Jeong Gu Lee

Occurrence of Glyptagnostus stolidotus Opik, 1961 (Trilobita, Late Cambrian) in the Machari Formation of Korea

GALACZ, A. 1988. First record of Paleocene nautiloids from Cuba. Palaontologisches Zeitschrift, 62:265-269. MILLER, A. K. 1947. Tertiary nautiloids of the Americas. Geological Society of America, Memoir 23, 234 p. , AND M. L. THOMPSON. 1937. Some Tertiary nautiloids from Venezuela and Trinidad. Eclogae Geologicae Helvetiae, 30:59-73. SCHMIDT, W., AND P. JUNG. 1993. Tertiary cephalopods from Jamaica, p. 347-352. In R. M. Wright and E. Robinson (eds.), Biostratigraphy of Jamaica. Geological Society of America, Memoir 182. TANABE, K., N. H. LANDMAN, R. H. MAPES, AND C. J. FAULKNER. 1993. Analysis of a Carboniferous embryonic ammonoid assemblage-implications for ammonoid embryology. Lethaia, 26:215-224. TEICHERT, C. 1964. Morphology of hard parts, p. K13-K53. In R. C. Moore (ed.), Treatise on Invertebrate Paleontology, Pt. K, Mollusca 3. Geological Society of America and University of Kansas Press, L wrence.

Ontogeny of the Late Cambrian trilobiteOlenus asiaticus Kobayashi, 1944 from the Machari Formation of Korea

Ontogeny of the Late Cambrian trilobiteOlenus asiaticus Kobayashi, 1944 was examined based on the material from theGlyptagnostus reticulatus Zone of the Machari Formation in Yongwol area, Korea. Protaspides are differentiated into anaprotaspid and metaprotaspid stages. Anaprotaspides are represented by circular dorsal shields with faintly segmented axis, while meta-protaspides have five axial rings, eye ridges, and a differentiated protopygidium. Most of meraspides, represented by disarticulated cranidia, are further divided into six morphological groups. The Group 1 is assumed to represent the meraspid degree 0, whereas the remaining groups are subdivided in convenience to describe the morphological development of cranidia. Morphological changes within the meraspid stages are gradual in general. The glabella is parallel-sided or tapers rearwards in the early meraspides, whereas it tapers forwards in the later forms. The preglabellar field appears in the Group 3 and becomes progressively longer in the later meraspid stages. The holaspid cranidia are distinct in having a subquadrate glabella with three pairs of lateral glabellar furrows.

A TERATOLOGICAL PYGIDIUM OF THE UPPER CAMBRIAN TRILOBITE EUGONOCARE (PSEUDEUGONOCARE) BISPINATUM FROM THE MACHARI FORMATION, KOREA

Abstract A teratological holaspid pygidium of Eugonocare (Pseudeugonocare) bispinatum (Kobayashi, 1962) is described from the Cambrian Machari Formation of Korea. The abnormality is represented by the development of two additional posterolateral spines on the left side. This feature probably resulted from a genetic defect. The nonlethal mutation caused formation on one side only of a spine array that mimics the spine arrangement of several Eugonocare species combined.