The trilobite Liostracina has been recognized as important in taxonomic and stratigraphic studies for more than a century. Until now, the genus Liostracina and family Liostracinidae have been known from only incomplete holaspid material, a degree 2 meraspis, and protaspides. A new locality in the Longha Formation (Cambrian: Guzhangian) of southeastern Yunnan, China, yields a rich collection of articulated holaspid exoskeletons and disarticulated sclerites of a new species, Liostracina fuluensis n. sp. These specimens reveal thoracic and ventral morphology that was previously unknown for Liostracina; they demonstrate that it has a rostral plate plus rostral and connective sutures, rather than a ventral median suture on the cephalic doublure. This confirms a natant hypostomal condition for the genus. Holaspid exoskeletal features, combined with evidence of a non-asaphoid-type protaspis, indicate that Liostracina is neither a primitive trinucleoid nor a primitive asaphoid. The family Liostracinidae is excluded from the superfamily Trinucleoidea and the order Trinucleida and reassigned to the order Ptychopariida.

UUID: http://zoobank.org/48dcbe31-e25d-4657-8441-732d5ea2b49d

In a recent communication on carbon isotope chemostratigraphy of the uppermost Cambrian strata, it was claimed that the Top of Cambrian Excursion (TOCE) is (1) an undocumented negative δ13Ccarb excursion; (2) ambiguously defined; (3) deliberately fictitious or, in the authors’ words, a ‘nihilartikel’; and (4) not synonymous with the Hellnmaria–Red Tops Boundary (HERB) Event. As the authors who have been involved in much of the discussion surrounding the TOCE since its introduction and in subsequent clarification, we wish to emphasize that the recent communication overlooks the fact that the TOCE is in fact a well-documented and clearly defined negative δ13Ccarb excursion, and that the term ‘HERB Event’ was originally used informally, without definition or reference data, for a negative δ13Ccarb peak, a peak later shown to occur within the TOCE excursion. Nearly a decade after the TOCE was named, the concept of the HERB Event was modified from a negative δ13Ccarb peak to a negative δ13Ccarb excursion, making it conceptually synonymous with the TOCE excursion. The recently published commentary is misleading and replete with misconceptions, as we discuss here.

Restudy of the limestone slab containing the type suite of Arthricocephalus chauveaui Bergeron, 1899 (Trilobita), the type species of Arthricocephalus Bergeron, 1899, shows that specimens of three species, each representing a separate genus, are present on the slab and were likely included in the original concept of the species. Besides A. chauveaui, the slab contains specimens of Oryctocarella duyunensis (Qian, 1961) and Duyunaspis duyunensis Zhang and Qian in Zhou et al., 1977. Bergeron (1899) illustrated one exoskeleton from the type suite of A. chauveaui only and apparently based much of his written description on that specimen. This specimen was clearly intended to be the type specimen of A. chauveaui. Subsequently, Lane et al. (1988) designated another specimen, which was not originally illustrated, as the lectotype, and this specimen is referable to Oryctocarella duyunensis. As revised here, Bergeron’s illustrated specimen should be regarded as the lectotype of A. chauveaui. Such designation stabilizes the concepts of both Arthricocephalus and A. chauveaui. Arthricocephalites Qian in Lu et al., 1974 and Haliplanktos Blaker and Peel, 1997 are regarded as junior synonyms of Arthricocephalus. Oryctocarella Tomashpolskaya and Karpinski, 1961, which was previously regarded as a junior synonym of Arthricocephalus, is revived as a valid genus. Oryctocarella includes a number of species previously assigned to Arthricocephalus. The type species of both Arthricocephalus and Oryctocarella, together with related species, are described on the basis of new material.

The skeleton of a new vauxiid sponge (Order Verongida), Angulosuspongia sinensis gen. et sp. nov., described on the basis of material from calcareous mudstones of the Kaili Formation (Cambrian Stage 5), Jianhe area, Guizhou, South China, is composed of two layers of fused spicules outlining hexagonal or polygonal openings. These vauxiid remains are the first reported from outside Laurentia, and represent only the second genus attributed to the family. Its age is close to but still slightly older than the Burgess Shale Biota, and it appears to be a primitive relative of other members of the Vauxiidae. The morphological differences between Chinese and Laurentian vauxiid sponges may be a result of vicariance. These specimens not only extend the geographic distribution of vauxiids, but also help to fill a chronostratigraphical gap between North Greenland and North American material and provide additional evidence for understanding the evolutionary history of the Demospongiae.

