Mena Schemm-Gregory

Jurassic Rhynchonellide Brachiopods from the Jordan Valley

Jurassic rhynchonellide brachiopods from the Jordan Valley are herein revised and new taxa are added to the faunal list. In this study of Jurassic rhynchonellides from Wadi Zarqa, northwestern Jordan, we recognize the following taxa: Eurysites rotundus, Cymatorhynchia quadriplicata, Daghanirhynchia triangulata, D. angulocostata, Pycnoria magna, Schizoria elongata, and Schizoria cf. intermedia. The following new taxa are described: Daghanirhynchia susanae sp. nov. and Amydroptychus markowitzi sp. nov. The Middle Jurassic Mughanniyya Formation of northwest Jordan is dominated by limestone beds. The sedimentary environment is interpreted as neritic, light, and nutrient-rich resulting in high faunal diversity. The high rhynchonellide endemism of this fauna is yet another confirmation of pronounced Middle Jurassic endemism along the southern Tethyan margin of the Ethiopian Province. Brachiopods of the Jordanian Mughanniyya Formation can be correlated with the fauna of the Aroussiah Formation in Sinai and the Zohar and Matmor formations in Southern Israel.

Taphonomy and palaeoecology of the green Devonian gypidulid brachiopods from the Aferdou El Mrakib, eastern Anti-Atlas, Morocco

On Aferdou El Mrakib, a large reef mound in the Maïder region (Anti-Atlas, Morocco), thick-shelled gypidulids of two genera are locally very abundant. Like Stringocephalus in the shallow water limestone formations in Germany, these Moroccan brachiopods of the genera Devonogypa and Ivdelinia often display greenish shells. By analysing these shells by EDX, it turned out that the colour was possibly caused by impurities of Fe2+-ions. The concentration varies, indicating that the colour is less dependent on the concentration than on shell thickness, because only the thickest parts of the shells appear green and thin-shelled forms never display the green colour. There is also some indication that the Fe content increases towards deeper shell layers (further away from the surface). In addition, we examined the quality and spatial distribution of sublethal injuries in over 200 specimens of Devonogypa and Ivdelinia. Shape, spatial distribution on the shells, and abundance of the sublethal injuries support the hypotheses that (1) the injuries had several causes, (2) some of these were inflicted by predators, probably cephalopods, and (3) many fractures and deformations might have been caused by the brachiopod shells hitting each other in dense populations in agitated water. The existence of dense clusters, built by the association of members of both genera or of only one taxon, is corroborated by the patchy occurrence of these brachiopods.

Revised Taxonomy and Autecology for the Brachiopod Genus Ambocoelia in the Middle and Late Devonian Northern Appalachian Basin (USA)

Abstract Brachiopods belonging to Ambocoelia occur ubiquitously in Middle and Upper Devonian strata of the northern Appalachian Basin. Originating during the Eifelian, Ambocoelia umbonata persisted through numerous biocrises, but went extinct during the late Frasnian Kellwasser Crisis. Ambocoelia umbonata var. gregaria, the only other form of this genus that is present within the New York Devonian succession, originated around the time of the Kellwasser Crisis and persisted locally into at least the latest Famennian. Examination of syntypic material of A. umbonata var. gregaria has resulted in the taxonomic revision of this form and elevation to Ambocoelia gregaria. Comparison of ontogenetic stages and environmental preferences of A. umbonata and A. gregaria suggests that the latter exhibits a paedomorphic morphology that may have evolved from A. umbonata through neoteny. Furthermore, these comparisons also give new autecological insights for Ambocoelia, suggesting that A. umbonata was capable of living i...

A New Givetian Athyridid Species from Northwest Africa Discovered By Three-Dimensional Reconstruction of Shell Morphology of Internal Molds

Abstract A new method of analyzing the internal shell morphology (including the complete brachidium of internal molds) of articulated brachiopod shells through the use of serial sections and digital three-dimensional reconstruction is presented. The method introduced is essential for the study of internal shell structures such as brachidia, or cardinalia, if computed tomography (CT) is not suitable or if a CT scanner is not available. A new species of Athyris from Givetian beds of Northwest Africa was selected to exemplify this method. To compare this species with figured serial sections in the literature, two-dimensional drawings of grinding surfaces are provided. Athyris africana n. sp. is only preserved as internal molds of articulated specimens. The new species is included in the evolutionary lineage of the group around Athyris concentrica. The faunal assemblage of A. africana n. sp. shows affinities to Western European and North American brachiopod faunas.

