A Middle Devonian Trilobite Assemblage from Venezuela

Maria Da Gloria Pires De Carvalho,John Moody

doi:10.1206/0003-0082(2000)292<0001:amdtaf>2.0.co;2

Abstract

Three new species of trilobites are described from the upper level of the Caño del Oeste Formation (Middle Devonian) of Venezuela. These taxa include a phacopinine, Viaphacops venezuelensis, n. sp., and two asteropyginines, Rhenops odremani, n. sp., and Greenops perijaensis, n. sp. The biogeographic implications of these records are discussed. Viaphacops is somewhat cosmopolitan in its distribution. The presence of Rhenops in Venezuela represents a profound range extension beyond the Rhenish-Bohemia region of the Old World Realm. The Venezuelan occurrence of Greenops represents a southerly range extension within the Eastern Americas Realm, reinforcing faunal similarities previously recognized among Devonian brachiopods and trilobites of Venezuela and North America.

Highlights

The Devonian marine invertebrate fauna from Venezuela has been known since the beginning of the 20th century (Yeakel, 1924; Weisbord, 1926; Liddle et al, 1943), following early expeditions to collect fossils from the type locality of the Cano del Oeste Formation (Middle Devonian; Eifelian–Givetian), which extends along the Cachirı river in the Perija Mountains
Liebermann and Kloc (1997) diagnosed Greenops on the basis of 18 characters: 6, 8, 21, 26, 28, 29, 31, 33, 34, 35, 42, 45, 47, 49, 50, 51, 57, and 66, of which 12 are discernible in the Venezuelan material (21, 28, 29, 31, 33, 34, 42, 45, 47, 49, 50, and 51); the remaining characters cannot be determined for preservational reasons
Greenops perijaensis differs from G. boothi (Green, 1837; the type species of the genus) in having S1 less deep and not as crescentshaped as in G. boothi; L0 without medial tubercle; shape of pleural lappets

Summary

Introduction

The Devonian marine invertebrate fauna from Venezuela has been known since the beginning of the 20th century (Yeakel, 1924; Weisbord, 1926; Liddle et al, 1943), following early expeditions to collect fossils from the type locality of the Cano del Oeste Formation (Middle Devonian; Eifelian–Givetian), which extends along the Cachirı river in the Perija Mountains. Benedetto (1979, 1984) subsequently described assemblages of pelecypods, trilobites, and brachiopods that were collected from several exposures of the Cano del Oeste Formation in the area of Cano Colorado (fig. 1).

Results

Conclusion