I.—Descriptions of New Upper Silurian Brachiopoda from Shropshire

1881 ◽  
Vol 8 (4) ◽  
pp. 145-156 ◽  
Author(s):  
Thomas Davidson
Keyword(s):  
Short Distance ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Hinge Plate ◽  
Upper Silurian ◽  
Marked Surface ◽  
Longitudinal Septum

Shell small, marginally sub-pentagonal, longer than wide, straight or slightly indented in front. Dorsal valve laterally gently convex, longitudinally concave, with a small median rib commencing at about the middle of the valve, and widening as it nears the front. Ventral valve very convex and keeled along the middle or divided longitudinally by a groove commencing at about half the length of the shell and extending to the front. Beak small, incurved, foramen minute, beak ridges strongly marked. Surface of valves smooth. In the interior of the dorsal valve, under the hinge-plate, a slightly elevated longitudinal septum or ridge extends to within a short distance of the frontal margin. To the hinge-plate are attached the principal stems of the loop, which, after giving off crural processes, extend to within a short distance of the front, where they become reflected so as to form the loop.

On New Brachiopoda, and on the Development of the Loop in Terebratella

The Geologist ◽  
1861 ◽  
Vol 4 (3) ◽  
pp. 96-99 ◽  
Author(s):  
Charles Moore
Keyword(s):  
Ventral Valve ◽  
Dorsal Valve ◽  
Longitudinal Groove ◽  
Considerable Portion ◽  
Longitudinal Septum

Shell inequivalve; punctuate, rather rugose, front deep, rounded; attached by a considerable portion of the ventral valve; beak slightly incurved; deltidium small and depressed. The ventral valve is flattened on its under side. Its interior is surrounded by an elevated, slightly granulated margin. Under the deltidium are seen two raised oval processes, separated by a longitudinal septum, which occupies the greater length of the shell. The exterior of the dorsal valve is rugose and flattened. The interior possesses a narrow, thin, punctuated margin, immediately succeeding which is a ridge of single granulations, which are stronger towards the frontal margin, gradually disappearing as the ridge passes upwards. Springing from the centre of this granulated ridge is a septum, slightly tapering from its base, on either side strongly serrated, between which is a central longitudinal groove. The septum occupies nearly the whole height allowed by the cavity of the shell, and divides it to nearly three-fourths of its length. From the top of the septum there are thrown off two extremely delicate lamellæ, forming a loop which curves downwards towards the front of the shell, where they bifurcate, and are then again united to the shell at its inner sides. Above the septum and attached lamellæ a band occurs, forming a bridge over the visceral cavity. This is united to the granulated ridge, which thus completely surrounds the inner portion of the valve.

scholarly journals Schizocrania (Brachiopoda, Discinoidea): taxonomy, occurrence, ecology and history of the earliest epizoan lingulate brachiopod

2016 ◽  
Vol 72 (3-4) ◽  
pp. 225-238 ◽  
Author(s):  
Michal Mergl ◽  
Lucie Nolčová
Keyword(s):  
Trophic Structure ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Early Devonian ◽  
Sea Floor ◽  
Open Sea ◽  
History Of ◽  
Barrandian Area ◽  
Floating Objects ◽  
First Time

The lingulate brachiopod Schizocrania (Trematidae, Discinoidea) is reviewed. Ptychopeltis is definitively synonymized with Schizocrania, because new data indicate that convexity of the shell, profile of the anterior margin commissure, density of the dorsal valve costellation, ornamentation of the ventral valve and shape of the pedicle notch are worthless for separation of these genera. Four Ordovician species of Schizocrania are reported from the Barrandian area: S. multistriata (Darriwilian), S. hornyi (Sandbian), S. incola (Sandbian) and the new species S. equestra sp. nov. (Katian). Occurrence of Schizocrania striata is confirmed for the first time around the S/D boundary in the Barrandian area. Schizocrania has a wide geographic range with mid-Ordovician to early Devonian occurrences in Laurentia, Avalonia, West Gondwana and the Silurian occurrence in Baltica. Schizocrania was the earliest lingulate brachiopod adhering to floating objects in an open sea (both living cephalopods and their empty drifting shells), but it was highly opportunistic, and used any vacant hard surface on the sea floor (conulariids, strophomenid brachiopods, trilobites) as a suitable substrate for settlement of the larva. Decline of the genus coincided with disappearance of planktic graptolites, and might have been caused by competition of rapidly evolving planktic dacryoconarids, increased predation pressure, and rebuilding of the trophic structure in the early Devonian seas.

scholarly journals V.—On the Denticulated Structure of the Hinge–line of Spirifera trigonalis, Martin

