Mesozoic mass extinctions and angiosperm radiation: does the molecular clock tell something new?

Angiosperms evolved rapidly in the late Mesozoic. Data from the genetic-based approach called ’molecular clock’ permit an evaluation of the radiation of flowering plants through geological time and of the possible influences of Me -sozoic mass extinctions. A total of 261 divergence ages of angiosperm families are considered. The radiation of flowe -ring plants peaked in the Albian, early Campanian, and Maastrichtian. From the three late Mesozoic mass extinctions (Jurassic/Cretaceous, Cenomanian/Turonian, and Cretaceous/Palaeogene), only the Cretaceous/Palaeogene event coincided with a significant, abrupt, and long-term decline in angiosperm radiation. If their link will be further pro -ven, this means that global-scale environmental perturbation precluded from many innovations in the development of plants. This decline was, however, not unprecedented in the history of the angiosperms. The implication of data from the molecular clock for evolutionary reconstructions is limited, primarily because this approach deals with only extant lineages

Late Cretaceous and Paleocene decapod crustaceans from James Ross Basin, Antarctic Peninsula

Seventeen species of decapod crustaceans have been described from Campanian through Paleocene rocks in the Santa Marta, López de Bertodano, and Sobral Formations of the James Ross Basin, Antarctica. Of these, nine are new species: Metanephrops rossensis, Glyphea australensis. Paguristes santamartaensis, Munidopsis foersteri, Retrorsichela laevis, Plagiophthalmous collinsi, Rhinopoupinia bicornis, Cristafrons praescientis, and Torynomma (Torynomma) australis. One new family, Retrorsichelidae, and three new genera, Retrorsichela, Rhinopoupinia, and Cristafrons, were also named. This assemblage includes the first notice of brachyurans from the Cretaceous of Antarctica; six species are described. The nephropid lobster Hoploparia stokesi (Weller), the most common decapod throughout the section, exhibits significant morphological change throughout its range from late Santonian or earliest Campanian to Paleocene; however, variation of key features is asynchronous. The raninid brachyuran, Cristafrons praescientis, is second in abundance to H. stokesi. The occurrence of Metanephrops rossensis and Munidopsis foersteri represents the oldest geological records for these genera and the recognition of species of Paguristes, Plagiophthalmous, Torynomma, and Necrocarcinus constitutes the first notice of these genera in Antarctica. Of those taxa that have living congenors, the species of Metanephrops, Linuparus, and Munidopsis occupied habitats at inner shelf depths in the Cretaceous whereas their extant descendants are restricted to outer shelf and bathyal depths. This diverse decapod fauna is dominated by genera that range into the Cenozoic and appears to be a pioneer assemblage

New lobsters (Decapoda, Nephropoidea) from the Cretaceous-Paleogene section of the Middle Vistula valley, east-central Poland

During fieldwork in the early 1990s at the then still active quarry near Nasiłów, on the left bank of the River Vistula (Wisła), accompanied by Professor Andrzej Radwański, some lobster remains were collected. A fragmentary anterior portion of a decapod crustacean carapace, recovered from a level about 2 m below the Cretaceous–Paleogene (K/Pg) boundary, in a siliceous chalk unit locally referred to as ‘opoka’, constitutes the oldest record of the thaumastocheliform genus Dinochelus Ahyong, Chan and Bouchet, 2010, D. radwanskii sp. nov. The other, more complete, individual is from c. 3 m above the K/Pg boundary, coming from marly gaizes or ‘siwak’; this is ascribed to a new species of Hoploparia M’Coy, 1849, H. nasilowensis sp. nov., the first to be recorded from Danian (lower Paleocene) strata. Although both ‘opoka’ and ‘siwak’ facies in the Nasiłów area are very rich in diverse biota, including some brachyurans, no macruran remains had so far been recorded from the region

A new Triassic decapod, Platykotta akaina, from the Arabian shelf of the northern United Arab Emirates: earliest occurrence of the Anomura

A Triassic decapod crustacean is described here for the first time from the Norian-Rhaetian Ghalilah Formation of the Musandam Peninsula, United Arab Emirates. The single specimen Platykotta akaina n. gen n. sp. is referred to a new family Platykottidae. The studied crustacean, initially with only the ventral exposure preserved, was collected from shallow-water, burrowed limestones. Using a chemical preparation, the dorsal view revealed a well-preserved, chitinous, granular carapace exhibiting characteristic carapace morphology and groove pattern of the Eocarcinoidea, the superfamily to which the new family is assigned. The dorsal view together with the ventral surface, rarely seen in the fossil record, provide new insight into the morphology of representatives of the Eocarcinoidea