A new Burgess Shale-type Lagerstätte is described from the middle Cambrian (Series 3, Drumian) Rockslide Formation of the Mackenzie Mountains, Northwest Territories, Canada. The Rockslide Formation is a unit of deeper water ramp to slope, mixed carbonate, and siliciclastic facies deposited on the northwestern margin of Laurentia. At the fossil-bearing locality, the unit onlaps a fault scarp cutting lower Cambrian sandstones. There it consists of a succession of shale and thick-laminated to thin-bedded lime mudstone, calcareous sandstone, and greenish-colored calcareous mudstone, overlain by shallower water dolostones of the Avalanche Formation, which is indicative of an overall progradational sequence. The Rockslide Formation is of similar age to the Wheeler and Marjum formations of Utah, belonging to the Bolaspidella Biozone. Only two 1 m thick units of greenish mudstone exhibit soft-bodied preservation, with most specimens coming from the lower interval. However, the biota is common but not as diverse as that of other Lagerstätten such as the Burgess Shale in its type area. The shelly fauna is dominated by the hyolith Haplophrentis carinatus Matthew, 1899 along with sparse linguliformean brachiopods, agnostoid arthropods, and ptychoparioid trilobites. The nonmineralized biota includes the macrophytic alga Margaretia dorus Walcott, 1911, priapulid worms, and the carapaces of a number of arthropods. The arthropods belong to Isoxys mackenziensis n. sp., Tuzoia cf. T. guntheri Robison and Richards, 1981; Branchiocaris? sp., Perspicaris? dilatus Robison and Richards, 1981; and bradoriids, along with fragments of arthropods of indeterminate affinities. The style of preservation indicates that most soft parts underwent complete biodegradation, leaving just the more resistant materials such as chitinous arthropod cuticles. The range of preservation and similarity to the coeval biotas preserved in Utah suggests that the composition of this Lagerstätte is probably representative of the community living on the relatively deep-water ramp or slope during middle Cambrian time in Laurentia. This would argue that the extraordinary diversity of the Burgess Shale at Mount Field is anomalous.

Until Recently, our understanding of the earliest history of the fish has been fragmentary in terms of the fossil record and conjectural with respect to many details of phylogeny. Fortunately, significant new information has become available in recent years, most notably from the discoveries of at least three taxa of agnathan fish from the Lower Cambrian Chengjiang Lagerstätte of Yunnan, China (Shu et al., 1999, 2003; Shu, 2003; see also Hou et al., 2002; Hou et al., 2004, p. 192-193; Zhang and Hou, 2004). Two of the taxa (Haikouichthys and Zhangjianichthys) are represented by numerous specimens, but it is noteworthy that amongst the forty-odd Burgess Shale-type occurrences apart from the Chengjiang Lagerstätte, chordates (or indeed cephalochordates and urochordates) are otherwise unknown. The one exception is the Burgess Shale itself, characterized by the rather enigmatic Pikaia gracilens (Conway Morris, 1982, 1998) and the much rarer chordate described herein. Apart from this exceptionally preserved material, the fossil record effectively only begins in the Ordovician (e.g., Sansom et al., 2001, 2005; Sansom and Smith, 2005), in as much putative fish scales from the latest Cambrian (Young et al., 1996) may be better interpreted as arthropodan (see Smith et al., 2001, p. 78). The difficulties of interpreting what is overall an extremely patchy record are further compounded by the fact that the relevance to this early history of the extant agnathan hagfish and lamprey has remained (and indeed to some extent remains) problematic, given the uncertainty as to which of the presumed archaic features have been overprinted by specializations for modes of life that might have had little counterpart in the ancestral forms.

