Gastroliths (stomach stones) are frequently reported in association with plesiosaur remains, especially elasmosaurids (e.g., Brown, 1904; Williston, 1904; Welles and Bump, 1949; Darby and Ojakangas, 1980; Everhart, 2000; Cicimurri and Everhart, 2001). Stones are also known from several other fossil and modern aquatic vertebrates, including fishes (Dapples, 1938; Thomson, 1966; Trewin, 1986), penguins (Emery, 1963; Stonehouse, 1967; Boswall and MacIver, 1975), crocodilians (Cott, 1961; Neill, 1971; Keller and Schaal, 1992), and pinnipeds (Fleming, 1951; Mohr, 1963; Bryden, 1999).

Entobia, a sponge boring commonly consisting of interconnected chambers and galleries (i.e., it is camerate), is a dominant agent of bioerosion in Mesozoic and Cenozoic marine carbonates. A similar camerate boring, Topsentopsis devonica, is widely recognized from the Devonian, and its classification is reappraised here. This paper synonymizes Topsentopsis with the senior synonym Entobia, making E. devonica n. comb. the oldest representative of the ichnogenus. New specimens of E. devonica borings in stromatoporoids and megalodont bivalves are described from the Frasnian Guilmette Formation of Nevada, which includes breccias of the Alamo Bolide Impact. The borings occur in skeletal substrates both within and above the impact event breccias, demonstrating their existence prior to the impact and their survival of the catastrophic event. The Nevada discovery extends the geographic distribution of the oldest Entobia to include the western and midcontinental United States, western Canada, and eastern Europe. E. devonica was an important bioerosive agent during the Givetian–Frasnian, but it is unknown following the Frasnian–Famennian mass extinction.

A new eschrichtiid mysticete was recovered from the Late Pliocene Yuchi Formation, Teshio Town, Hokkaido, Japan. The specimen is relatively well preserved, comprising a posterior part of the skull, periotics and tympanic bullae, several incomplete cervical and thoracic vertebrae, ribs, and forelimb elements including scapula, humerus, ulna, and several phalanges. Its small size, unfused epiphyses of vertebrae and long bones (humerus, radius, and ulna) indicate that the individual is physically immature. It is identified as eschrichtiid based on diagnostic characters, including paired occipital tuberosities, large occipital condyles, the posteriorly concave exoccipital lateral to the occipital condyle, the cochlear portion of the periotic extending anteromedially, the relatively small and somewhat triangular anterior process of the periotic, and the proportionally large vertebral foramen relative to the vertebral body. Because all verified eschrichtiids are of Pleistocene age, the Teshio eschrichtiid significantly extends the temporal range of the group.

Problematic phosphatic elements are reported for the first time from Bohemia, Czech Republic, and are attributed to Eurytholia bohemica n. sp. Similar mineralized elements, interpreted as sclerites, were known only in a very narrow interval from Middle-Late Ordovician beds bordering the Iapetus Ocean. This new report comes from the Silurian and Early Devonian and provides a significant range extension for these Problematica as well as an enlargement of their geographic extent. Comments open new perspectives in the interpretation of these elements.

The eodiscina comprises small, isopygous trilobites with either two or three thoracic segments. Small eyes may be present, but several genera and species lack visual organs. Eodiscoids are characteristic elements of many Cambrian faunas and are important for correlations of upper Lower Cambrian and lower Middle Cambrian strata (e.g., Robison et al., 1977; Ahlberg and Bergström, 1993; Geyer and Shergold, 2000; Fletcher, 2003).

Abundant and diverse trace fossils occur in deposits, recording an Early Devonian transgression in Bolivia. the very well-exposed Presto-El Peral section is located in the Interandean Belt 50 km northeast of Sucre. Trace fossils can be assigned to five associations from nearshore to offshore environments (namely Skolithos, Diplocraterion, Altichnus, Palaeophycus, and Zoophycos associations). They clearly illustrate the different colonization phases of the benthos with increasing marine influence. A deeper-water Helminthopsis association occurs in other complementary sections on the Eastern Cordillera. Variation of bioturbation intensity, ichnodiversity, and preservation potential is evaluated. the morphology of traces, mainly deep burrows, shows a significant gradient related to the behavior of tracemakers and the environmental changes. Main trends are consistent with the Seilacherian bathymetric model which is detailed here and/or emended with a well-exposed field example. A precise correlation is proposed with fossil benthic associations dominated by brachiopods. the whole gives an accurate model for benthos colonization and benthic marine zonation.

Coniasaurus Owen, 1850 was a small (50–100 cm in length) marine lizard that has been sporadically reported from Late Cretaceous marine deposits of Germany, England, and the United States. These deposits were formed throughout the basins of the Tethys and Western Interior Seas (Diedrich, 1997; Caldwell, 1999; Caldwell and Cooper, 1999; Liggett, 2004). Coniasaurus is thus far known only from incomplete specimens. However, sufficient material exists to show that it possessed four short limbs and an elongated skull, neck, trunk, and tail, and was equipped with a specialized dentition (Caldwell and Cooper, 1999). Caldwell and Cooper (1999) inferred that Coniasaurus likely occupied a niche similar to small sauropterygians.

A fossilized social insect nest, Socialites tumulus new ichnogenus and ichnospecies, is described from continental strata of the Upper Cretaceous Kaiparowits Formation in southern Utah. Nine discrete nest structures are preserved along a single bedding plane, within an area of about 25 m2. Fine-grained, ripple-laminated sandstone, interpreted as a fluvial crevasse splay deposit, drapes the nest structures and is thought to have rapidly buried and preserved much of the aboveground architectural morphology of the nest structures. Such social insects as ants and termites are considered as possible tracemakers. Comparison to fossil and modern nests suggests that Socialites tumulus is more similar to nests produced by ants than by termites. This trace fossil preserves rare, tangible evidence of nest construction by social insects during the Late Cretaceous, adding new information on insect diversity and habitat utilization in Mesozoic terrestrial ecosystems. Detailed study of these complex nest structures also aids in paleoenvironmental reconstruction, revealing multiple phases of nest construction, burial, and reestablishment.

