9 research outputs found
A new Neocalamites (Sphenophyta) with prickles and attached cones from the Upper Triassic of China
Remains of the extinct sphenophyte (horsetail) . Neocalamites are most widespread in the Middle-Upper Triassic and are typically represented by stem and leaf fragments. Here we report on spectacular new finds of . Neocalamites from the Late Triassic Yangcaogou Formation in Liaoning Province, China that include bedding surfaces dominated by nearly complete aerial stems with attached leaf whorls and rare bractless cones. They reveal a monopodial growth habit for the stems, which are covered with downward projecting prickles that probably provided protection against herbivores. These features provide the basis for a new proposed species, . Neocalamites horridus. The nodes bear whorls of very long leaves mainly free to their bases, and one specimen bears an attached cone on a long peduncle. Identical dispersed cones have also been recovered. The leaves of adjacent monopodial stems most likely interlocked to support growth in large stands akin to the role now played by branches in large modern . Equisetum species. The new Chinese . Neocalamites is among the most confidently reconstructed species, and indicates a greater diversity of sphenophyte morphology during the Mesozoic than previously realized.Fil: Zan, Shuqin. Geological Museum Of China; ChinaFil: Axsmith, Brian J.. University of Alabama at Birmingahm; Estados UnidosFil: Escapa, Ignacio Hernán. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Fraser, Nicholas. National Museum Of Scotland; Reino UnidoFil: Liu, Feng Xiang. Geological Museum Of China; ChinaFil: Xing, De-He. Shenyang Institute Of Geology And Mineral Resources; Chin
A New Fossil Conifer from the Triassic of North America: Implications for Models of Ovulate Cone Scale Evolution
This is the publisher's version, also available electronically from http://www.jstor.org/stable/2475100?seq=1#page_scan_tab_contents.See article for abstract
A Triassic seed with an angiosperm-like wind dispersal mechanism
The earliest record of a seed with a pappus-like, parachute seed dispersal mechanism, Edenia villisperma gen. et sp. nov., is described from the Upper Triassic of the eastern United States. The seed is small and roughly triangular. Clusters of long hairs emerge from a whorl of at least five circular scars just below the proximal end. This morphology indicates that the hair clusters represent modified lateral structures similar to the pappus of several eudicot angiosperm groups, but probably representing a case of convergent evolution of a similar structure in a gymnosperm. The seeds are usually found isolated, but one specimen indicates that they were born tightly packed together on an axis. A few earlier records exist of dispersal hairs, but this is the first clearly indicating a pappus-like structure. Although the exact affinities of Edenia are uncertain, this seed demonstrates that plants with highly advanced wind dispersal mechanisms occurred at least 55 million years earlier than previously thought
Evidence of White Pine (Pinus subgenus Strobus) Dominance From the Pliocene Northeastern Gulf of Mexico Coastal Plain
Plant fossils from the Citronelle Formation provide a rare window into the Pliocene flora and climate of the northeastern Gulf of Mexico Coastal Plain. Many of the taxa recovered to date inhabit the region today. However, analysis of Pinus pollen grains and fascicles indicates that the dominant pines were members of Pinus subgenus Strobus (i.e., white pines ). The fascicles have a small, bulbous base lacking a sheath, and bear four or five long, slender needles. These features are typical of white pines. Although macrofossils are rare, 77 to 100% of the dispersed Pinus pollen grains from five localities have sacci continuous with the corpus and verrucae on the cappula, which are characteristics of white pines. This is remarkable, as the northeastern Gulf of Mexico Coastal Plain today is devoid of white pines, and is instead considered a center of diversity for Pinus subgenus Pinus section Pinus subsection Australes. Today, Pinus strobus is the only white pine in the eastern North America and its southernmost distribution only extends into the mountains of Georgia, about 600 km north of the fossil sites. The historical biogeographic relationships of P. strobus to other North American forms are unclear. For example, its close relative, Pinus chiapensis, is present in northeastern Mexico and Central America. The current disjunction between P. strobus and P. chiapensis is 2400 km and includes an arid barrier to dispersal. P. chiapensis is also associated with several other species showing a similar biogeographic pattern. The fossils described here indicate that white pines were more widespread in North America in the recent geological past than previously thought, and imply possible connections between disjunct species that would not be suspected if only current species\u27 ranges and ecological tolerances were considered
