Alienopteris livingstonensis gen. et sp. nov., enigmatic petrified tree fern stem (Cyatheales) from the Aptian Cerro Negro Formation, Antarctica

The Albian fern flora of Alexander Island, Antarctica

“…The Cerro Negro Formation hosts Aptian floras that have been reported by Philippe et al (1995), Torres et al (1997), C esari et al (1999), Cantrill (2000a), C esari (2006 and Vera (2007Vera ( , 2009Vera ( , 2012Vera ( , 2013. Two well-known Cerro Negro Formation floras derive from Byers Peninsula and President Head on Snow Island.…”

“…Additional Livingston Island material has been assigned to Lophosoriaceae based on in situ spores, but it is distinct from L. cupulata and was referred to the new taxon Sergioa austrina C esari (C esari, 2006). Cyatheaceae has also been recovered from Livingston Island (C esari et al, 2001;C esari, 2006;Vera, 2009Vera, , 2013; some of this material was earlier assigned to Gleichenites sanmartini (C esari et al, 2001; C esari et al, 1999), but based on in situ spores it was then transferred to Eocyathea remesaliae (C esari, 2006). It is interesting to note that specimens once assigned to Gleichenites sanmartini encompass the families Lophosoriaceae (Cantrill, 1998(Cantrill, , 2000a and Cyatheaceae (C esari, 2006), indicating that morphologically similar specimens are not always closely related.…”

“…Apart from Alexander Island, macrofloras are known from the South Shetland Islands (Aptian to Maastrichtian, e.g., Cantrill, 1997Cantrill, , 1998Cantrill, , 2000aC esari et al, 1999;C esari, 2006;Vera, 2007Vera, , 2009Vera, , 2012Vera, , 2013 and the Larsen Basin on the east side of the Antarctic Peninsula (e.g., Hathway et al, 1998;Eklund, 2003;Eklund et al, 2004;Hayes et al, 2006;Kvacek, 2014). Ferns have been described in detail from several of these floras including those of the South Shetland Islands (e.g., Philippe et al, 1995;Torres et al, 1997;Cantrill, 1997Cantrill, , 1998 foliar characters, Cladophlebis bears similarity to several families including Osmundaceae, Dicksoniaceae, Schizaeaceae, and Dennstaedtiaceae.…”

Further evidence supporting high diversity of cyathealean tree ferns in the Early Cretaceous of Antarctica

“…The fossil record of cyathealeans shows an important taxonomic diversity since the Jurassic (Tidwell and Nishida, 1993;Tidwell and Ash, 1994), and many fossils (in particular permineralized stems) show anatomical features that preclude a classification among the molecular data-recognized taxa (e.g., Lantz et al, 1999;Stockey and Rothwell, 2004;Vera, 2009Vera, , 2013Vera and Herbst, 2015), suggesting that the diversity of tree ferns was probably higher than in present times. Recent studies using molecular data and dealing with the global biogeography of a particular family of the Cyatheales, the Cyatheaceae, suggest that this family diverged from the Dicksoniaceae during the Late Jurassic, and representatives of the crown Cyatheaceae would have been present since the mid-Cretaceous (96 MYA, Korall and Pryer, 2014).…”

“…Cyathealean tree ferns are an important element in the Cerro Negro Formation (Aptian) of Antarctica, represented by impressions/compressions of fertile fronds (Eocyathea remesaliae C esari, 2006, Sergioa austrina C esari, 2006, Lophosoria cupulata Cantrill, 1998, permineralized stems (Alienopteris livingstonensis Vera, 2009, Yavanna chimaerica Vera, 2013 and a yet unpublished taxon), and isolated spores (e.g. Cyatheacidites annulatus Cookson 1947) (Askin, 1983;Duane, 1994;Cantrill, 1998;Hathway et al, 1999;C esari et al, 2001;C esari, 2006;Vera, 2009Vera, , 2013.…”