On Parka decipiens

Don, Archibald William Robertson; Hickling, George

doi:10.1144/gsl.jgs.1915.071.01-04.25

Cited by 17 publications

(11 citation statements)

References 6 publications

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“…Parka and Pachytheca are representative of a number of morphologically similar, Devonian, thalloid plant fossils showing a 'cuticular' state of preservation. Parka decipiens Fleming 1831 has been the subject of taxonomic speculation for over a century; however, the work of Don and Hickling (1917) clearly demonstrated its plant affinities. They concluded that the flat, circular to oval thallus of Parka had an upper and lower epidermis circumscribing a parenchymatous tissue which produced sporangial discs containing masses of spores.…”

Section: Introductionmentioning

confidence: 99%

21.—Morphological and Ontogenetic Reconstructions of Parka decipiens Fleming and Pachytheca Hooker from the Lower Old Red Sandstone, Scotland

Niklas

1976

Earth and Environmental Science Transactions of the Royal Socie

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SynopsisMorphological examination of 56 specimens of Parka decipiens suggests that the thallus was dorsiventral with a many layered ventral cell-layer bearing dorsal sporangia originating from both the margin of the thallus and the underlying tissue. A disc-like holdfast is present, suggesting that at maturity Parka was attached to some substrate. Mathematical simulations of growth suggest that sporangia were produced by lateral proliferation of cells, while simulations of the frequency of cell dichotomy indicate that the order of sporangial packing on the dorsal surface is consistent with an underlying pseudoparenchyma. Latex replicas indicate the presence of filament dichotomy and corroborate to some extent the presence of a pseudoparenchyma. Intercalated, anticlinal cell divisions are demonstrated mathematically. Ontogenetic reconstructions of Parka suggest a similarity to the extant green algal genus Coleochaete. Growth stages of Coleochaete in their early stages of development are similar to the fossil Pachytheca, while mathematical and chemical comparison of Pachytheca with those of Parka suggest either a phylogenetic or ontogentic interpretation.

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Section: Introductionmentioning

confidence: 99%

21.—Morphological and Ontogenetic Reconstructions of Parka decipiens Fleming and Pachytheca Hooker from the Lower Old Red Sandstone, Scotland

Niklas

1976

Earth and Environmental Science Transactions of the Royal Socie

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“…The rest of the thallus is composed of small oval 1 Fleming (1831). " Don and Hickling (1917 (Fig. 20, 3) of wliieh there is no evidence that they were formed in tetrads, or that they^vere heterosporous.…”

Section: This Fossil Was Originally Described Under the Name Lycopoditesmentioning

