Blattaria assemblage from J/K sediments of Chernovskie Kopi in Transbaikalian Russia

The J/K fossil site Chernovskie Kopi in Transbaikalian Siberia (Russia) yielded insect fossils of 15 orders (Vassilenko 2005), descendants of the order Blattaria - the earliest termites (Vrsansky & Aristov 2014), and insect trace-fossils (Sukatcheva & Vassilenko, 2011). Recently described cockroach assemblage (Barna 2014) contains five species: Blattula sp. (Blattulidae), Rhipidoblattina sp. (Caloblattinidae), Archimesoblatta sp. (Mesoblattinidae), Mongolblatta sp. (Mesoblattinidae), Rhipidoblatta sp. (Caloblattinidae) and one undescribed species of the family Liberiblattinidae Vrsansky, 2002. Most of 41 specimens were photographed and drawn. The cockroach fossils, preserved as imprints in fine-grained, red-coloured argylites, are represented almost exclusively by imprints of forewings (only one hindwing and one pronotum was found) suggesting a significant transport prior to deposition. The composition of this cockroach assemblage is more simmilar to Early Jurassic assemblages from Australia (Martin 2010), and Germany and England (Vrsansky & Ansorge 2007), than to Middle and Late Jurassic assemblages (Vishniakova 1968). Venation deformities recognised on 22.5% of studied cockroach wings, support the claims of mass mutations occurrence near the J/K boundary (Vrsansky 2005) and along with low diversity of the assemblage point to a destabilized ecosystem.