Scutelluid trilobites from the Silurian of New South Wales

Abstract: Twenty‐six species (nineteen of them formally named) of scutelluid trilobites belonging to eight genera are described from limestones of the lower Wenlock to Ludlow Mirrabooka Formation and its stratigraphical equivalents in the Orange district of New South Wales. Two genera, Borenoria and Mirrabooka, are new. Japonoscutellum, previously employed mainly for several species from Japan, is a globally widely distributed genus in rocks of middle Llandovery to Ludlow age and includes a number of species previously assigned to Kosovopeltis. Japonoscutellum is remarkably diverse in the faunas from Orange where it is represented by eleven species, one of them known also from Kazakhstan. Flexiscutellum and Tosacephalus are regarded as junior synonyms of Decoroscutellum and Kosovopeltis, respectively. The homology of various scutelluid cephalic structures is discussed, in particular the cephalic borders and border furrows that have routinely been misidentified; the term ‘bolus’ is introduced for the variably developed swelling that is enclosed by S1 on the glabella of most scutelluids. New species are Australoscutellum iota, A. microps, A. pulex, A. trica, Borenoria cirrita, Decoroscutellum planes, Eoscutellum annosum, Illaenoscutellum tryo, Japonoscutellum borenorense, J. crassum, J. diascetum, J. gephyricum, J. guttulatum, J. serangicum, J. strabo, Kosovopeltis trepida, K. xynon and Mirrabooka harryi. Some of these trilobites show strong affinity with species from the Kurosegawa Terrane of south‐western Japan and the Chu‐Ili Terrane of Kazakhstan, as previously reported also for the effaced Illaenina from the same limestones. Australoscutellum and Mirrabooka are presently known only from eastern Australia. The new genus Securifrons is proposed for several species previously assigned to Kosovopeltis or Eokosovopeltis from the Sandbian or Katian to Llandovery of North Greenland, Canada, Scotland, South China and New South Wales.     

Heterochrony in the Silurian radiation of encrinurine trilobites

Divergence of Silurian encrinurine trilobite clades from common ancestry may be modelled as hetero-chronic pattern. Comparing ontogenies of ancestral late Ordovician Encrinuroides and the descendant punctarus and uariolaris plexi of Silurian Encrinurus provides a test of this hypothesis. Heterochrony in the punctarus plexus is dissociated with respect to entire organisms, but regionally global throughout cranidia (paedomorphic states) and pygidia (peramorphic states). Regulatory dissociation may explain the apomorphous enrollment strategy of this group. The uariolaris plexus, for which a growth series of Balizoma dimitroui (Perry & Chatterton) provides ontogenetic data, shows a complex of peramorphic cephalic character states. Changes in developmental timing thus provide a mechanism by which morphologic and ecologic divergence of closely-related clades was catalyzed in the Llandovery encrinurine radiation. Paedomorphic and dissociated Lineages of the odontopleurid Leonaspis provide a comparable example of divergent heterochronic pattern associated with coexisting (in the same biofacies) species of comparatively recent common ancestry.     

Proetid trilobites from the middle Telychian (Llandovery,Silurian) Ningqiang Formation,Shaanxi, China

Four proetid trilobite species, Chuanqianoproetus guizhouensis Yin in Yin and Li, 1978, C. shuangheensis Wu, 1977, C. sp., and Latiproetus guizhouensis Yin in Yin and Li, 1978, are described from the Ningqiang Formation in Ningqiang County, Shaanxi, China. They are middle Telychian (Llandovery, Silurian) in age. Chuanqianoproetus and Latiproetus are both regarded as members of the subfamily Warburgellinae; the former has been considered to be a junior subjective synonym of Astroproetus, but on the basis of its morphology we argue here that they represent two independent genera. The poorly sorted bioclastic grainstones containing trilobite sclerites may indicate their deposition in turbulent conditions on an open marine platform.     

Middle Telychian (upper Llandovery, Silurian) graptolites from boreholes of northwestern Libya: Their biostratigraphic significance and palaeogeographical implication

A low-diversity but stratigraphically and palaeobiogeographically important graptoloid association comprising Metaclimacograptus flamandi (Legrand), Parapetalolithus meridionalis (Legrand), and Torquigraptus australis Štorch was identified in the core samples of wells A1-66, F1-66 and A1-43 in the Ghadamis Basin of Libya. The former two species have been originally recovered from Algeria. All three taxa are common and widespread in the middle Telychian strata of Spain (Central Iberian Zone and western Iberian Cordillera) and France (Brittany). In European sections, the species are associated with other, moderately diverse graptoloid fauna, which enables a more precise and worldwide biostratigraphic correlation of Saharan boreholes and surface sections. The present faunal association indicates a middle Telychian age (upper crispus, griestoniensis and lowermost crenulata/tullbergi biozones) for the strata and suggests palaeobiogeographical links between North African pericratonic basins and Ibero-Armorican shelves. M. flamandi has not been found outside this NW-Gondwanan realm.     

