New dinoflagellate cyst taxa have been recovered from Pliocene deposits in the Antwerp area of Belgium, where a detailed analysis of the Kattendijk and Lillo formations has yielded a diverse dinoflagellate record for the southern margin of the North Sea Basin. Four new species and two new genera of dinoflagellate cysts are recognized: the gonyaulacaceans Spiniferites coniconcavus n. sp. and Pyxidinopsis braboi n. sp., the goniodomacean Desotodinium wrennii n. gen. and sp., and the protoperidiniacean Scaldecysta doelensis n. gen. and sp. The protoperidiniacean genus Barssidinium Lentin, Fensome, and Williams, 1994 has been emended from new observations on the tabulation of Barssidinium pliocenicum (Head, 1993) Head, 1994a emend. The excellent preservation of the Belgian material accounts for these new observations. Barssidinium wrennii Lentin, Fensome, and Williams, 1994 is considered a taxonomic junior synonym of Barssidinium pliocenicum (Head, 1993) Head, 1994a, which thus becomes the correct name for the type of the genus. The new marine incertae sedis palynomorph Waaslandia geminifera n. gen. and sp. is also proposed.

Small silicified anthaspidellid sponges identified as Gallatinospongia conica Okulitch and Bell, 1955 are described for the first time from the Upper Cambrian of the Great Basin where the sponges are found in situ within dendrolitic microbial reefs. This association forms the oldest anthaspidellid-microbial reefs of Laurentia.

We compare cladistic, phenetic, stratophenetic, and typological methods of recognizing species within a single well-sampled, long-lived Ordovician bryozoan genus, Peronopora Nicholson, 1881. A consensus of 11 methods recognizes 14 species within Peronopora, each of which has both cladistic and phenetic support, and support by at least four different methods. Comparison of methods was based on: 1) the number of species recognized; 2) the degree of splitting of consensus groups; 3) consistency in determining first and last appearance datums, and stratigraphic ranges; 4) consistency in the number of specimens assigned to species; 5) stability in recognizing geographic distributions; and 6) correlations with character heritability. The five methods most closely approaching consensus were: 1) Ward clustering on Euclidean distance; 2) K-means splitting; 3) Ward clustering on correlation coefficients; 4) cladistic parsimony; and 5) cladistic parsimony plus iterative discriminant analysis. The three methods farthest from consensus were: 1) stratophenetics; 2) average linkage on Euclidean distance; and 3) conventional typology. Cladistic parsimony is the only method that can recognize all 14 consensus clusters. We argue that the overall advantages of parsimony analysis outweigh the merits of the various phenetic approaches in recognizing paleontological species. We also argue that given sufficient allochrony in sampling, cladistic structure is detectable both within and among species. Recognizing species based on fixed character states would require at least 72 species in our material.

The crown groups of Pachut and Anstey (2002) are herein recognized as monophyletic species in the sense of Mishler and Theriot (2000), one of which we designate as a new species, P. browni. Six of our eight nonmonophyletic stem groups are recognized in this paper as metaspecies in the sense of Donoghue (1985) and Gauthier et al. (1988). Two of our stem groups are phenetically indistinguishable from phyletically contiguous crown groups, and we attribute the failure of parsimony analysis to recognize the monophyly of these groups to homoplasy.

Abundant silicified shell plates (valves) of some of the oldest-known chitons were recovered from the Late Cambrian Notch Peak Formation of Utah. The chiton fauna is dominated numerically by Matthevia wahwahensis new species, but also includes another mattheviid, Eukteanochiton milleri new genus and species, and a preacanthochitonid, Orthriochiton utahensis new genus and species. Robustum from the Early Ordovician Gasconade Formation of Missouri is herein reinterpreted as a septemchitonid chiton, and Hemithecella, from the Late Cambrian-Early Ordovician of the eastern United States, is once again considered a mattheviid chiton. Mattheviid valves are unique among chitons in that they are massive, elongate, and contain one or two tunnels; these characteristics have led some to exclude this family from the Polyplacophora. However, mattheviids and other chitons share many valve characters, including granules, an apical shelf, a thin anterior margin, bilateral symmetry, three valve types, and a shell layer perforated with canals. Furthermore, recently described chiton valves from the Silurian of Gotland, the Ordovician of Wisconsin, and the Cambrian-Ordovician of Missouri are gradational between the Notch Peak mattheviid valves and those of younger polyplacophorans. Also, Matthevia wahwahensis n. sp. has valves with a flat apical area, allowing for valve overlap, and so provides a link between the unusual chiton Matthevia variabilis, which had nonoverlapping, spiky valves, and Chelodes, a less disputed chiton. Known fossil assemblages reveal that, along the coastline of Laurentia during the Cambrian-Ordovician, chitons were diverse, consisting of at least four families and with much variation in valve shape.

