Oguracaulis banksii gen. et sp. nov., a mid-Mesozoic tree-fern from Tasmania, Australia

Abstract

Oguracaulis banksii gen. et sp. nov. is described from permineralised specimens from Upper Jurassic-Lower Cretaceous strata near Ida Bay, Tasmania. The specimens consist of large fem stems and adhering petiole bases covered with thick root mantle. Their stems are characterised by a dictyostele with a sclerenchymatous sheath, numerous medullary bundles, an undivided leaf and petiolar vascular trace and multicellular epidermal hairs. This fossil fern provides evidence for the common origin for many of the modern cyatheaceous tree ferns including the cibotioids.

First megafossil evidence of Cyatheaceous tree fern from the Indian Cenozoic

“…Later, Ogura (1941a, b) described a number of taxa, viz., Cyathocaulis tateiwai, C. yabei from the early Cretaceous of Korea and Philippines, and Cibotium iwatense from the late Cretaceous of Japan. Other Cretaceous genera with cyatheaceous affinity are Cauloperis brownii from England (Renault 1883), Yezopteris polycycloides, Cyathocaulis yezopteroides, Cibotiocaulis from Japan, Saghalien, and Korea (Nishida 1981a(Nishida , 1989, Oguracaulis banksii from Tasmania (Tidwell et al 1989), Conantiopteris schuchmanii from California (Lantz et al 1999) and Rickwoodopteris hirsuta from western North America (Stockey and Rothwell 2004).…”

Laurasian legacies in the Gondwanan tree fern order Cyatheales

“…Non-overlapping fossil and extant geographic distributions are observed in several groups of ferns 16,[20][21][22][23][24][25][26] , including several tree fern families. In particular, the fossil record places multiple Cyathealean lineages within Laurasia during the Jurassic and Cretaceous, and up to the Ecocene 18,[27][28][29][30][42][43][44][83][84][85][86] , and some of the oldest known fossils (Late Jurassic) have been found in Eurasia and Northern America 29,42 . For instance, the Early Cretaceous Kuylisporites mirabilis and Cyathea cranhamii are the two oldest known representatives of the Cyatheaceae and were recovered from sites in Siberia 42 and Canada 29 , respectively.…”

“…More specifically, I hypothesize that the disappearance of (most) tree ferns from Laurasian landmasses was likely triggered by changing climate during the Cenozoic, which began to shift into the drier and colder conditions that lead to the disappearance of tropical climates 19,94 . For instance, the Thyrsopteridaceae, now restricted to a single species in the Juan Fernández Island off the coast of South America 41,44 , is believed to have been more diverse and wide spread in the past, with fossils from the Cretaceous-Late Eocene uncovered in Japan 97 , Southeast Asia 44 , Australia 84,98 , and North America 99 .…”

Divergent evolutionary trajectories of bryophytes and tracheophytes from a complex common ancestor of land plants

“…Fossil Taxon and Specimen: Oguracaulis banksii [Z2286, Tasmania Museum and Art Gallery, Hobart, Tasmania] from the Lune River Fossil Site (Early to Middle Jurassic), Ida Bay, Tasmania [99]. Phylogenetic Justification: Phylogenetic analysis based on characters derived from fossilized stems placed Oguracaulis banksii as sister to Thyrsopteris [100].…”