Abundant silicified polyplacophorans from numerous localities in the Ordovician in Kentucky and other localities in Virginia, Wisconsin, and Minnesota are described systematically. New species are: Spicuchelodes cressmani, Calceochiton floweri, Preacanthochiton baueri, Orthriochiton recavus, Helminthochiton blacki, H. marginatus, and Alastega martini; new genera and species are: Listrochiton weiri, Litochiton crebatus, and Amblytochiton incomptus; and new families are Litochitonidae and Alastegiidae. Hemithecella expansa Ulrich and Bridge in Butts, 1941 and Chelodes cf. C. mirabilis (Butts, 1926), from the Chepultepec Formation in Virginia are also described. Comparisons are made with Chelodes whitehousei Runnegar, Pojeta, Taylor, and Collins, 1979 from Australia and Calceochiton hachitae Flower, 1968 from New Mexico.

Listings of the fauna associated with the chitons are given for the Kentucky occurrences; taphonomic discussions of these are included.

Malongitubus kuangshanensis Hu, 2005 from the early Cambrian Chengjiang Lagerstätte of China is redescribed as a pterobranch and provides the best evidence to demonstrate that hemichordates were present as early as Cambrian Stage 3. Interpretation of this taxon as a hemichordate is based on the morphology of the branched colony and the presence of resistant inner threads consistent with the remains of an internal stolon system. The presence of fusellar rings in the colonial tubes cannot be unambiguously proven for Malongitubus, probably due to early decay and later diagenetic replacement of the thin organic material of the tubarium, although weak annulations are still discernible in parts of the tubes. The description of M. kuangshanensis is revised according to new observations of previously reported specimens and recently collected additional new material. Malongitubus appears similar in most features to Dalyia racemata Walcott, 1919 from the Cambrian Stage 5 Burgess Shale, but can be distinguished by the existence of disc-like thickenings at the bases of tubarium branching points in the latter species. Both species occur in rare mass-occurrence layers with preserved fragmentary individuals of different decay stages, with stolon remains preserved as the most durable structures. Benthic pterobranchs may have occurred in some early Cambrian shallow marine communities in dense accumulations and provided firm substrates and shelter for other benthic metazoans as secondary tierers.

The thallus of a new noncalcified dasycladalean alga, Wiartonella nodifera n. gen. n. sp., from the mid-Silurian Eramosa Lagerstätte of Ontario, Canada, comprises a narrow main axis with laterals in whorls (euspondyl). Laterals branch to the second order and show a distinct expansion (node) at the termination of first-order lateral segments. Morphologic differences between specimens are interpreted as ontogenetic stages similar to those displayed by extant Dasycladales, including late-stage shedding of higher-order lateral segments. Examination of reproductive functional morphology using biophysical modeling indicates that the expanded terminations of the first-order lateral segments probably are not homologous with gametophores, and that reproduction instead was either endospore or cladospore, with details of the ontogenetic sequence pointing to the latter. The distinctive lateral morphology displayed by this species adds to the list of morphological innovation achieved by dasycladalean algae during a significant burst of evolutionary activity that unfolded between the Middle Ordovician and late Silurian.