1884 ◽  
Vol 1 (1) ◽  
pp. 18-20 ◽  
Author(s):  
John Young
Keyword(s):  
Outer Edge ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Hinge Line ◽  
Lower Carboniferous ◽  
Fossiliferous Limestone ◽  
The Way

Recently, when examining some weathered fossiliferous limestone shale from the Lower Carboniferous strata of East Kilbride, Lanarkshire, my attention was attracted to some fragments of the valves of Spirifera trigonalis, Martin, in which I noticed, on the hinge-line of the dorsal valve, a row of small, round, hollow pits, and on the hinge-line of the ventral valve, a corresponding row of small, projecting, rounded denticles. These characters I had not noticed before, and on searching further, I found other fragments of the valves showing the same thing. This led to an examination of more perfect specimens of this Spirifera, contained in my own collection, and that of Dr. J. R. S. Hunter, of Braidwood, Carluke, and in one example, where the valves had slightly opened through pressure, on clearing away the shale, I found, on the outer edge of the ventral valve, a distinct row of small projecting denticles, that had evidently fitted into hollow pits or sockets in the dorsal valve, but from the way the valves had shifted in this specimen these were not seen. These denticles, when looked at externally, are nearly as numerous, and much of the same size, as those seen in many of the hinge-lines of shells of the genus Area, only in this genus, the teeth are the same in each valve, and lock into each other.

The Carboniferous System in Scotland Characterized by its Brachiopoda

The Geologist ◽  
1860 ◽  
Vol 3 (1) ◽  
pp. 14-25
Author(s):  
Thomas Davidson
Keyword(s):  
Great Difficulty ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Hinge Line ◽  
The Subject ◽  
Spiral Coils ◽  
Extinct Genus ◽  
External Shape

The shells of which this genus is composed differ much in their external shape and appearance, hence the great difficulty of correctly determining the limits of certain species. The character of this extinct genus are now so well understood that it is scarcely necessary to make any further allusion to the subject; but we may briefly repeat, for the sake of the less initiated, and in order to shorten the descriptions of the various species, that all possess a straight hinge-line, and a triangular or sub-parallel area, which is divided by a triangular fissure, this last being more or less covered, or contracted, by the means of one or two curved plates, to which the term pseudo-deltidium has been applied. The pseudo-deltidium is rarely preserved in the carboniferous specimens, but did certainly exist in the perfect or living individuals. The valves are articulated by the means of curved teeth developed on either side of the fissure in the ventral valve, and which fit into corresponding sockets in the opposite or dorsal one. In the larger valve the teeth are supported by vertical plates of greater or lesser dimensions, and in the space between these on the bottom of the shell are situated the muscular impressions. The adductor, or occlusor muscle leaves a narrow mesial oval-shaped scar, and on either side are situated the cardinal, or divaricator muscular impressions. In the interior of the smaller, or dorsal valve there exists two large conical spiral coils, which nearly fill the interior of the shell, the ends being directed outwardly towards the cardinal angles, while the bases of the hollow conical spires nearly meet at the hinge side, but are wide apart in front.

The Carboniferous System in Scotland Characterized by its Brachiopoda

The Geologist ◽  
1860 ◽  
Vol 3 (6) ◽  
pp. 219-240
Author(s):  
Thomas Davidson
Keyword(s):  
Ventral Valve ◽  
Dorsal Valve ◽  
Entire Surface ◽  
Hinge Line ◽  
Cardinal Process

The shells composing this species vary but slightly in shape, being marginally semicircular, concavo-convex, and about one-third wider than long. The hingeline is straight, and either a little shorter, with its cardinal angles rounded, or somewhat longer than the greatest width of the shell, with rectangular or slightly acute and extended terminations. Both valves are provided with narrow sub-parallel areas, the ventral one, which is the largest, being divided by a small fissure, partially covered with a pseudo-deltidium; while in the middle of the ventral one there exists a prominent V-shaped cardinal process. The ventral valve is moderately convex, and flattened towards its auriculate cardinal extremities. The beak, which is small and incurved, does not overlie the hinge-line; while the dorsal valve assumes in different specimens a greater or lesser degree of concavity, and follows the curves of the opposite one. Exteriorly the surface of the ventral valve is covered with numerous small thread-like radiating striæ, which increase in number by occasional bifurcation, or interstriations at various distances from the beak, so that as many as one hundred and twenty ribs may be counted round the margin of certain specimens, while at irregular distances small spines projected from the rounded surface of the striæ. In addition to these, on each side of the beak there exists along the cardinal edge from five to nine slanting tabular spines, which become longer and larger as they approach the extremities of the cardinal edge. The surface of the dorsal valve is striated as in the ventral one; and minute perforations or punctures may be perceived over the entire surface of the shell, and which are the exterior orifices of the canals which traverse the shell, as in Productus.

