Museum of Northern Arizona Bulletin 67 (2011)

Sinodiscus changyangensis was suggested as the most primitive eodiscoid (Fortey, 1990; JeB in Whittington and Kaesler, 1997; Cotton and F ortey, 2005), of which the new material, in addition, enables a discussion on the trunk segmentation schedule, and the result reveals that it possesses the same schedule on the trunk segmentation with other primitive eodiscoid trilobites, i.e. the liberation of the thoracic segments is not accompanied by insertion of new segments into the pygidium and a new segment is added in a later growth stage, which differs from those of agnostoids in that the segment growth on the pygidial exoskeleton is accomplished in the early meraspid period.

REFERENCES COTTON, t. J., AND r. A. FORTEY. 2005. Comparative morphology and relationships ofthe Agnostida. p. 95 -36. In

S. Koenemann and R. A. Jenner (eds), Crustacea and arthropod relationships. Crustacean Issues, 16,440 p. FORTEY, R. A. 1990. Ontogeny, hypostome attachment and trilobite c1assification. Palaeontology, 33:529 - 576. HUGHES, N. c., A. MINELLI, AND G. Fusco. 2006. The ontogeny oftrilobite segmentation: a comparative approach.

Paleobiology, 32:602-627. JELL, P. A. 1997. Introduction to Suborder Eodiscina, p. 384-386. In,.R. L. Kaesler (ed.), Treatise on Invertebrate

Paleontology. Pt. O. Arthropoda 1, Trilobita (revised). Geological Society of America and University of Kansas Press, Lawrence.

Lu, Y.-H., W.-T. ZHANG, Y.-Y. QIAN, Z.-L. ZHU, Z.-Y. ZHOU, Y. QIAN, S.-G. ZHANG, AND H.-J. Wu. 1974. Cambrian Trilobita, p. 82-107. In Palaeontological atlas of Southwest China. Geological Publishing House, Beij ing. (In Chinese)

ZHANG, W.-T., Y.-H. Lu, Z.-L. ZHU, Y.-Y. QIAN, H.-L. LIN, Z.-Y. ZHOU, S.-G. ZHANG, AND J.-L. YUAN. 1980. Cambrian trilobite faunas ofsouthwestem China. Palaeontologica Sinica, New Series B, 16:1-497. (In Chinese with English summary)

ZHOU T.-M., Y.-R. LIU, X.-S. MENG AND Z.-H. SUN. 1977. Trilobita. p. 107-266. In Palaeontological Atlas of Central and South China. Vol. 1. Geological Publishing House, Beij ing. (In Chinese)

CORRELATING THE CAMBRIAN IN THE SOUTH-EASTERN MEDITERRANEAN REGIONS OFGONDWANA

OLAF ELICKI

Freiberg University, Geological Institute, Bemhard-von-Cotta Street 2, 09599 Freiberg, Germany, <elicki@geo.tu-freiberg.de>

The fossil content and stratigraphie position of Cambrian successions in the south-eastem margin of the Mediterranean (Jordan & Israel, Egypt, Libya), have not been weIl known until recently. The lack of fossils along with problematic depositional facies (continental to marginal-continental) has prec1uded stratigraphie definition and limited correlation efforts.

In the Jordan/Israel region the continental deposits and open-marine sediments (silicic1astics and carbonates) are thin but weIl developed. In Egypt (silicic1astics ofthe Sinai Peninsula and Eastem Desert) and in Libya (silicic1astics), by contrast, only successions interpreted as marginal-continental and mostly non-marine are known. In all these regions the Cambrian sediments (and/or 'probable Cambrian' and/or 'Infra-Cambrian') unconformably overlay the Proterozoic basement, starting with or consisting exc1usively of continental facies. The stratigraphie age of these sediments is inferred from overlying fossiliferous late early to middle Cambrian (as in Jordan and Israel: trilobites, small shelly fossils etc.; carbonates) or Ordovician strata (as in Egypt and Libya; silicic1astics) as weIl as some geochronological data that has come from the unconformably underlying rocks.

During re cent field work in Jordan, Egypt and Libya, sections were measured, facies realms were delineated and for the first time marine trace fossils have been recorded from all the mentioned regions. From Jordan (Dead Sea), a distinctly more comprehensive trilobite fauna and the first micro-fauna have been documented. The only opportunity to calibrate the successions of all these areas within a broader

280

Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada

international scheme has been limited to body fossils found exc1usively in the Jordan/Israel open-marine carbonates. The trilobites particularly indicate that the maximum extent of marine transgression in this paleogeographic region occurred very c10se to the traditional Lower-Middle Cambrian boundary interval (Hawke Bay-Type transgression: Elicki & Geyer, submitted). According to the trilobite content ofthe Jordanian successions (Kingaspis campbelli, Redlichops blanckenhorni, Tayanaspis orientalis, Hesa problematica, Myopsolenites palmeri, M hyperion, Enixus cf. antiquus), the best correlation is with the (possibly upper part of) the Morocconus Zone (formerly the Cephalopyge Zone). Should Ovatoryctocara granulata be selected to mark the base of Cambrian Series 3 and Stage 5, the Jordanian trilobite fauna would indicate the basal strata ofthose units (Elicki & Geyer, submitted).

