Early Frasnian acanthodians from central Iran

Two vertebrate-bearing horizons in the basal Frasnian carbonate of the Chahriseh section, northeast of Esfahan, yielded microremains of thelodonts, placoderms, acanthodians, actinopterygians, chondrichthyans, and sarcopterygians, considerably expanding the vertebrate faunal list for the strata. Acanthodians comprise a diverse association of climatiids, diplacanthids, and ischnacanthiforms, including the previously recorded climatiid Nostolepis sp. cf. N. gaujensis, as well as one new climatiid genus and several taxa left in open nomenclature. Climatiid Iranolepis ginteri gen. et sp. nov. is diagnosed by having scales with a highly raised medial crown area separated by steep slopes from lateral crown areas; an odontocytic mesodentine of maximum extent in the crown, distinguished by extensive network of fine canaliculi with abundant tiny osteocytes; and a poorly developed stranggewebe system. Other scales with fan-like symmetrically grooved crowns conform to the Diplacanthus-type histologically, and have many characters in common with Milesacanthus antarctica from the Aztec Siltstone of Antarctica. Osseous gnathal elements include mesodentinous tooth whorls from an ischnacanthiform or climatiid, and ischnacanthiform jaw bones with large chambers for vascular canals, distinctly separated cylindrical tooth cusps along the lingual ridge, and wide-based, triangular, weakly striated cusps on the main lateral ridge. The acanthodian association, accompanied by the Frasnian conodonts of the middle Mesotaxis falsiovalis to Palmatolepis hassi zones and zonal thelodonts Turinia hutkensis and Australolepis seddoni, is proving useful for biostratigraphy, showing similarities with assemblages from both Gondwana and the Old Red Sandstone Continent

FRASNIAN (UPPER DEVONIAN) BRACHIOPODS FROM ARMENIA: BIOSTRATIGRAPHIC AND PALAEOBIOGEOGRAPHIC IMPLICATIONS

An assemblage of seven brachiopod species belonging to the orders Rhynchonellida, Atrypida and Spiriferida are studied from three localities (Ertych, Djravank and Noravank) of Central Armenia. The examined material is recovered from shallow water nodular limestones and provides insights into the diversity of Frasnian brachiopods on that part of the northern margin of Gondwana preserved within the South Armenian Block. The revision of Atrypa (Planatrypa) ertichensis, a biostratigraphically significant species for the Frasnian of the Lesser Caucasus (Armenia and Nakhichevan), revealed the presence of frills, an ornamental feature rarely observed in Atrypa (Planatrypa) representatives and considered as unknown in this species. Taxonomic discussion also involves the selection of neotypes for Ripidiorhynchus gnishikensis and A. (P.) ertichensis. The newly described taxon, Angustisulcispirifer arakelyani n. gen., n. sp., appears to be one of the most biostratigraphically important species for the Frasnian of Armenia. The size variability of Cyphoterorhynchus koraghensis and Desquamatia (Seratrypa) abramianae is documented quantitatively for the first time and it shows a continuous and progressive growth without any distinct groupings; the former is a palaeobiogeographically important species for the Frasnian strata of the northern Gondwana margin. Pending the revision of the Pakistani and Iranian material ascribed to C. koraghensis, that may include several subspecies, a plaster cast of its lectotype from the Frasnian of Kuragh in Chitral (northwest Pakistan) and the holotype as well as one of the paratypes of Cyphoterorhynchus koraghensis interpositus from the Frasnian Bahram Formation of the Ozbak-Kuh region in eastern Iran are illustrated herein. Finally, a new Frasnian brachiopod zone, namely the Ripidiorhynchus gnishikensis–Angustisulcispirifer arakelyani assemblage Zone is here introduced for the studied sections. Although its base and top cannot be identified, it is constrained to the Frasnian based on conodonts identified in the Djravank section. It may be considered as a partly lateral equivalent of the Cyrtospirifer subarchiaci–Cyphoterorhynchus arpaensis brachiopod Zone established in Nakhichevan

Early Frasnian thelodont scales from central Iran and their implications for turiniid taxonomy, systematics and distribution

<p>The early Frasnian turiniid thelodont <i>Neoturinia hutkensis</i> gen. nov. is re-described on the basis of a new large scale set from the Chahriseh section in central Iran. Detailed morphological and histological information supports a new generic affinity for this species, which was previously assigned to <i>Turinia</i>. The generic affinity of other turiniid thelodonts from Gondwana is tested by a phylogenetic analysis based on scales, which proposes that most taxa from Gondwana form a clade separate from that comprising the first-studied Laurussian forms, including the type species <i>Turinia pagei</i> Powrie, <a href="#cit0064" target="_blank">1870</a>. This suggests that many of the <i>Turinia</i> species from Gondwana should be separated from this genus and need to be revisited. On the strength of the analysis, younger Gondwanan taxa in the mid–early Late Devonian should probably be referred to the new genus; one Late Silurian taxon from eastern Gondwana is removed. A biogeographic analysis, using a parsimony ancestral state method, is also conducted in order to discuss dispersal patterns in relation to the achieved model of interrelationships.</p> <p>http://zoobank.org/urn:lisd:zoobank.org:pub:03499C12-344D-4296-A633-201CDB982445</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Hairapetian, V., H. Blom, and S. Turner. 2016. Early Frasnian thelodont scales from central Iran and their implications for turiniid taxonomy, systematics and distribution. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1100632.</p

