Robert B. Blodgett

ORDOVICIAN SPHINCTOZOAN SPONGES OF ALASKA AND YUKON TERRITORY

ABSTRAcr-In Coal Creek Canyon, Utah, the Spring Canyon Member of the Blackhawk Formation is divisible into four regressive hemicycles of deposition, each representing the downdip part of a nearshore-to-offshore sequence. The first and fourth hemicycles are best developed. Individual bedding units span middle-shoreface to lower-offshore lithofacies, the latter corresponding to a thin intertongue of Mancos Shale. Trace fossil assemblages include ~22 ichnospecies and 17 ichnogenera: Ancorichnus, Aulichnites, Chondrites, Cylindrichnus, Ophiomorpha, Palaeophycus, Phoebichnus, Planolites, Rosselia, Schaubcylindrichnus, Scolicia, Skolithos, Taenidium, Teichichnus, Terebellina, Thalassinoides, and Uchirites. Diversity and abundance of ichnospecies are greater in nearshore than in offshore lithofacies. Distal deposits are typified by obscure bioturbate textures: Cylindrichnus concentricus, Palaeophycus heberti, and Rosselia socialis are prevalent through the remainder of the lithofacies suite. Ophiomorpha irregulaire and Schaubcylindrichnus coronus are most common in middle-shoreface beds and Chondrites ichnosp. in upper-offshore beds; Ophiomorpha nodosa and O. annulata also are common in this part of the sequence.Extensive assemblages of Ordovician sphinctozoan sponges from Alaska and the Yukon Territory extend the early Paleozoic circum-Pacific record of the order. Sponges described here are of Llandeilian-Ashgillian (Middle and Upper Ordovician) ages. The fossils are, in part, from the White Mountains area, in the Nixon Fork terrane of west-central Alaska, and, in part, from the Livengood area, in the White Mountain terrane (Churkin et al., 1982). The easternmost sponges described here are from Jones Ridge, in the western Yukon. Fossil distributions suggest that the Jones Ridge rocks are autochthonous with North America and that the White Mountain terrane has not travelled far because it appears to have stratigraphic analogues across the Tintina Fault. Distributions also suggest that the Nixon Fork terrane has not travelled far, based on faunal similarities ofgastropods and brachiopods of the terrane, particularly, with those from North America. The new genera and species, Alaskaspongia nana and Pseudoporefieldia micella, the new porate species, Corymbospongia betella and Angulongia minuta, and the new aporate species, Cystothalamiella ducta and Cystothalamiella polyducta, represent the new taxa of the assemblage. In addition to these, Imperatoria media Rigby and Potter, 1986, Girtyocoelia(?) epiporata Rigby and Potter, 1986, and Cliefdenella obconica Rigby and Potter, 1986, along with Imperatoria? sp. and a distinct, though unidentifiable, genus and species make up the total fauna of eleven species.

LLANDOVERIAN (EARLY SILURIAN) RADIOLARIANS FROM THE ROAD RIVER FORMATION OF EAST-CENTRAL ALASKA AND THE NEW FAMILY HAPLOTAENIATUMIDAE

Abstract Well-preserved Early Silurian radiolarians were recovered from siliceous rock fragments contained in a limestone boulder from the Road River Formation, Yukon River area, east-central Alaska. The radiolarians represent five genera, one of which, Parasecuicollacta, is new, and 17 species, nine of which are new: Secuicollacta magnitesta, S. tatondukensis, S. parvitesta, S. alaskensis, Parasecuicollacta bipola, P. hexactina, P. multispinosa, P. nannoglobosa, and Diparvapila pygmaea. Among the 17 species, 11 belong to the family Rotasphaeridae. The ectopically placed spicule, which is the diagnostic characteristic of the subfamily Secuicollactiniinae within the family Haplentactiniidae, is shown to be one of the primary units, a diagnostic feature of the family Rotasphaeridae. Three species are assigned to the family Haplotaeniatumidae, which is newly established in this paper. The family is characterized by the concentric and spiral arrangement of shell with a proloculus and commonly the presence of a pylome, and by the absence of an internal spicule. Several other taxa are extremely rare and are of uncertain taxonomic position. This fauna is characterized by very plentiful rotasphaerids, whereas all the other radiolarian taxa are very rare. The Road River fauna is similar to that from the Cherry Spring Chert of Nevada, thought to be late Rhuddanian based on a sparse graptolite fauna, and is very similar to an unreported Early Silurian Canadian Arctic fauna, whose stratigraphic range based on the graptolite fauna is within the early Telychian. Conodonts, chitinozoans, scolecodonts, and graptolites were also recovered from the siliceous rock fragments. Five genera and seven species of chitinozoans, four genera and five species of conodonts, and two uncertain taxa of graptolites were identified. Their biostratigraphy indicates that the Alaskan radiolarian fauna belongs to the upper Aeronian to lower Telychian of the Llandoverian.

