An interesting case of close external similarity (homoeomorphy) is revealed by the study of an Early Jurassic rhynchonellide brachiopod from Livari, Rumija Mountain, southern Montenegro. Shell ...microstructure was used as the primary diagnostic tool, applied before serial sectioning to study internal characters. Sepkoskirhynchia sphaerica gen. et sp. nov. is erected based on the presence of coarse fibrous shell microstructure and hamiform crura. Because of these primary diagnostic characters, the new genus is placed in the rhynchonellide family Basiliolidae. The shell microstructure of the new taxon is characterised by a differentiated secondary layer of coarse fibrous type. The fibres are rhombic or subquadrate in cross-section, in the external sublayer they are 55-60 μm wide and 40-50 μm thick, internally other sublayers are thinner with fibres 35-40 μm wide and 20-25 μm thick. The main character that distinguishes the new genus is that the secondary layer is differentiated into several sublayers, while in externally homoeomorphic Soaresirhynchia it is built of a single layer. The new taxon was found in the brachiopod and crinoidal limestones from the periplatform facies of the Dinaric Carbonate Platform.
An upper Pliensbachian-Aalenian brachiopod succession is reported from Ponor Mountain, Western Balkan Mountains, Bulgaria. This includes nine species (6 rhynchonellides and 3 terebratulides) from ...eight genera. A new genus Bulgariarhynchia and two new species, Bulgariarhynchia ponorensis and Capillirhynchia brezenensis, are formally described. A single species Homoeorhynchia ? aff. prona was found in the upper Pliensbachian. Most of the brachiopods derived from the Toarcian-Aalenian interval, and comprise: Pseudogibbirhynchia jurensis, Rhynchonelloidea angulata, Globirhynchia subobsoleta, Sphaeroidothyris uretae, Lobothyris? hispanica, and Telothyris jauberti. The brachiopod assemblages were dated using coeval ammonite biostratigraphy. Both ammonites and brachiopods display clear northwest European affinities. The new brachiopod taxa are considered autochthonous for the Balkan Mountains. Three biofacies (BF2, BF3 and BF5) were recognised and implied alternating suboxic to anoxic bottom water conditions. A few geochemical proxies are indicative of the early Toarcian Oceanic Anoxic Event (T-OAE) in the stratigraphic column. The main T-OAE pulse was fixed at the coeval positive δ
13
C and negative δ
18
O excursions, as well as increases in Hg/TOC ratios and redox-sensitive elements. The late Pliensbachian-earliest Toarcian time span was found to be the most hostile for the brachiopods. Above it, brachiopods lived in less stagnant environments.
urn:lsid:zoobank.org:pub:22EF76B7-6A4B-4E54-A5BC-38C87125253E
The Middle Jurassic terebratulide brachiopods from the Jordan Valley, northwestern Jordan, are herein revised and systematically described and new taxa are added to the faunal list. A new genus and ...species Jordanithyris ardainensis gen. et sp. nov., is introduced from the upper Bathonian (Hamam Formation) and lower Callovian (Mughanniyya Formation) of the Arda section. In the upper Bathonian Hamam Formation (consisting of limestone, dolomite, alternating sandstone, and marlstone beds), Ptyctothyris quillyensis occurs. The assemblage Arabatia bihinensis, Ectyphoria sinaiensis, Ptyctothyris quillyensis, Dorsoplicathyris dorsoplicata, and Tubithyris jurayfahiensis is recorded in the lower Callovian limestone beds with marlstone interbeds of the Mughanniyya Formation. Brachiopods of the Jordanian Hamam and Mughanniyya formations can be correlated with the fauna of the Aroussiah Formation in Sinai and the Zohar and Matmor formations in southern Israel. The sedimentary environment is interpreted as the protected shallow inner shelf, and nutrient rich habitat resulting in high faunal diversity. The high degree of endemism of this fauna is yet another confirmation of the representative pronounced Middle Jurassic endemism along the southern Tethyan margin of the Ethiopian Province.
