Taxonomy and paleobiology of some Middle Cambrian Scenella (Cnidaria) and Hyolithids (Mollusca) from western North America

22 p., 10 fig.http://paleo.ku.edu/contributions.htm

Systematics, paleobiology, and taphonomy of some exceptionally preserved trilobites from Cambrian Lagerstätten of Utah

Mid-Cambrian biotas of the Spence, Wheeler, Marjum, and Weeks formations in Utah are exceptionally diverse. Continued collecting has produced additional trilobites here assigned to one new genus, Meniscopsia, and 25 new species. The new species, all known from complete or nearly complete dorsal exoskeletons, are Amecephalus jamisoni, Athabaskia gladei, Bolaspidella jarrardi, Bolaspidella reesae, Burlingia halgedahlae, Coosella kieri, Ehmaniella whitei, Glossopleura campbelli, Glossopleura yatesi, Ithycephalus stricklandi, Kootenia randolphi, Kootenia youngorum, Meniscopsia beebei, Menomonia sahratiani, Modocia comforti, Modocia kohli, Modocia whiteleyi, Norwoodia boninoi, Olenoides skabelundi, Olenoides vali, Polypleuraspis cooperi, Ptychoparella lloydi, Ptychoparella mettae, Zacanthoides liddelli, and Zacanthoides marshalli. Descriptions of two other species, Triadaspis bigeneris and Zacanthoides typicalis, are expanded to include new information from complete dorsal exoskeletons. The ventral cephalic presence of a functional rostral-hypostomal suture in the corynexochoid Zacanthoides marshalli further demonstrates that a fused rostral-hypostomal plate is not a unique defining character of the order Corynexochida, adding to evidence that the Corynexochida may be a polyphyletic taxon. The ventral cephalic presence of a median suture, associated with a rostellum in Norwoodia boninoi, order Ptychopariida, is further evidence for a polyphyletic origin of the median suture, previously cited as a unique apomorphic character defining the order Asaphida, which needs revision. The presence of a mineralized alimentary tract and digestive glands in some specimens of Meniscopsia beebei and Coosella kieri suggests that the gut was fluid filled at the time of burial and that the species were predaceous. Collapsed glabellas are interpreted as further evidence of fluid-filled gut tracts in some of the new species. Many of the articulated trilobites preserved in mid-Cambrian Lagerstätten of Utah were probably buried under rapidly deposited sediment clouds on a storm-prone marine shelf. Occasionally, trilobite clusters were buried. Encrustation of fully articulated individuals with calcitic cone-in-cone deposits in the Wheeler and Marjum formations is a likely consequence of concretionary-type growth within a biofilm shortly after death

Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China

The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point (GSSP) defining the conterminous base of the third series and the fifth stage of the Cambrian System. The series and the stage are respectively named the Miaolingian Series and Wuliuan Stage, after the Maioling Mountains in southeastern Guizhou and the Wuliu sidehill, Jianhe County, in eastern Guizhou Province, South China, where the GSSP is located. The GSSP is exposed in a natural outcrop near the Balang Village at a position of 26° 44.843′N latitude and 108° 24.830′E longitude. It is defined at the base of a silty mudstone layer 52.8 m above the base of the Kaili Formation in the Wuliu-Zengjiayan section, coinciding with the first appearance of the cosmopolitan oryctocephalid trilobite Oryctocephalus indicus (base of the O. indicus Zone). Secondary global markers at or near the base of the series and stage include the peak of a rather large negative carbon isotopic excursion (ROECE excursion), the simultaneous appearance of many acanthomorphic acritarch forms, a transgressive phase of a major eustatic event, and the last appearance of intercontinental polymerid trilobites, either Bathynotus or Ovatoryctocara. Faunal turnovers close to the base of the Miaolingian Series and Wuliuan Stage have been recognized as being at the base of the Oryctocephalus indicus Zone of Amgan Stage in Siberia, the Delamaran Stage in Laurentia, the Oryctocephalus indicus Zone in the Indian Himalaya and North Greenland, near the base of the Delamaran Stage in Australia, and within the Eccaparadocides sdzuyi Zone in Iberia and the Ornamentaspis frequens Zone in Morocco

Devonian and Mississippian conulariids of North America. Part B. <i>Paraconularia</i>, <i>Reticulaconularia</i>, new genus, and organisms rejected from Conulariida

Volume: 55Start Page: 411End Page: 47

Asymmetry in the fossil record

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.

The phylogenetic position of Echmatocrinus brachiatus, a probable octocoral from the Burgess Shale

Volume: 41Start Page: 193End Page: 20