Fossil Friday: Nakridletia — The Rise and Fall (and Possible Resurrection) of a Fossil Insect Order
This Fossil Friday features the reconstruction drawing of Strashila incredibilis, an extremely weird fossil insect from the Late Jurassic of Siberia. It was first described by Rasnitsyn (1992) as a new species, genus, and family, and attributed to an unknown order of holometabolan insects, possibly related to scorpionflies and fleas. Rasnitsyn suggested that strashilids were wingless blood-sucking ectoparasites of warm-blooded animals, most likely on the hairy wing membrane of pterosaurs. He based his interpretation on the putative presence of sucking-piercing mouthparts (that were later allegedly destroyed by improper preparation with alcohol) and large pincers on the hind limbs that supposedly were used to grab the host’s hairs or feather-like filaments.
In their leading textbook on insect evolution, Grimaldi & Engel (2005) agreed that strashilids were ectoparasitic mecopteroid insects, but considered their relationship as obscure and a closer affinity to fleas as insufficiently documented. Vrsansky et al. (2010) concurred with Rasnitsyn’s view and explicitly affirmed that such ectoparasitism can be interpreted as evidence for endothermy and sociality in pterosaurs. The latter authors described a very similarly looking new family Vosilidae from the Middle Jurassic Daohugou site in China, and erected a new insect order Nakridletia to accommodate these strange supposed parasites.
Challenged by Fantasy
A few years later, this whole parasite interpretation was challeged to be mere fantasy by Huang et al. (2013), who studied new and very well-preserved material from the Middle Jurassic of China. They synonymized Vosilidae with Strashilidae and concluded that these insects were just amphibious flies of the modern family Nymphomyiidae. Even though some corrections of the earlier descriptions are without doubt valid (e.g., the absence of functional sucking-piercing mouthparts), the latter work is also compromised by some confusing issues (the fossils have no similarity with known Nymphomyiidae) and obvious errors (e.g., a confusion of dipteran march flies with ephemeropteran mayflies in Suppl. Fig. 8), of which the most important concerns the alleged presence of wings: there is only a single of the 11 studied fossil specimens that does possess anything resembling a wing-like strucure. This specimen only features a single supposed forewing, which seems much too large and somewhat out of place. Also the broad and lobed shape of this structure is very much unlike any dipteran forewings. In my view a superimposed plant remain would be a more likely alternative interpretation of this alleged wing. Furthermore, there are no halteres visible in any of the well-preserved specimens, which should be present in all dipteran insects as their typical club-like vestiges of hind wings that function as vibrating gyroscopes.
Huang et al. suggested that strashilids were amphibious or aquatic even as adult flies and, similar to living Nymphomyiidae, shed their wings after emergence and mating for oviposition in the water. However, even though the larvae of nymphomyiids are aquatic like many dipteran larvae, there are no living examples for aquatic adults. Also, all known adult Nyphomyiidae have a very elongate and slender body, unspecialized legs, and narrow wings with long hairs. Thus, they are not even remotely similar to the anatomy of strashilids. Last but not least, no putative nymphomyiid-like larvae were ever discovered in the same layers or even any other fossil localities of the same age at all. Nevertheless, the reinterpretation by Huang et al. (2013) seems to be generally considered and quoted as the final word on this matter, even in the notorious Wikipedia. No experts ever looked into this issue again.
A Darwinian Perspective
So , were strashilids a distinct order of parasitic insects or just aquatic flies? I suggest that the reinterpretation of Huang et al. (2013) is far from bulletproof and the validity of order Nakridletia should be reconsidered. From an intelligent design perspective there is another much more important thing to note: strashilids were perfectly adapted to a peculiar way of life with unique modifications, which appeared abruptly in the Middle Jurassic without any known precursors or obvious relatives that could be strashilid ancestors. This meets the expectations from a design approach much better than those from a Darwinian perspective.
References
Grimaldi D & Engel MS 2005. Evolution of the Insects. Cambridge University Press, New York (NY), xv+755 pp.
Huang D, Nel A, Cai C, Lin Q, Engel MS 2013. Amphibious flies and paedomorphism in the Jurassic period. Nature 495, 94–97. DOI: https://doi.org/10.1038/nature11898
Rasnitsyn AP 1992. Strashila incredibilis, a new enigmatic mecopteroid insect with possible siphonapteran affinities from the Upper Jurassic of Siberia. Psyche 99(4), 323–334. DOI: https://doi.org/10.1155/1992/20491
Vršanský P, Ren D, Shih C 2010. Nakridletia ord. n. – enigmatic insect parasites support sociality and endothermy of pterosaurs. AMBA Projekty 8, 1–16. https://www.researchgate.net/publication/285797717
No comments:
Post a Comment