GIVETIAN–FRASNIAN BOUNDARY CONODONTS FROM KERMAN PROVINCE, CENTRAL IRAN

The Middle - Late Devonian boundary is investigated based on twenty-two conodont species and subspecies from three sections in the north and west of Kerman, southeastern central Iran. Upper Givetian - lower Frasnian carbonates of the basal part of the Bahram Formation transgressively overlie the sandstone beds of the top of (?) Early - Middle Devonian Padeha Formation. These massive skeletal limestones encompass the G-F boundary. The base of Frasnian is identified by the appearance of early forms of Ancyrodella rotundiloba . It helps to compare our biozones to those of global stratotype in southern France. A new species, Polygnathus hojedki n. sp. is described here. New range is suggested for P. praepolitus 

The Permian–Triassic boundary section at Baghuk Mountain, Central Iran: carbonate microfacies and depositional environment

Sections at Baghuk Mountain, 45 km NNW of Abadeh (Central Iran), have excellent exposures of fossiliferous marine Late Permian to Early Triassic sedimentary successions. Detailed bed-by-bed sampling enables the analysis of microfacies changes of three successive rock units across the Permian–Triassic boundary. The Late Permian Hambast Formation is mainly the result of biogenic carbonate production. Its carbonate microfacies is dominated by biogen-rich and bioturbated nodular limestones, indicating a well-oxygenated aphotic to dysphotic environment. The biogen-dominated carbonate factory in the Permian ceased simultaneously with the main mass extinction pulse, which is marked by a sharp contact between the Hambast-Formation and the overlaying Baghuk Member (= ‘Boundary Clay’). The clay and silt deposits of the Baghuk Member with some carbonate beds show only a few signs of bioturbation or relics of benthic communities. The Early Triassic Claraia Beds are characterised by a partly microbially induced carbonate production, which is indicated by frequent microbialite structures. The depositional environment does not provide evidence of large amplitude changes of sea level or subaerial exposure during the Permian–Triassic boundary interval. The deposition of the Baghuk Mountain sediments took place in a deep shelf environment, most of the time below the storm wave base.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Museum für Naturkunde – Leibniz-Institut für Evolutions- und Biodiversitätsforschung (3498

Stegocornu and associated brachiopods from the Silurian (Llandovery) of Central Iran

A Llandovery (mid-upper Aeronian) brachiopod fauna is described for the first time from the Niur Formation of Central Iran. It is dominated by two succeeding rhynchonellide species Stegocornu procerum Dürkoop, 1970 and Stegocornu denisae sp. nov. In addition, there are three common and four rarer brachiopod species, including Dalejina? rashidii sp. nov., Isorthis (Ovalella) inflata sp. nov. and Striispirifer? ocissimus sp. nov. The Stegocornu Association gives a distinct biogeographic signature to the mid to late Llandovery rhynchonellide-dominated shallow-water brachiopod faunas of Central Iran, Kope-Dagh and Afghanistan. Its proliferation in temperate latitude peri-Gondwana was one of the earliest signs of biogeographical differentiation of the brachiopod faunas in the early Silurian. The affinities of Stegocornu and Xerxespirifer are discussed

Pre-mass extinction decline of latest Permian ammonoids

The devastating end-Permian mass extinction is widely considered to have been caused by large-scale and rapid greenhouse gas release by Siberian magmatism. Although the proximate extinction mechanisms are disputed, there is widespread agreement that a major extinction pulse occurred immediately below the biostratigraphically defined Permian-Triassic boundary. Our statistical analyses of stratigraphic confidence intervals do not comply with a single end-Permian extinction pulse of ammonoids in Iran. High turnover rates and extinction pulses are observed over the last 700 k.y. of the Permian period in two widely separated sections representative of a larger area. Analyses of body sizes and morphological complexity support a gradual decline over the same interval. Similar pre-mass extinction declines and disturbances of the carbon cycle have sometimes been reported from other regions, suggesting a widespread, but often overlooked, environmental deterioration at a global scale, well before the traditional main extinction pulse

The Permian–Triassic boundary section at Baghuk Mountain, Central Iran: carbonate microfacies and depositional environment

