From the early Cambrian of Yunnan, China, new chancellorid scleritomes assigned to Allonnia junyuani new species are described and compared with scleritomes of Chancelloria eros Walcott, 1920 from the Middle Cambrian of Utah, USA and isolated phosphatized chancellorid sclerites from the Georgina Basin of North Australia. Characters of the entirely preserved chancellorids offer new insight into the paleobiology of Chancelloridae. An irregular thickening at the inferred base of the narrow body end of Chancelloria eros from Utah is interpreted as a root bulb that anchored the sessile animal in the soft bottom sediment. Sclerites show gradual increase in size from the narrower towards the broader upper end of the chancellorid body. A central “gastral” lumen was not directly observed in any of the investigated specimens, but the orientation of sclerites towards the outer body surface indicates that the fossils are secondarily flattened due to compaction and were originally hollow. Taphonomy of isolated chancellorid sclerites from the Georgina Basin, Australia, indicates a biomineralization very different from that of sponge spicules, including the spongin spiculoids of demospongid Keratosa. Allonnia junyuani from Chengjiang (Yunnan) exhibits a prominent epidermis, probably with stable epithelian cell-to-cell connections. This feature excludes a sponge affiliation of the Chancelloridae and points towards a systematic position of this group within the epithelian-bearing animals and thus well above the Porifera.

Specimens of Peronopora Nicholson, 1881, are abundant in Upper Ordovician rocks of the North American Midcontinent. Based on the positions of units in the Composite Conodont Standard Section, we have sampled 211 specimens over a stratigraphic interval of 9.1 million years. The average duration of sample spacing is 61,664 years but is commonly as small as 32,800 yr.

Thirty-four morphometric characters were measured in each specimen and were converted into multistate characters; character-state breaks were established based upon each character's ability to discriminate between phenetic groupings. Each character was subsequently weighted based on the number of derived states, degree of independence from other attributes, and estimated heritability.

Cladistic analysis of these data indicate that there are eight species in Peronopora each consisting of an optimally defined crown group and a basal stem group (or paraclade). Character states shared by stem and crown groups define species but, within species, stem and crown groups also differ in some character states. The species are, in ascending order from the base of the tree, Peronopora decipiens (Rominger, 1886), P. compressa (Ulrich, 1979), P. pauca Utgaard and Perry, 1964, P. milleri Nickles, 1905, P. horowitzi new species, P. vera Ulrich, 1888, P. sparsa Brown and Daly, 1985, and finally P. dubia (Cumings and Galloway, 1913). Diagnostic keys permit the unique assignment of each specimen to a species and the separation of members of stem groups from those of crown groups. Thirty-one characters are required to discriminate between all 211 specimens. This contrasts with previous studies of Peronopora where eight or fewer characteristics were used. Of the ten characters most useful in discrimination, only three had been used in the conventional species literature. This accounts, largely, for only 29.8 percent (51 of 171) of previously identified specimens being classified as members of the same species in this analysis. Discriminant function analysis of original measurements, using species identity as the grouping criterion, produces statistically significant separation of species.

It appears that stratigraphic position had an explicit and undue effect on previous concepts of species many of which could not be recognized independently of stratigraphic position. All species of Peronopora appear, or are inferred to have appeared, within the Lexington Limestone between the base of the Grier Member and the top of the Millersburg Member. The cladogram indicates that species evolved in a sequential order, but their first appearance datums have been stratigraphically punctuated. Three species have ranges terminating in the Early to Middle Maysvillian, one in the Middle Richmondian, and four in the Late Richmondian. The latter four (or five) of these species died out in the extinction associated with the unconformity at the top of the Richmondian.