In this study, a new assemblage of Ediacaran metazoan fossils is reported from the basal Stáhpogieddi Formation on the Digermulen Peninsula of Arctic Norway, including Anulitubus n. gen. Moczydłowska in Moczydłowska et al., Anulitubus formosus n. gen. n. sp. Moczydłowska in Moczydłowska et al., Coniculus n. gen. Moczydłowska in Moczydłowska et al., Coniculus elegantis n. gen. n. sp. Moczydłowska in Moczydłowska et al., Fistula n. gen. Moczydłowska in Moczydłowska et al., and Fistula crenulata n. gen. n. sp. Moczydłowska in Moczydłowska et al. The specimens are three-dimensionally preserved and include tubular and conical skeletons that are morphologically distinguished by their body-wall constructions, radial symmetry, polarity, segmentation, and annulation. The skeletons are interpreted to be biomineralized by primary silica based on computed micro-tomographic, petrographic, geochemical, and spectroscopic evidence of originally rigid body wall with layers of constant thicknesses, composed of opal, microcrystalline quartz, and an admixture of carbonaceous material, which differ from the host sediment mineralogy and do not show replacement or encrustation. The fossil-bearing interval immediately overlies strata of Gaskiers age and can be bracketed within 580–541 Ma, but it is estimated to be ca. 575 Ma on the basis of averaged sedimentation rates and biostratigraphic correlations with Ediacaran biota found in up-section deposits of ca. 558–555 Ma. Future new findings of such fossils in different preservation modes and further multi-collector inductively coupled plasma mass spectrometry, which shows the silicon fractionation and traces its biogenic origin versus inorganic mineralization, may corroborate the interpretation of biogenic silicification of these earliest skeletal fossils.

UUID: https://zoobank.org/6bccada1-870e-47b0-b819-82685152ea54

Temnospondyl amphibians are common in non-marine Triassic assemblages, including in the Fremouw Formation (Lower to Middle Triassic) of Antarctica. Temnospondyls were among the first tetrapods to be collected from Antarctica, but their record from the lower Fremouw Formation has long been tenuous. One taxon, ‘Austrobrachyops jenseni,’ is represented by a type specimen comprising only a partial pterygoid, which is now thought to belong to a dicynodont. A second taxon, ‘Cryobatrachus kitchingi,’ is represented by a type specimen comprising a nearly complete skull, but the specimen is only exposed ventrally, and uncertainty over its ontogenetic maturity and some aspects of its anatomy has led it to be designated as a nomen dubium by previous workers. Here, we redescribe the holotype of ‘C. kitchingi,’ an undertaking that is augmented by tomographic analysis. Most of the original interpretations and reconstructions cannot be substantiated, and some are clearly erroneous. Although originally classified as a lydekkerinid, the purported lydekkerinid characteristics are shown to be unfounded or no longer diagnostic for the family. We instead identify numerous features shared with highly immature capitosaurs, a large-bodied clade documented in the upper Fremouw Formation of Antarctica and elsewhere in the Lower Triassic. Additionally, we describe a newly collected partial skull from the lower Fremouw Formation that represents a relatively mature, small-bodied individual, which we provisionally refer to Lydekkerinidae; this specimen represents the most confident identification of a lydekkerinid from Antarctica to date.

When not found with fossil bone, gastroliths (fossil gizzard stones) may be hard to identify. One attribute that is potentially useful is their high degree of surface polish, presumably caused by abrasion in the animal's gizzard. A novel video laser light scattering instrument is used to characterize the surface roughness of suspected moa gastroliths, as well as similar (non-gastrolith) quartz rocks that were polished by ocean waves. The instrument is fairly successful at distinguishing between the two types of samples.

