Nocticolid cockroaches are the only known dinosaur age cave survivors

Abstract

There is little fossil evidence for cave arthropods. Small size, disfunctional wings, extremely long antenna, dense minute setation, palidity and reduced eyes are typical adaptations to life in caves shown by the cockroach Mulleriblattina bowangi gen. et sp. n., found together with epigeic Crenocticola svadba sp. n., both from Myanmar amber and belonging to the cavernicolous cockroach family Nocticolidae. These lineages of earliest still living cavernicoles suggest large, numerous caverns, lava tubes or caves within the source area. They provide the first unequivocal evidence for the Mesozoic origin of any living troglomorphic organism, and explain the “long branches” in DNA analyses. Phylogenetic trees show little hierarchical structure and place Latindiinae and Myrmecoblatta within the explosively radiating Nocticolidae. Biogeography indicates a common cosmopolitan Early Cretaceous ancestor except for 8 (of 49) species of true Nocticolidae, which diverged during the Late Cretaceous breakup of Gondwana. A review of all troglofauna documents no other unequivocal pre-Cenozoic cave biotas (including vertebrates). Stable environments and small populations result in a short-time (˂3 Ma) origination of bizarre forms and long term extinctions (˃30 Ma).