The systematic position of endemic Early Miocene pectinid taxa of Patagonia contained in the uppermost horizons of the San Julián and Monte León formations and in the basal and middle beds of the Chenque Formation is revised. Two new genera are proposed: Reticulochlamys new genus with R. proximus (Ihering) as its type species and Jorgechlamys new genus with J. juliana (Ihering) as its type species. Two new species are described: Reticulochlamys zinsmeisteri new species from the Monte León Formation and Reticulochlamys borjasensis new species from the Chenque Formation.

New specimens of the arthropod Pectocaris Hou, 1999 have yielded important new information. The entire body of Pectocaris spatiosa Hou, 1999 is known. Odaraia? eurypetala Hou and Sun, 1988 is transferred to Pectocaris. In addition to the finlike lateral flukes, setal imprints and new specimen indicate a median fluke as in the Burgess Shale Odaraia. The cephalic region bears stalked eyes and the crustacean characteristics first and second antennae and mandibles. The mandibles are succeeded by about 53 pairs of branchiopod-type appendages, each corresponding to a head or body segment. Branchiopod characters include endites with setae turned backwards, the elongation of the telson, and its fluke-shaped rami. Pectocaris has a fairly basal position in the phylogenetic tree of the extant crustaceans and probably belongs to the branchiopod crustaceans. It is the first arthropod with definite crustacean characteristics described from strata from below the Upper Cambrian.

A review of all known species of the scutelluine trilobite Paralejurus corroborates its distinction from contemporaneous representatives of the subfamily. The overall morphology together with observed habitat conditions favor the view of its having had a semiendobenthic life habit analogous to that of many earlier illaenids. Particular features that are shared with the Silurian Rhaxeros, such as the pronounced convexity of the exoskeleton and the wide axis, are considered as homeomorphies related to a burrowing lifestyle rather than the expression of phyletic relationships. The data set based on conodont biostratigraphy reveals earliest occurrences of Paralejurus in the Pragian and the disappearance of last representatives at the base of the Middle Devonian. In the lower Early Devonian Paralejurus was restricted to the North Gondwana margin and related microplates. Later and in consequence of geodynamic plate movements that led to the reduction of oceanic barriers, the Paralejurus dormitzeri group succeeded in spreading to the epicontinental margin of Laurussia in Late Emsian times. New material from Southern Morocco, including Paralejurus spatuliformis n. sp. and Paralejurus tenuistriatus n. sp., and the first representative of the genus from Spain, Paralejurus carlsi n. sp., are described. Paralejurus dormitzeri rehamnanus Alberti, 1970 is considered an independent species emphasized by the discovery of complete exoskeletons.

Carniaster orchardi n. gen. and sp. (Echinodermata: Asteroidea) is only the fourth Triassic asteroid known from material complete enough to warrant a generic name. Data indicating familial and ordinal positions are not available. All four Triassic genera belong to the exclusively post-Paleozoic crown group. Carniaster does not appear to differ significantly from other described Triassic genera, and it probably represents a broadly basal lineage within the crown group diversification. Available morphological data suggest no ecologic parameters that would be unusual among living asteroids. Carniaster is the first complete Triassic asteroid known from beyond Europe.

