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The Middle and Upper Ordovician sequence of the Langkawi Islands, northwestern peninsular Malaysia, contains 20 species of conodonts belonging to 15 genera and four unidentified species, which are described and illustrated. The following four biostratigraphic zones ale established for the study area: the Scolopodus striatus assemblage zone, the Periodon sp. A range zone, the Baltoniodus alobatus range zone, and the Hamarodus europaeus range zone, in ascending order. The Middle Ordovician fauna belongs to the low-latitude, warm-water Australian Province. Conodonts of the H. europaeus zone represent the HDS (Hamarodus europaeus-Dapsilodus mutatus-Scabbardella altipes) biofacies, which has been reported from the cool-water North Atlantic Faunal Region. The middle Arenigian limestones in the study area were deposited on a shallow-water shelf, whereas the late Arenigian to middle Darriwilian limestones formed in hemipelagic deeper-water conditions on an outer shelf or slope.

A moderately diverse crinoid fauna from the Early Mississippian, Tournaisian, part of the Bahram Formation is reported from exposures in the vicinities of Hutk and Shams Abad, north of Kerman in southeastern Iran. Conodonts from the crinoid-beating beds represent two faunas and indicate an age of Upper Siphonodella crenulata Biozone to Gnathodus typicus Biozone. Recognition of a Tournaisian age for this part of the Bahram Formation revises the previously assigned Famennian age and indicates that Famennian strata are much thinner, if present, in southeastern Iran. The fauna occurs in thin-bedded marls and limestones at the top of a shaley slope-forming sequence that grades upward into resistant cliff-forming limestones. Most crinoid specimens are crowns (many retaining part of the proximal stem) that have been flattened by compaction. At the genus level the crinoids include five camerates, three cladid dendrocrinids, ten other cladids, three flexibles, and one articulate. In addition, loose arm fragments and occasional cup fragments are common, along with abundant pluricolumnals and columnals in the fauna. Dominance of cladids over camerates probably reflects the argillaceous sediment in the mixed carbonate/ siliciclastic platform environment of the fauna. This is the most diverse Tournaisian fauna reported from the northern margin of Gondwana and represents an equatorial fauna living at approximately 20[degrees]S latitude. Stronger affinities are with North American and European crinoid faunas than with Chinese and Australian faunas. Shallow-shelf conodonts from the crinoid-bearing beds are dominated by species of Polygnathus. Palaeoniscoid fish remains and shark teeth from the same beds support a shallow-shelf environment. New taxa proposed are Dichocrinus shamsensis new species; D. labyrinthus new species; Springeracrocrinus conicus new species; Atelestocrinus hutkensis new species; Zangucrinus abadensis new genus and species; Glossocrinacea new superfamily; Gelasinocrinus revimentus new genus and species; Amabilicrinidae new family; Amabilicrinus iranensis new genus and species, A. bahramensis new species; Derorhethocrinus elongatus new genus and species; Corematocrinidae new family; Lorocrinus zanguensis new genus and species; Blothrocrinus yazdii new species; Culmicrinus cylindratus new species; Paracosmetocrinus delicatus new species; Taxocrinus quadribrachiatus new species; Meristocrinus ovatus new species; and Hutkocrinus kermanensis new genus and species. Revision of the Glossocrinidae also resulted in designation of two new genera not present in the Iranian fauna: Bufalocrinus new genus (type species Catactocrinus? torus Webster and Harley, 1999, from the Late Devonian, Famennian, of Colorado) and Nudalocrinus new genus (type species Culmicrinus jeffersonensis Laudon and Severson, 1953, from the Tournaisian of Montana).

The conodont fauna from nine sections across a platform-to-basin transect in northeastern British Columbia includes species of Early Ordovician (Tremadocian) to Early Silurian (Llandovery) age. A collection of 9,110 conodont elements was recovered from 205 samples taken from nine stratigraphic sections that preserve the platform succession of the Kechika, Skoki, Beaverfoot, McCusker and Nonda Formations and their off-shelf equivalents, the Ospika, Robb, Kenny and Laurier Formations of the Road River Group. The fauna is assigned to 106 species representing 67 genera; the Ordovician species are representative of two faunal realms. One new genus, left in open nomenclature, is described. Five new species include Drepanoistodus latus and four new species left in open nomenclature assigned to the following genera: Walliserodus, Multioistodus?, Pseudooneotodus, and Belodina. The Midcontinent Realm zones recognized include, in ascending order, the Acodus kechikaensis, Oepikodus communis, Jumudontus gananda, Tripodus laevis to Plectodina aculeata zones, Phragmodus undatus and Gamachignathus ensifer? zones. Zonal species of the Atlantic Realm are Microzarkodina flabellum, Eoplacognathus suecicus, Baltoniodus variabilis, Pygodus anserinus, and Amorphognathus tvaerensis. The Silurian fauna, of lower diversity than the Ordovician fauna, is representative of the Distomodus staurognathoides and Pterospathodus amorphognathoides zones.