The Paleozoic to Mesozoic grade ‘Protozygoptera’ is revised. It appears to be composed of two main lineages, namely the superfamily Permagrionoidea, and the Archizygoptera. The latter taxon forms a monophyletic group together with Panodonata (=crown-Odonata plus their closest stem-relatives). Therefore, the ‘Protozygoptera’ as previously understood is paraphyletic. Diagnostic characters of the ‘Protozygoptera’, Permagrionoidea, and Archizygoptera are re-evaluated. The Permolestidae is considered as a junior synonym of the Permagrionidae. The following new taxa are described: Permolestes sheimogorai new species, Permolestes soyanaiensis new species, Epilestes angustapterix new species, Solikamptilon pectinatus new species (all in Permagrionidae); Lodeviidae new family (for Lodevia); Luiseiidae new family (including Luiseia breviata new genus and species); Kennedya azari new species, Kennedya pritykinae new species, Kennedya ivensis new species, Progoneura grimaldii new species (all in Kennedyidae); Engellestes chekardensis new genus and species (in Bakteniidae); and Azaroneura permiana new genus and species (in Voltzialestidae). The Kaltanoneuridae and Oboraneuridae are revised. The evolution of protozygopteran Odonatoptera during the transition from the Permian to the Triassic is discussed. The larger taxa of the permagrionoid lineage apparently did not cross through the Permian–Triassic boundary, unlike the more gracile Archizygoptera. This last group shows a remarkable longevity from the late Carboniferous to the Early Cretaceous. It also presents a great taxonomic and morphological stability, with genera ranging from the Permian to the Triassic, and a wing venation pattern nearly unchanged from the late Carboniferous to the Late Triassic. The mass extinction at the end of the Permian period seemingly had a minor effect on these tiny and delicate insects.

The ichnogenus Curvolithus Fritsch, 1908, originally described from the Ordovician of the Prague Basin, typically comprises ribbonlike or tonguelike, flattened, endostratal traces with three rounded lobes on the upper surface. However, considerable confusion persists regarding the ichnotaxonomic status and diagnostic features of its ichnospecies. The type specimens of this ichnotaxon, overlooked in most subsequent reports, are redescribed herein. Curvolithus multiplex Fritsch, 1908, the type species, is retained for specimens with a trilobate upper surface and a quadralobate lower surface, in contrast to the criteria adopted by subsequent authors. The other ichnospecies originally proposed from the type locality, C. gregarius Fritsch, 1908, actually consists of a series of grouped parallel scratch marks forming ridges and should be removed from Curvolithus. Subsequently, four ichnospecies were defined: C.? davidis Webby 1970; C. annulatus Badve and Ghare 1978; C. aequus Walter et al. 1989; and C. manitouensis Maples and Suttner 1990. Curvolithus? davidis shows the typical trilobation of Curvolithus apparently in its lower surface, but the morphology of the upper surface is uncertain. Accordingly, it does not warrant ichnospecific assessment, and is regarded as a nomen dubium. The nature of the annulations on the trilobate upper surface of C. annulatus is unclear, and this ichnospecies is also best considered as a nomen dubium.Curvolithus aequus has a bilobate lower surface and probably represents washed out specimens of Didymaulichnus. Finally, C. manitouensis comprises specimens with a smooth, trilobate upper surface and a smooth, quadralobate lower surface, and is best regarded as a junior synonym of C. multiplex. Curvolithus multiplex has been used incorrectly for Curvolithus with a trilobate upper surface and a trilobate to unilobate lower surface. The new ichnospecies, Curvolithus simplex, is proposed herein for such traces. Curvolithus is interpreted as a locomotion trace (Repichnia) of endostratal carnivores, possibly gastropods, flatworms, or nemerteans. Curvolithus is a component of the Cruziana ichnofacies in shallow-marine facies, either of normal salinity or slightly brackish, in the latter case typically associated with fan deltas.

Detailed qualitative analysis of the Pa element and multielement analysis emphasizing the associated Pb element have led to the present revision of the Frasnian species of Ancyrognathus. Diagnostic characters of the Pa element, such as the platform outline, carinal pattern, and shape of the pit, as well as salient features of the Pb element, are the basis of this revision. As a consequence, the restriction in the definition of A. triangularis, formerly a heterogeneous concept including several discrete species, has in turn led to the recognition of a substantially increased number of species of Ancyrognathus.

The lowest occurrence of Ancyrognathus primus is used here to delimit the base of Zone 6 of the Montagne Noire Frasnian sequence. The exact relationship of the Montagne Noire zonation to the published standard zonation is problematical. For example, the base of the range of A. triangularis is possibly above the zone for which it is the nominal species in the standard zonation. Two new species are named herein, A. coeni and A. seddoni, both of which have been widely illustrated in the literature, and three new species are recognized in open nomenclature.

