Two primitive trematopid amphibians (Temnospondyli, Dissorophoidea) from the Upper Carboniferous of the Czech Republic

Abstract

ABSTRACTSpecimens of trematopid amphibians from the Asturian (Upper Carboniferous) of Nýřany, Czech Republic, are redescribed as two taxa, namelyMordex calliprepesSteen andMattauschia(gen. nov)laticepsFritsch.Mordex calliprepesis represented by a single post-metamorphic specimen and has the diagnostic trematopid characters of the nasal region.Mattauschia laticepsis represented by one adult partial skull and mandible plus some fragments and two small post-metamorphic specimens including the species name-bearer. It has the trematopid-type modified lacrimal and a large but oval naris and appears to be the most primitive trematopid yet described. The stratigraphically sequential large trematopidsMattauschia,Fedexia,EcolsoniaandAchelomashow progressive acquisition of the derived features that characterise the terminal formAcheloma.Mordexhas a combination of primitive and derived characters and its position within the family is less clear. The many ‘branchiosaurs' in the Nýřany assemblage include specimens that could be larvae of bothMordexandMattauschiabut certain attribution is not possible and they are assigned to Olsoniformesincertae sedis.MordexandMattauschiaappear to be terrestrial exotic elements in the Nýřany tetrapod assemblage, but with possible larvae in the lake assemblage. Representatives of at least four Palaeozoic dissorophoid families were present in late Middle Pennsylvanian/Asturian strata implying diversification of the Dissorophoidea prior to this time.