International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

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TRANSITIONAL JURASSIC/CRETACEOUS COCKROACH ASSEMBLAGE (INSECTA, BLATTARIA) FROM THE SHAR-TEG IN MONGOLIA

Published: Dec 2004

Pages: 457 - 468

Authors: PETER VRSANSKY

Abstract: A unique Upper Jurassic assemblage of cockroaches with 7 new and one unidentified species occurs in the Shar-Teg in Mongolia (Shartegoblattina elongata gen. et sp. nov., Elisamoides mantiformis gen. et sp. nov., Breviblattina minor gen. et sp. nov., Mongolblatta accurata gen. et sp. nov., Blattula mongolica sp. nov., Blattula vidlickai sp. nov., Elisama pterostigmata sp. nov.). The assemblage is the most progressive among Jurassic sites worldwide and displays taxa characteristic for the warm and dry Lower Cretaceous assemblages: a mantid species, two species of Blattulidae represented by Blattula–Elisama complex (in the Cretaceous replaced by two sister and additional species of Elisama) including small representatives which probably occupied the niche of the Cretaceous Holocompsidae–Vitisminae, and diverse Mesoblattinidae. Additional aberrant species preliminarily placed in the Liberiblattinidae display strong synapomorphies with the mantises. Mesoblattinidae are also known from the Lower Jurassic of Europe and Upper Jurassic of Asia and Africa (generally less diverse assemblages). These assemblages are characterized by the diverse Caloblattinidae and also the Blattulidae, which are also present in Shar-Teg. The assemblage contains a similar ratio of fore- and hindwings probably resulting from an active decomposition. The presence of frequent malformations — vein fusions in different independent taxa, which indicates some ecological stress factors in the paleoenvironment — is unusual.

Keywords: Jurassic, Mongolia, systematics, taxonomy, taphonomy, phylogeny, new genera, new species, Blattaria, Mantodea

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