A review of Coelostegus prothales Carroll and Baird, 1972 from the Upper Carboniferous of the Czech Republic and the interrelationships of basal eureptiles.

We redescribe the holotype and only known specimen of the early eureptile Coelostegus prothales from the Upper Carboniferous of the Czech Republic using photogrammetric scanning and a virtual 3D rendition of its skull. New information is available on several skull and lower jaw bones, including the postorbital, supratemporal, tabular, postparietal, angular, and prearticular. The new data also permit the correct identification of previously undetected or mis-identified elements (e.g., supratemporal; quadratojugal; angular). We provide an amended diagnosis of Coelostegus and a new reconstruction of the skull in dorsal and lateral views. To evaluate the affinities of Coelostegus, we code this taxon in two recently published taxon-character matrices. Parsimony and Bayesian analyses do not permit firm conclusions on the phylogenetic position of Coelostegus or, indeed, the status and extrinsic relationships of protorothyridid amniotes. Coelostegus emerges either as the sister taxon to the recently redefined Diapsida (Araeoscelidia; Varanopidae; Parareptilia; Neodiapsida), as one of the most basal protorothyridids, or as a derived stem-group amniote in various parsimony-based analyses, or as the basalmost protorothyridid in one Bayesian analysis, with protorothyridids forming a paraphyletic array relative to Diapsida. We review the cranial similarities and differences between Coelostegus and other protorothyridid genera and discuss the implications that various phylogenetic results have for our understanding of early amniote relationships.

Origin of origami cockroach reveals long-lasting (11 Ma) phenotype instability following viviparity.

Viviparity evolved in bacteria, plants, ˃141 vertebrate lineages (ichthyosaurs, lizards, fishes, mammals, and others), and in 11 of 44 insect orders. Live-birth cockroaches preserved with brood sac (3D recovered two times optically) included Diploptera vladimir, Diploptera savba, Diploptera gemini spp.n., D. sp.1-2, and Stegoblatta irmgardgroehni from Green River, Colorado; Quilchena, Republic; McAbee, Canada; and Baltic amber, Russia (49, 54, and 45 Ma). They evolved from rare and newly evolved Blaberidae; they radiated circumtropically, later expanded into SE Asia, and have now spread to Hawaii and the SE USA. Association of autapomorphic characters that allow for passive and active protections from parasitic insects (unique wing origami pleating identical with its egg case-attacking wasp) suggest a response to high parasitic loads. Synchronized with global reorganization of the biota, morphotype destabilization in roaches lasted approximately 11-22 Ma, including both the adaptation of novel characters and the reduction of others. Thus, while viviparity can be disadvantageous, in association with new Bauplans and/or behaviors, it can contribute to the evolution of taxa with viviparous representatives that are slightly selectively preferred.