Amphibious flies and paedomorphism in the Jurassic period


The species of the Strashilidae (strashilids) have been the most perplexing of fossil insects from the Jurassic period of Russia and China1,2. They have been widely considered to be ectoparasites of pterosaurs or feathered dinosaurs, based on the putative presence of piercing and sucking mouthparts and hind tibio-basitarsal pincers purportedly used to fix onto the host’s hairs or feathers1,2,3,4,5,6. Both the supposed host and parasite occur in the Daohugou beds from the Middle Jurassic epoch of China (approximately 165 million years ago)7,8. Here we analyse the morphology of strashilids from the Daohugou beds, and reach markedly different conclusions; namely that strashilids are highly specialized flies (Diptera) bearing large membranous wings, with substantial sexual dimorphism of the hind legs and abdominal extensions. The idea that they belong to an extinct order2 is unsupported, and the lineage can be placed within the true flies. In terms of major morphological and inferred behavioural features, strashilids resemble the recent (extant) and relict members of the aquatic fly family Nymphomyiidae. Their ontogeny are distinguished by the persistence in adult males of larval abdominal respiratory gills, representing a unique case of paedomorphism among endopterygote insects. Adult strashilids were probably aquatic or amphibious, shedding their wings after emergence and mating in the water.

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Figure 1: Strashila daohugouensis sp. nov. from the Middle Jurassic epoch of Daohugou, China.
Figure 2: Vosila sinensis from the Middle Jurassic epoch of Daohugou, China.
Figure 3: Strashila daohugouensis sp. nov. from the Middle Jurassic epoch of Daohugou, China.
Figure 4: Ecological reconstruction of Strashila daohugouensis sp. nov. from the Middle Jurassic epoch of Daohugou, China.


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We are grateful to C. C. Labandeira for suggestions; A. P. Rasnitsyn for early discussions; and J. Sun for reconstructions. Financial support was provided by the National Basic Research Program of China (2012CB821903), the National Natural Science Foundation of China (91114201 and J1210006), the Outstanding Youth Foundation of Jiangsu Province (BK2012049), the Chinese Academy of Sciences (KZCX2-YW-QN104), and the US National Science Foundation (DEB-0542909).

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D.H., A.N., C.C., Q.L. and M.S.E. participated in morphological studies, D.H. designed the program, D.H., A.N. and M.S.E. prepared the manuscript.

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Correspondence to Diying Huang.

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The authors declare no competing financial interests.

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The LSID has been deposited in ZooBank.

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Huang, D., Nel, A., Cai, C. et al. Amphibious flies and paedomorphism in the Jurassic period. Nature 495, 94–97 (2013).

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