Malformations of trilobites are classified as healed injuries, teratological conditions, and pathological conditions. An improved method of recognizing such malformations combines information about the conditions under which cell injury can occur, the processes by which animal tissues react to injury, and trilobite morphology.

Study of healed injuries of polymeroid trilobites shows that injuries attributed to sublethal predation tend to be most commonly preserved on the pleural lobes, the posterior half of the body, and the right side. Statistically significant differences in the number of predation scars between the right and left sides is interpreted as evidence of right-left behavioral asymmetry in some predators of trilobites or the trilobites themselves. Asymmetrical, or lateralized, behavior in present-day animals is one manifestation of handedness, and is usually related to a functional lateralization of the nervous system. Evidence of behavioral lateralization in some Paleozoic predators or prey suggests that those organisms also possessed lateralized nervous systems. Right-left differences in preserved predation scars on trilobites date from the Early Cambrian (Olenellus Zone), and are the oldest known evidence of behavioral asymmetry in the fossil record.

Other examples of structural or behavioral asymmetry from the fossil record of animals are cited. Lateralization is recognized in representatives of the Arthropoda, Annelida, Bryozoa, Echinodermata, Cnidaria, Mollusca, Chordata, and Conodonta, and in trace fossils.

A deep core from Warren County, Ohio, has yielded numerous fossils of Cambrian age. The specimens, which are among the first recorded from Cambrian rocks of Ohio, suggest revisions in the inferred ages of the Eau Claire and Mount Simon Formations in the Cincinnati Arch region. Trilobites indicative of Dresbachian (late Middle Cambrian to early Late Cambrian) and possibly Franconian (Late Cambrian) age are present in the upper Eau Claire Formation. By implication, the underlying Mount Simon Formation must be of earlier Dresbachian age or perhaps older. Identified trilobites from the Eau Claire Formation seem to be characteristic of inner-shelf lithofacies of Laurentia. Other body fossils from the Eau Claire Formation include inarticulate brachiopods and a graptolite. Body fossils in the lower Knox Dolomite include trilobite sclerites and echinoderm ossicles. Trace fossils are present in both units.

The trilobite Phacops rana var. milleri Stewart, 1927, was based on five specimens collected from the Silica Shale (Middle Devonian) in a quarry formerly owned by the Sandusky Cement Company, near Silica, Lucas County, Ohio. The “cotypes” (=syntypes of modern terminology) were catalogued as number 16266 in the Orton Geological Museum of The Ohio State University. Study of specimens in the OSU collection reveal four extant syntypes belonging to two subspecies of Phacops rana (Green, 1832). Three complete specimens and one separate eye are represented. A cephalon mentioned by Stewart (1927, p. 59) is missing and presumed lost. Of the extant specimens, three belong to P. rana milleri and one belongs to P. rana crassituberculata Stumm, 1953.

Although enrollment has long been recognized as an important, perhaps advantageous, life posture in certain trilobites, some aspects of this phenomenon are poorly understood. Taphonomic evidence indicates that the preservation of enrolled trilobites is a two-stage process involving: 1) factors that evoked enrollment; and 2) depositional and geochemical factors that resulted in preservation of the trilobites in an enrolled condition.

The Alden Pyrite Bed, Ledyard Shale Member, Ludlowville Formation (Middle Devonian, Givetian) of western New York, a well-known stratigraphic marker bed, is formally described herein. This bed yields an extraordinary number of enrolled phacopine trilobites. This study suggests that trilobites, like certain modern arthropods, enrolled in response to inhospitable conditions, including environmental toxicity and/or rapid sediment influx. Frequency of occurrence data from the Alden Pyrite Bed and underlying and overlying beds of the Ledyard Shale indicate that the trilobites Greenops boothi (Green) and Phacops rana (Green) both enrolled in response to adverse conditions at the sediment-water interface. Prolonged adversity compelled the trilobites to remain, and eventually die, in an enrolled state. Rapid and deep burial within a fine-grained sediment precluded scavenger dismemberment and favored geochemical conditions which culminated in pyritization and preservation.