NEW EMSIAN (LATE EARLY DEVONIAN) GASTROPODS FROM LIMESTONE MOUNTAIN, MEDFRA B-4 QUADRANGLE, WEST-CENTRAL ALASKA (FAREWELL TERRANE), AND THEIR PALEOBIOGEOGRAPHIC AFFINITIES AND EVOLUTIONARY SIGNIFICANCE

Abstract A significant number of small-sized gastropods are described from Emsian (late Early Devonian) strata on the south flank of Limestone Mountain, Medfra B-4 quadrangle, west-central Alaska, providing the first detailed taxonomic inventory of Emsian gastropods from the Farewell terrane of southwestern and west-central Alaska. The fauna is distinctly of Old World Realm character, and contains not a single species in common with Emsian faunas of nearby nonaccreted rocks of western Canada and east-central Alaska (“Western Canada Province” of Blodgett et al., 2001a). The genera Balbinipleura Bandel and Frýda, 1996 and Nanochilina Frýda, 1998, as well as the subgenus Palaeozygopleura (Rhenozyga) Frýda, 2000, are reported for the first time in the Devonian of the Western Hemisphere. The gastropod fauna includes members of three (i.e., Archaeogastropoda, Caenogastropoda, and Heterobranchia) of the five modern gastropod subclasses, illustrating that these gastropod lineages were separated from each other since the Early Devonian. New taxa include the new genera Arctozone, Farewellia, and Medfrazyga, represented by the new species Arctozone cooki, Farewellia heidelbergerae, and Medfrazyga clauticae. Further new species include Quadricarina (Quadricarina?) noklebergi, Balbinipleura krawczynskii, Decorospira lepaini, Decorospira? minutula, Palaeozygopleura (Rhenozyga) reifenstuhli, and Nanochilina gubanovi. In addition, the following previously described gastropods are also discussed and illustrated: Alaskiella medfraensis Frýda and Blodgett, 1998; Alaskacirrus bandeli Frýda and Blodgett, 1998; and Kuskokwimia moorei Frýda and Blodgett, 2001a.

Late Early Devonian (Late Emsian) eospiriferinid brachiopods from Shellabarger Pass, south-central Alaska, and their biogeographic importance; further evidence for a Siberian origin of the Farewell and allied Alaskan accreted terranes