Geometric models for the reconstuction of soft-tissue lophophore shape and arrangement have been designed for extinct fenestrate bryozoans (Starcher and McGhee, 2000) and for extinct fenestrate graptolites (Starcher and McGhee, 2003). We wish to add the material given in the following three tables as an addendum to our paper in the March 2003 issue of the Journal of Paleontology. These tables will enable other researchers to characterize quickly and quantitatively the geometry of lophophore shapes and arrangements in the colonial meshworks of extinct organisms, and will add quantitative measures of soft-tissue characteristics of extinct modular organisms to the already existing morphometric characterizations of hard-tissue skeletal aspects of colonial meshworks (Hageman, 1991; Holdener, 1994; Hageman et al., 1998).

Termites (order Isoptera) are highly eusocial members of the superorder Dictyoptera. Species generally live in large, highly organized colonies with morphologically specialized worker and gyne castes, and in some lineages a soldier caste also occurs. The termites play an essential ecological role in the decomposition and recycling of a nutritionally poor, highly resistant, but extremely abundant substance: lignocellulose. This digestion is aided by symbionts (either intestinal Protista in lower termites, or fungi or intestinal bacteria in higher termites). In addition, methane excretion from termites contributes 2%–5% of the partial pressure of this gas in the Earth's atmosphere (Sugimoto et al., 2000). Considering all of these factors it is easy to understand why the approximately 2,900 termite species are among the most significant insects in many ecosystems throughout the world.

This paper presents sponges from the Late Cretaceous El Rayo Formation, Puerto Rico. Siliceous sponges are common fossils in the Late Cretaceous of Europe (see for example Schrammen, 1910–1912; Moret, 1926; Weidenmayer, 1994; Pisera, 1999). So far only rare siliceous sponges from the Late Cretaceous of the Caribbean region have been reported: lithistid ?Jerea Lamouroux, 1821, hexactinellids Ventriculites Mantell, 1822, and Plocoscyphia Reuss, 1846 from Trinidad (Thomas, 1935; Trechmann, 1935), and Callopegma Zittel, 1878 from the Cariblanco Formation, Puerto Rico (Howell, 1966). The sponges studied by us are heavily silicified and thus only their approximate determination was possible, but among bodily preserved sponges they are undoubtedly lithistids with tetraclone and rhizoclone desmas. Among loose spicule material, fragments of hexactinellid skeleton dominate, tetraclone and dicranoclone lithistids desmas are common, and hexactinellid lychniscosid skeletons are very rare.

Lower paleozoic facies relationships, fossils, and depositional systems of the Northwest Ordos Basin, northern China, are sparsely documented in western world literature (Meng et al., 1997; Kessel, 2005). Recent field work in this area during the summer of 2004 recovered a single specimen of a new chiastoclonellid sponge. That sponge, described here, was collected from a measured section of Lower Paleozoic rocks exposed in the Suhaitu area, in the northern part of the Zhuozi Shan Range, northwestern Ordos Basin (Fig. 1), in southern Inner Mongolia Province. The Zhuozi Shan Range is part of the western Ordos fold and thrust belt, a Late Jurassic–Early Cretaceous tectonic feature, that brought Lower Paleozoic rocks to the surface (Darby and Ritts, 2002; Darby, 2003). Early Paleozoic rocks exposed in the area are dominantly carbonates with minor siliciclastic rocks and they span from the Early Cambrian through the Middle Ordovician (Yang et al., 1992; Meng et al., 1997). They are unconformably overlain by Middle Carboniferous units across the North China Block (Meng et al., 1997).

Palaeoscolecidans represent an extinct class of vermiform organisms with a prominent annulation ranging from the Lower Cambrian to the Upper Silurian. Since the first descriptions in the 1950s, they have been attributed to different groups, but recently they have been linked to the priapulids (Conway Morris, 1997). Palaeoscolecids are mainly considered to represent members of Ecdysozoa. Their position within this clade is still under discussion, but cladistic analyses indicate that they are either close relatives of nematomorphs (Hou and Bergström, 1994) or part of an extinct sister clade to the priapulids (Wills, 1998; Dong et al., 2004). The outer cuticle of palaeoscolecidan segments possesses microelements mineralized by calcium phosphate, which are often found isolated in the conodont collections obtained from carbonates after acid treatment. Kraft and Mergl (1989), van den Boogaard (1989b), Hinz et al. (1990), and Müller and Hinz-Schallreuter (1993) clearly showed the evidence that these isolated sclerites originate from certain palaeoscolecidan taxa. The specimens documented in this paper represent such fragmented material from the Manitou Formation of west-central Colorado. Extensive taxonomic and morphologic reviews of the palaeoscolecidans were provided by Müller and Hinz-Schallreuter (1993), Conway Morris (1997), Wrona and Hamdi (2001), and Ivantsov and Wrona (2004).

Ceratopsids, horned herbivorous ornithischians from the Cretaceous of North America, are unique among dinosaurs in the form and expression of their cranial ornamentation. All ceratopsid genera possess a bony parieto-squamosal frill that projects over the neck region and some degree of development of nasal and orbital horns. These horns vary in form and location, from low bosses (e.g., Pachyrhinosaurus Sternberg, 1950) to long, conical horns (e.g., Triceratops Marsh, 1889 postorbital horns). Internal structural changes occurred along with these extreme external modifications of the skull (Forster, 1996).