Many specimens of the conulariid Paraconularia magna (Ries) from the Tackett Formation (Upper Pennsylvanian, Missourian) of Oklahoma exhibit repaired or unrepaired injured exoskeletons. Scalloped, cleft, and embayed patterns are interpreted to be repaired sublethal damages produced by unknown events or organisms. Punctures, which are the first reported in conulariids, were not followed by exoskeletal repair and were probably lethal. Cladodont sharks are implicated as possible predators of P. magna because of a close correspondence in size and pattern between the dentition of some sharks and the punctures preserved in conulariid exoskeletons.

Fragmentary fossils from Late Devonian rocks, previously identified as phyllocarid arthropods, are referable to “Vermes.” Specimens identified as Dithyrocaris (=Mesothyra) sp. from the Chagrin Shale in northeastern Ohio are assigned to Sphenothallus cf. S. carbonarius (M'Coy). Thus, there are no records of rhinocaridid arthropods from the Chagrin. Fossils identified as “cercopods” of the echinocaridid, Echinocaris asiaticus Reed, from the Wetwin shales in Burma, are not arthropod remains, but are tubes produced by a gregarious worm. Echinocaris asiaticus is now represented only by a single partial carapace.

Yuknessia Walcott, 1919 recently was transferred from the green algae to the Phylum Hemichordata on the basis of new details observed for the type species, Y. simplex, from the Burgess Shale Formation (Cambrian Stage 5) of British Columbia. This has prompted reexamination of material attributed to Yuknessia from various Cambrian localities in South China. Findings preclude both a Yuknessia and a hemichordate affinity for all of the Chinese study material, and most of this material is formally transferred to Fuxianospira Chen and Zhou, 1997, a taxon common in the Chengjiang biota. Comparable material from the Cambrian Marjum, Wheeler, and Burgess Shale formations of North America is also assigned to Fuxianospira, and this reassignment expands both the paleogeographic and stratigraphic range of this taxon. All aspects of the study specimens, including details obtained from scanning electron microscopy, are consistent with an algal affinity, as proposed in the original descriptions of the Chinese material.

Exceptionally preserved specimens of the Cambrian stem-group brachiopod Mickwitzia occidens Walcott, 1908 are described in detail from the Indian Springs Lagerstätte in Nevada, USA. Shell structure and preserved mantle setae from these specimens reveal a variable diagenetic (taphonomic) history and provide insight into the phylogenetic position of mickwitziids. Morphologic and morphometric comparison to M. monilifera (Linnarsson, 1869) from Sweden and M. muralensis Walcott, 1913 from British Columbia, Canada reveals clear species-level distinctions. Scanning electron microscopic analysis allows revision of the generic diagnosis. The Mickwitzia shell is characterized by the presence of inwardly pointing phosphatic cones and tangential setae-bearing tubes. The inwardly pointing cone structures are not consistent with setal bearing structures as previously thought, but rather represent endopunctae-like structures. Acrotretid-like shell structures and shell-penetrating setae in M. occidens strengthen the previously proposed close relationship between stem-group brachiopods and tommotiids, a group of small shelly fossils.

Commensal epizoozoans and episkeletozoans are rarely preserved attached to the external exoskeleton of the Late Ordovician trilobite Flexicalymene. Of nearly 15,000 Flexicalymene specimens examined, 0.1% show epizoozoans or episkeletozoans. Factors limiting Flexicalymene fouling include a shallow burrowing life style, frequent molting of the host, larval preference for other substrates, observational bias caused by overlooking small fouling organisms, and the loss of the non-calcified, outermost cuticle prior to fossilization or as the trilobite weathers from the encasing sediment. Trepostome bryozoans, articulate and inarticulate brachiopods, cornulitids, and a tube-dwelling/boring nonbiomineralized organism represent the preserved members of the Late Ordovician marine hard substrate community fouling Flexicalymene. This assemblage of organisms is less diverse than the hard substrate community fouling Late Ordovician sessile epibenthic organisms. Fouling is not restricted to only large Flexicalymene specimens as observed in previous studies but occurs in medium to large individuals interpreted as early to late holaspid specimens.