Two eospiriferinid taxa,Myriospirifer n. sp. aff.M. myriofilaHavlíček 1978 andJanius cf.J. vetulus (Eichwald 1860), are described from an unnamed late Emsian (late Early Devonian) limestone unit in the Shellabarger Pass area, Talkeetna C-6 Quadrangle, south-central Alaska. These biogeographically distinctive species, along with other co-occurring brachiopod taxa such as the gypidulinid genusIvdelinia and the rhynchonellidSibirirhynchia alata (Khodalevich) indicate strong biogeographic affinities with Emsian faunas of Siberia (including Kolyma, Taimyr, and the Kuznetsk Basin) and the Urals. This Alaskan fauna is from the Farewell Terrane, an accreted terrane, which also shows strong Siberian affinities in the Middle Cambrian, Late Ordovician, Late Silurian-Lochkovian, early Emsian (late Early Devonian), and Permian time-intervals, suggesting that the Farewell Terrane is a continental margin sequence rifted away from the Siberian continent. Based on their close faunal ties with Siberia and with the Farewell Terrane, Siberian origins are also indicated for other major Alaskan terranes: the Alexander Terrane of southeastern Alaska, the Arctic Alaska Superterrane, and the York Terrane of northern Alaska. The only truly North American portion of Alaska is east-central Alaska (including the Nation Arch), bounded on the north by the Porcupine River and on the south by the Yukon River and Tintina Fault. Faunas from the latter area are nearly identical to those from miogeoclinal and cratonic strata of northwestern and Arctic Canada, and are very distinct from those present in the accreted terranes making up the greater portion of Alaska.KurzfassungZwei eospiriferinide Taxa,Myriospirifer n. sp. aff.M. myriofilaHavlíček 1978 undJanius cf.J. vetulus (Eichwald 1860) werden von einer nicht weiter benannten Kalkstein Einheit des oberen Ems (spätes Unterdevon) aus dem Gebiet des Shellabarger Pass, Talkeetna C-6 Planquadrat, südliches Zentral Alaska, beschrieben. Diese biogeographisch charakteristischen Arten, zusammen mit anderen Brachiopoden-Taxa aus der Vergesellschaftung, wie Vertreter der gypiduliniden GattungIvdelinia und der RhynchonellideSibirirhynchia alata (Khodalevich), lassen eine starke biogeographische Beziehung zu Faunen des Ems von Sibirien (einschließlich Kolyma, Taimyr und das Kuznetsk Becken) und des Urals erkennen. Die hier beschriebene Fauna Alaskas stammt aus der Farewell-Formation, einer Formation, die bereits im Mittelkambrium, im oberen Ordoviz, im oberen Silur-Lochkovium, im unteren Emsium (spätes Unterdevon) und in den permischen Zeitabschnitten starke Beziehungen zu sibirischen Faunen aufwies. Dies legt die Vermutung nahe, daß es sich bei der Farewell-Formation um eine randliche, kontinentale Abfolge handelt, die vom sibirischen Kontinent wegdriftete. Aufgrund ihrer faunistischen Ähnlichkeiten, lassen auch andere große Formationen Alaskas auf eine sibirische Herkunft schließen: die Alexander-Formation SE-Alaskas, die arktische Alaska-Großformation und die York-Formation N-Alaskas. Der einzige Abschnitt Alaskas mit wirklich nordamerikanischer Herkunft ist das östliche Zentral-Alaska (einschließlich der Nation Arch), umrahmt von den Flüssen Porcupine im N und Yukon im S sowie der Tintina-Verwerfung. Faunen aus diesem letztgenannten Gebiet sind fast identisch mit solchen von miogeoklinalen, kratonischen Lagen des nordwestlichen und arktischen Kanada. Sie sind jedoch deutlich unterscheidbar von Faunen aus den übrigen Formationen Alaskas.

UPPER MIDDLE DEVONIAN (GIVETIAN) GASTROPODS FROM THE KERSADIOU FORMATION, BRITTANY, FRANCE

Gastropods are described for the first time from the Kersadiou Formation (middle Givetian) in the vicinity of Brest, Brittany, northwestern France. Twenty-three species of gastropods are recognized. New taxa include the new genera, Calvibembexia, Kersadiella, Breizospira, Finisterella, Parahormotomina, and Nodoloxonema, represented by the new species Calvibembexia lethiersi, Kersadiella babini, Breizospira crozonensis, Finisterella tibidiensis, Parahormotomina sibertae, and Nodoloxonema plusquelleci. Further new species include: Sinuitina (Sinuitina) morzadeci, Crenistriella armoricana, Patellilabia (Phragmosphaera) ponceti, Angyomphalus (Eoangyomphalus) weyanti, Eoplatyzona ongaroae, Murchisonia oehlerti, and Hormotomina fiacrensis. The biogeographic affinities of the fauna show a strikingly unusual admixture of Eastern Americas Realm taxa such as Hormotomina and Crenistriella. This suggests that during the middle Givetian, the Massif Armoricain (northwestern France) represented an area of Realm-boundary mixing between the Old World and Eastern Americas Realms, while older Devonian gastropod faunas of the Massif Armoricain are wholly of Old World Realm type.

