In spite of a long geological record from the Paleozoic Era to the present, most paleontological documentation of multivalved chitons (Mollusca: Polyplacophora) is based on individual, loose plates. Indeed, the tendency of the chitinous girdle in which the eight calcareous plates are articulated to disintegrate usually does not allow their post-mortem association to be observed (e.g., Smith, 1960; Squires and Goedert, 1995; Dell'Angelo et al., 1998).

In their monograph Review of the Pelycosauria, Romer and Price (1940), proposed that the earliest synapsids (“pelycosaurs”) were cosmopolitan, despite the observation that amniotes appeared to be restricted to the paleotropics during the Late Carboniferous and Early Permian (290–282 Ma). Romer and Price (1940) accounted for the scarcity of terrestrial tetrapods, including “pelycosaurs,” in Lower Permian beds elsewhere to the absence of coeval continental deposits beyond North America and Europe. Indeed, most workers recognized a geographical and temporal gap between Permo-Carboniferous “pelycosaurs” and therapsid synapsids. Recent research has confirmed that varanopid and caseid “pelycosaurs” were components of therapsid-dominated Late Permian faunas preserved in Russia and South-Africa (Tatarinov and Eremina, 1975; Reisz, 1986; Reisz et al., 1998; Reisz and Berman, 2001).

Superbly preserved tarsi of a new, undescribed, primitive member of Diadectidae and of Diadectes, the best known member of the family, are described. The major distinction between them is the retention of sutures in the astragalus of the former which clearly indicate an origin from the fusion of three separate ossifications considered homologues of the primitive amphibian tibiale, intermedium, and proximal centrale. Among the Diadectomorpha (includes also Limnoscelidae and Tseajaiidae) only Diadectidae possesses an astragalus, which is considered a synapomorphy of the family within this grouping. Furthermore, the sister-group relationship of the new, undescribed diadectid to the other diadectids demonstrates a transformational, phylogenetic homology of the astragalus via the ontogenetic fusion of the primitive amphibian tarsal bones. The astragalus of diadectids is identical to those of late Paleozoic terrestrial amniotes in structure and relationship to neighboring elements. This, plus the wide acceptance of a close relationship between Diadectomorpha and Amniota, is cited as suggestive of an identical developmental origin of their astragali.

In diadectids, including fully mature individuals, an unusual reduction or absence of ossification of some central and distal tarsal bones has resulted in an unique tarsus with large unoccupied areas and a structural pattern in which the only bony link between the tarsus and the digits is via the fourth distal tarsal, producing a crude facsimile of the lacertilian mesotarsal joint. Such a joint would have permitted, as in lacertilians, a wide range of movements which may have served several important functions: 1) maintaining an anteriorly directed pes to maximize the force of its posterior thrust during limb retraction, 2) placement of the pes close to the body midline for greater stride length and more efficient support and greater maneuverability during locomotion.

New fossiliferous localities in the Borchers Badlands of southwestern Kansas add to our knowledge of rodent community change across the Plio-Pleistocene and Blancan-Irvingtonian boundaries. We report fossil rodents from ten local faunas in the Badlands that range stratigraphically from beneath the Huckleberry Ridge ash (2.10 Ma [million years ago]) to a level just beneath the Cerro Toledo B ash (1.23–1.47 Ma). The late Blancan Borchers local fauna (l.f.), includes the Meade Basin highest stratigraphic datum (HSD) for the following taxa that characterize or are found in earlier Blancan faunas: Alilepus, Geomys quinni, Sigmodon minor, and Geochelone. Borchers currently also has the HSDs for Reithrodontomys pratincola and Ondatra zibethicus lidahoensis, but the prior temporal distribution of these taxa in the Meade Basin is unknown. The stratigraphically lowest Pleistocene (Irvingtonian) l.f. in the Badlands, Nash 72, includes the lowest stratigraphic datum (LSD) for Cynomys, Reithrodontomys moorei, Microtus, and Mictomys kansasensis, all of which are found above Nash 72 and beneath the Cerro Toledo B ash. Prodipodomys is last seen at Nash 72, and Sigmodon curtisi is first encountered at Short Haul, a locality slightly younger than Nash 72. A preliminary hypothesis of age based on stratigraphic position places the Nash 72 l.f. at about 1.80 Ma, suggesting that this fauna and the genus Microtus may characterize both the Plio-Pleistocene and Blancan-Irvingtonian boundaries in the Borchers Badlands.