confidence: 99%

Devonian floras; a study of the origin of Cormophyta

Arber¹,

Arber²

1921

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INTRODUCTION It is now clear that in Devonian times, two terrestrial floras, quite distinct as regards affinity, existed, one in the earlier part, and one in the later portion of the Devonian period. The former Avill here be termed the Psilopliyton flora; it consisted largely, as we hope to show, of Thallophyta belonging, for the most part, to a group now quite extinct which we propose to term the Procormophyta or Propteridophyta. The later flora consisted chiefly, but not entirely, of plants which were obviously Pteridophyta. This assemblage we propose to term the Archaeo-2)teris flora. Our knowledge of both these floras, though still far from complete, has been entirely revolutionised during the last few years by the publication, both at home and abroad, of a series of memoirs, to which we shall presently refer more in detail. These invaluable contributions have necessitated a complete revision of the whole subject, and since no general account of these floras, including these recent advances, at present exists, we propose to commence by a brief enumeration of the characters of their more important genera. We have purposely omitted from our review all the more doubtful types about which little or nothing is known beyond the existence of very obscure or fragmentary examples. We have further in Chapter III of this Ijook confined our attention to a critical summary of the essential features of the morphology and anatomy of the genera belonging to the Psilopliyton flora, reserving for a separate chapter (p. 46) the entire discussion of the question of their affinities and systematic position. Finally in yet a further Chapter we discuss the very important bearing of these new discoveries on the phylogeny of Cormophyta and in particular of the various Pteridophytic lines of descent. The researches to which we particularly refer are firstly Kidston and Lang's^memoir on the Scottish plant Rhyniâ Kidston and Lang (1917). Old Bed Facies Upper Old Red (Cheirolepis, Holoptychius and Asterolepis fauna) i| AGE OF FLORAS 5 The horizon of the plant-bearing beds in the Old Red of Scotland can in most cases be determined by the associated fish faunas. Important specimens, including Psilophyton in a petrified condition^, recently discovered in the Dryden Shales at Rhynie, Aberdeenshire, by Dr Mackie^are, however, exceptional in that the precise horizon has not yet been ascertained. These beds are, however, regarded as not younger than Middle Old Red^, but since this genus is known to range throughout Devonian time, the precise horizon of these beds is immaterial from this point of view. Ireland. The plant-bearing sandstones of the Old Red of the South of Ireland are referred to the Upper Old Red (Upper Devonian) on the evidence of the associated fish remains. England. The few plants known from the Devonian of England come from the type beds of the Upper Devonian (Baggy or Cucullaea beds) in North Devon. Belgium. Two plant-bearing horizons occur in Belgium which on stratigraphical grounds are assigned to the Lower and Upper Devoni...

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“…The rest of the thallus is composed of small oval 1 Fleming (1831). 2 Don and Hickling (1917). 3 Dawson and Penhallow (1891); Penhallow (1892).…”

Section: And 22)mentioning

confidence: 99%

“…(1) a large thallus (natural size); (2) the folded lamina (x2); (3) spores ( X 150). After Don and Hickling (1917).…”

Section: Ill]mentioning

confidence: 99%

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Devonian floras, a study of the origin of Cormophyta; with a preface by D.H. Scott.

Arber¹

1921

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The horizon of the plant-bearing beds in the Old Red of Scotland can in most cases be determined by the associated fish faunas. Important specimens, including Psilophyton in a petrified condition^, recently discovered in the Dryden Shales at Rhynie, Aberdeenshire, by Dr Mackie^are, however, exceptional in that the precise horizon has not yet been ascertained. These beds are, however, regarded as not yoimger than Middle Old Red^, but since this genus is known to range throughout Devonian time, the precise horizon of these beds is immaterial from this point of view. Ireland. The plant-bearing sandstones of the Old Red of the South of Ireland are referred to the Upper Old Red (Upper Devonian) on the evidence of the associated fish remains. England. The few plants kno^vn from the Devonian of England come from the type beds of the Upper Devonian (Baggy or Cucullaea beds) in North Devon. Belgium. Two plant-bearing horizons occur in Belgium which on stratigraphical grounds are assigned to the Lower and Upper Devonian respectively. These are the "Poudingue de Burnot" and the "Psammites du Condroz." Germany. A small but important flora from near Herborn in Hesse-Nassau has been recently referred to the Silurian. On the fossil plant evidence, however, there can be no doubt that it is of Devonian age, and belongs, in all probability, to the Upper Devonian. Bohemia. The large flora from the horizon {hi) of Barrande's system of classification of the Devonian rocks of Bohemia was likewise originally referred to the Silurian. The Devonian age of these beds is now, however, admitted. More recently it has been Lower Old Red Sandstone (Forfarshire, Perthshire, etc.

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On Parka decipiens

Cited by 17 publications

References 6 publications

21.—Morphological and Ontogenetic Reconstructions of Parka decipiens Fleming and Pachytheca Hooker from the Lower Old Red Sandstone, Scotland

21.—Morphological and Ontogenetic Reconstructions of Parka decipiens Fleming and Pachytheca Hooker from the Lower Old Red Sandstone, Scotland

Devonian floras; a study of the origin of Cormophyta

Devonian floras, a study of the origin of Cormophyta; with a preface by D.H. Scott.

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