Stratigraphy and paleontology of Lower Permian rocks north of Cananea, northern Sonora, Mexico

Abstract Lower Permian carbonate and overlying red bed clastic rocks are present in a 2xa0km2 stratigraphic window in the vicinity of Rancho La Cueva, Santa Cruz sheet (scale 1:50,000), northern Sonora, Mexico. This exposure lies unconformably beneath predominantly intermediate Upper Cretaceous volcanics yielding 40Ar/39Ar ages of 73.4±0.18 and 71.1±0.35xa0Ma. The lower part of the Permian succession consists of light- to medium-gray colored limestones of the Colina Limestone, with a minimum thickness of 235xa0m. Sedimentary features suggest shallow water, slightly restricted depositional environments. Although lacking observable fossils for the most part, two intervals of richly fossiliferous, silicified shell beds are present near the base and top of the Colina Limestone. The lower fauna consist mostly of gastropods and bivalves. The presence of a new microdomatid gastropod species, Glyptospira sonorensis n. sp., close to Glytospira arelela Plas, suggests a late Wolfcampian age for this horizon. The upper fauna are predominantly molluscan dominated (gastropods and bivalves), but some brachiopods (productids and the rhynchonellid genus Pontisia) are also present. Gastropod genera include Bellerophon, Warthia, Euomphalus (represented by the species, Euomphalus kaibabensis Chronic), Baylea, Worthenia, Naticopsis, Goniasma, Kinishbia, Cibecuia, and Glyptospira. The gastropods suggest a Leonardian (late Early Permian) age for this horizon, and many of the species have previously been recorded from the Supai Group and Kaibab Formation of northern and central Arizona. The Colina Limestone is conformably overlain by 11.2xa0m of light-gray lime mudstone and dolostone, assigned here to the Epitaph Dolomite, which in turn is succeeded by 58.8xa0m of red-colored sandstone and gray lime mudstone, assigned here to the Scherrer Formation. This Lower Permian succession is significant because it further strengthens the stratigraphic ties of southeastern Arizona rocks with those of northern Sonora and confirms the presence of North American cratonal stratigraphy in the northern part of the state of Sonora, Mexico.

TWO NEW CIRROIDEAN GENERA (VETIGASTROPODA, ARCHAEOGASTROPODA) FROM THE EMSIAN (LATE EARLY DEVONIAN) OF ALASKA WITH NOTES ON THE EARLY PHYLOGENY OF CIRROIDEA

A~STRACT-Two new cirroidean gastropod genera, Alaskiella (family Porcelliidae) and Alaskacirrus (family Cimdae), from the Emsian (late Early Devonian) of west-central Alaska (Medfra B-4 quadrangle) are described. The shell of Alaskiella medfraensis new genus and species exhibits inclined heterostrophic coiling. This shell character is known among other members of the subclass Archaeogastropoda, but is recorded for the first time within members of the superfamily Cirroidea. Inclined heterostrophic coiling of the shell was probably developed independently in several different groups of the subclass Archaeogastropoda. The new genus Alaskacirrus, represented by Alaskacirrus bandeli new species, is the oldest and only known Paleozoic member of the family Cimdae. This suggests that the family Cimdae was separated from the family Porcelliidae since at least Early Devonian time and that it most probably developed from the subfamily Agnesiinae of the family Porcelliidae. Thus, the stratigraphic range of the family Cimdae is at least from Lower Devonian to Cretaceous, an interval of about 350 million years.

