A large cockroach from the mesosaur-bearingKonservat-Lagerstätte(Mangrullo Formation), Late Paleozoic of Uruguay

Abstract

Barona arcuata, n.gen et n.sp., a left forewing of a relatively large cockroach of the Order Blattaria, is described from mesosaur-bearing lagoonal shales of the Mangrullo Formation (north-eastern Uruguay). While most of the insect remains recovered from the Mangrullo Formation come from sandy limestones, associated to scarce isolated mesosaur bones and pygocephalomorph crustaceans, the cockroach wing here described was found in the overlaying green to brownish, gray and dark black shales associated to intercalated bentonites and evaporitic gypsum crystals. Barona arcuata shares some features with typical Late Carboniferous taxa such as its general venation pattern and outline of the wing, four main and powerful veins arising close together from near the base of the wing, Sc simple forked, pectinate, reaching the costal border through a long fork, R and M bifurcating and terminating in the wing margin above and below the apex respectively, short and narrow CuA, and the presence of a broad interspace between CuP and AA. Cross venation seems to be absent or it was not preserved. Some characters might relate Barona arcuata to the Late Carboniferous-Early Permian Neothroblattinidae such as the presence of sigmoidal veins in the anal area, a condition not found in any of the remaining representatives of the Palaeozoic Blattaria. Intriguingly, the Uruguayan blattarian also presents a strong similarity with Qilianiblatta namurensis Zhang, Schneider & Hong, 2012 from the Westphalian of China, clearly a smaller taxon that is also difficult to relate to any of the preexistent families. The apparent plesiomorphic venation pattern of the new species which is reminiscent of that present in the oldest known blattarians, is in agreement with a Permo-Carboniferous (Gzhelian-Asselian) age for the Mangrullo Formation also supported by the presence of a macrofloral assemblage dominated by arborescent lepidondendrids and other lycopsids and the pygocephalid-like morphology of the pygocephalomorph crustaceans from the same levels.

Mesosaur taxonomy reappraisal: are Stereosternum and Brazilosaurus valid taxa?

“…Because of their short time range and restricted geographic distribution, mesosaurs were considered good stratigraphic fossils for the Early Permian of Gondwana. However, their basal position in recent phylogenetic studies (Laurin & Piñeiro, 2017MacDougall et al, 2018) and the fact that they are part of a community in which pygocephalomorph crustaceans, insects and plants suggest a Late Carboniferous or a transitional Permo-Carboniferous age for the strata (see Huene, 1940;Calisto & Piñeiro, 2019), mesosaurs could have a ghost lineage that lead their origin to at least Late Carboniferous (Piñeiro et al, 2012a). Their remains are recorded from Uruguay, Brazil, Namibia and South Africa, although some scarce and fragmentary fossils were also reported from Paraguay (Beder, 1923;Filippi, 2001;Piñeiro, 2002Piñeiro, , 2006.…”

“…All these issues led previous authors to even place mesosaurs as basal synapsids (Huene, 1941), basal diapsids (MacGregor, 1908) and more recently, basal anapsid parareptilians (Modesto, 1999;MacDougall et al, 2018) or basal sauropsids (Laurin & Reisz, 1995;Laurin & Piñeiro, 2017. Even though appearing to be so different, all these hypotheses place the origin of mesosaurs into the Late Carboniferous, as the associated plants and invertebrates suggest (Huene, 1940;Calisto & Piñeiro, 2019).…”

Late Paleozoic–Early Mesozoic Insects: State of the Art on Paleoentomological Studies in Southern South America

“…An insect wing impression recovered by Halle (1911) (Pinto, 1972b(Pinto, , 1987a(Pinto, , 1987b(Pinto, , 1990Pinto & Ornellas, 1980Rösler et al, 1981;Huguet et al, 2002;Kirejtshuk, 2020), and the Uruguay. The Late Paleozoic insects are overwhelmingly represented by isolated wings preserved as impressions Calisto & Piñeiro, 2019) (Fig. 5; Tab.…”

El Río Hum (actual Río Negro) antes y después de la Represa de Rincón del Bonete en San Gregorio de Polanco (Tacuarembó, Uruguay)

“…Es claro que ni la Formación San Gregorio-Tres Islas ni la Formación Cerro Pelado (en caso de que pueda ser mejor caracterizada), pueden ostentar una edad Carbonífero tardío-Pérmico temprano, dado que esa edad fue asignada al paquete sedimentario de los pelíticos grises suprayacente, que incluye a la Formación Mangrullo dentro del grupo Melo (Bossi & Navarro, 1991). A través de estudios detallados de sus fósiles excelentemente preservados, los cuales han caracterizado a la Formación Mangrullo como un Konservat Lagerstätte que preserva de manera excepcional tanto fósiles de animales, como de plantas, estructuras delicadas como nervios, glándulas y músculos y hasta comportamientos que ayudan a reconstruir la biología de las especies representadas (Piñeiro et al, 2012;Piñeiro et al 2016;Calisto & Piñeiro, 2019;Piñeiro et al, 2021, Nuñez Demarco et al, 2022, su edad está siendo calibrada dentro del Carbonífero Superior (Calisto & Piñeiro, 2019).…”