Costistricklandia is a common, easily recognizable pentamerid brachiopod in upper Llandovery to lowest Wenlock rocks of eastern Laurentia, Avalonia and Baltica. In this paper, the poorly known Costistricklandia canadensis (Billings) is re-described from the upper Telychian Rockway Dolomite of the Niagara Escarpment, Ontario. Compared to the relatively complete record of the Stricklandia-Costistricklandia evolution in the Welsh Borderland and the Baltic region, true representatives of the Stricklandia lens lineage are sporadic in North America, including those from the Merrimack Formation of Anticosti Island, the Red Mountain Formation of Alabama, the Hopkinton Formation of Iowa, and the Nonda Formation of the northern Rocky Mountains. Although the exact mode of speciation in the Stricklandia-Costistricklandia and the Pentamerus-Pentameroides transitions remains debatable, the common association of Costistricklandia and Pentameroides make them a useful concurrent biozone for correlating middle to upper Telychian rocks of North America and Europe. Paleobiogeographically, the Pentameroides-Costistricklandia Fauna marks the third major pulse of pentamerid faunal migration between Laurentia and its adjacent paleo-plates during the Early Silurian, following the limited intercontinental dispersal of the early Llandovery Virgiana Fauna and the quasi-cosmopolitan dispersal of the middle Llandovery Pentamerus Fauna.

Brachiopods are common in the lower part of the late Early to Middle Devonian Bird Fiord Formation that is a carbonate-clastic transition succession found in Arctic Canada. These brachiopods, which lived in a shallow, near-shore, marine environment, includes three new genera: Borealistrophia, Arcticastrophia, and Grinnellathyis. The strophomenid Borealistrophia, which is characterized by two pairs of straight side septa, prominent and thick socket ridges, a thick but short median septum, and a cordate ventral muscle field, is found in the Baad Fiord, Blubber Point, and Norwegian members on Bathurst, Devon, North Kent, and Ellesmere islands. The strophomenid Arcticastrophia, which is distinctive because of its stout transmuscle septa, its narrow and low medium septum, and elevated ventral muscle field, is found in the Baad Fiord Member on Bathurst and Devon islands. The athyridid Grinnellathyris, which is characterized by an imperforated cardinal plate and inverted U-shaped jugum, is found in the Baad Fiord Member on Bathurst, North Kent, and Devon islands. The similarities between Grinnellathyris and Johnsonathyris Savage, Eberlein, and Churkin, 1978, in terms of their shell size and internal structures, may indicate that the latter evolved from the former.

Evolutionary relationships between the Echinoconchidae, Productidae, Buxtoniinae, and Juresaniinae (Phylum Brachiopoda, Order Productida) have been the subject of debate for the better part of a century. The original (Muir-Wood and Williams, 1965) and revised (Brunton et al., 2000) Brachiopoda volumes of the Treatise on Invertebrate Paleontology use markedly different classifications and emphasize different characters. The 1965 Treatise classification for these taxa primarily was based on internal features, especially the cardinal process; the revised Treatise (2000) relied on external ornament and shell shape. Multiple phylogenetic analyses (global parsimony, stratocladistics, nearest-neighbor) of 14 genera, representing all of the relevant subfamilies and outgroups, are in strong agreement that 1) the subfamily Buxtoniinae belongs in the family Echinoconchidae, not to the Productidae; 2) the subfamily Juresaniinae is more closely related to the Echinoconchinae than to the Buxtoniinae; and 3) that internal characters, such as a shafted cardinal process and anterio-medial position of the brachial valve adductor field, provide the best phylogenetic signal, and are synapomorphic for the Echinoconchidae. Jackknifing and Bremer Support corroborate these results.