Ardmosteges Orchamus New Genus, New Species, in the Early Pennsylvanian of Oklahoma–Possible Ancestor to the Permian Richthofenoid Brachiopods

1996 ◽  
Vol 70 (S46) ◽  
pp. 1-25
Author(s):  
Patrick K. Sutherland
Keyword(s):  
New Species ◽  
Early Development ◽  
New Genus ◽  
Unique Feature ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Shell Material ◽  
Southern Oklahoma ◽  
Upward Growth ◽  
First Time

Ardmosteges orchamus, new genus, new species, from the Early Pennsylvanian Morrowan sequence in southern Oklahoma, is characterized by a well-developed early aulostegid stage, followed by a fully developed richthofenoid stage. It differs markedly from any previously described genus. The nature of the early development, with a rounded aulostegid shell and a prominent interarea in the ventral valve, suggests that it evolved from the Aulostegidae. The most unique feature of Ardmosteges is that it shows for the first time, a documented mechanism for the addition of new shell material above the hinge area in the ventral valve in shells that proceeded to develop a richthofenoid cone. Shell layers were extended posteriorly from the margins of the ventral valve onto the interarea of that valve indicating that the mantle grew onto the hinge area from each side. This irregular and asymmetrical process gradually filled the space above the hinge and was followed by the upward growth of a typical richthofenoid cone. In the proposed development of the Permian richthofenoids from Ardmosteges it is postulated that the characteristic interarea of Ardmosteges was suppressed during extreme development of a distinctly cylindrical cone.Ardmosteges provides the missing link between the Aulostegidae and the Richthofenoidea. Its characters are primitive compared to those of the Permian richthofenoids but it is similar in having a deeply recessed opercular dorsal valve, protective spines in the vestibule above the dorsal valve, and in being attached by rhizoid spines.

New Lower Ordovician Brachiopods from the Llandeilo-Llangadock District

1949 ◽  
Vol 86 (4) ◽  
pp. 226-238 ◽  
Author(s):  
Alwyn Williams
Keyword(s):  
Ventral Valve ◽  
Dorsal Valve ◽  
Hinge Line ◽  
Lower Ordovician

External characters.—Plano-convex with a moderately deep ventral valve and a plane to slightly convex dorsal valve. Outline is semi-oval with the greatest width just anterior to the long straight hinge-line. Ventral interarea, wide, long, apsacline, dorsal interarea, anacline.

scholarly journals A soft-bodied lophophorate from the Silurian of England

2010 ◽  
Vol 7 (1) ◽  
pp. 146-149 ◽  
Author(s):  
M. D. Sutton ◽  
D. E. G. Briggs ◽  
David J. Siveter ◽  
Derek J. Siveter
Keyword(s):  
The Body ◽  
Molecular Evidence ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Significant Element ◽  
Stem Group

Soft-bodied taxa comprise an important component of the extant lophophorate fauna, but convincing fossils of soft-bodied lophophorates are extremely rare. A small fossil lophophorate, attached to a brachiopod dorsal valve, is described from the Silurian (Wenlock Series) Herefordshire Lagerstätte of England. This unmineralized organism was bilaterally symmetrical and comprised a subconical body attached basally to the host and partially enclosed by a broad ‘hood’; the body bore a small, coiled lophophore. Where the hood attached laterally, there is a series of transverse ridges and furrows. The affinities of this organism probably lie with Brachiopoda; the hood is interpreted as the homologue of a dorsal valve/mantle lobe, and the attachment as the homologue of the ventral valve and/or pedicle. The ridges are arranged in a manner that suggests constructional serial repetition, indicating that they are unlikely to represent mantle canals. Extant brachiopods are not serially structured, but morphological and molecular evidence suggests that their ancestors were. The new organism may belong to the brachiopod stem group, and might also represent a significant element of the Palaeozoic lophophorate fauna.

The brachiopod family Gemmellaroiidae

1993 ◽  
Vol 67 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Richard E. Grant
Keyword(s):  
New Species ◽  
Type Species ◽  
New Genus ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Conical Shape ◽  
Normal Manner ◽  
The Family ◽  
Hinge Axis

Gemmellaroia is a conical Permian brachiopod that traditionally has been assigned to the superfamily Richthofeniacea [sic] on the basis of its conical shape and a myocoelidium in the ventral valve. It has been considered unique among brachiopods in opening the shell by having the dorsal valve move straight up, rather than rotating around a hinge axis. Evidence is adduced to warrant transfer of the genus and its cohorts to the superfamily Derbyoidea (totally unrelated to the richthofenioids) and to demonstrate that it was capable of opening in the normal manner, rotating the dorsal valve about a hinge axis. Members of the family include Gemmellaroia (Cossmann, 1898), Loczyella Frech, 1901, Tectaria (Likharev, 1928), and Cyndalia (new genus with type species C. rudistiformis new species).

