scholarly journals Origin of the holothurians (Echinodermata) derived by constructional morphology

Fossil Record ◽  
2002 ◽  
Vol 5 (1) ◽  
pp. 141-153 ◽  
Author(s):  
R. Haude
Keyword(s):  
Structural Transformation ◽  
Middle Devonian ◽  
Lower Devonian ◽  
Body Wall ◽  
De Novo ◽  
Functional Improvement ◽  
Constructional Morphology ◽  
Preliminary Description ◽  
Calcareous Ring ◽  
Respiratory Trees

According to a recent hypothesis, the holothurians originated by a process of extreme paedomorphism as "giant larvae", with "<i>de novo</i>" developed radial systems. However, the present approach, which follows the principles of constructional morphology, supports former views that the holothurian predecessor must have been echinoid-like. After constitution of a (reliable) early predecessor construction as a model with machine analogies, subsequent steps of structural transformation are explained by functional improvement and economy. Following results are discussed: (i) Holothurians have to be derived from a postlarval precursor; (ii) "Apodida" (as molecular-genetically derived first holothurians) must originally have been pedate; (iii) ophiocistioids would not be cladistic “holothurians” but a precursor construction of the taxon echinoids plus holothurians; (iv) the Lovenian structure of the calcareous ring of <i>Nudicorona</i> (Middle Devonian), possible radial series in <i>Palaeocucumaria</i> (Lower Devonian), and distribution of the podia in two new holothurian body fossils from the Lower and Middle Devonian (preliminary description as <i>Prokrustia tabulifera</i> n. gen., n. sp. and <i>Podolepithuria walliseri</i> n. gen., n. sp.) obviously corroborate homology of holothurian and other echinoderm radial systems; (v) different extent of podial and body wall skeletonization suggests the existence of respiratory trees by no later than the Middle Devonian. <br><br> Nach einer neueren Erklärung, die sich auf eine Theorie zur Homologisierung von larvalen und adulten Strukturen von Echinodermen stützt, sollen die Holothurien über extreme Paedomorphose, d.h. über „Riesen-Larven” mit neugebildeten postoralen Radial-Systemen entstanden sein. Dagegen läßt sich anhand eines konstruktions-morphologischen Verfahrens zeigen, daß Holothurien auf einen Echiniden-artigen Vorläufer zurückzuführen sind. So wird zunächst eine (wahrscheinliche) frühe Vorläufer-Konstruktion der Echinozoen nach Maschinen-Analogien konstituiert. Die daran anschließenden strukturellen Transformationen werden nach funktionellen und energetischen Kriterien begründet. Sie führen zwanglos zu Konstruktionen, die nicht nur rezenten Formen entsprechen, sondern offensichtlich auch durch bekannte und neue paläozoische Fossilien bestätigt werden. Im Einzelnen werden folgende Ergebnisse zur Diskussion gestellt: (i) Holothurien sind von einer post-larvalen Vorläufer-Konstruktion abzuleiten; (ii) die füßchenlosen „Apodida” (als molekulargenetisch früheste Holothurien) müssen zunächst vollständige Radien mit Podia besessen haben; (iii) bei den (nur paläozoischen) Ophiocistioiden handelt es sich nicht kladistisch um „Holothurien”, sondern sie repräsentieren eine Vorläufer-Konstruktion des Taxon Echiniden plus Holothurien; (iv) die Loven'sche Struktur des Schlundrings von <i>Nudicorona</i> (Mittel-Devon), die möglicherweise radialen Strukturen bei <i>Palaeocucumaria</i> (Unter-Devon) und die Verteilung der Podia in zwei neuen, vollständig erhaltenen Holothurien aus dem Unter- und Mittel-Devon (vorläufige Beschreibung als <i>Prokrustia tabulifera</i> n. gen., n. sp. und <i>Podolepithuria walliseri</i> n. gen., n. sp.) stützen die konstruktions-morphologische Begründung der Homologie der Radial-Systeme bei Holothurien und den übrigen Echinodermen; (v) das deutlich unterschiedliche Ausmaß der Skelettierung von Podia bei den neuen Holothurien-Funden scheint anzudeuten, daß die analen Respirations-Strukturen der Holothurien spätestens ab dem Mittel-Devon vorhanden sind. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.20020050110" target="_blank">10.1002/mmng.20020050110</a>

scholarly journals I.—On a New Cephalaspis Discovered in America, etc.

1870 ◽  
Vol 7 (75) ◽  
pp. 397-399
Author(s):  
E. Ray Lankester
Keyword(s):  
Middle Devonian ◽  
Lower Devonian ◽  
The North ◽  
North Side

Principal Dawson, of Montreal,. Canada, has placed in my hands for description a remarkably interesting specimen, indicating a species of the genus Cephalaspis in transatlantic Silurio-Devonian beds. He writes, “The specimen was found by one of my assistants, Mr. G. F. Kennedy, B.A., when collecting with me, in a bed charged with remains of Psilophyton, on the north side of Gaspé Bay. The geological horizon is below the middle of the Gaspé Sandstones, but several hundreds of feet above their actual base, so that the specimen may be regarded as either Lower Devonian or Lower Middle Devonian.