The Upper Cretaceous “redbeds” of the lower Tremp Formation (South-Central Pyrenees, Spain) contains an ichnofauna consisting of Taenidium barretti, Taenidium bowni, Loloichnus isp., Arenicolites isp., Planolites isp., and Palaeophycus isp. This ichnofauna occurs in deposits formed in tide-influenced meander loops and their associated overbank mudflats. Evaluation of the taphonomic controls on the Tremp ichnofauna shows that (1) two morphotypes of Taenidium barretti are controlled by the substrate consistence, (2) Arenicolites may be enlarged by erosion processes, and (3) Taenidium barretti and Planolites isp. are not the same ichnotaxa showing different types of preservation. The meniscate fill in Taenidium barretti suggests that this structure was produced by deposit feeders. The Tremp ichnofauna is grouped into two trace-fossil assemblages, a depauperate subaquatic monospecific Planolites suite and an assemblage representing the Scoyenia Ichnofacies. Trace-fossil distribution reflects paleoenvironmental changes in the meandering channels along the stratigraphic section with the Planolites suite in the lowermost part of the lower interval and the Scoyenia Ichnofacies in the middle and upper intervals. The lowermost suite may be likely formed seaward of the maximum salinity limit, under extreme brackish-water conditions, whereas the Scoyenia Ichnofacies records a freshwater assemblage that was formed landward of the maximum salinity limit, reflecting deltaic progradation.

The well-exposed and fossiliferous Permian carbonates in China have yielded Early and Late Permian species of the Sweetognathus complex that permit worldwide stratigraphic evaluation of members of the group. The sporadic appearance of species of Sweetognathus and related genera throughout the Permian in western North America and Iran, in particular, may represent iterative evolution and homeomorphy. The pectiniform element morphologies of the several species are interpreted as most important for evolutionary studies and document a partial Permian biostratigraphy in China that aids in the interpretation of less complete sequences elsewhere. A new genus, Pseudosweetognathus, and four new species, Pseudosweetognathus costatus, Sweetognathus subsymmetricus, S. paraguizhouensis, and Iranognathus nudus, are described.

The Goodland/Comanche Peak Limestone, Kiamichi Formation and basal Duck Creek Limestones around Fort Worth Texas yield a limited number of cosmopolitan ammonite and inoceramid bivalve taxa that allow precise correlation with the sequence that has been used as a standard in northwest Europe. The upper part of the Goodland/Comanche Peak Limestones yields species of Dipoloceras that show the base of the Upper Albian substage, provisionally defined as the first appearance of D. cristatum (Brongniart, 1822), to lie within this unit. Brancoceras aff. cricki Spath, 1934, Mortoniceras (Deiradoceras) beloventer new species, and Actinoceramus cf. concentricus (Parkinson, 1819) parabolicus Crampton, 1996a, co-occurs with D. cristatum in the Comanche Peak Limestone. The Kiamichi Formation yields rare Mortoniceras (Mortoniceras) pricei (Spath, 1922), M. (Deiradoceras) prerostratum Spath, 1921, M. (D.) bipunctatum Spath, 1933, and Actinoceramus sulcatus (Parkinson, 1819) morphotypes that allow correlation with the European Hysteroceras orbignyi and Hysteroceras varicosum subzones of the Mortoniceras inflatum zone. The basal Duck Creek Limestone yields Mortoniceras (Deiradoceras) sp. and Hysteroceras cf. varicosum (J. de C. Sowerby, 1824), and can also be correlated with the varicosum subzone.

Concepts of the family Hyolithidae Nicholson fide Fisher and the genera Hyolithes Eichwald and Orthotheca Novak have been expanded through time to encompass a variety of morphologically dissimilar shells. The Hyolithidae is here considered to include only those hyolithid species which have a rounded (convex) dorsum; slopes on the dorsum are inflated, and the venter may be flat or slightly inflated. Hyolithes encompasses species which possess a low dorsum and a prominent longitudinal sulcus along each edge of the dorsum; the ligula is short and the apertural rim is flared. The emended concept of Orthotheca includes only those species of orthothecid hyoliths which have a subtriangular transverse outline and longitudinal lirae covering the shell on both dorsum and venter.