A species of the rudist bivalve genus Mexicaprina Coogan, 1973, from the mid-Cretaceous Mai Paso Formation of the Guerrero terrane, southwestern Mexico, is described as new: M. alata. At the type locality of this new species, a 6.5 m thick Mexicaprina-rich floatstone bed conformably overlies a taxonomically diverse build-up of reef corals. This type of facies relationship and implied faunal association has not been observed previously at any other site. Specimens of the type species, M. cornuta Coogan, 1973, also were found at the same locality, but 90 m stratigraphically below the lowest occurrence of M. alata. Compilation and detailed biostratigraphic analysis of the reported occurrences of Mexicaprina demonstrate that the age of the genus ranges from late Albian to early Cenomanian. However, most occurrences are late Albian and the Cenomanian age determinations are questionable and possibly late Albian also. The occurrence of species of Mexicaprina in the allochthonous Guerrero terrane, together with the relatively limited geographic distribution of the genus in the late Albian and early Cenomanian of the Gulf Coast of Mexico, Texas, and Honduras, indicates that this region of the Guerrero terrane was part of the Caribbean paleobiogeographic province during late Albian to early Cenomanian time. This occurrence also suggests that this portion of the Guerrero terrane was very close, possibly accreted, to the southwestern margin of North America by the close of the Early Cretaceous.

This paper presents a phylogenetic analysis of the “Fallotaspidoidea,” a determination of the biogeographic origins of the eutrilobites, and an evaluation of the timing of the Cambrian radiation based on biogeographic evidence. Phylogenetic analysis incorporated 29 exoskeletal characters and 16 ingroup taxa. In the single most parsimonious tree the genus Fallotaspidella Repina, 1961, is the sister taxon of the sutured members of the Redlichiina Richter, 1932. Phylogenetic analysis is also used to determine the evolutionary relationships of two new species of “fallotaspidoids” distributed in the White-Inyo Range of California that have been previously illustrated but not described. These species had been referred to Fallotaspis Hupé, 1953, and used to define the occurrence of the eponymous Fallotaspis Zone in southwestern Laurentia. However, these two new species need to be reassigned to Archaeaspis Repina in Khomentovskii and Repina, 1965. They are described as Archaeaspis nelsoni and A. macropleuron. Their phylogenetic status suggests that the Fallotaspis Zone in southwestern Laurentia is not exactly analogous to the Fallotaspis Zone in Morocco, where that division was originally defined. Thus, changes to the biostratigraphy of the Early Cambrian of southwestern Laurentia may be in order. Furthermore, specimens of a new species referable to Nevadia Walcott, 1910, are recognized in strata traditionally treated as within the Fallotaspis Zone, which is held to underlie the Nevadella Zone, suggesting further biostratigraphic complexity within the basal Lower Cambrian of southwestern Laurentia.

Phylogenetic analyses of the Olenellina and Olenelloidea, along with the phylogenetic analysis presented here, are used to consider the biogeographic origins of the eutrilobites. The group appears to have originated in Siberia. Biogeographic patterns in trilobites, especially those relating to the split between the Olenellid and Redlichiid faunal provinces are important for determining the timing of the Cambrian radiation. Some authors have argued that there was a hidden radiation that significantly predated the Cambrian, whereas others have suggested that the radiation occurred right at the start of the Cambrian. The results from trilobite biogeography presented here support an early radiation. They are most compatible with the notion that there was a vicariance event relating to the origin of the redlichiinid trilobites, and thus the eponymous Redlichiid faunal province, from the “fallotaspidoids,” whose representatives were part of the Olenellid faunal province. This vicariance event, based on biogeographic patterns, is likely related to the breakup of Pannotia which occurred sometime between 600–550 Ma, suggesting that the initial episodes of trilobite cladogenesis occurred within that interval. As trilobites are relatively derived arthropods, this suggests that Númerous important episodes of metazoan cladogenesis precede both the earliest trilobitic part of the Early Cambrian, and indeed, even the Early Cambrian.