Late Silurian brachiopods from Darhan Mumingan Joint Banner, Inner Mongolia

Seven brachiopod species (including three new species) and three undetermined forms are described and figured here from an unnamed stratigraphic unit which mainly consists of argillaceous and bioclastic limestone near the stratotype of the Late Silurian Xibiehe Formation of the Xibiehe section in the Darhan Mumingan Joint Banner, north of the Bateaobao area, Inner Mongolia. Three new species, Eoschizophoria minuta, Navispira navicula and Howellella asiatica are established with transverse serial sections for their interiors. All brachiopod taxa described here show that this unnamed stratigraphic unit is higher than the Late Silurian Xibiehe Formation in the Xibiehe section and is possibly transitional between the Late Silurian and the Early Devonian. Authors temporarily regard this unit as the upper part of the Xibiehe Formation in this paper.     

Late Ordovician and early Silurian Proetida (Trilobita) from north-western and central Europe

Species belonging to genera of three families of the Proetida (Proetidae, Rorringtoniidae and Toernquistiidae) are described from the upper Ashgill of southern Sweden, and the same or related species noted from the adjacent parts of northern and central Europe. Proetidae are represented by Paraproetus brevifrons (Angelin), Ogmocnemis irregularis Kielan, Ogmocnemis jaanussoni sp. nov. and Parvigena putealis sp. nov.; it is argued that all belong to the Cornuproetinae, not Tropidocoryphinae where they were previously classified. Ogmocnemis is resurrected for some Upper Ordovician species included previously in Decoroproetus . The rorringtoniid genera Rorringtonia and Madygenia are recognised for the first time in southern Sweden, and it is argued that these are probably closely related, and both are included in the same family; both are recorded for the first time from Silurian (Llandovery) strata. Zetaproetus is claimed to be a junior subjective synonym of Rorringtonia. Solariproetus , first described from north-west China, is assigned to the Toernquistiidae as a late, derived member, and S. prosthemesos sp. nov. is described from late Rawtheyan strata in the Holy Cross Mountains, Skåne and the English Lake District. Comments are given on the stratigraphical and palaeogeographical distribution of these taxa.     

First African oryctocephalid trilobites from the Lower–Middle Cambrian boundary interval

Oryctocephalid trilobites from Lower Middle Cambrian strata of the eastern Anti-Atlas, Morocco, are the first described Oryctocephalidae known from Africa. They represent the new genus and species Shergoldiella vincenti. However, a similar species was earlier described as Tonkinella sequei Liñán et Gozalo, 1999, from coeval lower Middle Cambrian strata of the Iberian Chains, northern Spain. This Iberian species is imperfectly preserved and assigned herein to Shergoldiella with reservations. If this assignment is correct, it would reinforce earlier suggested correlations between Morocco and Spain. Nevertheless, Shergoldiella suggests a morphocline from a typical oryctocephalid-type morphology towards the Tonkinella-type morphology. Close similarity with Ovatoryctocara ovata suggests a similar stratigraphic position in accordance with earlier suggested intercontinental correlations.     

Fish otoliths from the Pliocene Heraklion Basin (Crete Island,Eastern Mediterranean)

The Pliocene Eastern Mediterranean fish record is revealed through the study of a 60-m thick stratigraphic sequence near the village Voutes (Heraklion, Crete). Forty-two species belonging to twenty families are identified. Calcareous nannoplankton biostratigraphy places the studied sequence within the biozone MNN16a (latest Zanclean). The stratigraphic distribution of 31 species is modified. Among these, 12 species are reported for the first time in the Eastern Mediterranean Zanclean, while 19 species are first reported outside the Ionian Sea. The Voutes fish fauna presents a diversified benthic and benthopelagic assemblage filling a significant gap in the fossil record.     

Late Ordovician-Early Silurian fluctuations in sea level from eastern Anticosti Island, Quebec

Over 1,000 m of Upper Ordovician to Lower Silurian mixed carbonate and clastic strata on Anticosti Island are nearly tectonically undisturbed, despite their proximity to the Northern Appalachians fronting Quebec's Gulf of St. Lawrence. Natural cliffs exposed along the coast and rivers in the eastern part of the island make a relatively conformable sequence belonging to the Ashgill and Llandovery Series. Fossil communities interpreted as depth-associated in life are especially repetitious in the Becscie, Gun River, Jupiter, and Chicotte Formations (Llandovery Series), and to a lesser degree in the Upper Vaureal and Ellis Bay Formations (Ashgill Series). Preliminary study of the pattern of changeovers in Eocoelia, Pentamerus and Stricklandia communities suggests that Anticosti seas deepened and shallowed three and a half times during the Early Silurian. High water peaks were reached during B₁-B₂, C₁-C₂ and C₄-C₅ times, with a final deepening trend beginning in late C₅ time. Age determinations of these events are based on the occurrence of graptolites (with some new records from Anticosti) keyed to the standard graptolite zones, and species of the Eocoelia lineage are also useful for correlation. The profile of the Anticosti sea-level curve compares well with other curves reconstructed from the Lower Silurian of New York, Michigan, and Iowa. Widespread synchronism in sea-level changes on the North American platform is thus corroborated.     

