Nanjing Institute of Geology and Palaeontology

Stephen R. Westrop, Jennifer D. Eoff, Tin-Wai Ng, Alyce A. Dengler and Jonathan M. Adrain

All recent work has assigned the genera Cheilocephalus Berkey, 1898 and Oligometopus Resser, 1936 to the family Cheilocephalidae Shaw, 1956, a small group of largely Laurentian trilobites from the Late Cambrian Steptoean Stage. New data from Nevada and Newfoundland indicate that the Cheilocephalidae is polyphyletic and that Cheilocephalus and Oligometopus are allied with different superfamilies. The Cheilocephalidae, which includes Cheilocephalus and Pseudokingstonia Palmer, 1965, is assigned to the Dameselloidea Kobayashi, 1935, and a pygidium from the Cow Head Group of Newfoundland indicates that Cheilocephalus first appears in the late Marjuman. The Dameselloidea disappeared on other continents at an extinction interval at the end of the Marjuman, but Cheilocephalus survived and underwent modest diversification in Laurentia in the succeeding Steptoean Stage. Oligometopus is transferred to the leiostegioidean family Leiostegiidae Bradley, 1925. The genus shows closest affinities with such Gondwanan genera as Idamea Whitehouse, 1939, and its appearance in mid-Steptoean strata records immigration of the Leiostegoidea into shelf-margin environments of Laurentia.

Tin-Wai Ng, Louis Suh-yui Teng

The late Neogene Kangkou and Tungho limestones of the Coastal Range of eastern Taiwan contain diverse fossil assemblages, but their paleoecology has not been quantitatively studied before. Cluster and non-metric multi-dimensional scaling (NMS) analyses were conducted using data from eight localities. Six fossil assemblages are recognized, with some overlap between them: Planktic Foraminifera (PF), Benthic Foraminifera (BF), Encrusting Foraminifera (EF), Bryozoan-Echinoderm-Algae-Mollusk (BEAM), Algae (A), and Coral (C) assemblages. The first two major axes of the NMS analysis can be interpreted as primarily representing water depth and substrate type. These assemblages represent various shallow marine settings with low to moderately high biodiversity.

Lucy A. Muir, Tin-Wai Ng, Xiang-Feng Li, Yuan-Dong Zhang, Jih-Pai Lin

Several species of palaeoscolecidan worm have been found in the Tonggao Formation (earliest Floian) of Guizhou Province, China. Two new palaeoscolecidan taxa are described (Sanduscolex regularis n. gen. n. sp. and Ashetscolex nuppus n. gen. n. sp.); another palaeoscolecidan (Wronascolex sp.) is left in open nomenclature. This is the youngest known occurrence of Wronascolex. A possible large free-living nematode is described and illustrated, representing the earliest known nematode in the fossil record, and a rare example from a marine setting."

"TIN-WAI NG, JIN-LIANG YUAN AND JIH-PAI LIN

The use of carbon isotope excursion in Cambrian stratigraphical correlation is a stan- dard practice at both the intercontinental and intracontinental scales. The Steptoean positive carbon isotope excursion (SPICE) is one of the prime examples in this regard in correlating the base of the Paibian Stage and Furongian Series. A lack of definite SPICE evidence in the North China craton has been a challenge in precision correla- tion between North China and other palaeo-continents. This study provides new car- bonates carbon isotope data from the type locality of the Changshan Formation in Hebei Province, North China. Our new d13Ccarb data provide new objective evidence for the presence of the SPICE in North China. The sampling section is relatively con- densed, and the interval of the SPICE curve is less than one and half-metres after anal- ysing 64 samples (the sampling interval within the SPICE is less than 10 cm). The onset of the SPICE curve in Tangshan, Hebei, occurs in the barren interval between the Neodrepanura and Chuangia trilobite zones. According to Peng (2009 a,b), this could imply the middle part of the Prochuangia-Paracoosia trilobite Zone in North China and can be correlated with the base of the Paibian Stage and Furongian Series."

JIN-LIANG YUAN, JORGE ESTEVE AND TIN-WAI NG

Monkaspis daulis (Walcott 1905) is the first enrolled trilobite to be documented from the Kushan Formation (Guzhangian, Cambrian Series 3) of Northern China. It has a wide pygidium that allowed a sphaeroidal enrolment type to be achieved, covering the cephalon and anterior trunk segments. Monkaspis daulis is micropygous, but the pygidium is proportionally larger than that of many other Cambrian trilobites, and there is a slightly variable number of segments in the trunk. Articulation structures are very well developed through the trunk, but interlocking or coaptative devices are poorly developed with the exception of the terrace lines and a novel structure, a ‘pos- terior arch’, in the pygidium, which would have prevented shear. The absence of genal spines that would otherwise have inhibited sinking into the mud substrate may have enabled Monkaspis daulis to use the enrolment procedure to excavate a hole in the sed- iment for taking shelter.