Phylogeny and revision of Messatoporus Cushman (Hymenoptera, Ichneumonidae, Cryptinae), with descriptions of sixty five new species

Zootaxa ◽  
2013 ◽  
Vol 3634 (1) ◽  
pp. 1-284 ◽  
Author(s):  
BERNARDO F. SANTOS ◽  
ALEXANDRE P. AGUIAR
Keyword(s):  
New Species ◽  
Morphological Characters ◽  
Valid Species ◽  
Gradual Transition ◽  
Ventral Valve ◽  
Dorsal Valve ◽  
Distribution Maps ◽  
Character Set ◽  
Posterior Area ◽  
New Distribution

The large New Worldgenus Messatoporus Cushman is diagnosed, redefined, described, and its species revised. A total of 89 valid species are recognized, of which 65 are described as new. All previously known species are redescribed and illustrated. The following synonyms are proposed: M. jocosus (Provancher) and M. rufiventris Cushman under M. discoidalis (Cresson), syn. nov. and M. tricolor (Szépligeti) under M. variegatus (Szépligeti) syn. nov. The following new species are proposed: M. advenus, M. albiaterartus, M. allomeros, M. amarelus, M. amazonensis, M. amplithorax, M. andinus, M. anepomius, M. apiopharkis, M. argentinus, M. atlanticus, M. atrifoveus, M. aurantius, M. badius, M. basiflavus, M. bennetii, M. bicolor, M. bimaculatus, M. campanulatus, M. caxiuanensis, M. citreocephalus, M. complexifemur, M. concavivenus, M. convexus, M. copiosus, M. depressifrons, M. dialeipsis, M. dissidens, M. dominicanus, M. elektor, M. ellipsicavus, M. euryoikos, M. igneus, M. interceptus, M. keraiopetalus, M. laevilatus, M. latissulcus, M. longicaudis, M. longitergus, M. lordos, M. lunatus, M. maculiscus, M. matucanus, M. nigriangulatus, M. nigriscapus, M. nigriscutus, M. occidentalis, M. opacus, M. orientalis, M. paeneater, M. pallidus, M. paradoxus, M. paralissonotus, M. pleuriflavus, M. semialbiventris, M. semiaurantigaster, M. subalaris, M. tenuiorbis, M. tenuissimus, M. teutonicus, M. titans, M. unidentatus, M. unimaculatus, M. versicolor and M. xanthogaster spp. nov. As well, a lectotype is designated for M. townesi Alayo and Tzankov, and Messatoporus nigrispina (Cameron) is transferred to Prosthoporus Porter, comb. nov.. A key to species based on both sexes is also presented, and new distribution records and distribution maps are provided. The validity and relationships of the genus are investigated cladistically using 162 morphological characters for 27 species of Messatoporus and 105 outgroup taxa. Tree search was conducted using TNT under implied weighting, with values of 1–6 for the concavity constant (K). All analyses recovered Messatoporus as a monophyletic group, supported by 7–11 synapomorphies. The results also support the monophyly of the six studied genera of Osprynchotina, in a clade including also Dotocryptus Brèthes. Messatoporus is diagnosed by the combination of the following features: apicolateral corners of clypeus projected; mandible long and tapered, ventral tooth much shorter than dorsal one or indistinct; transverse sulcus at base of propodeum long and shallow; anterior margin of propodeum concave; posterior area of propodeum almost always transversely wrinkled; first metasomal spiracle placed approximately on midlength; median dorsal carina of first metasomal segment absent; ovipositor basally cylindrical, apically depressed, with ventral valve enclosing completely dorsal valve as a sheath. A second analysis including all species of the genus was performed SANTOS & AGUIAR 4 · Zootaxa 3634 (1) © 2013 Magnolia Press to evaluate the phylogeny at the genus level. The character set for that analysis included 104 characters considered of phylogenetic importance within the genus, and used the same tree searching protocol as the first one. A distinct and gradual transition is detected, from species more similar to the remaining Osprynchotina to a significantly different morphotype with several convergences with the Gabuniina. These convergences are interpreted as adaptations to host location and substrate perforation, and may be related to use of more deeply concealed hosts.

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