Late Devonian gastropods from the Canning Basin, Western Australia

Frasnian and Famennian gastropods from the Canning Basin, Western Australia, constitute one of the most diverse Late Devonian gastropod faunas known, with 28 taxa, including four new genera and 14 new species. This is the first formal description of Famennian gastropods from Australia. New genera described are the pleurotomarioids Tasselliana australis gen. et sp. nov., Playfordia australis gen. et sp. nov. and Westralospira dickinsi gen. et sp. nov., and the platyceratid Cancelloplatyceras abowsheri gen. et sp. nov. New species described are Retispira christinae, Euconospira nodosa, Mourlonia teichertensis, Baylea teicherti, Euryzone hullensis, Hesperiella canningensis, Brokenriveria virginensis, ?Gyronema minutiforma, Roemeriella alticonus and Palaeozygopleura canningensis. The plexus of nodose and lirate Devonian gyronematines continues through the Late Devonian, exemplified by Brokenriveria and Pseudoplagiothyra. The range of Brokenriveria is here extended from Givetian to Famennian. Conspicuously and oddly ornamented Murchisonia also extended into the Late Devonian following the Early-Middle Devonian radiation of such forms. The absence of large numbers of Platyceras (sensu stricto) continues to be a feature of eastern Australian faunas during the Devonian, but strong links to the Old World Realm Faunas are evident.

NEW EARLY DEVONIAN GASTROPODS FROM THE FAMILIES CRASSIMARGINATIDAE (NEW FAMILY) AND SCOLIOSTOMATIDAE (NEW FAMILY), ROYAL CREEK AREA, YUKON TERRITORY, CANADA

Abstract Two new distinctive families, Crassimarginatidae and Scoliostomatidae, each characterized by unusual gerontic apertural morphotypes, are established on the basis of study of the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. The Early Devonian genus CrassimarginataJhaveri, 1969, is transferred from the family Palaeotrochidae and placed, together with the new genus Yukonoconcha, into the new family Crassimarginatidae, which is characterized by a pupiform shell with an explanate outer apertural lip in the gerontic growth stage. The new family Scoliostomatidae unites Devonian gastropod genera (ScoliostomaBraun, 1838; BrilonellaKayser, 1873; AnarconchaHorný, 1964; Eoscoliostoma new genus; MitchelliaKoninck, 1877; and Pseudomitchellia new genus), which are characterized by a distinctive, free, twisted (both outwards and backwards) gerontic final half whorl. More detailed morphological comparison of members of this family has allowed their division into two new subfamilies: the Scoliostomatinae and Mitchelliinae. New genera include Yukonoconcha, Eoscoliostoma, and Pseudomitchellia. The former two genera are represented each by a single new species from Yukon Territory, Yukonoconcha pedderi and Eoscoliostoma norrisi. The latter genus is represented by two species, the type Pseudomitchellia bohemica (Perner) from the Koněprusy Limestone (Pragian) of the Czech Republic and Pseudomitchellia macqueeni new species from Yukon Territory.

Early jurassic spiriferid brachiopodsfrom Alaska and their paleogeographic significance

Spiriferid brachiopods are described in detail for the first time from the Jurassic of North America. The specimens are referred to the genera Liospiriferina and Callospiriferina, both originally described from the Early Jurassic of Morocco and Spain by Rousselle (1977). The species identified herein, Liospiriferina rostrata and Callospiriferina tumida, are known from Europe, South America, and northern Africa, with L. rostrata also recorded from Indonesia. The new occurrences in Alaska indicate a lower-latitude placement during the Early Jurassic, at least temperate latitudes, for the Farewell (probably during the Sinemurian) and Peninsular (Sinemurian-basal Toarcian) terranes. Liospiriferina and Callospiriferina range through much of the Early Jurassic. These new occurrences are significant because they indicate further parallels between the composition of Mesozoic brachiopod faunas of Europe, where faunas were initially monographed in the nineteenth century, and those of North America and South America. The spiriferids therefore show evidence of survival in North America beyond end-Triassic extinctions, underscoring the global nature of the continuity of the Spiriferida into the Jurassic before their demise by the end of the Early Jurassic. In terms of the composition of Mesozoic brachiopod faunas spiriferids have been identified as preferring deeper-water shelf environments. It has not been determined if this was the case for these Jurassic spiriferids: the collections studied herein show Liospiriferina to be associated with sandy lithologies while Callospiriferina was collected from a black shale. Based on external morphology Liospiriferina is closely homeomorphic with the cosmopolitan Triassic athyrid brachiopod Oxycolpella. However, on closer examination and preparation of serial sections of internal structures the Alaskan specimens showed the presence of dental lamellae, a large, persistent median septum, a spiralium (spiral brachidium), and punctate shell, indicating affinities to the Spiriferida. The material had originally been tentatively identified as terebratulids.