New aplodontid material recovered from Hepburn's Mesa, Montana, stimulated reexamination of Ansomys, a genus of aplodontid previously known only from Asia. A cladistic analysis of the known species of Ansomys, as well as new material from Hepburn's Mesa and a few other morphologically similar species, prompted reconstruction of the biogeographic history of the genus. One new species, A. hepburnensis, from the Barstovian of Montana, is described, and two other species, A. nexodens and A. descendens, are placed in Ansomys rather than in Pseudallomys and Plesispermophilus, respectively. Addition of these three species to Ansomys extends its distribution throughout the Holarctic in the mid-Miocene. Stratigraphic ranges combined with phylogenetic relationships between species suggest this wide distribution as early as the late Oligocene, which is unique among aplodontid genera. The distribution, the rarity, the unusually small size, and the complex cusp morphology of Ansomys suggest a very specialized ecology for members of this clade.

Anourosoricini are among the most specialized shrews in terms of dentition and mandibular structure, showing carnivore-like specializations such as carnassial function and reduction and disappearance of third molars. The tribe is documented from the Upper Neogene of Europe, Asia, and North America, and from the Quaternary of Asia, where a single relict species has survived until the present day.

The Mediterranean area functioned as a sink area for the Anourosoricini. Their source area was a northern, more humid, and more forested zone extending from France to the Ukraine. Southward-directed range shifts resulted in the intermittent presence of the tribe in the Mediterranean region during more humid intervals. The dense Upper Miocene micromammal succession from the Teruel and Calatayud-Daroca basins, central Spain, shows that Crusafontina endemica was present in the area around 10.2 and between 9.7–9.5 Ma. It is succeeded by the dentally more gracile C. fastigata n. sp. at 9.0–8.8 Ma. The larger and more robust C. vandeweerdi n. sp., a form sharing features with Paranourosorex, peaks at ∼7 Ma. The last major acme occurs around 6.3 Ma and is represented by Amblycoptus jessiae. The final disappearance of the tribe from the area takes place at 5–4.5 Ma.

The Anourosoricini provide a well-documented pre-Quaternary example of recurrent climate-controlled north-south range expansion. The proposed paleobiogeographic model presumes that southward mammal migrations are driven by changes in the precipitation regime rather than the temperature regime of the Mediterranean region. A comparison to paleoecological interpretations based on the independent rodent record shows that Anourosoricini avoid areas with low levels of precipitation and low soil humidity. A mean annual precipitation minimum of 600 mm/yr is about the threshold value for populations of the tribe to survive locally.

The available evidence suggests eastward dispersal of a primitive Crusafontina species from Eurasia into North America at about the same time when Hipparion crossed the Bering Strait in a westward direction.

A new Middle Permian plant assemblage from South Ash Pasture in King County, Texas, may be the youngest and is certainly the most unusual flora known from the Permian of either West Texas or adjoining north-central Texas. Found serendipitously in the evaporite-rich upper Blaine Formation (Pease River Group, Guadalupian Series), the flora is of very low diversity despite intensive collecting efforts, and the affinities of nearly all taxa are enigmatic. The most common elements are parallel-veined leaves that resemble cordaites but that could be isolated pinnules of a pinnate leaf. Gigantopterid foliage is present but not assignable to any known taxon. A single foliar conifer specimen is too incomplete for assignment. Numerous reproductive organs, however, and an abundance of axes may represent conifers. Conchostracans, palaeoniscoid fish scales, and small heteropolar coprolites also occur in the deposit, which originated as a small, claystone-dominated channel fill in a coastal plain setting.

A new ichnotaxon, Paradictyodora antarctica, is proposed for complex spreite trace fossils from the Upper Cretaceous of Antarctica and Eocene of Tierra del Fuego, Argentina. This complex, three-dimensional, vertical spreite structure enlarges upwards, displaying a prismatic-to-conical shape that consists of subvertical folded laminae, produced by the lateral migration of a subvertical J-shaped tube anchored at its base. Overall morphology and mode of formation distinguishes this new ichnotaxa from other ichnogenera such as Daedalus, Dictyodora, and Heimdallia. Paradictyodora occurs in fodinichnia-dominated ichnocoenosis developed in distal fine-grained deposits of deepwater fan delta systems.