&lt;jats:title&gt;Abstract&lt;/jats:title&gt;&lt;jats:p&gt;Sections at Baghuk Mountain, 45 km NNW of Abadeh (Central Iran), have excellent exposures of fossiliferous marine Late Permian to Early Triassic sedimentary successions. Detailed bed-by-bed sampling enables the analysis of microfacies changes of three successive rock units across the Permian–Triassic boundary. The Late Permian Hambast Formation is mainly the result of biogenic carbonate production. Its carbonate microfacies is dominated by biogen-rich and bioturbated nodular limestones, indicating a well-oxygenated aphotic to dysphotic environment. The biogen-dominated carbonate factory in the Permian ceased simultaneously with the main mass extinction pulse, which is marked by a sharp contact between the Hambast-Formation and the overlaying Baghuk Member (= ‘Boundary Clay’). The clay and silt deposits of the Baghuk Member with some carbonate beds show only a few signs of bioturbation or relics of benthic communities. The Early Triassic &lt;jats:italic&gt;Claraia&lt;/jats:italic&gt; Beds are characterised by a partly microbially induced carbonate production, which is indicated by frequent microbialite structures. The depositional environment does not provide evidence of large amplitude changes of sea level or subaerial exposure during the Permian–Triassic boundary interval. The deposition of the Baghuk Mountain sediments took place in a deep shelf environment, most of the time below the storm wave base.&lt;/jats:p&gt

The Changhsingian (Late Permian) ammonoids from Baghuk Mountain (Central Iran)

The Changhsingian (Late Permian) Hambast Formation of sections at Baghuk Mountain (Central Iran) has yielded diverse ammonoid assemblages composed of the genera Pseudogastrioceras, Shevyrevites, Arasella, Dzhulfites, Paratirolites, Clivotirolites gen. nov., Esfahanites gen. nov., Alibashites, Lutites gen. nov., Abichites and Stoyanowites. The succession of ammonoid species allows for a subdivision of the rock unit into biozones, which largely correlate with the occurrences in north-western Iran. Three new genera, Clivotirolites Korn & Hairapetian gen. nov., Esfahanites Korn & Hairapetian gen. nov. and Lutites Korn & Hairapetian gen. nov., as well as 19 new species are described: Shevyrevites corrugatus Korn & Hairapetian sp. nov., Arasella falcata Korn & Hairapetian sp. nov., Dzhulfites brevisellatus Korn & Hairapetian sp. nov., Paratirolites rubens Korn & Hairapetian sp. nov., Paratirolites lanceolobatus Korn & Hairapetian sp. nov., Paratirolites robustus Korn & Hairapetian sp. nov., Paratirolites baghukensis Korn & Hairapetian sp. nov., Paratirolites aduncus Korn & Hairapetian sp. nov., Clivotirolites decoratus Korn & Hairapetian gen. et sp. nov., Clivotirolites petilus Korn & Hairapetian gen. et sp. nov., Esfahanites armatus Korn & Hairapetian gen. et sp. nov., Lutites paucis Korn & Hairapetian gen. et sp. nov., Lutites lyriformis Korn & Hairapetian gen. et sp. nov., Lutites profundus Korn & Hairapetian gen. et sp. nov., Lutites alius Korn & Hairapetian gen. et sp. nov., Lutites plicatus Korn & Hairapetian gen. et sp. nov., Abichites ovalis Korn & Hairapetian sp. nov., Abichites infirmus Korn & Hairapetian sp. nov. and Stoyanowites parallelus Korn & Hairapetian sp. nov. The material described here is, together with the material from NW Iran, the most diverse assemblage known from the interval before the end-Permian mass extinction

Sporadoceratid ammonoids from the Shotori Range (east-central Iran) - a case of putative gigantism caused by hydraulic sorting?

The Shotori Range of east-central Iran (east of Tabas) has yielded Famennian ammonoid assemblages dominated by the family Sporadoceratidae. Four genera Maeneceras Hyatt, 1884, Iranoceras Walliser, 1966, Sporadoceras Hyatt, 1884 and Erfoudites Korn, 1999 are represented. The conodont assemblage of one sample containing Iranoceras revealed an Upper marginifera Zone age. The ammonoid assemblages are characterised by comparatively large specimens; they reach conch diameters of 300 mm (including the body chamber) and the mean size is larger than 100 mm. The preservation of the material from the Shotori Range and size comparison with sporadoceratid assemblages from the Anti-Atlas of Morocco and the Rhenish Mountains of Germany suggest that hydraulic sorting has resulted in a bias towards large conchs, explaining the size distribution, rather than latitudinal differences. The new species Maeneceras tabasense is described; the genus Iranoceras is revised with a new description of the two species Iranoceras pachydiscus (Walliser, 1966) and Iranoceras pingue (Walliser, 1966)