading events, rather than arising from a flashpoint. Moreover, time in between the portions of a cascade event (the separate events that make up the whole) allow each event to become discrete and influenced by the module being affected before it occurs; each module then becomes a culprit in the event that follows, but is itself discrete.

  3. Sorry to be so late on this, but module evolution occurs in no other taxa. Placed in a matrix with lots of other pterosaurs, Darwinopterus nests with Wukongopterus and, as Jaime mentioned, Pterorhynchus. These form a clade, and unfortunately, a dead end leaving no descendants. The origin of the four various clades of pterodactyloid-grade pterosaurs has another, more parsimonious explanation, involving largely ignored tiny taxa. All of these evolve cranial, pedal and everything in between traits changing randomly as in all other taxa, reptile or not.

    • No cladogram phylogeny has taxa leaving descendants. It leads to sister-taxa, which share common ancestors; that ancestor leaves descendants, but is itself not morphologically identifiable (save by the commonality among its most basal members, and basal members of that CA’s sister taxa. This isn’t a phyllogram, but a cladogram, where in the former groups can be originated within other groups, and one can also posit a species is the direct ancestor of another species.

      What I remark on is a conservation of variation around a certain node, be it monophyletic and leaving no loose ends, or paraphyletic, and being a gradient towards Pterodactyloidea-proper. That I make allusions to a consistent clade (with Pterorhynchus wellnhoferi within this supposed Wukongopteridae) doesn’t mean that I think Pterorhynchus wellnhoferi is a wukongopterid: there are still some massive differences, as noted by several authors who considered exactly this possibility; it has been included in various phylogenies, and so far this exclusive topology Dave mentions hasn’t been recovered. The one way to improve on it is to include MORE characters, describe MORE variation in BETTER detail, and include MORE taxa; not one of these, but all of them.

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