Silurian (Ludlow) acastid trilobites from Gotland and Scania,Sweden

Acastid trilobites from Ludlow strata on Gotland include three stratigraphically non-overlapping species ofAcastella Reed:Acastella madidipes n. sp. (Hemse Marl and Eke Beds),A. breviceps (Angelin 1851) (Burgsvik Beds), andA. amatrix n. sp. (Hamra Beds, and probably Burgsvik Beds). Type and other material ofA. breviceps (Angelin) from the Klinta Formation, Scania, is revised. Meraspid and early holaspid material ofAcastella is described. Some characters supportAcaste and allied taxa of mostly Wenlock age as a monophyletic subfamily Acastinae.Acastella as widely recognized is a grade with Devonian species more closely related to Asteropyginae than to the Ludlow type species. Baltic Ludlow-P?00ED;dolí species previously placed inScotiella Delo form a distinct group,Ewacaste n. gen., that includes a species from the uppermost Eke Beds on Gotland.     

Dendroclimatological potential of three juniper species from the Turkestan range,northwestern Pamir-Alay Mountains,Uzbekistan

Key message

Intensity and magnitude of the growth-climate relationship depends on juniper species and sites. Juniperus seravschanica at low elevations shows highest potential for April–September drought reconstruction in the Turkestan range (Pamir-Alay), Uzbekistan.

Abstract

We present a detailed dendroclimatological study of three juniper species, Juniperus seravschanica Kom., Juniperus semiglobosa Regel and Juniperus turkistanica Kom., sampled at six sites of different elevation (2100–2700 m a.s.l.), exposition (west and south) and steepness (10°–30°) in the Zaamin National Park, Turkestan range, Pamir-Alay mountain system in eastern Uzbekistan. Simple correlation statistics and redundancy analyses were applied to detect species- and site-specific climate responses during the twentieth century, which were additionally investigated in the high-frequency domain by identifying extreme growth years. Our results show that tree-ring formation of J. seravschanica at our low-elevation site is strongly limited by April to September drought conditions, while J. semiglobosa inherits a weak and variable climate response with respect to elevation. J. turkistanica growth at high altitudes is positively associated with warm spring and summer temperatures. Species-specific growth extremes are triggered by incoming air masses from the Atlantic and Arctic, highlighting the connection of synoptic climate regimes across Eurasia. From a dendroclimatic perspective, J. seravschanica exhibits a high potential for reconstructing past drought and pluvials, but under sustained temperature rise also J. semiglobosa will likely increase its sensitivity to drought. Moreover, J. turkistanica at its distribution limit at the tree line is a suitable proxy of summer temperature. Our findings clearly demonstrate that a careful selection of the site, overall topography and elevation as well as the different juniper species are important for successfully reconstructing past climate in Uzbekistan.

     

An updated Telychian (Late Llandovery, Silurian) conodont zonation based on Baltic faunas

Five conodont zones, Pterospathodus eopennatus ssp. n. 1, P. eopennatus ssp. n. 2, P. amorphognathoides angulatus , P. a. lennarti and P. a. lithuanicus , are described in the interval previously known as the P. celloni Zone. The new zones are grouped into two superzones: the first two form the P. eopennatus Superzone and the other three the P. celloni Superzone. All zones correspond to the intervals of the total ranges of the nominal taxa and to the boundaries between the zones to the levels at which one taxon was evolutionally replaced by another. The lower boundary of the P. a. amorphognathoides Zone is redefined. The P. eopennatus ssp. n. 2, P. a. angulatus and P. a. amorphognathoides zones are further subdivided into the Lower and Upper subzones. Although the zones described are mainly based on data from Estonia, they can be recognized all over the world, in most sections containing Telychian strata and from where adequate data are available. Most of the subzones can so far be applied only in a limited area.     