The maximum-transgressive and regressive upper (silicic1astic) portion ofthe Jordanian successions yields rich trace fossil assemblages dominated by arthropod ichnia (Hofmann et al. submitted). Among them, some cruzianid/rusophycid trace fossils are remarkable: e.g., Cruziana aegyptica, Cruziana salominis and others. On the one hand, these trace fossils are c10sely connected to the biostratigraphically defined trilobite body fossils in Jordan. On the other hand, they occur in thin marine intercalations within the stratigraphically problematic sandstone successions in Egypt and probably in Libya. In Jordan, obviously, these trace fossils are more or less coeval to the mentioned trilobite fauna and they occur during the maximum flooding and regressive part of the marine flooding cyc1e. In Egypt (Sinai Peninsula and Eastern Desert) and in Libya (Al Qarqaf Arch), the few, thin marine horizons containing these trace fossils also indicate the maximum stage ofthe Cambrian eustatic rise. It is widely accepted, that the areas of the Middle East and those of north-eastern Africa were c10sely connected during the Cambrian. So, the stratigraphie correlation of the successions of these regions is roughly possible by correlation of the maximum transgression stage and by correlation of the shared ichno-taxa. Distinct ichno-taxa (see above) in turn, can be calibrated by the c10sely related trilobite assemblages in Jordan.

The problem with this model is that the ichno-stratigraphic and also the ichno-taxonomic concepts do not have the same precision as those of body fossils (especially of trilobites). So, it cannot be said with certainty, for example, if Cruziana aegyptica does have astriet biostratigraphie value for detailed correlation or ifthere are paleoecological effects in some extent, limiting its function as an index ichno-fossil.

Summarizing, it can be stated that: (1) A correlation ofthe maximum ofthe Cambrian transgression at the modem south-eastern margin of the Mediterranean (north-eastern Africa and Middle East) can be correlated c10sely to the base of Cambrian Stage 5 (Series 3) due to trilobites. (2) A correlation of marine carbonate and sandstone successions is a possibility because of the J ordanian co­occurrences ofbody fossils and trace fossils. (3) A rough correlation ofthe Jordanian ichnotaxa with those from Sinai Peninsula and Eastern Desert (Egypt) seems to be reasonable. (4) Recent findings of trace fossils from Libya (only one distinct stratum in various regions of the Al Qarqaf Arch, west-central Libya) seem to fit in the same stratigraphie level. Consequently, it must be conc1uded that the prospects for a very detailed biostratigraphie definition and a detailed correlation of the Cambrian strata of the south-eastern Mediterranean are generally limited. Nevertheless, the new findings in Libya and Egypt together with the distinctly improved knowledge on the trace and body fossil content from Jordan opens an opportunity to reconstruct, to fix (stratigraphically) and to correlate the main transgression pulse of this pa1eogeographic region and to fit them into the international scheme with better precision.

EVIDENCE OF TRILOBITE SCA VENGING FROM THE 'MIDDLE' CAMBRIAN, CZECH REPUBLIC

OLDRICH FATKA1, PETR BUDIL2

, AND MICHAL SZABAD3

I Department of Geology and Palaeontology, Faculty of Science, Charles University, Albertov 6, Praha 2, CZ -128 43, Czech Republic, <fatka@natur.cuni.cz>; 2Czech Geological Survey, Klarov 3, Praha 1, CZ­11821, Czech Republic; <budil@cgu.cz>.and 30brancu miru 75, 261 02 Pribram VII, Czech Republic.

281

Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada

Museum of Northern Arizona Board of Trustees

La V elle McCoy - Chair J ack Metzger Allan Affeldt Beverly Miller Drew Barringer Barbara Poley w. David Connell Wayne Ranney J. Kent Corbin James M. Reed Frank R. Garcia Henry Roe, Ph.D. Sam Henderson Brad Ryan Elaine Kasch Margaret Taylor Ramson Lomatewama Eunice Tso Jim Lyon

Original Printing ofthe Museum ofNorthern Arizona Bulletin 67 ISBN 089734-142-2

© Museum ofNorthern Arizona 3101 N. Fort Valley Road Flagstaff, Arizona 86001

2011

Exeeutive Editor: David D. Gillette Printed by MeNaughton and Gunn, Ine.

Cover-180 degree panorama looking north into upper Shinumo Amphitheater, Grand Canyon, Arizona. Dox Castle is on the left in the foreground and moving fram left to right is Muav Creek, Merlin and Modred Abyss, and Gawain Abyss on the right. Photograph by Eben Rose.

Logo-designed by Frederick A. Sundberg; drawing of Nephroloenellus geniculatus generously provided by Sam Gon IH.

1