Eighteen species of Hyolithes and one species of Orthotheca from the Appalachian region and Western Interior were reexamined in light of more modern taxonomic concepts and standards of quality for type material. Reexamination of type specimens of H. similis Walcott from the Lower Cambrian of Newfoundland, H. whitei Resser from the Lower Cambrian of Nevada, H. billingsi Walcott from the Lower Cambrian of Nevada, H. gallatinensis Resser from the Upper Cambrian of Wyoming, and H. partitus Resser from the Middle Cambrian of Alabama indicates that none of these species represents Hyolithes. Hyolithes similis is here included under the new genus Similotheca, in the new family Similothecidae. Hyolithes whitei is designated as the type species of the new genus Nevadotheca, to which H. billingsi may also belong. Hyolithes gallatinensis is referred to Burithes Missarzhevsky with question, and H. partitus may represent Joachimilites Marek. The type or types of H. attenuatus Walcott, H. cecrops Walcott, H. comptus Howell, H. cowanensis Resser, H. curticei Resser, H. idahoensis Resser, H. prolixus Resser, H. resseri Howell, H. shaleri Walcott, H. terranovicus Walcott, and H. wanneri Resser and Howell lack shells and/or other taxonomically important features such as a complete aperture, rendering the diagnoses of these species incomplete. Their names should only be used for the type specimens until better preserved topotypes become available for study. Morphology of the types of H.? corrugatus Walcott and “Orthotheca” sola Resser does not support placement in the Hyolitha; the affinities of these species are uncertain.

Specimens of the discoid, chambered megafossil Kullingia delicata (Fedonkin) occur near the base of member 2 of the Chapel Island Formation on the Burin Peninsula of Newfoundland. Morphologic and taphonomic features suggest that these fossils can be interpreted as the impressions of pelagic chondrophorines. Kullingia provides a link between Ediacaran and Paleozoic forms, and thus supports the view that the Chondrophorina represents a conservative evolutionary lineage extending back into the Precambrian.

Inozoans are described from patch reefs on the carbonate platform of eastern Sichuan, from the uppermost Permian Laolongdong reefs in the Changxing Formation (Kazanian–Tatarian) at Beipei, northwest of Chongqing, and from Middle and Upper Permian reefs from the Maokou (Kungurian), Wujiaping (Ufimian), and Changxing Formations at Xiangbo, Longlin County, in northwestern Guangxi. Classification of inozoans, particularly late Paleozoic ones, is still in a state of flux, but genera recognized to date can be keyed using the general nature of the spongocoel, canals, and growth form.

New genera described are Intratubospongia, Grossotubenella, Cavusonella, and Radicanalospongia. The new species described are Stellispongia radiata, S. minor, Peronidella beipeiensis, P. regulara, P. parva, Intratubospongia typica, I. tenuiperforata, I. multisi-phonata, I. minima, Grossotubenella parallela, Cavusonella caverna, and Radicanalospongia normala. A Corynella that is not identifiable to species and a sphinctozoan-like inozoan(?) sp. A that has a fibrous-appearing internal skeleton but is poorly preserved are also described. Inozoans and other sponges are major frame-builders in the Permian reefs of South China and our fauna is one of the most diverse late Paleozoic assemblages described to date.

A newly discovered Late Ordovician (early Ashgill) brachiopod assemblage from the Linhsiang Formation in the middle part of the Yangtze Platform, South China, bridges the paleobiogeographical gap between the early Ashgill Foliomena-bearing associations known previously from the upper and the lower parts of the Yangtze Platform. Characterized by minute shells in calcareous to siliciclastic mudstones, the fauna contains 13 brachiopod genera, of which two plectambonitoids are new: Hadroskolos and Jingshanella. Cluster and principal component analyses, based on 29 global occurrences of the Foliomena fauna in Laurentia, Avalonia, Kazakhstan, Baltica, Sardinia, Bohemia, Sibumasu, North China, and South China, revealed broad trends of spatial and temporal faunal differentiation in terms of taxonomic compositions. The analyses demonstrate for the first time that early Foliomena-bearing associations of Caradoc age occupied primarily deepwater (distal shelf) environments with a siliciclastic or calcareous mud substrate. The fauna attained its widest paleogeographical distribution and paleoecological range (midshelf to shelf margin settings) during the early Ashgill.

Twenty-four nearly complete carapace samples were collected at three different localities of the Maastrichtian (Late Cretaceous) Cárdenas Formation in San Luis Potosí, east-central Mexico. The material has been assigned to five families: the Callianassidae, Dakoticancridae, Carcineretidae, ?Majidae, and Retroplumidae. Two genera of callianassid shrimp are described, Cheramus for the first time in the fossil record. Dakoticancer australis Rathbun is reported as the most abundant crustacean element; one new genus and species of carcineretid crab, Branchiocarcinus cornatus, is erected, and a single, fragmentary specimen is questionably referred to the Majidae. The three localities reflect paleoenvironmental differences, exhibited by different lithologies, within marginal marine, lagoon environments. The record of dakoticancrid crabs in the Cardenas Formation extends the paleobiogeographic range of the family and the genus Dakoticancer. Carcineretid crabs, although not abundant, seem to have been a persistent element of crustacean assemblages in clastic environments during the Late Cretaceous of the ancestral Gulf Coast of Mexico.