A Jurassic (Bathonian-Callovian) Daghanirhynchia brachiopod fauna from Jordan

A Jurassic (Bathonian-Callovian) brachiopod fauna from Jordan consists of seven rhynchonellid species all belonging to the genus Daghanirhynchia of which two are new: Daghanirhynchia rawyaensis and D. jordanica. Emended diagnoses are given for Daghanirhynchia daghaniensis and D. macfadyeni. Additional taxa described include Daghanirhynchia angulocostata, D. susanae and D. triangulata. Threedimensional reconstructions illustrate the internal morphology of the articulated shells for the first time in this genus. The material studied herein was collected from Wadi Zarqa in northwestern Jordan, almost due north of the Dead Sea, and to the east of the Rift Valley. Most species seem to be geographically restricted within the Jurassic Ethiopian Province, however specimens from Somalia and Ethiopia are larger in size than in other parts of the Province and shell size increases in stratigraphically younger specimens. The occurrence of Daghanirhynchia in India is the only appearance of the genus outside the Ethiopian Province.

Catalogue of the Krantz Brachiopod Collection at the Science Museum of the University of Coimbra (Portugal).

The specimens of the Krantz Brachiopod Collection of the Science Museum of the University of Coimbra (Portugal) are revised according to modern taxonomy and presented in systematic order according to inventory number, type species, figured representative and, as far as possible, detailed information regarding stratigraphy and collecting localities. The collection itself contains 170 lots yielding 474 specimens and representing 15 of the 27 brachiopod orders. The material comes from Europe, Russia, and the United States and represents all Palaeozoic and Mesozoic periods; the majority of the brachiopods are from the Devonian of Germany, mostly collected in classical outcrops from the Rhenish Slate Mountains, many of which are no longer accessible.

A new delthyridoid spiriferid genus from the Dra Valley, Morocco, and its phylogenetic affinities (Brachiopoda, Lower Devonian)

Multiplicatispirifer, a new delthyridoid brachiopod genus with a gently divergent capillate micro-ornamentation and bifurcating costae on flanks, sulcus and fold, has been identified in the Mdâouer-el-Kbîr Formation of the Dra Valley (southern Anti-Atlas, Morocco). Its type speciesMultiplicatispirifer foumzguidensis n. gen., n. sp., at present the only species of this genus, is described. This form has hitherto been determined asFimbrispirifer orStruveina by various authors. In this work, the new genus is compared with the multiplicate and capillate spiriferid genera with bifurcating costae which also have costae in the sulcus and on the fold:Costispirifer andPerryspirifer from North America,Elymospirifer from South China,Borealispirifer from Asia andMultispirifer from Central Europe. The relation ofMultiplicatispirifer to the fimbriateFimbrispirifer, Struveina andVandercammenina, from which it is distinguished by its capillate micro-ornamentation, is discussed. The new genus is hitherto only known from the Moroccan southern Anti-Atlas. Its colsest relatives, taxa ofCostispirifer, occur in the Eastern American Realm (Gaspé, Canada and the eastern United States) and the Nevada Province (western United States).Multiplicatispirifer occurrences are restricted to the Lower/Upper Emsian boundary interval (upper Lower Devonian). The reasons for a possible migration corridor between North America and North Africa before Emsian time are discussed.KurzfassungIn der Mdâouer-el-Kbîr-Formation in der Dra-Ebene (südlicher Anti-Atlas, Marokko) wurde eine neue delthyridoide Brachiopoden-Gattung identifiziert.Multiplicatispirifer ist durch eine leicht divergierende kapillate Mikrostruktur und bifurkierende Rippen auf den Flanken, im Sinus und auf dem Sattel charakterisiert. Die TypusartMultiplicatispirifer foumzguidensis n. gen., n. sp., zur Zeit die einzige bekannte Art dieser Gattung, wird beschrieben. Bisher wurde diese Form von unterschiedlichen Bearbeitern zuFimbrispirifer oderStruveina gestellt. In der vorliegenden Arbeit wird die neue Gattung mit multiplikaten und kapillaten Spiriferen verglichen, die bifurkierende Rippen wie auch einen berippten Sinus und Sattel aufweisen:Costispirifer undPerryspirifer aus Nord-Amerika,Elymospirifer aus Süd-China,Borealispirifer aus Asien undMultispirifer aus Mittel-Europa. Die Verwandtschaft vonMultiplicatispirifer zu den fimbriaten GattungenFimbrispirifer, Struveina undVandercammenina, von denen sie sich durch ihre kapillate Mikrostruktur unterscheidet, wird diskutiert. Die neue Gattung ist bisher nur aus dem marokkanischen Anti-Atlas bekannt. Ihre nächsten Verwandten, Taxa vonCostispirifer, treten im ostamerikanischen Faunenreich (Gaspé, Kanada, und Ostküste der Vereinigten Staaten) sowie in der Faunenprovinz Nevada (westliche USA) auf. Das Vorkommen vonMultiplicatispirifer ist auf den Grenzbereich Unter-/Ober-Emsium beschränkt (oberes Unter-Devon). Die Gründe für einen möglichen Migrations-Korridor zwischen Nord-Amerika und Nord-Afrika zur Zeit des Emsiums werden diskutiert.