The purpose of this study is to describe a new decapod crustacean from the Profeti region, Italy, and to interpret its palaeontological significance. Further, we include a taxonomic summary of fossil carideans. Macruran decapod crustaceans of Profeti occur flattened on bedding plane surfaces of light-brown lithographic limestone. Surrounding rock is poorly lithified, making preparation easy. The material examined, housed in the Geology Department of the University of Naples, consists of 53 specimens ascribed to Palaemon antonellae n. sp. (Infraorder Caridea Dana, 1852; family Palaemonidae Rafinesque, 1815). All specimens are exuviae, with thin and fragile carapaces and abdomens and fragmentary bodies and appendages.

During the Late Ordovician, arborescent and frondose trepostome, and cystoporate Bryozoa were frequently bored in a manner distinctly different from Trypanites, Palaeosabella, and Vermiforichnus, domichnia that are commonly associated with these organisms. Maysvillian and Richmondian bryozoan taxa on the Cincinnati Arch were particularly infested by an unidentified organism that used the interior of bryozoan branches as its domicile. The domichnial trace Sanctum laurentiensis is newly described. Dwelling openings range in size from 1.1 mm to 3.2 mm and are located singly on surfaces of colony branches, commonly in a somewhat protected position. The circular opening leads through the exozone into an elongate or saccate chamber representing a variably shaped excavation of the bryozoan endozone. Traces ranging from 3.0 mm to 8.8 mm wide and 9.7 mm to 53 mm long are documented. Thin sections demonstrate that chambers were unlined and had irregular interior walls resulting from organismal mining of zooecial tubes.

Cavity makers likely were multiple individuals of amphipod-like crustaceans (Arthropoda) that fed outside their domicile. Bryozoan colonies were occupied while upright, either entirely or partially live, or in some cases dead and overgrown by other bryozoans. Avoidance of predation and the ability to dwell and feed in a higher tier than that of infaunal tracemakers at the sediment-water interface were potential benefits of this domichnium. Presence of cavities reduced the strength of host branches, thus having a profound effect on colony morphology and growth over its lifetime. Unlike the many epizoans that used trepostomes as substrates with little long-term affect, Sanctum laurentiensis significantly impacted its bryozoan host.

During the field season of 1870, F. V. Hayden collected a number of sandstone blocks that contained the remains of a large fossil lizard (Middle Eocene Bridger Formation, Sweetwater County, Wyoming). Though mostly unprepared, the visible bones were described by Leidy (1870) as Saniwa ensidens (USNM 2185; holotype). Fifty years later all the blocks associated with USNM 2185 were prepared prior to Gilmore's (1922) more complete description of Saniwa ensidens and his assignment of the taxon to the Varanoidea. Gilmore (1922) notes that the skeletal remains in the blocks were partially disarticulated to dissociated despite the excellent articulation of some components (e.g., palatal elements and right and left maxillary fragments [Gilmore, 1922, p. 809; pl. 1). Gilmore (1928) altered the diagnosis of Saniwa ensidens (USNM 2185) by adding characterizations of a premaxilla, right and left anterior maxillary fragments, and anterior tips of the dentaries. Gilmore (1928, p. 57) stated that these missing elements were found after further preparation of the blocks when the type specimen was mounted for display.

In recent years, the authors, along with colleagues, have documented the lower Virgilian ammonoid faunas of the Midcontinent and north-central Texas (Boardman et al., 1989, 1994a, 1994b; Work and Boardman, 1995, 1996). Generic diversity for this interval is the highest in any Upper Pennsylvanian succession: at least 18 genera (representing 15 families) have been recovered from the Colony Creek Shale in north-central Texas alone (Boardman et al., 1989). An additional, previously unrecognized ammonoid from the correlative Little Pawnee Shale in southeastern Kansas is described herein as Mapesites chautauquaensis new genus and species. It is a highly original taxon with no obvious close relatives.