Rudists are a principal biotic component of Cretaceous carbonates in Tibet and in the Western Tarim Basin. Barremian to Maastrichtian carbonate units are widespread on the northern margin of the Indian Plate and in Tethyan tectonic slices that were welded onto Eurasia in successive stages during the Late Cretaceous and Paleogene. In far northwestern Tibet, Barremian-Cenomanian endemic rudists and cosmopolitan orbitolinid foraminifera occupied isolated carbonate platforms in the eastern Tethys. Rudists, corals, and stromatoporoids composed bioherms up to 10 m thick and several kilometers in lateral extent. A unique endemic requieniid rudist, Rutonia, is compared to morphologically similar but older, less derived genera. Associated specimens in this assemblage are indeterminate requieniid valves, monopleurids, and two genera with three radiolitid species that are re-described and taxonomic positions re-evaluated. In southern Tibet, mainly endemic Campanian-Maastrichtian radiolitid rudists and cosmopolitan larger benthic foraminifera contributed to carbonate shelves on the northern Indian Plate near the Cretaceous equator. In the Western Tarim Basin Cenomanian strata yield Tethyan rudist species.

Coiling morphometric analysis using the three-dimensional morphology Raup diagram shows that Requieniidae valves in contact with the substrate are convergent with the basic gastropod shell. More derived strongly coiled, younger requieniids were adapted to encrusting or semi-infaunal habits. Stratigraphic analysis confirms that Requieniidae diversity crises coincided with Cretaceous oceanic anoxic events

Two end members of valve geometry each appear to be primitive and derived characters respectively and separate the family Requieniidae into two clades that are here recognized as two new subfamilies. The end members are defined by the coiling geometry, whether the spire is close to the plane of commissure or it is translated along the coiling axis and by myophore structures. The older matheroniform clade has a low spirogyrate LV that is translated slightly from the commissure along the coiling axis; this group is composed of Matheronia (and its subgenus Monnieria), Hypelasma, Lovetchenia, Rutonia, and Kugleria. Genera in the younger clade have a tall trochospiral LV that is translated along the coiling axis and consists of Requienia, Toucasia, Pseudotoucasia, Apricardia, Bayleoidea, and Bayleia. Claditics support these relationships.

The paleontological site of Cal Guardiola (UTM 31T DG1702), on the western bank of the Torrent de Vallparadís (Terrassa, Catalonia, Spain), was discovered in early 1997 during the construction of a socio-sanitary building next to the Mútua de Terrassa. A report on the geology and stratigraphy of Cal Guardiola was published by Berástegui et al. (2000), including a preliminary report on the fauna. This preliminary study suggested an estimated age for Cal Guardiola of ca. 1.0 Ma (Berástegui et al., 2000). Unpublished paleomagnetic analyses, carried out by Miguel Garcés, indicate a reverse magnetization for the sampled sediments, which can be correlated to below the Brunhes-Matuyama geomagnetic boundary (pers. com. of M. Garcés in Postigo Mijarra et al., 2007), thus being older than 0.8 Ma. This dating roughly corresponds to the later part of the Epivillafranchian biochron (1.2 to 0.9 Ma), which in Europe is best represented by the faunal assemblages from Untermassfeld in Germany, Le Vallonnet in France, and Colle Curti and Slivia in Italy (Palombo et al., 2008 and references therein). The faunal assemblage from Cal Guardiola represents one of the latest Epivillafranchian faunas from Europe and thus deserves particular attention for unraveling the chronology of the dispersal events that took place during the Epivillafranchian-Galerian turnover. However, thus far only the primate remains from Cal Guardiola have been published (Alba et al., 2008), while the rest of the fauna remains unpublished. Here we describe the carnivore remains from Cal Guardiola, which record one of the latest occurrences of the hyenid Pachycrocuta in Europe and further attests the coexistence of two distinct ursid lineages by the latest Early Pleistocene in Europe.