Talexirhynchia , a new rhynchonellid genus from the Jurassic Ethiopian Province of Jordan

A new genus and species of a rhynchonellide brachiopod from the Jurassic of Jordan, Talexirhynchia kadishi gen. et sp. nov., is described. The specimens were collected from the Mughanniyya Formation (Callovian) of Wadi Zarqa from alternating claystones, siltstones, and marly limestones with minor dolomite, dolomitic limestone, and coquinas that represent the upper part of the Jurassic sequence in Jordan. The environment of deposition was neritic; food supply and light were unlikely to have been limiting factors. The specimens are related to Ethiopian-Somali taxa and are consistent with the endemism that characterizes the rhynchonellide brachiopod faunas of the Jurassic Ethiopian Province. Specimens of Talexirhynchia lived with the umbo in an upright position directed toward the seafloor or with the dorsal valve slightly above the ventral valve. Juveniles were attached to the seafloor by the pedicle; carbonate shell material as well as other debris scattered on a limy substrate, such as shells and rocks, could have served as an attachment site for juveniles. With increasing growth, the loss of the pedicle and a semi-infaunal position resulted in an increasingly incurved ventral umbo that concealed the foramen.KurzfassungEine neue rhynchonellide Brachiopoden-Gattung und––Art, Talexirhynchia kadishi gen. et sp. nov., aus dem Jura von Jordan wird beschrieben. Die Exemplare wurden in der Mughanniyya Formation (Callovium) von Wadi Zarqa gesammelt und kommen in abwechselnden Lagen von Tonsteinen, Siltsteinen und mergeligen Kalken mit geringen Anteilen an Dolomiten, dolomitischen Kalken und Coquinas vor, die die jüngsten jurassischen Ablagerungen Jordaniens repräsentieren. Die Schichten wurden in neritischer Fazies abgelagert, die wahrschein reich an Nahrungsangebot und Licht durchflutet war. Die gesammelten Exemplare sind mit äthiopischen-somalischen Taxa verwandt und spiegeln den Endemismus wieder, der die rhynchonellide Brachiopodenfauna der jurassischen Äthiopischen Provininz charakterisiert. Vertreter von Talexirhynchia leben in senkrechter Position mit der Dorsalklappe gering höher als die Ventralklappe und dem Wirbel zum Meeresboden hin gerichtet. Juvenile Exemplare waren mit dem Stiel an Schalenmaterial und anderem Schuttdebris, z.B. Schalen oder Steine, der auf dem Meeresboden verteilt vorlag, festgehaftet. Mit zunehmender Größe änderte sich die Lebensweise in eine semi-infaunale Position, die zu einem Verlust des Stieles und eines ständig weiter gebogenen ventralen Wirbels bis hin zu vollständigen Bedeckung des Stiellochs, führte.

Correlation of the Middle Jurassic (Callovian) Formations Across the Dead Sea Rift

We have correlated the highest of the Middle Jurassic units exposed on both sides of the Dead Sea Rift (DSR) in Jordan, Israel, and adjacent Egypt. Because the scarcity of cosmopolitan ammonites renders correlation of these units within the standard biostratigraphic time scale difficult, we compared the brachiopod and molluscan faunas in order to constrain the ages of Jurassic formations in the Levant. The Callovian Mughanniyya Formation in the Zarqa–Arda area of northwest Jordan, east of the DSR, is compared with the Zohar and Matmor formations of the Negev (Israel) and Gebel Minshera (Sinai, Egypt), west of the DSR, as well as with the Arroussiah Formation of Gebel El-Maghara (northern Sinai, Egypt). The Mughanniyya Formation is correlative with the lowermost part of the Zohar Formation in the Negev, which is coeval with the lowermost part of the Arroussiah Formation in Sinai (Egypt).

A NEW SPECIES OF CYRTOSPIRIFER (BRACHIOPODA) FROM THE MIDDLE DEVONIAN OF THE WESTERN SAHARA (NORTHWESTERN AFRICA)

A new species of Cyrtospirifer is described from the Middle to Upper Givetian of the Western Sahara (Northwest Africa). Cyrtospirifer tindoufensis new species differs in its smaller number and coarser medial and flank plications and equibiconvex shell profile from the other Givetian species of Cyrtospirifer that all occur in Europe and to which the new species probably gives rise. The new implications of the proposed phylogeny of the earliest cyrtospiriferids and their origin from the Western Sahara are discussed. The palaeogeographic distribution of the cyrtospiriferids during the Givetian and Frasnian is shown and its migration ways are described considering the global transgression and regression cycles.