Faunal data provide critical constraints upon tectonic models, particularly in such areas of extreme structural complexity as the region adjacent to the eastern syntaxis of the Himalaya. Trilobites reported to have been collected from the Yunling collage at Yinchangou, northwestern Yunnan, are here assigned to Kunmingaspis yunnanensis Chang, 1964, and the concept of the genus Kunmingaspis is reconsidered. Although there is debate about to the paleogeographic affinities of the Yunling collage, the apparent presence of this species supports previous arguments for faunal links between the Yangtze platform and the Himalayan margin during Early and Middle Cambrian time. A significant tectonic event of Late Cambrian/Early Ordovician age present in the western central Himalayan margin suggests that the Lhasa block collided with India at that time, but the northward extent of that block remains unclear. The recently discovered Late Cambrian trilobite fauna of Bhutan may hold the key to establishing faunal relationships between the Tethyan Himalaya, Sibumasu, and the Yangtze platform during this interval. No Cambrian sedimentary rocks are yet known from the Lhasa or Qiangtang blocks of Tibet and so there is no direct evidence for the existence of Cimmeria during the Cambrian Period.

A single large specimen of carcineretid crab from the Cretaceous Puerto Romero unit of Colombia constitutes the basis for a new species, Ophthalmoplax triambonatus. A re-diagnosis of the Carcineretidae results in the assignment of five genera to the family: Carcineretes Withers, 1922; Branchiocarcinus Vega, Feldmann, and Sour-Tovar, 1995; Mascaranada Vega and Feldmann, 1991; Ophthalmoplax Rathbun, 1935; and Woodbinax Stenzel, 1952. The cross-sectional profile of O. triambonatus suggests that it was a back-burrower, rather than an active swimmer.

Crinoid columnals are major faunal components of interbedded shales and carbonates of the Upper Ordovician Kope to Fairview formations (Edenian-Maysvillian) of the Cincinnati Arch region. Six species can be identified on the basis of distinctive morphological characters of the columnals. Crinoid distribution was plotted from point-counted carbonate samples taken through a 68-m thick composite section of the Kope to Fairview formations in Campbell County, Kentucky. This section spans a shallowing-upward, third-order depositional sequence (C1), part of C2, and the Edenian-Maysvillian Stage boundary. The slender cladid crinoid Merocrinus occurs in the lowermost Kope below the base of this section. The slender disparids Cincinnaticrinus and Ectenocrinus occur throughout the section but are most abundant in the lower 25 m where the shale percentage is 60–90 percent. The larger, more robust disparid Iocrinus appears within the carbonate-rich Grand Avenue member of the Kope at 40–50 m, and the large, plated camerate Glyptocrinus first appears just above the Grand Avenue and becomes the dominant crinoid above the C1–C2 sequence boundary that lies just above the Kope-Fairview contact. The largest and most robust crinoid in this sequence, Anomalocrinus, occurs at the top of the Grand Avenue Member. Siliciclastic ratio and biofacies composition indicate that the occurrence of larger, more robust crinoid taxa is correlated with shallowing depth. Crinoid trophic niche differentiation is also correlated with decreasing depth and the concomitant increase in water movement caused by waves and currents. The deeper water disparids have a nonpinnulate filtration fan with low branch density and wider ambulacral grooves. The shallower water camerate Glyptocrinus has a pinnulate filtration fan with high branch density and narrower ambulacral grooves. These relationships are consistent with the predictions of aerosol filtration theory.

A relatively large new specimen of the callocystitid rhombiferan Novacystis hawkesi Paul and Bolton, 1991, is described from the Wenlock (Middle Silurian) Thornloe Formation of east-central Ontario. This new specimen adds to the known morphology of Novacystis hawkesi, including the plating of the thecal side opposite the periproct, the presence of four pectinirhombs in standard callocystitid placements, and brachiole morphology. It also confirms the unusual placement of the periproct previously described for this species. A phylogenetic analysis of Callocystitidae indicates that, as presently defined, Callocystitinae sensu Paul and Bolton is polyphyletic and Apiocystitinae is paraphyletic. Novacystis forms part of a small, relatively primitive echinoderm fauna, probably of middle Wenlock age from the Timiskaming area, suggesting that shallow cratonic areas of the Canadian shield area may have served as refugium for archaic echinoderm taxa.