A microevolutionary event involving the conodont Paroistodus lineage is documented in the Gualcamayo Formation (Middle Ordovician), Argentine Precordillera. A detailed sampling of limestones throughout the upper part of the San Juan Formation and the lower member of the Gualcamayo Formation yielded over 14,000 well-preserved conodont elements. Paroistodus originalis (Sergeeva, 1963) was recorded through the upper 230 m of the San Juan Formation and the lower member (10 m thick) of the Gualcamayo Formation. The derived species Paroistodus horridus (Barnes and Poplawski, 1973) was recorded throughout the middle member of the Gualcamayo Formation (65 m thick). The intermediate linking forms between both species are identified as two new taxa: Paroistodus horridus primus Albanesi, 1998b, and P. h. secundus Albanesi, 1998b. They were recorded in the uppermost 70 cm of the lower member. Apparently, the speciation event occurred under stressed environmental conditions with the drowning of the carbonate platform, i.e., the San Juan Formation, and the beginning of a deeper and restricted environment represented by the Gualcamayo black shales. The demise of the carbonate production was caused by a sea level rise and a significant influx of volcanic ashes. The punctuated speciation event occurred within an allopatric setting while the Precordillera occupied an isolated (Iapetus) oceanic position in its overall drift from Laurentia to Gondwana.

The Plum Brook Shale of north-central Ohio lies disconformably between the Eifelian (lower Middle Devonian) Delaware Limestone and the middle Givetian (upper Middle Devonian) Prout Dolomite. Its diverse conodont fauna indicates that it represents a transgression into the area in earliest Givetian time accompanied by the products of a notable adaptive radiation within two lineages of Icriodus. One of these (I. expansus Group) includes I. expansus, I. arkonensis and I. brevis, and complete intergradation of forms suggests that the group at this level involves conspecific ecotypes. A more extensive radiation involved descendants of I. regularicrescens (I. regularicrescens Group), including three new species, I. eriensis, I. janeae and I. ohioensis. Other representatives of this lineage occur here as well as in strata of comparable age in the type region of the Givet Limestone as described by Bultynck (1987). A third lineage is represented by I. excavatus in both areas, but evidence of radiation within this branch is limited to the Giver Limestone. Remarkable diversity also occurs among forms considered herein to involve Polygnathus pseudofoliatus and its descendants. The existence of intermediate forms and shared characteristics between and among the various species, including some that first appeared well before the end of the Eifelian, implies that they may be conspecific ecotypic variants at this level. New morphotypes within this group are treated informally. The greatest overall diversity occurs just above the basal Plum Brook, in strata interpreted to reflect inner-sublittoral conditions. The entire Plum Brook belongs to the upper ensensis Zone. A considerable part of the type Givetian placed in the Lower varcus Subzone by Bultynck (1987) lies below the lowest occurrence of its index species (P. timorensis); it contains some of the species found in the Plum Brook, and much of this section may also belong to the ensensis Zone.

Early Devonian (Lochkovian; eurekaensis Zone) conodonts occur in discontinuous limestone beds in the Caballos Novaculite at five localities in the northwestern half of the Marathon uplift, west Texas. Similar conodont faunas at all five localities indicate that the limestone beds lie at one biostratigraphic horizon within the Caballos. The upper novaculite member directly overlies the limestone horizon at one locality, giving the upper novaculite a maximum age of Lochkovian. The limestone beds are dominantly skeletal calcarenites that represent shallow-water carbonate material transported into a deeper water setting by gravity processes. Restriction of the limestones to the northwestern margin of the uplift and provenance of reworked clasts and redeposited Ordovician and Silurian conodonts suggest a North American shelf source and are evidence of the close proximity of some strata exposed in the Marathon uplift to North America in the Early Devonian. Icriodus gravesi n. sp. is described from the limestone fauna.

Exceptionally well preserved Lower Triassic conodonts from Oman include an array of Neospathodus species, many of which are new. Those from the upper Lower Triassic, or Spathian, are described in conjunction with a restudy of conodont type material from Chios, Greece, and an assessment of contemporary collections from Pakistan and western North America. The taxonomic scope of three key species from Chios, Neospathodus homeri, N. triangularis, and N. gondolelloides, is revised. Seven new species are described from Oman: N. abruptus, N. brevissimus, N. brochus, N. crassatus, N. curtatus, N. pusillus, and N. symmetricus; and one new species, N. clinatus, is described from Pakistan. The allied Icriospathodus collinsoni is also described from Oman. The occurrence and range of Neospathodus species are presented in the context of the ammonoid succession in the Spathian of North America. Both N. homeri and N. triangularis, as revised, have shorter ranges and are more age diagnostic than previously thought. Neospathodus gondolelloides is a distinct taxon, and not synonymous with Chiosella timorensis. Five informal faunal divisions are identified based on Neospathodus and allied species. In ascending stratigraphic order, these are typified by Icriospathodus collinsoni, Neospathodus homeri, N. triangularis, N. symmetricus, and N. gondolelloides. Oman collections represent three of these faunas, which occur also in the Columbites through Prohungarites/Subcolumbites ammonoid beds of western U.S.A.