A new genus and species of Sclerodactylidae (Echinodermata: Holothuroidea: Sclerothyoninae) from the Pacific coast of Panama, and assignment of Neopentamera anexigua to Sclerothyoninae

Zootaxa ◽  
2018 ◽  
Vol 4429 (1) ◽  
pp. 157
Author(s):  
LUCIANA MARTINS ◽  
MARCOS TAVARES
Keyword(s):  
Body Wall ◽  
New Genus ◽  
Pacific Coast ◽  
The Body ◽  
The Other ◽  
Monotypic Genus ◽  
New Genus And Species ◽  
The Pacific ◽  
Calcareous Ring

Paulayellus gustavi, a new sclerodactylid genus and species, is described from the Pacific coast of Panama. The new genus and species is assigned to the subfamily Sclerothyoninae based on a suite of characters, which include the radial and interradial plates of the calcareous ring united at the base only. Paulayellus gen. nov. differs from the other Sclerothyoninae genera in having posterior processesof radial plates undivided. Additionally, differs from Sclerothyone, Thandarum and Neopentamera in having knobbed buttons, plates and cups in the body wall (whereas the body wall is furnished only with tables and plates in Sclerothyone, Temparena and Thandarum, and only with knobbed buttons and plates in Neopentamera). The new genus is, so far, monotypic. The also monotypic genus Neopentamera proved to have the radial and the interradial plates of the calcareous ring united at the base only, as typically found in the Sclerothyoninae, and is therefore transferred to that subfamily. The discovery of a new genus in the Sclerothyoninae and the transfer of Neopentamera required the amendation of the diagnosis for the subfamily. A key to the Sclerothyoninae is given. 

scholarly journals Epigenetic Effect of Cadmium on Global De Novo DNA Hypomethylation in the Cadmium-Induced Ventral Body Wall Defect (VBWD) in the Chick Model

2011 ◽  
Vol 120 (2) ◽  
pp. 475-480 ◽  
Author(s):  
Takashi Doi ◽  
Prem Puri ◽  
Amanda McCann ◽  
John Bannigan ◽  
Jennifer Thompson
Keyword(s):  
Body Wall ◽  
De Novo ◽  
Dna Hypomethylation ◽  
Wall Defect ◽  
Epigenetic Effect

scholarly journals Sterol biosynthesis in the echinoderm Asterias rubens

1975 ◽  
Vol 146 (1) ◽  
pp. 25-33 ◽  
Author(s):  
A G Smith ◽  
L J Goad
Keyword(s):  
Body Wall ◽  
De Novo ◽  
Mevalonic Acid ◽  
The Body ◽  
Sterol Biosynthesis ◽  
Asterias Rubens ◽  
Nonsaponifiable Lipid ◽  
Major Sterol ◽  
Dietary Origin ◽  
Isolated Tissues

1. [2(-14)C]Mevalonic acid injected into the echinoderm Asterias rubens (Class Asteroidea) was effectively incorporated into the non-saponifiable lipid. 2. The most extensively labelled compounds were squalene and the 4,4-dimethyl sterols with much lower incorporations into the 4α-monomethyl and 4-demethyl sterol fractions. 3. Labelled compounds identified were squalene, lanosterol, 4,4-dimethyl-5α-cholesta-8,24-dien-3β-ol and 4α-methyl-5α-cholest-7-en-3β-ol; these are all intermediates in sterol biosynthesis. 4. The major sterol in A. rubens, 5α-cholest-7-en-3β-ol, was also labelled showing that this echinoderm is capable of sterol biosynthesis de novo. 5. No evidence was obtained for the incorporation of [2(-14)C]mevalonic acid into the C28 and C29 components of the 4-demethyl sterols or 9β,19-cyclopropane sterols found in A. rubens and it is assumed that these sterols are of dietary origin. 6. Another starfish Henricia sanguinolenta also incorporated [2(-14)C]mevalonic acid into squalene and lanosterol. 7. Various isolated tissues of A. rubens were all capable of incorporation of [2(-14)C]mevalonic acid into the nonsaponifiable lipid. With the body-wall and stomach tissues radioactivity accumulated in squalene and the 4,4-dimethyl sterols, but with the gonads and pyloric caecae there was a more efficient incorporation of radioactivity into the 4-demethyl sterols, principally 5α-cholest-7-en-3β-ol.