Middle Jurassic terebratulide brachiopods from the Jordan Valley are herein described and a new taxon is added to the previous faunal list. The Callovian rocks (Mughanniyya Formation) of the Tel el ...Dhahab section have yielded the following terebratulide taxa: Sphriganaria capax, S. costata, S. costellata, S. curtirostra, S. expansa, S. irregularis, S. subcircularis, S. nasuta, S. sp. 1, and S.? sp. 2. A new species Sphriganaria anyamiae sp. nov. is formally described herein. Internal characters of Sphriganaria costata, S. expansa, and S. nosuta have been studied. On the basis of shell microstructure, crural bases, outer and inner hinge plates were differentiated and defined for the first time in the genus Sphriganaria. The secondary layer is homogeneous built of very fine fibres, predominantly anisometric-like in cross-section, 25‒40 μm wide and 8‒15 μm thick. The Callovian Mughanniyya Formation of northwest Jordan is dominated by highly fossiliferous limestones intercalated with marlstone beds with very diverse brachiopod fauna, deposited in shallow, low-energy waters very near the equator. A paleobiogeographic interpretation of the brachiopod faunas in the Ethiopian Province suggests that brachiopods migrated from the north in the Early Jurassic and later became isolated for the remainder of the period.
Middle Jurassic terebratulide brachiopods from the Jordan Valley are herein revised and new taxa are added to the previous faunal list. The Callovian rocks (Mughanniyya Formation) of the Tel el ...Dhahab section has allowed recognising two new terebratulide taxa: Kutchithyris simoni sp. nov. and Trigonithyris wilsoni sp. nov, which are formally described herein. Additionally, three terebratulide species: Bihenithyris barringtoni, Ptyctothyris daghaniensis, and Sphriganaria cardioides are reported for the first time from Jordan, all of them recorded together Bihenithyris weiri, a more widespread taxa in the Ethiopian Province. The Callovian Mughanniyya Formation of northwest Jordan is dominated by highly fossiliferous limestone beds intercalated with marlstones deposited on a low angle carbonate ramp in a shallow protected, inner shelf setting. Brachiopods of the Jordanian Mughanniyya Formation can be correlated with the Callovian brachiopod faunas of the Aroussiah Formation in Sinai and the Zohar and Matmor formations in southern Israel. The high degree of endemism of the terebratulide brachiopods under study here is yet another confirmation of the pronounced Middle Jurassic endemism along the southern Tethyan margin of the Ethiopian Province.
Cenoceras intermedius (J. Sowerby) is one of the most widespread species among the Early Jurassic nautiloid fauna and its geological range still controversial up to the present day. The specimen of ...Cenoceras intermedius from the sandy bioclastic limestones of Rgotina (Getic nappe of eastern Serbia), is a large half conch representing the phragmocone. Viewing our findings in light of previous results suggests the main morphological changes occurred during the ontogenetic evolution. The coiling starts with a round-square whorl section, to become almost quadrangular (penultimate whorl) and trapezoidal-triangular for the last one. Moreover, the siphuncle foramen moves within the septum towards the venter border from a slight upper position against the centre in the inner whorls. It exhibits a typical suture line for the genus Cenoceras with two saddles and three lobes. This finding certainly extends the geological range of the species to after the Sinemurian contrary to several earlier works that confined it only to this stage. This assertion is based on the accurate assignment of the nautiloid-bearing bed of Rgotina to the early Pliensbachian by the index species Uptonia jamesoni. The Serbian specimen supports the species' palaeobiogeographic widespread range within the north-western margin of the Neo-Tethys Ocean framework.
The systematic position of the Early Jurassic brachiopod genus Arzonellina (Sulser) based on new material from Montenegro assigned to Arzonellina stachei (Bittner) and the type species Arzonellina ...exotica (Sulser), known from southern Switzerland, are discussed. Based on the unusual internal characters, hitherto unknown in detail, the new family Arzonellinidae is erected within the order Terebratulida. An emended diagnosis for the genus Arzonellina is given. The external and internal characters of Arzonellina stachei (Bittner) are described; the specimens came from talus blocks of white recrystallised limestone (rudstones) from Smokovac, southern Montenegro. Arzonellina was originally described from Arzo in the Southern Swiss Alps; the Dinaric Carbonate Platform of Montenegro can now be added to its palaeobiogeographic distribution, with both occurrences located on the Apulian microplate. Associated fauna at both Arzo and Smokovac point to a Sinemurian age for Arzonellina.