Epizoozoans fouling the carcasses or molt ensembles of 16 Flexicalymene specimens provide insight into the life habits of the host and these fouling organisms. Trepostome bryozoans, articulate and inarticulate brachiopods, and cornulitids preferentially attached to elevated portions of the dorsal exoskeleton, and preferentially aligned in either the direct line or lee side of currents generated by Flexicalymene walking on the sea floor or swimming through the water column.

Two new conulariid species, Conularia clarkei Babcock and C. paraguayensis Babcock from the Vargas Peña Shale, are the first Silurian conulariids to be described from Paraguay. They increase to three the number of Silurian species to be described from South America. The concept of Conularia Miller in Sowerby, 1820, is emended. It includes as junior synonyms Conularia (Plectoconularia) Bouček, 1939, Diconularia Sinclair, 1952, and Yangoconularia Xu and Li, 1985. The age of the Vargas Peña Shale has long been disputed, but conclusions based on organic-walled microfossils indicate an Early Silurian (Llandoverian) age for the unit.

Small phosphatic fossils recovered from acid residues of the Galena Group Middle (Ordovician) of Wisconsin were recently described by Clark et al. (1999) as weird things. Here, we report that specimens identified by those authors as Thing 3 and Thing 6 are fragments of conulariids belonging to two species that occur widely through Middle Ordovician strata of eastern North America. Similarly disintegrated, conspecific specimens from the Trenton Limestone of northwestern Indiana, and articulated, conspecific specimens from Ohio and New York, are introduced for comparison.

Lake deposits of the Pagoda Formation (Upper Carboniferous?-Lower Permian) at Mt. Butters, Shackleton Glacier area, central Transantarctic Mountains, Antarctica, yield a low diversity biota including a new species of conchostracan, Cyzicus (Lioestheria) shackletonensis. Locally, conchostracans occur in large numbers near the tops of thin coarsening-upward cycles in siliciclastic sediments. Regionally, the Pagoda Formation consists of glacigenic deposits of the Gondwanide ice sheet that covered much of the land in southern high latitudes. At Mt. Butters, the lake deposits document the presence of an ice-margin lake in front of the advancing ice sheet. Deposition from suspension within the lake was interrupted by introduction of sand and silt deposited in the conchostracan-bearing, upward-coarsening sequences. Conchostracans of the Pagoda Formation are associated with other arthropods (euthycarcinoids and ostracodes), and wood fragments; burrows produced by small animals moving just beneath the sediment surface are abundant in some horizons. Few conchostracan occurrences are known from the Carboniferous-Permian of Antarctica; this is the second recorded occurrence, and it increases the number of described species to three.

Asymmetry is a fundamental aspect of the biology of all organisms, and has a deep evolutionary history. The fossil record contains evidence of both morphological and behavioural asymmetries. Morphological asymmetry is most commonly expressed as conspicuous, directional asymmetry (either lateral asymmetry or spiral asymmetry) in body fossils. Few examples of fluctuating asymmetry, a form of subtle asymmetry, have been documented from fossils. Body fossil evidence indicates that morphological asymmetry dates to the time of the appearance of the first life on Earth (Archaean Eon). Behavioural asymmetry can be assumed to have been concomitant with conspicuous morphological asymmetry, but more direct evidence is in the form of trace fossils. Trace fossil evidence suggests that behavioural asymmetry, including nervous system lateralization, was in existence by the beginning of the Palaeozoic Era.

This Volume marks the inaugural issue of the Paleontological Society Papers. This series, established by The Paleontological Society in 1996, replaces the Paleontological Society Short Course Notes, which ceased to be published in November 1995, and the Paleontological Society Special Publications, which ceased to be published in June 1996. Most of the contributions in the new series are invited papers presented at the Short Courses on Paleontology sponsored by the Society at the annual meetings of the Geological Society of America.

Manuscripts submitted to the Paleontological Society Papers must conform strictly to guidelines in order to ensure timely publication of each volume. Manuscripts, to be included in the series, should be no more than 25 single-spaced pages in length, and submitted to the volume editor by February 15 of the intended year of publication.