New evidence for laurasian corystosperms: Umkomasia from the Upper Triassic of Northern China
Recent finds of remarkable fossil plants from the Upper Triassic Yangcaogou Formation in Liaoning Province, PR China include branched, cupule-bearing structures referable to the corystosperm ovulate organ Umkomasia. This material is described and assigned to the proposed new species Umkomasia asiatica. The collection includes numerous isolated cupules and fragments of ultimate cupule-bearing axes. Two specimens consisting of portions of the main axis with attached, cupulate lateral axes have also been found. The main axis was at least 6.5 cm long, with each lateral axis bearing one to at least three pairs of stalked, ovoid cupules. The new Umkomasia is similar to U. franconica from the Jurassic of Germany, which is the only other known laurasian species, but the cupules are smaller and more elongated. It is also similar to many gondwanan forms, including the type species U. macleanii. Leaves associated with the Chinese Umkomasia species are tentatively referred to Thinnfeldia, and may have been produced by the same plant. Associated ovoid seeds with elongated, curved micropyles are similar to those of gondwanan species of Umkomasia. The fossils described here are, therefore, significant in representing the first report of corystosperm reproductive structures from Asia, and only the second report of Umkomasia from the entire northern hemisphere. The new Chinese fossils also support leaf-based evidence that the Corystospermales were present in Laurasia as early as the Late Triassic
Modifications of the transfer technique for studying complex plant structures
The transfer technique is a method for exposing compression fossils that entails embedding the specimen in an adhesive material and dissolving the matrix in appropriate acids. This technique has been used for many years, and played an important role in several classic paleobotanical studies. However, in recent years it appears to have fallen into relative disuse and is not discussed at all in recent compilations of paleobotanical techniques. This is unfortunate, as the method is often extremely effective, especially for revealing the detailed structure of complex plant organs. In this paper, case studies using fossil conifer ovulate cones are presented. The first entails a modification of the classic transfer technique using a polyester resin as the embedding medium on an unnamed cone from the Triassic of Pennsylvania. The second study entails producing serial sections through a polyester resin embedded cone of Telemachus from the Triassic of Antarctica in a manner analogous to the classic cellulose acetate peel method. This modification is most useful when the organic material is too fragile for the more classic method. The results of these case studies are presented in the hope of re-stimulating use of the transfer technique in paleobotany. © 2009 Elsevier B.V. All rights reserved.Fil: Escapa, Ignacio Hernán. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; Argentina. University of Kansas; Estados UnidosFil: Axsmith, Brian J.. University of South Alabama; Estados UnidosFil: Taylor, Thomas N.. University of Kansas; Estados UnidosFil: Taylor, Edith L.. University of Kansas; Estados Unido
A new Neocalamites (Sphenophyta) with prickles and attached cones from the Upper Triassic of China.
Remains of the extinct sphenophyte (horsetail) Neocalamites are most widespread in the Middle–Upper Triassic and are typically represented by stem and leaf fragments. Here we report on spectacular new finds of Neocalamites from the Late Triassic Yangcaogou Formation in Liaoning Province, China that include bedding surfaces dominated by nearly complete aerial stems with attached leaf whorls and rare bractless cones. They reveal a monopodial growth habit for the stems, which are covered with downward projecting prickles that probably provided protection against herbivores. These features provide the basis for a new proposed species, Neocalamites horridus. The nodes bear whorls of very long leaves mainly free to their bases, and one specimen bears an attached cone on a long peduncle. Identical dispersed cones have also been recovered. The leaves of adjacent monopodial stems most likely interlocked to support growth in large stands akin to the role now played by branches in large modern Equisetum species. The new Chinese Neocalamites is among the most confidently reconstructed species, and indicates a greater diversity of sphenophyte morphology during the Mesozoic than previously realized