An increase in interest to the Pliensbachian palaeobiogeography of Europe makes urgent consideration of palaeontological data from the regions not taken into account earlier. The representative ...bivalve records of eastern Serbia and some other European territories (a total of 88 species belonging to 42 genera) permits quantitative assessment of similarity of the Pliensbachian faunas with the Jaccard Index, the Czekanowski's Quantified Coefficient, and the Gower Index. It is established that the Pliensbachian bivalves of eastern Serbia are most similar to those of Bulgaria and France; the similarity to several other European territories is moderate and surprisingly almost the same. The similarity of the Pliensbachian bivalves between the Danubian and Infra-Getic tectonic units constituting the territory of eastern Serbia is significant. The interpretation of the results of this study in the light of the palaeobiogeographical reconstructions implies that the Northwestern European biochore is heterogeneous because of different similarity of the regions within this unit. The bivalve fauna of Portugal is relatively more distinct from the other territories considered in this study (Germany, England, France, etc.). Eastern Serbia was located at or near the transition between Northwestern European (Boreal) and Mediterranean (Tethyan) biochores, and its bivalve fauna is the most similar to those of Bulgaria and France. The results of the present study also show that ammonites and especially brachiopods are more suitable tools for the Pliensbachian palaeobiogeographical reconstructions than bivalves.
•Strong similarity of Pliensbachian bivalves of eastern Serbia, Bulgaria and France•Similar Pliensbachian bivalve assemblages of Danubian and Infra-Getic units•Location of eastern Serbia at or near Boreal-Tethyan transition
Quantitative assessment of regional diversity patterns reveals trajectories of faunal development on the basin scale and helps to understand its dependence on palaeoenvironmental changes, ...global-scale biotic evolution, and major events in the history of the Earth. A total of 86 species, 50 genera, 18 families, and 9 superfamilies of Early and Middle Jurassic brachiopods are established in the Getic and Danubian tectonic units of eastern Serbia. Compilation of their stratigraphic ranges allows analysis of their total diversity, number of appearances and disappearances, and turnovers. In both units, brachiopods radiated rapidly in the Early Pliensbachian. Then, their diversity declined, and these fossils disappeared. A new radiation took place in the Late Bajocian, and brachiopods remained diverse until the end of the Bathonian. They disappeared before the Callovian in the Getic Unit and in the Early Callovian in the Danubian Unit. The Early Pliensbachian radiation was significantly stronger than the Late Bajocian at the level of species; the strength of these radiations was more or less comparable at higher taxonomic levels. The strength of turnovers among brachiopods differed through geological time. The composition of the Middle Jurassic brachiopod assemblages was more or less stable. Regional shoreline shifts, basin depth changes, palaeobiogeographical changes, and plate tectonic re-organizations were possible controls on regional patterns of brachiopod diversity dynamics. However, the latter also reflects some diversity patterns documented globally and in some other regions (the Bakony Mountains, the Swiss Jura Mountains, and the Northern Caucasus).
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•Early Pliensbachian and Late Bajocian brachiopod radiations in eastern Serbia•Diversity dynamics did not differ between Getic and Danubian tectonic units.•Early Toarcian mass extinction influenced possibly on regional brachiopod assemblages.•Regional diversity dynamics depended significantly on palaeoenvironmental changes.•Regional diversity dynamics reflected some global brachiopod diversity patterns.
Rich brachiopod assemblages are known from the Lower and Middle Jurassic deposits of the Danubian and Getic tectonic units (eastern Serbia). A quantitative assessment of the relevant palaeontological ...data can shed light on the relationship of these units in the palaeospace. In the present study, the brachiopod assemblages from the Danubian and Getic tectonic units are compared with similarity indices (the Jaccard similarity of species, genera, families, and superfamilies, and the Czekanowski and Gower similarity of the genus–species, family–species, and superfamily-species diversity structures). This analysis is applied to five geological time slices when brachiopods flourished regionally, namely the Early Pliensbachian, the Late Bajocian, the Early Bathonian, the Middle Bathonian, and the Late Bathonian. Generally, the values of the indices imply moderate similarity. The similarity was significantly lower in the Middle Jurassic relatively to the Early Jurassic. The similarity of the Early Pliensbachian brachiopods of the Danubian and Getic tectonic units was significant relatively to the similarity between some European regions. The documented decrease in the similarity through the geological time can be explained by the increase in the global palaeobiogeographical differentiation in the Middle Jurassic.
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•E Pliensbachian, L Bajocian, E, M, L Bathonian brachiopods from eastern Serbia•Moderate similarity of brachiopods between Danubian and Getic tectonic units•Similarity decreased significantly in M Jurassic relatively to E Jurassic.•Global palaeobiogeographical differentiation as trigger of similarity decrease
