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Parent H.,National University of Rosario | Weis R.,Section Paleontologie | Mariotti N.,University of Rome La Sapienza | Falahatgar M.,Payame Noor University | And 2 more authors.
Rivista Italiana di Paleontologia e Stratigrafia | Year: 2013

Ammonites and belemnites from a Middle Jurassic section at Telma-Dareh (Alborz Mountains, northern Iran) are described. The lithology of the studied section consists of an alternation of marls and limestones attributed to the Dalichai Fm., overlying the top of the Shemshak Fm. (sandstones) and underlying the Lar Fm. (limestones). Fossils are rather abundant but concentrated in ten scattered levels, ranging from the Aalenian (Scissum-Murchisonae zones) up to the Bajocian. Ammonites (Tmetoceras scissum, Leioceras cf.comptum, Ludwigia cf. murchisonae, Onychoceras} sp., and Leptosphinctes sp.), belemnites (Brevibelus breviformis, Holcobelus cf. muniert) and bivalves are the most abundant and well-preserved fossils; accessory elements are scarce brachiopods and gastropods. The palaeobiogeographic affinities of the belemnite fauna is Subboreal-Submediterranean, whereas the ammonites have Submediterranean-Tethyan affinities. The Aalenian age of the lower part of the Dalichai Fm. at Telma-Dareh differs from the Bajocian age attributed by other authors to this formation in other localities.

Weis R.,Section Paleontologie | Mariotti N.,University of Rome La Sapienza | Wendt J.,University of Tubingen
Palaontologische Zeitschrift | Year: 2015

The rare belemnite Rhabdobelus avena (Dumortier in Mayer, 1869) is described for the first time from Tethyan sediments of the Central Apennines (Bosso river valley) and western Sicily (Rocca Busambra). These records extend the stratigraphic occurrence of Rhabdobelus Naef, 1922 from the Upper Toarcian to the uppermost Lower Bajocian. Systematic review of the genus Rhabdobelus enables recognition of five taxa (R. avena, R. donovani, R. aff. donovani, R. exilis, R. serpulatus) and their respective phylogenetic relationships; furthermore, lectotypes are designated for R. avena, R. donovani, and R. serpulatus, and a neotype is designated for R. exilis. The distribution pattern of rhabdobelid belemnites and substantial changes in their rostrum morphology suggest adaptive radiation during the Aalenian and Early Bajocian, with a trend from European shelf environments to Tethyan hemi-pelagic habitats. © 2014, Springer-Verlag Berlin Heidelberg.

O'Hara T.D.,Khan Research Laboratories | Hugall A.F.,Khan Research Laboratories | Thuy B.,Section Paleontologie | Moussalli A.,Khan Research Laboratories
Current Biology | Year: 2014

Our understanding of the origin, evolution, and biogeography of seafloor fauna is limited because we have insufficient spatial and temporal data to resolve underlying processes [1]. The abundance and wide distribution of modern and disarticulated fossil Ophiuroidea [2], including brittle stars and basket stars, make them an ideal model system for global marine biogeography if we have the phylogenetic framework necessary to link extant and fossil morphology in an evolutionary context. Here we construct a phylogeny from a highly complete 425-gene, 61-taxa transcriptome-based data set covering 15 of the 18 ophiuroid families and representatives of all extant echinoderm classes. We calibrate our phylogeny with a series of novel fossil discoveries from the early Mesozoic. We confirm the traditional paleontological view that ophiuroids are sister to the asteroids and date the crown group Ophiuroidea to the mid-Permian (270 ± 30 mega-annum). We refute all historical classification schemes of the Ophiuroidea based on gross structural characters but find strong congruence with schemes based on lateral arm plate microstructure [3, 4] and the temporal appearance of various plate morphologies in the fossil record. The verification that these microfossils contain phylogenetically informative characters unlocks their potential to advance our understanding of marine biogeographical processes. © 2014 Elsevier Ltd.

Thuy B.,Section Paleontologie | Marty D.,Paleontologie A16 | Comment G.,Paleontologie A16
Swiss Journal of Geosciences | Year: 2013

Although much effort has been put into attempts to unravel the Mesozoic ophiuroid fossil record, surprisingly little attention has been paid to the geological history of family-level compositions of brittle star assemblages. Here, we describe new ophiuroid material from the Late Oxfordian Bure Member as exposed in a construction site along the federal Highway A16 (Transjurane Highway) near Boncourt-Queue au Loup (Swiss Jura Mountains). The remains are exceptionally well preserved and partially articulated, enabling detailed morphological observations at a level comparable to Recent material. Three species are identified; they are here shown to display unequivocal affinities with extant ophiuroid lineages. The assemblage comprises a new ophiacanthid genus and species, Juracantha hottingeri, which is closely related to extant Ophientrema, an ophiolepidid close to extant Ophiozonella described here as a new genus and species, Eozonella bergeri, and a species previously described as Ophiacantha? francojurassica, which is here reassigned to the extant ophionereidid genus Ophiodoris. The assemblage was found in association with Nanogyra oyster buildups encrusted by serpulids and associated with partially-articulated crinoids, deposited in a shallow subtidal setting. Its family level composition is highly unusual with respect to modern equivalents, and instead is reminiscent of modern bathyal assemblages. © 2013 Swiss Geological Society.

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