Stromatomorpha californica Smith is a massive, calcified, tropical to subtropical organism of the Late Triassic that produced small biostromes and contributed in building some reefs. It comes from the displaced terranes of Cordilleran North America (Eastern Klamath terrane, Alexander terrane, and Wrangellia). This shallow-water organism formed small laminar masses and sometimes patch reefs. It was first referred to the order Spongiomorphidae but was considered to be a coral. Other affinities that have been proposed include hydrozoan, stomatoporoid, sclerosponge, and chambered sponge. Part of the problem was diagenesis that resulted in dissolution of the siliceous spicules and/or replaced them with calcite. Well-preserved dendroclone spicules found during study of newly discovered specimens necessitate an assignment of Stromatomorpha californica to the demosponge order Orchocladina Rauff. Restudy of examples from the Northern Calcareous Alps extends the distribution of this species to the Tethys, where it was an important secondary framework builder in Upper Triassic (Norian-Rhaetian) reef complexes. Revisions of Stromatomorpha californica produce much wider pantropical distribution, mirroring paleogeographic patterns revealed for other tropical Triassic taxa. Review of Liassic material from the Jurassic of Morocco, previously assigned to Stromatomorpha californica Smith var. columnaris Le Maitre, cannot be sustained. Species previously included in Stromatomorpha are: S. stylifera Frech (type species, Rhaetian), S. actinostromoides Boiko (Norian), S. californica Smith (Norian), S. concescui Balters (Ladinian-Carnian), S. pamirica Boiko (Norian), S. rhaetica Kühn (Rhaetian), S. stromatoporoides Frech, and S. tenuiramosa Boiko (Norian). Stromatomorpha rhaetica Kühn described from the Rhaetian of Vorarlberg, Austria shows no major difference from S. californica. An example described as S. oncescui Balters from the Ladinian-Carnian of the Rarau Mountains, Romania, is very similar to S. californica in exhibiting similar spicule types. However, because of the greater distance between individual pillars, horizontal layers, and the older age, S. oncescui is retained as a separate species. The net-like and regular skeleton of Spongiomorpha sanpozanensis Yabe and Sugiyama, from the Upper Triassic of Sambosan (Tosa, Japan), suggests a closer alliance with Stromatomorpha, and this taxon possibly could be the same as S. californica.

Fossil ophiuroids (Echinodermata) have been recovered from rocks of the Comanche Series (Albian, Early Cretaceous) at Cerro de Cristo Rey, New Mexico. This is the first report of fossil ophiuroids from Mesozoic rocks in New Mexico.

Reading the voluminous lists of synonymy of the taxa described in this report, it may seem useless at first glance to add yet more descriptions and potentially continue an already confused situation. However, as taxonomists know, long lists of synonymy may indicate that certain taxa serve as a “garbage-can” for specimens which lack distinctive morphological features. An example of a “garbage-can taxon” is the pseudorthoceratid genus Mooreoceras Miller, Dunbar, and Condra, 1933, which originally was very broadly defined and therefore comprised about 40 species.

Wagler (1830) described a new genus of colubrid snake from Sri Lanka and assigned it the generic name Aspidura (Reptilia: Serpentes: Colubridae) for which the type species Aspidura brachyorrhos (Boie, 1827) (syn. Scytale brachyorrhos Boie, 1827) was placed. Since this description, five more species have been described and assigned to the genus: Aspidura copei Günther, 1864; Aspidura deraniyagalae Gans and Fetcho, 1982; Aspidura drummondhayi Boulenger, 1904; Aspidura guentheri Ferguson, 1876; and Aspidura trachyprocta Cope, 1860, all of which are geographically restricted to Sri Lanka.

Abundant articulated specimens of the oryctocarine trilobite Oryctocarella duyunensis from the lower Cambrian (Stage 4, Series 2) Balang Formation at the Bulin section in western Hunan Province, South China, permit the description of all meraspid degrees. The maximum number of thoracic segments observed in this collection is 11. Meraspid growth was accompanied by progressive and gradual change in overall form, and this animal showed an homonymously segmented trunk with variation in the number of pygidial segments during ontogeny. Such variation permits a variety of plausible explanations, but a model of successive instars defined by the number of thoracic segments, and in suborder by the number of pygidial segments, is highly unlikely to explain the growth pattern because it would result in the loss of trunk segments between some instars. Degree-based ontogenetic staging is compatible with the variation observed.