The uppermost Emsian and lower Eifelian in the Kielce Region of the Holy Cross Mts. Part I: Lithostratigraphy

2015 ◽  
Vol 65 (2) ◽  
pp. 141-191 ◽  
Author(s):  
Krystian Wójcik
Keyword(s):  
Middle Devonian ◽  
Lower Devonian ◽  
Central Poland ◽  
Dolomite Formation

Abstract The paper provides a description of primary geological logs, characteristics and formal lithostratigraphy of the uppermost Emsian and lower Eifelian of the Kielce Region of the Holy Cross Mts., central Poland. Nine sections of this interval, representing the whole area of the Kielce Region, and ranging between the Lower Devonian clastics of the Winna Formation and the Middle Devonian carbonates of the Kowala Formation were studied. The succession is divided into the Barania Góra Dolomite and Limestone Formation and the Wojciechowice Dolomite Formation. Six members are distinguished within the former. In the western part of the region these are (in stratigraphical order): Porzecze Claystone Member, Dębska Wola Dolomite Member, Dąbrowa Limestone Member, and Brzeziny Dolomite Member. In the eastern part, the formation is divided into the Janczyce Dolomite Member and the Jurkowice Dolomite Member. Additionally, the Wszachów Dolomite Member and Nowy Staw Dolomite Member are distinguished within the overlying Wojciechowice Formation. The thickness of the uppermost Emsian-Eifelian succession ranges from ca. 200 m in the eastern part to ca. 130 m in the western part of the Kielce Region

Transcurrent motion determined paleomagnetically in the Northern Appalachians and Caledonides and the Acadian Orogeny

1976 ◽  
Vol 13 (9) ◽  
pp. 1236-1243 ◽  
Author(s):  
W. A. Morris
Keyword(s):  
North America ◽  
Middle Devonian ◽  
Lower Devonian ◽  
Upper Devonian ◽  
Paleomagnetic Data ◽  
Taconic Orogeny ◽  
Paleomagnetic Poles ◽  
Acadian Orogeny ◽  
Opening And Closing

After correction for Mesozoic and Tertiary opening of the Atlantic, Ordovician and Silurian – Lower Devonian paleomagnetic poles from Britain are significantly different to contemporaneous results from North America. Upper Devonian poles from the two regions are similar. The discrepancy observed in the Ordovician and Silurian – Lower Devonian data is interpreted as due to major sinistral transcurrent faulting during the Middle Devonian concurrent with the short lived Acadian Orogeny. Rate of motion on this fault (or faults) was approximately 9 ± 4 cm/y. A consequence of this interpretation is that the Caledonide ocean was apparently narrow during the interval Ordovician to Devonian. However, inaccuracies in the paleomagnetic data permit the opening and closing of small ocean basins (≤ 1000 km), which may be related to the more extended Taconic Orogeny.

scholarly journals Devonian lithostratigraphic units (Belgium)

2002 ◽  
Vol 4 (1-2) ◽  
pp. 39-69 ◽  
Author(s):  
Pierre BULTYNCK ◽  
Léon DEJONGHE
Keyword(s):  
Middle Devonian ◽  
Lower Devonian ◽  
Lithostratigraphic Units ◽  
Regressive Events

This contribution briefly describes seventy Devonian formations from the Dinant and Namur Synclinoria, the Vesdre Nappe and the Theux Window, that were revised or introduced during the previous two decades. The descriptions of the formations are organized in four parts, Lower Devonian, Middle Devonian, Frasnian and Famennian, corresponding to major and minor transgressive and regressive events and demonstrating each typical lithological characteristics. In each part, the following presentation has been adopted: the formations occurring in the Southern part of the Dinant Synclinorium are first described from base upwards, followed by a description of the formations restricted to the central and/or northern part of the Dinant Synclinorium, the Namur Synclinorium, the Vesdre Nappe and the Theux Window.

scholarly journals Problematic Sclerites Eurytholia from the Lower and Middle Devonian of the Czech Republic

2019 ◽  
Vol 53 (1) ◽  
pp. 1-11
Author(s):  
Michal Mergl
Keyword(s):  
Czech Republic ◽  
New Species ◽  
Middle Devonian ◽  
Lower Devonian ◽  
Time Range ◽  
Formal Description ◽  
The Czech Republic ◽  
Barrandian Area ◽  
First Time ◽  
A New Species

AbstractProblematic phosphatic sclerites Eurytholia are reported for the first time from the Middle Devonian. Unequivocal sclerites were observed in limestones of Emsian to late Eifelian age in six localities of the Barrandian area of the Central Bohemia of the Czech Republic. Formerly observed size and shape variations of Eurytholia sclerites prevent formal description of a new species on few specimens of Emsian and Eifelian age. Therefore the new specimens are identified as Eurytholia aff. bohemica. Their presence indicates longer time range of the Eurytholia animal, covering not only the Ordovician, the Silurian and the earliest Devonian as known formerly, but also late Lower Devonian and the Middle Devonian. Similar features in morphology and histology of Eurytholia indicate relationship to a conodont Pseudooneotodus and a support suggestion about the vertebrate origin of Eurytholia sclerites.

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