The borden formation in northeastern Kentucky contains a significant, largely undescribed, Osagean (upper Tournaisian to lower Viséan) ammonoid succession. Lower Osagean strata in the Nancy Member contain a diverse Pericyclus Zone assemblage characterized by Muensteroceras oweni (Hall), M. parallelum (Hall), Kazakhstania colubrella (Morton), Imitoceras ixion (Hall), and Masonoceras kentuckiense Work and Manger. This interval, which ranges into the basal Cowbell Member, was referred to the Muensteroceras oweni Assemblage Zone by Gordon and Mason (1985) and Gordon (1986) and indicates correlation to the lower Ivorian Stage of the Belgian Tournaisian succession. The succeeding middle Osagean interval in the middle and upper part of the Cowbell Member contains Merocanites drostei Collinson and Dzhaprakoceras which presumably represent the lower, or Tournaisian (upper Courceyan or lower Chadian), portion of the Fascipericyclus–Ammonellipsites Zone. An even higher middle Osagean assemblage with Polaricyclus bordenensis new species and Winchelloceras allei (Winchell, 1862) occurs in the upper part of the Nada Member, near the top of the Borden Formation, and is the basis for the current report.

Graptolites are the most important biostratigraphic tool in the study of the Silurian of the Argentine Precordillera. Since, however, the graptolites are concentrated primarily in the Lower Llandovery and Ludlow of the region, the ages of parts of some stratigraphic units are poorly known. The recovery of a small Upper Llandovery graptolite assemblage in the lower one-third of the La Chilca Formation of the Talacasto area helps in resolving this problem, and that assemblage is the focus of this study. Brachiopods, trilobites, bivalves, and ostracodes are present in the same stratigraphic intervals, but are less common and less studied and, thus, of less biostratigraphic value.

In 1956 two fossil specimens were exposed in concretions associated with two crushed body chambers of the orthoconic nautiloid Rayonnoceras sp. recovered from the Fayetteville Shale (Chesterian, upper Mississippian) of northern Arkansas. The two specimens were subsequently described as a new genus and species of demosponge, Vintonia doris Nitecki and Rigby and placed in the new family Vintoniidae (Nitecki and Rigby, 1966). The specimens were described as silicified. Nitecki and Rigby's analysis, based on the presence of an assumed skeletal net resembling the spongin net of Recent sponges, suggested that the specimens were demosponges with sycon structure. The “net” was considered spongin because of its geometric pattern and cellular appearance. That interpretation led to the placement of the specimens in the Order Keratosida despite the presence of an apparently well-developed ectosomal region, a feature that is not common in the Keratosida (Nitecki and Rigby, 1966).

The inoceramid bivalves first appeared in the Permian of Australia (Browne and Newell, 1966; Waterhouse, 1970), thrived during certain intervals in the Jurassic (e.g., the Toarcian; Harries and Little, 1999), and dominated many benthic marine communities globally from the late Early through the Late Cretaceous. Despite excellent preservation (the prismatic, outer calcitic layer is retained in many cases), ubiquitous presence in Late Mesozoic marine deposits, and intense study (e.g., Tröger, 1967; Kauffman et al., 1977; Crampton, 1996; Walaszczyk and Cobban, 2000; Walaszczyk et al., 2001), no evidence of predatory drilling in inoceramids has been reported to date. Indeed, evidence of predation of any sort on inoceramids throughout their evolutionary history is limited (Harries and Ozanne, 1998; though see Ozanne and Harries, 2002, for an exception to this). There have been several documented examples of non-predatory borings in inoceramids likely made post mortem by organisms such as bryozoans (Morris, 1990) and acrothoracian barnacles. Rare instances of potential nondrilling predatory attacks on inoceramids by fish (Speden, 1971) and ptychodid sharks (Kauffman, 1972), also have been described (see summary in Harries and Ozanne, 1998).