Revue de micropaléontologie 51 (2008) 167–181 Original article Upper Tremadoc–Lower Arenig? Anisograptid–Dichograptid fauna from the Cabitza Formation (Lower Ordovician, SW Sardinia, Italy) Faune ` a Anisograptid´ es–Dichograptid´ es du Tr´ emadocien sup´ erieur–Ar´ enigien inf´ erieur ? de la Formation de Cabitza (Ordovicien inf´ erieur, SW Sardaigne, Italie) Gian Luigi Pillola a,∗ , Sergio Piras a , Enrico Serpagli b a Dipartimento di Scienze della Terra, Universit` a di Cagliari, Via Trentino 51, 09127 Cagliari, Italy b Dipartimento del Museo di Paleobiologia e dell’Orto Botanico, Universit` a di Modena e Reggio Emilia, Via Universit` a 4, 41100 Modena, Italy Abstract The discovery of the anisograptid graptolite Araneograptus murrayi (Hall, 1865), the dichograptids Clonograptus (Clonograptus) cf. rigidus (Hall, 1858) and Clonograptus (Clonograptus) cf. multiplex (Nicholson, 1868) and of two unassigned species of Didymograptus in the Late Tremadoc–Early Arenig? sediments of the Fluminese area (SW Sardinia) adds new data on the biostratigraphy and palaeoecological setting of the Cabitza Formation, as well as on the paleobiogeographical distribution of these taxa. © 2007 Elsevier Masson SAS. All rights reserved. R´ esum´ e La d´ ecouverte du graptolite Anisograptid´ e Araneograptus murrayi (Hall, 1865), des Dichograptid´ es Clonograptus (Clonograptus) cf. rigidus (Hall, 1858) et Clonograptus (Clonograptus) cf. multiplex (Nicholson, 1868) et de deux esp` eces ind´ etermin´ ees de Didymograptus dans les s´ ediments du Tr´ emadocien sup´ erieur–Ar´ enigien inf´ erieur? du Fluminese (SW Sardaigne) fournit des nouvelles donn´ ees sur le contexte pal´ eo´ ecologique et sur la biostratigraphie de la partie sup´ erieure de la formation de Cabitza, ainsi que sur la distribution pal´ eobiog´ eographique de ces taxa. © 2007 Elsevier Masson SAS. All rights reserved. Keywords: Graptolites; Caryocarids; Early Ordovician; Cabitza Formation; Sardic phase; Sardinia Mots cl´ es : Graptolites ; Caryocarid´ es ; Ordovicien inf´ erieur ; Formation de Cabitza ; Phase Sarde ; Sardaigne 1. Introduction Graptolites have been known in Lower Ordovician sediments of southwestern Sardinia since the first half of the 20th century. Novarese (1920) reported the occurrence of Dictyonema sp. on a loose rock specimen found, five years earlier, at Monte Cani (near Gonnesa). In the same year, Taricco (1920) described this material, consisting of several incomplete colonies and, despite their fragmentation, assigned them to “Dictyonema flabelliforme Eichwald, 1840”. The Dictyonema-bearing levels were regarded ∗ Corresponding author. E-mail address: pillolag@unica.it (G.L. Pillola). by Taricco (in Novarese and Taricco, 1922: p. 320) as belonging to the Acadian (sic.) “Gruppo degli Scisti” (Cabitza Formation) and he ingenuously extended the range of “D. flabelliforme” into the Middle Cambrian. Subsequently, the presence of “Dictyonema” in Sardinia was usually rejected, disregarded or questioned (Lecompte, 1949) and the upper part of the Cabitza Formation continued to be con- sidered Middle Cambrian in age (Cocozza, 1967, 1980; Rasetti, 1972). More recent research carried out in the Gonnesa region (Monte Cani) led to the discovery of the Rhabdinopora flabel- liformis (Eichwald, 1840) bearing layers (Gandin and Pillola, 1985; Pillola, 1987; Barca et al., 1987). These in situ specimens were tentatively assigned to the morphotype “graptolithinum” 0035-1598/$ – see front matter © 2007 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.revmic.2007.08.002