The evolutionary history of the living African rodent families is a topic of considerable debate, yet it is generally agreed that the modern cane rats (Thryonomys Fitzinger, 1867) and dassie rats (Petromus Smith, 1831) have an evolutionary history within the infraorder Phiomorpha (e.g., Wood, 1968). Phiomorphs possess hystricognathous mandibular morphology, multiserial incisor enamel, and hystricomorphous attachment of the masseteric musculature (e.g., Lavocat, 1978; Holroyd, 1994). In his initial work on the group, Wood (1968) placed all phiomorph taxa into a single family, and named a handful of morphologically diverse species based mainly on size. Lavocat (1978) later revised the taxonomy of the group, raising many of the differences among species to the family level. More recently, Holroyd (1994) observed that these contrasting views likely stemmed from the fact that Wood's phiomorph work emphasized the overall similarity of Paleogene specimens from the Fayum of Egypt, whereas Lavocat endeavored to explain the diverse Miocene rodent faunas from East Africa, envisioning that each of the Miocene forms had an ancestor among the Paleogene taxa. In this paper we adopt Holroyd's (1994) revised version of family-level relationships among the phiomorphs.

Compared to their Recent counterparts, fossil abalone are rare and poorly known. Their taxonomy is problematic, because most of the 35 fossil species have been described from single specimens and shell characteristics of Recent species are extremely plastic. Thus, the use of fossil species in phylogeny is questionable. Abalone first appear in the Upper Cretaceous (Maastrichian) with one species each in California and the Caribbean, are unknown in the Paleocene, and appear again in the late Eocene and Oligocene of New Zealand and Europe. They are regularly found from the late Miocene to the Recent in tropical to temperate regions worldwide. Most records are from intensely studied areas: SW North America, Caribbean, Europe, South Africa, Japan, and Australia. Despite their highest present-day diversity being found in the Indo-Pacific, their scarcity in the fossil record in this region is remarkable. The family may have originated in the central Indo-Pacific, Pacific Rim, or Tethys. An extensive list of all known fossil records including new ones from Europe and western North America is given. Fossil and Recent abalone both apparently lived in the shallow, rocky sublittoral in tropical and temperate climates. No on-shore/off-shore pattern is detected.

A fossil priapulid, Eximipriapulus globocaudatus new genus new species, is described from the Cambrian Chengjiang Lagerstätte of Yunnan, China. The exceptional preservation of the animal reveals morphological details that allow direct comparison with extant priapulids. The body is divisible into a partially eversible pharynx, a smooth collar, a scalid-bearing introvert, a neck with triangular scalids, an unsegmented trunk with annulations, and a distinctly expanded terminal region. Several specialized regions of the alimentary canal are recognized: a pharynx (lined by cuticle and bearing teeth), esophagus, midgut, hindgut, and a terminal anus. The sample includes a putative juvenile. The animal is inferred to have been an active burrower using a double-anchor strategy, practicing both deposit feeding and carnivory. Inclusion of Eximipriapulus in the most recent character matrix for cladistic analysis of fossil and Recent priapulids resolves the new genus within the priapulid crown group.

Fifteen limnic ostracodes species have been recorded in the Alagamar Formation, Potiguar Basin: Cypridea araripensis Silva, 1978a; Cypridea? sp., Harbinia sinuata (Krömmelbein and Weber, 1971); Harbinia crepata n. sp., Harbinia dimorphica n. sp., Harbinia alta Antonietto et al., 2012; Paracypria? elongata n. sp., Ilyocyprimorpha berthoui (Colin and Dépêche, 1997); Ilyocypris? sp., Brasacypris subovatum n. sp., Candona? sp., Theriosynoecum colini n. sp., T. guzzoi n. sp., T. silvai (Silva, 1978b) diagnosis emended by Do Carmo et al. (2004b); and Darwinula martinsi Silva, 1978c diagnosis emended by Do Carmo et al. (2004b). Nine of these species have also been recorded outside of the Potiguar Basin, either in other Cretaceous basins in Brazil or coeval strata in western Africa. Despite the controversy about dating the local Alagoas Stage and the relatively large range of the Zone Harbinia spp. 201–218, the material studied in this paper belongs to the interval corresponding to the well-defined palynological zone coded as P-270, which is mid-upper Aptian in age.

Davydov et al. (1995) recently proposed the Aidaralash Creek section in northern Kazakhstan (Figures 2 and 3) as the Global Stratotype Section and Point (GSSP) for the base of the Permian System. The proposed boundary is the level in an evolutionary sequence where Streptognathodus wabaunsensis Gunnell gives rise to a descendent with an isolated node field on the inside of the upper platform surface. This morphotype constitutes a new and distinct species for which we propose the name Streptognathodus isolatus new species.