Late Mississippian and earliest Pennsylvanian trilobite faunas of North America are dominated by the Paladin and Kaskia clades. Phylogenetic analysis of middle Carboniferous species of these clades demonstrates the close ancestral relationship between these groups. The Kaskia clade consists of eight species: K. chesterensis Weller, 1936, K. osagensis (Cisne, 1967), K. longispina (Strong, 1872), K. wilsoni (Walter, 1924), K. genevievensis (Walter, 1924), K. rosei (Cisne, 1967), K. gersnai n. sp., and K. rollinsi n. sp. Kaskia Weller, 1936 ranges from late Osagean to middle Chesterian (early Visean-early Serpukhovian) and is restricted to cyclothemic shelf and nearshore deposits. Species of Kaskia appear to have evolved in areas of shallow water and high environmental stress. The Paladin clade consists of 12 species including previously named species P. morrowensis (Mather, 1915), P. girtyianus Hahn and Hahn, 1970, P. rarus Whittington, 1954, P. helmsensis Whittington, 1954, and P. moorei (Branson, 1937). New species belonging to this clade are Paladin moorefieldensis n. sp., P. pleisiomorphus n. sp., P. imoensis n. sp., P. mangeri n. sp., and P. wapanukaensis n. sp. This group ranges from the early Chesterian to early Morrowan (late Viseanlate Bashkirian). Species of Paladin appear to be confined to outer shelf shelf-edge and off-shelf facies where presumably deeper water environments existed. This is manifested in their paleogeographic distribution, which is paleoenvironmentally controlled.

The new nuculid bivalve Trigonucula (Gonionucula) aciloides new subgenus and species from the upper Triassic Nayband Formation of Central Iran is described. Gonionucula differs from Trigonucula s.s. by the presence of oblique ribs, which either deviate from a concentric pattern at the anterior shell part, or, as in the newly described type species, consist of a complex pattern of chevron-like ribs on the central part of the flank, plus an additional set of opisthocline to more or less acline ribs on posterior part of the flank. The oblique ribs of Gonionucula probably aided energy-efficient burrowing, which was advantageous in competing for food resources with less efficiently burrowing detritus feeders. The number of burrowing bivalve species with oblique ribs generally rose towards the end of the Triassic, which probably reflects increasing competition at a time when most niches were re-occupied after the end-Permian mass extinction event. The fact that oblique ribs were rare in Paleozoic bivalves suggests that the level of competition was higher in post-Paleozoic biota, which is in accordance with a general increase in metabolic rates, predation pressure, and ecospace occupation in the course of the Mesozoic.

Brachiopods of the order Chileida have been recorded previously only from rocks of early to mid-Cambrian age (Botomian–Amgaian). They are typified by having a calcareous strophic shell with a delthyrium and colleplax, and these characters are shown to be present in species of the two new genera Tolen and Trifissura, from the Late Ordovician of Kazakhstan and the Silurian of Sweden and Britain, respectively. In specimens of Trifissura, the triangular colleplax is phosphatized secondarily by bacterial activity. It is suggested that the phosphatized colleplax represents an organic pad and that served as the original attachment structure of Trifissura by encrustation. Tolen and Trifissura represent the first post-Cambrian record of chileides from the Ordovician and Silurian; the new family Trifissuridae forms the first phylogenetic link between Cambrian chileides and Carboniferous–Permian isogrammides.

New shell microstructure data for the Triassic pectinid Pleuronectites reinforce shell morphological data suggesting that its family Pectinidae was derived from the superfamily Aviculopectinoidea and not from the Pernopectinidae-Entolioidesidae-Entoliidae clade. This would make the superfamily Pectinoidea, as defined by recent authors, polyphyletic. This would also imply that alivincular-alate ligaments evolved independently in the Pernopectinidae-Entolioidesidae-Entolidae and Pectinidae clades.