Huemacaspis (Trilobita, Kerfornellinae) from the Late Ordovician of the Argentine Cordillera Oriental

The trilobite genus Huemacaspis P?IBYL and VANěK, 1980 is redescribed from well-preserved material from the Santa Gertrudis Formation (early Caradoc), Argentine Cordillera Oriental. The new species H. gallinatoensis is described and figured. Huemacaspis is widely distributed in the southern part of the Central Andean basin during the early Caradoc and it is a key taxon for the correlation of different units from the Cordillera Oriental and Sierras Subandinas of Argentina and the Cordillera Oriental of Bolivia. This taxon is one of the few records of trilobites of early Caradoc age found in the shallow shelf environments of southwestern Gondwana. Huemacaspis is accommodated within the Kerfornellinae, a subfamily otherwise known from southern Central Europe and northern Africa. The trilobite fauna from the early Caradoc of the Central Andean basin suggests a faunal exchange with the latter regions indicating the persistence of a broadly similar biogeographic pattern to that documented in earlier Ordovician times.     

A new basal hadrosauroid dinosaur from the Late Cretaceous of Uzbekistan and the early radiation of duck-billed dinosaurs

Levnesovia transoxiana gen. et sp. nov., from the Late Cretaceous (Middle–Late Turonian) of Uzbekistan, is the oldest well-documented taxon referable to Hadrosauroidea sensu Godefroit et al. It differs from a somewhat younger and closely related Bactrosaurus from Inner Mongolia (China) by a tall sagittal crest on the parietals and the absence of club-shaped dorsal neural spines in adult specimens. Levnesovia, Bactrosaurus and possibly Gilmoreosaurus represent the earliest radiation of Hadrosauroidea, which took place during the Cenomanian–Turonian and possibly in North America. The second, Santonian-age radiation of Hadrosauroidea included Aralosaurus, Hadrosauridae and lineages leading to Tanius (Campanian) and Telmatosaurus (Maastrichtian). Hadrosauridae appears to be monophyletic, but Hadrosaurinae and Lambeosaurinae originated in North America and Asia, respectively.     

Late Ordovician–Early Silurian facies development and environmental changes in the Subpolar Urals

The continuous Upper Ashgill–Sheinwoodian carbonate succession in the most eastern Kozhym River area in the Subpolar Urals comprises the Yaptikshor (Rawtheyan), Kamennaya baba (Hirnantian), Ruchej and Manyuku (Llandovery–?Sheinwoodian) formations. The facies of the deep subtidal Yaptikshor Fm. mark an abrupt sea‐level rise following emergence of the Bad’ya reef (Rawtheyan). Carbonate breccias at the base of the Kamennaya baba Fm. correlate with the beginning of the Hirnantian glaciation and change upwards towards the Ordovician–Silurian boundary with the development of light‐grey massive boundstone/packstone shoal deposits. An abrupt change in facies to the Rhuddanian–Aeronian Ruchej Fm. continental slope environment marked the start of a long‐term sea‐level rise. The uppermost Aeronian–?Sheinwoodian is represented by submarine canyon carbonate conglobreccias of the Manyuku Fm. unconformably underlying the Balban’yu reef. The rapid facies changes at the base of the Hirnantian and at the Ordovician–Silurian boundary were of global eustatic origin. In contrast, the abrupt changes in the Rawtheyan and the formation of the Manyuku Fm. conglobreccias were of local or regional origin associated with tectonics. They were followed by the start of a regional transgression (Yaptikshor Fm.) and a global transgression marked by the initiation of the Balban’yu Reef in the Sheinwoodian.     

The Early Silurian brachiopod Eocoelia from the Hudson Bay Basin, Canada

Eocoelia akimiskii sp. nov. from the Lower Silurian (upper Telychian) Attawapiskat Formation of Akimiski Island, James Bay, Nunavut, is the first and oldest Eocoelia to be described from the Hudson Bay Basin, one of three largest inland basins of North America. The new species lacks dental plates, dental cavities, and marginal deflection or lip, which indicates a post-Aeronian form of the well-known Eocoelia lineage. In rib numbers, Eocoelia akimiskii falls between E. curtisi and E. sulcata , being closer to E. sulcata . In rib strength, however, the new species is more closely allied to E. curtisi . Although Eocoelia is currently assigned to the Rhynchonellida because of its lack of spiralia, several features (particularly the lack of a septalium, the presence of a unique notothyrial platform and cardinal process, and dense, free-hanging fibrous growth frills) of the genus and other leptocoeliids are distinctly atypical of the rhynchonellides. The new species occurs in an inter-reef, shelly packstone facies within the Attawapiskat Formation, which is characterized by coral-stromatoporoid reefs with abundant, diverse, reef-dwelling brachiopods and other shelly organisms. The close association of Eocoelia akimiskii with the Attawapiskat reefs supports a shallow subtidal (BA2) setting generally assigned to the Eocoelia Community. The reefs themselves, however, host an extremely abundant brachiopod fauna dominated by Pentameroides , Trimerella , Septatrypa , and Gypidula . Four species of Clorinda are also common elements of the reef-dwelling brachiopods. This demonstrates that the concept of the classic Early Silurian level-bottom brachiopod communities cannot be directly applied to reef-dwelling brachiopod communities.