Permian conodonts were recovered for the first time from the Dingjiazhai Formation, a well-known diamictite-bearing stratigraphic unit in the Gondwana-derived Baoshan Block in West Yunnan, Southwest China. The conodont fauna occurs in limestone units within the upper part of the formation and consists of Sweetognathus bucaramangus (Rabe), S. whitei (Rhodes), Mesogondolella bisselli (Clark and Behnken), and an unidentified ramiform element. Based on the known stratigraphic distribution of 5. bucaramangus (Rabe), the fauna is referable to the upper Sweetognathus whitei-Mesogondolella bisselli Zone, and thus is dated as middle Artinskian according to the current definition of the stage. The Dingjiazhai Formation is overlain paraconformably by the Woniusi Formation, which is represented mostly by basalts and basaltic volcaniclastics related to rifting volcanism during the separation of the Baoshan Block from Gondwanaland. The present discovery of conodonts from the upper part of the Dingjiazhai Formation reveals that the glaciogene diamictites in the Dingjiazhai Formation are older than middle Artinskian, and the inception of rifting volcanism of the Baoshan Block is later than middle Artinskian.

Occurrence of an essentially warm water element, Sweetognathus bucaramangus (Rabe), in the Dingjiazhai conodont assemblage notwithstanding, the entire fossil faunas including brachiopods and fusulinoideans from the limestone units of the formation can be best interpreted as a middle latitudinal, non-tropical, and still substantially Gondwana-influenced assemblage developed at the northern margin of Gondwanaland just after deglaciation in the southern hemisphere during Early Permian time. This time could be regarded as the beginning of the Cimmerian Region, which had mixed or transitional paleobiogeographic characteristics between the Paleoequatorial Tethyan and cool/cold Gondwanan realms, and which became well developed during Middle Permian time.

A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian;˜79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Additionally, bird teeth are identified in the assemblage and are described in this review.

Bivariate plots were used to document the variation in the theropod teeth, especially in the features that distinguish between Richardoestesia gilmorei, R. isosceles, Saurornitholestes, and Dromaeosaurus. Considerable overlap is present in all plots, so although the teeth are morphologically distinct, they are not easily distinguished by quantitative means.

The Polychaetes of the Mazon Creek biota have been documented previously (Dawson, 1881; Thompson and Johnson, 1977; Thompson, 1979; Fitzhugh et al., 1997). Owing mainly to their rarity, several genera of fossil polychaetes had been noted but not described. Active amateur collecting of Mazon Creek concretions has allowed a number of uncommon, undescribed, flabelligerid annelid specimens to be cataloged into private and museum collections. All flabelligerid individuals are considered to be of one species.

The West Indian Top-shell, Cittarium pica (Linnaeus, 1758), is a very classic and common species of the Caribbean faunal province. Until now the only known fossil occurrence of Cittarium pica, and of the genus Cittarium, is from Pleistocene deposits restricted to the Caribbean province (Clench and Abbott, 1943). Despite the turbiniform shell, the monotypic genus Cittarium belongs to the family Trochidae and was assigned to the tribe Gibbilini Stoliczka, 1868 by Hickman and McLean (1990). This paper reports a new species of Cittarium and the only record outside the Caribbean province. More than twenty million years separate the single modern species of Cittarium and the new fossil species. All material collected is deposited in Museum national d'Histoire Naturelle, Paris (MNHN).

The Midyear Council Meeting of The Paleontological Society (PS) was called to order by President Patricia H. “Tricia” Kelley on 10 March 2001 at 8:10 hrs in Room 291 of Mendenhall Laboratory on the campus of The Ohio State University. Attending were Council members William I. Ausich, Thomas W. Kammer, Carl W. Stock, Christopher G. Maples, Nigel C. Hughes, Seth Finnegan, Ann F. “Nancy” Budd, Mark A. Wilson, Dale A. Springer, Russell H. “Tim” White, Jed Day, and Elizabeth “Liz” Nesbitt. Steven J. Hageman, and Peter J. Harries were also present.