Paleozoic corals are very rare in rocky shore settings. The only Paleozoic encrusting coral so far reported from this environment is Favosites sp. from Ordovician rocky shore deposits in Manitoba, Canada (Johnson and Baarli, 1987). Reading and Poole (1961) reported corals and brachiopods that occur between, and “coating,” boulders from a Silurian rocky shore in England, but it appears that the corals and brachiopods only occur in the sediment enveloping the boulders, not as encrusters on the surfaces of the boulders. One reason for the sparse record of Paleozoic corals in rocky shore settings is the scarcity of described Paleozoic rocky shore deposits themselves. Johnson (1988) found only 20 examples of Paleozoic rocky shores in a compilation of references on ancient rocky shores from the literature. The paucity of described ancient rocky shores has been attributed to the prevalence in the past of epicontinental seas with little relief upon which to develop rocky shores and with higher wave attenuation farther from shore (Boucot, 1981; Harland and Pickerill, 1984). Johnson (1988) concluded that the major reason for the rarity of ancient rocky shores in the literature is the difficulty with which they are recognized and studied, owing to the relatively poor exposure of most unconformity surfaces. The rocky shore environment was also probably hostile to many Paleozoic coral genera. Recent scleractinian corals may serve as analogues because they are also not very abundant in rocky shore settings despite their great abundance in similar shallow-water, high-wave-energy reefal environments. Turbidity and relative substrate stability may be important limiting factors for corals in rocky shore environments. Many corals are known to be highly sensitive to sediment in the water column. Substrate stability (Wilson, 1987) and the scouring effects of sand in high-energy environments (Palmer and Palmer, 1977) also have been shown to affect the abundance and diversity of organisms encrusting cobbles and boulders.

Little is known about the habit and spatial distribution of Early Permian tropical vegetation, a sharp contrast with the Pennsylvanian from which many in-situ “T0” assemblages are known. Even less is known about the potential interaction of plants and vertebrates. Here we report the discovery of a small stand of 34 probable Supaia White plants from the Abo Formation of New Mexico. The plants were growing on a mudflat, subject to periodic flooding and exposure. The same mudflat hosts trackways of vertebrates that appear to have walked around or between the Supaia plants. The stems are preserved as molds, and vary from 20 mm to 70 mm in diameter, averaging 42.4 mm, indicating heights of approximately 2.5–4 m. The plants, which may be described as small trees given their estimated height, are as close as 110 mm to their nearest neighbor and average nearly 300 mm apart. A series of lines or filled fissures, which we interpret as roots, radiates from the base of each stem. Leaves of Supaia thinfeldioides White are the only foliage found in association with these stems, on bedding planes above and at the base of the lowest expression of the stem molds. Associated vertebrate trackways either congregate around some of the stems or wend their way between the stems and include those of a single large temnospondyl amphibian (Limnopus Marsh) and many of small predatory parareptiles (Dromopus Marsh). This study demonstrates that S. thinfeldiodes were small-statured, weedy, opportunistic plants. It also shows that contemporaneous vertebrates prowled such environments, presumably either for food, shelter, or both given detectable pace and path.

Although Nuculoidea corbuliformis (Hall and Whitfield) is the most widespread Devonian nuculid species in North America, the hinge and internal morphology have not been adequately described. A newly excavated hinge shows the dentition and resilifer to be fundamentally similar to those of other species of Nuculoidea, while the resilifer morphology and shell shape more closely link N. corbuliformis to post-Devonian nuculid species. An internal mold of a probable N. corbuliformis found among Hall's original syntypes (here restudied) shows typical nuculid interior morphology. These new data allow the problematic genus Nuculoidea Williams and Breger to be further clarified.

Comparisons with N. corbuliformis suggest that N. aquisgranensis (Beushausen), N. herzeri (Nettleroth), N. neda (Hall and Whitfield), N. niotica (Hall and Whitfield), N. trigona (Spriestersbach), N. macrorhyncha (Spriestersbach), and N. subtrigona (Simpson) are subjective junior synonyms.

Encrinurinae from the Ludlovian Brownsport Formation in west central Tennessee include Balizoma ramskoeldi n. sp., Fragiscutum glebale Campbell, 1967, and Mackenziurus sp. Balizoma ramskoeldi is most similar to Ludlovian species in England and Gotland. The discovery of F. glebale in Tennessee extends the geographic range of this species, known also from the correlative Henryhouse Formation in Oklahoma. Fragiscutum is an eastern/southern Laurentian endemic; Balizoma is of Wenlockian–Přidolían range, with its most widespread Euramerican distribution in the Ludlow. The stratigraphic range of Mackenziurus is extended into the Ludlow.