Colonial metazoans that lived symbiotically with hermit-crabs create striking and distinctive fossils. Examples of such fossils recorded (Schindler and Portell, 1993) from Cenozoic deposits in Florida include the scleractinian coral Septastrea marylandica (Conrad, 1841) (see Darrell and Taylor, 1989), the hydrozoan Cystactinia ocalana Brooks, 1964, and the bryozoan Hippoporidra edax (Busk, 1859) [recorded as H. calcarea (Smitt) by Scolaro, 1970]. In all of these fossils, the symbiotic colony covers the entire external surface of a gastropod shell with a thick encrustation. Growth of the colony outwards from the shell aperture in the form of a helicospiral tube greatly extends the size of the chamber available for the hermit-crab occupant. In no known fossil examples of symbioses are the hermit-crabs preserved in situ. However, modern analogues, along with functional morphological considerations, provide good criteria for inferring that this peculiar colonial growth pattern occurred in response to the presence of a symbiotic hermit-crab, at least for examples within the Lower Jurassic-Recent range known for fossil hermit-crabs (see Walker, 1992; Taylor, 1994).

Gastropods belonging to the extinct family Cirridae Cossmann, 1916 are relatively rare elements of Mesozoic marine communities. The unusual change in shell coiling from dextral to sinistral during their ontogeny represents a character which makes their recognition in the fossil record easy. This shell feature is also known from members of the Paleozoic family Porcelliidae Koken in Zittel, 1895, uniting the planispirally coiled Porcelliinae with the sinistrally coiled Agnesiinae Knight, 1956. This heterostrophy is not homologous with that of the Heterobranchia (Frýda and Blodgett, 2001). Shells of Porcelliinae and Agnesiinae bear an apertural slit, in contrast to the Mesozoic Cirridae. According to Bandel (1993a), slit-bearing members of the Porcelliidae evolved into the Cirridae without slit during the Triassic. Therefore Bandel (1993a) united both families into one natural group, the Cirroidea. That name has now been changed into Porcellioidea, according to the older family name (see discussion in Bandel and Frýda, in press). The oldest representatives of the Porcelliidae were reported from Silurian strata (Frýda, 1997). The youngest Cirridae are known from Late Cretaceous strata (Kiel and Bandel, 2002). Frýda and Blodgett (1998) described an Emsian (Early Devonian) porcellioid—Alaskacirrus bandeli—without slit as in the Mesozoic Cirridea, and pointed out that phylogenetic relationships of the Paleozoic Porcelliidae and Mesozoic Cirridae are still uncertain. The placement of the Porcellioidea within the Archaeogastropoda is based on the discovery of an archaeogastropod-type protoconch in the Paleozoic Porcelliidae (Yoo, 1994) as well as in the Mesozoic Cirridae (Bandel, 1993a). In addition, Bandel (1993a) mentioned the presence of a nacreous inner layer in a Mesozoic cirrid. This observation was from an unpublished master's thesis (Hänsel, 1992) supervised by him. Hänsel (1992) demonstrated that nacre is present in shells of the Late Cretaceous cirrid Sensuitrochus ferreri Quintero and Revilla, 1966 (Fig. 1.1), using peels of polished and etched shells to determine the shell structure. Although this observation is important for the interpretation of the higher taxonomic position of the Cirridae, it was never published. The aim of the present study is to document the presence of nacreous shell in the Mesozoic cirrid Sensuitrochus ferreri, using scanning electron microscopy.

The specimen studied here represents the first fossil Euzygoptera Bechly, 1996 described in South America. The lack of fossil damselflies from this subcontinent is probably an artifact related to the scarcity of fossil insect collections. Differences in the world fossil record of these insects (as many others) could be correlated to the level of activity of researchers in the different continents. Thus the fossil Lestinoidea Calvert, 1901 (sensu Bechly, 1996) are mainly known from Europe (Nel and Paicheler, 1994) where a long history of paleoentomology (and paleontology of Odonata) took place. From North America there is only one record in the Eocene of the USA (Cockerell, 1940), despite an ancient and long activity in this field. From Asia the group is known from the Oligo-Miocene of Turkey (Nel and Paicheler, 1994) and from the Miocene of Japan (Fujiyama, 1985). What does not fit in this hypothesis is the curious lack of records from Asia, despite the high number of paleoentomologists of the Russian school. The possible explanation of this could be that Russian researchers have preferred historically to study Paleozoic and Mesozoic rather than Cenozoic insects. Thus, due to the recent increasing number of paleoentomologists, new discoveries similar to the present one shall probably modify the present fragmentary fossil record of Lestinoidea.