title: A specialized new species of Ashicaulis (Osmundaceae, Filicales) from the Jurassic of Liaoning, NE China.
abstract: A new species of structurally preserved fern rhizome, Ashicaulis plumites (Osmundaceae, Filicales), is described from the Middle Jurassic Tiaojishan Formation in western Liaoning Province, NE China. The new species is characterized by a peculiar sclerenchyma mass in the petiolar vascular bundle concavity. This sclerenchyma mass varies from a linear-shape to a mushroom-like shape with a remarkable outward protuberance, which distinguishes the present new species from other Ashicaulis species. Such a protuberance is very rare among osmundaceous ferns, and should represent a unique type for sclerenchymatous tissue in the osmundaceous vascular bundle concavity. Recognition of the peculiar structure of this new fossil species enriches anatomical diversity of permineralized osmundaceous ferns, indicating that the family Osmundaceae might have experienced a remarkable diversification during the Middle Jurassic in NE China. The new species show anatomical similarities to Osmunda pluma Miller from the Palaeocene of North America. The occurrence of A. plumites in the Middle Jurassic of China provides a new clue for understanding the evolution of some members of the living subgenus Osmunda.
authors: College of Palaeontology, Shenyang Normal University, Shenyang, 110034, China.
authors: Ning
authors: N
authors: Tian
authors: Yong-Dong
authors: YD
authors: Wang
authors: Marc
authors: M
authors: Philippe
authors: Wu
authors: W
authors: Zhang
authors: Zi-Kun
authors: ZK
authors: Jiang
authors: Li-Qin
authors: LQ
authors: Li
mesh_terms: D005075:Biological Evolution; D002681:China; D053476:Extinction, Biological; D029624:Ferns / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D005580:Fossils; D005843:Geography; D018515:Plant Leaves / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics; D018517:Plant Roots / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics; D018547:Plant Stems / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics; D027343:Rhizome / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics; D013997:Time Factors; D052584:Xylem / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics