On the Anatomy and Morphology of Lateral Branch Systems of Archaeopteris

Beck, Carl

doi:10.2307/2441474

Cited by 31 publications

(57 citation statements)

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“…This postdates by about 85-100 Myr that implied under Beck's hypothesis (2)(3)(4)(5) and is slightly earlier than the first appearances of the five groups of extant seed plants in the fossil record. Our estimated time when extant seed plants shared their last common ancestor supports the conclusion from cladistic and stratigraphic analyses of extinct and extant taxa (49,50) that all major groups of extant seed plants, with the possible exception of angiosperms, were products of diversification that occurred between the Lower Pennsylvanian and the Upper Triassic (51).…”

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confidence: 70%

“…Beck (2)(3)(4)(5), although not discussing angiosperms, proposed that the two main lineages of gymnosperms, coniferopsids (conifers, Ginkgo, and Gnetales) and cycadopsids (cycads), diverged independently from two lineages of the progymnosperms, with coniferopsids from Archaeopteridales and cycads from Aneurophytales. Because Archaeopteridales and Aneurophytales appeared in the Middle Devonian, Beck's hypothesis implies that the two gymnosperm lineages diverged about 375 million years (Myr) ago.…”

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confidence: 99%

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Chloroplast and nuclear gene sequences indicate late Pennsylvanian time for the last common ancestor of extant seed plants.

Savard

Strauss

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

134

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We have estimated the time for the last commoancor of extant seed plants by using molecular clocks constructed from the ofthe chloroplastic gene coding for the large subunit of ribulose-1,5-blphosphate carboxylase/oxygenase (rbcL) and the nuclear gene coding for the snail subunit of rRNA (Rrnl8). Phylogenetic analyses of nucleodde sequences indicated that the earliest divergence of extant seed plants is likely represented by a split between conufer-cycad and ansperm linea . Relative-rate tests were used to assess homogeneity of substution rates among lineages, and annual anglosperms were found to evolve at a faster rate than other taxa for rbcL and, thus, these sequences were excluded from construction of molecular clocks. Five distinct molecular cocks were calibrated using substitution rates for the two genes and four divergence times based on fossil and published molecular cock estimates. The five mated times for the last common ancestor of extant seed plants were in agreement with one another, with an average of 285 million years and a range of 275-290 million years. This implies a subsantily more recent ancestor of all extant seed plants than suggsed by some theories of plant evolution.Although progymnosperms are accepted as the ancestral group to all seed plants, the time when the five groups of extant seed plants (cycads, conifers, Ginkgo, Gnetales, and angiosperms) shared their last common ancestor is unclear because of uncertainty about ancestor-descendant relationships between progymnosperms and seed plants (1, 2). Beck (2-5), although not discussing angiosperms, proposed that the two main lineages of gymnosperms, coniferopsids (conifers, Ginkgo, and Gnetales) and cycadopsids (cycads), diverged independently from two lineages of the progymnosperms, with coniferopsids from Archaeopteridales and cycads from Aneurophytales. Because Archaeopteridales and Aneurophytales appeared in the Middle Devonian, Beck's hypothesis implies that the two gymnosperm lineages diverged about 375 million years (Myr) ago. Alternatively, Rothwell (6, 7) hypothesized that the two gymnosperm lineages both evolved from Aneurophytales via the seed fern complex, suggesting a more recent diversification of extant seed plants.Phylogenetic analysis of conserved gene sequences from extant plant taxa has contributed tangibly to our understanding of the early diversification of seed plants (8-11). Chloroplast and nuclear gene sequences have also been used to construct molecular clocks and to estimate the times for key events in the evolutionary history of flowering plants (12).However, before applying molecular clocks to date evolutionary events, approximate constancy of evolutionary rate over time needs to be established (13) by using procedures for assessing rate homogeneity over taxa (14,15) or over lineages (16).Here we estimate the time when extant seed plants shared their last common ancestorby using molecular clocks derived from nucleotide sequences of the chloroplast gene coding for the large subunit of ribulose-1,5-bispho...

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confidence: 70%

mentioning

confidence: 99%

Chloroplast and nuclear gene sequences indicate late Pennsylvanian time for the last common ancestor of extant seed plants.

Savard

Strauss

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

134

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“…Under most circumstances, better histological detail can be revealed by the thin-section method outlined below. A form of this technique was first employed by Beck (1967Beck ( , 1971. The method given here differs from Beck's original procedure by (1) the presence of a plastic re-embedding step, (2) the use of the same plastic for adhesion of the sections to glass slides, and (3) the more complete demineralization of the thin-sections.…”

Section: Technique For Limonite Permineralizationsmentioning

confidence: 99%

“…Part of the reason for this may be due to the fact that techniques applied to these specimens have been less successful, in general, than those applied to pyritic specimens, although excellent results have been obtained in some instances (Beck, 1967(Beck, , 1971Leclercq and Lele, 1968;Fairon-Demaret, 1977;Mustafa, 1978;Scheckler, 1978).…”

Section: Introductionmentioning

confidence: 99%

Techniques for preparation of pyrite and limonite permineralizations

Stein

Wight

Beck

1982

Review of Palaeobotany and Palynology

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Procedures are presented for the preparation of fine-polished surfaces of pyrite permineralizations, and demineralized thin-sections of limonite permineralizations. A major new feature in both procedures involves the re-embedding in plastic of individual cut sections in order to promote stability of the often crumbly material during further preparation. Pyrite sections are kept flat during polymerization of the plastic by means of a binder clip press. The technique for limonite permineralizations is characterized by the use of plastic not only for re,embedding individual sections but also for adhesion of sections to glass slides. Following this, sections are ground thin and demineralized with hydrochloric acid. We strongly recommend use of the thin-section technique for all studies utilizing limonite permineralizations because this method permits a much greater resolution of detail than is possible with other methods. INTRODUCTIONOne of the major problems in studying the internal structure of Devonian plants has been a lack of consistently reliable techniques for recovering the maximum information from fossils permineralized by pyrite (iron sulfides) and limonite (hydrated iron oxides), the most common forms of preservation in these plants.Pyritic specimens have contributed to paleobotanical knowledge for at least half a century. One of the early contributions was the study of the internal structure of Aneurophyton germanicum from the Middle Devonian of the Rhineland by Kr~iusel and Weyland (1929). Soon, thereafter, studies by Arnold (1935Arnold ( , 1940 and Read (1938) of pyritic Middle Devonian axes (Iridopteris, Reimannia, Arachnoxylon, Triloboxylon and others) from New York further emphasized the importance of this form of preservation. Only a small part of the potential information in these specimens was recovered by these early studies, however, because of limitations in the techniques and methodology employed.0034--6667/82/0000--0000/$02.75

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“…New York, West Virginia (USA); Calgary (Canada); Bear Island (Norway); Heist-op-den-Berg (Belgium); Southeastern Mountainous Altay (Russia); Jiangsu, Hubei (China) Arnold, 1936;Carluccio et al, 1966;Andrews, 1970;Beck, 1971;Phillips et al, 1972;Scheckler, 1978;Wu et al, 1982;Cai, 1981;Feng, 1984;Hao & Mei, 1987;Yang, 1987;Yang, 2005;Osborne et al, 2004;Gutak et al, 2011 A. sphenophyllifolia New York (USA); Heilongjiang (China) Carluccio et al, 1966;Cai, 1981 A. fissilis Ellesmere Island (Canada); Southeastern Mountainous Altay (Russia) Gensel & Andrews, 1984;Osborne et al, 2004;Gutak et al, 2011A. howitti Australia White, 1986 Eastern Cape (South Africa) Anderson et al, 1995 Archaeopteris sp. America; China; Canada; Columbia; Russia; Venezuela Beck, 1971;Cai, 1981;Osborne et al, 2004 Note: This Two permineralized axes, ca. 2.0 cm and 4.5 cm long, were embedded in Epon resin, transversely and longitudinally sectioned at less than 1.0-mm intervals, then ground.…”

Section: Methodsmentioning

confidence: 99%

Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian (Frasnian) of South China

Guo

Wang

2011

J of Sytematics Evolution

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Archaeopteris macilenta is one of the most widespread plants in the Late Devonian. Based on fossils from the Frasnian Huangjiadeng Formation, Yichang District of Hubei Province, for the first time we study in detail the anatomy of this progymnosperm plant in South China. Ultimate axes are protostelic with three xylem sympodia and lack secondary tissue. Penultimate axes are eustelic, bearing eight sympodia and a thin band of secondary xylem. Radially symmetrical sympodia of mesarch primary xylem produce traces of appendages in a spiral arrangement. Archaeopteris macilenta and A. halliana (A. roemeriana) are dominant in the Frasnian and Famennian, respectively. Comparisons with these two species from other tectonic plates indicate consistent stelar architectures. Global spread, continuous occurrence, and identical anatomy during the Late Devonian indicate that Archaeopteris survived the Frasnian–Famennian extinction event. In this time, endemic genera and cosmopolitan taxa, including Archaeopteris, suggest the palaeogeographic isolation of South China and certain associations with other plates.

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On the Anatomy and Morphology of Lateral Branch Systems of Archaeopteris

Cited by 31 publications

References 3 publications

Chloroplast and nuclear gene sequences indicate late Pennsylvanian time for the last common ancestor of extant seed plants.

Chloroplast and nuclear gene sequences indicate late Pennsylvanian time for the last common ancestor of extant seed plants.

Techniques for preparation of pyrite and limonite permineralizations

Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian (Frasnian) of South China

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