Ordovician trilobite faunas from eastern Kazakhstan

Staff: L.E. Popov, R. M. Owens, L. M. E. McCobb [with M. Ghobadi Pour, Gorgan University, Iran]

Introduction

A moderately diverse fauna collected some decades ago comprises some 20 genera of trilobites from the upper part of the Karagach Formation, of Caradoc age. The graptolites from the trilobite-bearing horizons suggest correlation with the Eastonian Regional stage of Australia. Most of the trilobites belong to genera that have a wide geographical distribution, but some, such as Birmanites and Dulanaspis are characteristic of low latitude, eastern peri-Gondwanan faunas.

Leonid Research image
A new species of Agerina from the Upper Ordovician Karagash Formation of Tarbagatai Range in eastern Kazakhstan is somewhat unusual because it has a short median spine in front of the anterior cranidial border not characteristic of other species referred to the genus. It is also among the latest survivors of the Family Leiostegidae, which proliferated in equatorial and temperate latitude peri-Gondwana in the Late Cambrian to Mid Ordovician.

Since the collapse of the former USSR, there is a considerable decline in geological and palaeontological studies in newly emerged states of Kazakhstan, Kyrgyzstan and Uzbekistan. For instance, presently there are no specialists working on the Ordovician and Silurian trilobites in whale Kazakhstan and Central Asia. Moreover significant palaeontological collections and geological information accumulated for the period of more than half a century in the local geological services and academic institutions is in danger of total loss and destruction because of lack of qualified specialists. Therefore a proper study of accumulated palaeontological materials with subsequent publication will help to save this valuable information that gives a great benefit to the international science. In present, the early Palaeozoic geology of Kazakhstan, Central Asia and whale the Middle East is the subject of strong discussion and controversies because of conflicting views on palaeogeography and geological history of the region. The study of trilobite faunas bearing distinct biogeographical signatures will give a good test for these conflicting plate tectonic models. Internationally, publications based on the studies formulated in this project may represent valuable contribution to the ongoing IUGS-503 Project.