First Furongian (late Cambrian) trilobites from the Cantabrian Zone (northwestern Spain).

ACEÑOLAZA, G.F., ALBANI, R., BERNARDEZ, E., GARCÍA-BELLIDO, D.C., GUTIÉRREZ-MARCO, J.C. & RÁBANO I.,

Praga

Conferencia; 5th International conference on trilobites and their relatives; 2012

Czech Geological Survey & Charles University

The Spanish record of late Cambrian trilobites is very sparse, being so far restricted to few strata occurring in the Najerilla Formation of the Sierra de la Demanda (Colchen, 1967; Shergold et al., 1983) and from the Valtorres, Valconchán and lowermost Borrachón formations of the western Iberian Chain (Shergold and Sdzuy, 1991, with earlier references). Outside Iberia, Furongian trilobites are also rare, in part due to the existence of major erosive unconformities and diachronic stratigraphic gaps related to the denudation of rift shoulders during a multi-stage rifting, probably connected to the opening of the Rheic Ocean (Alvaro et al., 2007). Nevertheless, Furongian trilobite assemblages do occur in scattered peri-Gondwanan sections from the southern Montagne Noire (SE France: Feist and Courtessole, 1984; Shergold et al., 2000; Alvaro et al., 2001, 2003), SW Sardinia (Italy: Loi et al., 1996), central Anti-Atlas (Morocco: Destombes et al., 1987; Geyer et al., 2002), and central Turkey (Shergold and Sdzuy, 1984). During excavation of a tunnel for the Cantabrian Highway (A-8) in northern Spain, a thick intercalation of dark shales (‘El Fabar Beds’: ca. 40 m) was discovered within the La Matosa quartzite member of the Barrios Formation, located in the eastern Asturian domain (Aramburu and García-Ramos, 1993) of the Cantabrian Zone of the Iberian Massif. A palynological sample from these beds yielded a rich and well-preserved acritarch assemblage, composed of 19 taxa identified at the species level, and 7 more left in open nomenclature. Among them, the genera Acanthodiacrodium, Lusatia andet al., 1983) and from the Valtorres, Valconchán and lowermost Borrachón formations of the western Iberian Chain (Shergold and Sdzuy, 1991, with earlier references). Outside Iberia, Furongian trilobites are also rare, in part due to the existence of major erosive unconformities and diachronic stratigraphic gaps related to the denudation of rift shoulders during a multi-stage rifting, probably connected to the opening of the Rheic Ocean (Alvaro et al., 2007). Nevertheless, Furongian trilobite assemblages do occur in scattered peri-Gondwanan sections from the southern Montagne Noire (SE France: Feist and Courtessole, 1984; Shergold et al., 2000; Alvaro et al., 2001, 2003), SW Sardinia (Italy: Loi et al., 1996), central Anti-Atlas (Morocco: Destombes et al., 1987; Geyer et al., 2002), and central Turkey (Shergold and Sdzuy, 1984). During excavation of a tunnel for the Cantabrian Highway (A-8) in northern Spain, a thick intercalation of dark shales (‘El Fabar Beds’: ca. 40 m) was discovered within the La Matosa quartzite member of the Barrios Formation, located in the eastern Asturian domain (Aramburu and García-Ramos, 1993) of the Cantabrian Zone of the Iberian Massif. A palynological sample from these beds yielded a rich and well-preserved acritarch assemblage, composed of 19 taxa identified at the species level, and 7 more left in open nomenclature. Among them, the genera Acanthodiacrodium, Lusatia andet al., 2007). Nevertheless, Furongian trilobite assemblages do occur in scattered peri-Gondwanan sections from the southern Montagne Noire (SE France: Feist and Courtessole, 1984; Shergold et al., 2000; Alvaro et al., 2001, 2003), SW Sardinia (Italy: Loi et al., 1996), central Anti-Atlas (Morocco: Destombes et al., 1987; Geyer et al., 2002), and central Turkey (Shergold and Sdzuy, 1984). During excavation of a tunnel for the Cantabrian Highway (A-8) in northern Spain, a thick intercalation of dark shales (‘El Fabar Beds’: ca. 40 m) was discovered within the La Matosa quartzite member of the Barrios Formation, located in the eastern Asturian domain (Aramburu and García-Ramos, 1993) of the Cantabrian Zone of the Iberian Massif. A palynological sample from these beds yielded a rich and well-preserved acritarch assemblage, composed of 19 taxa identified at the species level, and 7 more left in open nomenclature. Among them, the genera Acanthodiacrodium, Lusatia andet al., 2000; Alvaro et al., 2001, 2003), SW Sardinia (Italy: Loi et al., 1996), central Anti-Atlas (Morocco: Destombes et al., 1987; Geyer et al., 2002), and central Turkey (Shergold and Sdzuy, 1984). During excavation of a tunnel for the Cantabrian Highway (A-8) in northern Spain, a thick intercalation of dark shales (‘El Fabar Beds’: ca. 40 m) was discovered within the La Matosa quartzite member of the Barrios Formation, located in the eastern Asturian domain (Aramburu and García-Ramos, 1993) of the Cantabrian Zone of the Iberian Massif. A palynological sample from these beds yielded a rich and well-preserved acritarch assemblage, composed of 19 taxa identified at the species level, and 7 more left in open nomenclature. Among them, the genera Acanthodiacrodium, Lusatia andet al., 1996), central Anti-Atlas (Morocco: Destombes et al., 1987; Geyer et al., 2002), and central Turkey (Shergold and Sdzuy, 1984). During excavation of a tunnel for the Cantabrian Highway (A-8) in northern Spain, a thick intercalation of dark shales (‘El Fabar Beds’: ca. 40 m) was discovered within the La Matosa quartzite member of the Barrios Formation, located in the eastern Asturian domain (Aramburu and García-Ramos, 1993) of the Cantabrian Zone of the Iberian Massif. A palynological sample from these beds yielded a rich and well-preserved acritarch assemblage, composed of 19 taxa identified at the species level, and 7 more left in open nomenclature. Among them, the genera Acanthodiacrodium, Lusatia andAcanthodiacrodium, Lusatia and Cristallinium are especially abundant, and the acritarch association was correlated by Albani et al. (2006) as equivalent to theare especially abundant, and the acritarch association was correlated by Albani et al. (2006) as equivalent to the Protopeltura praecursor trilobite biozone of eastern Newfoundland (basal Cambrian Stage 10 of the Furongian series: see Rushton et al., 2011). In adition to the palynoflora, macrofossils from the El Fabar beds include some obolid brachiopods, phyllocarid crustaceans and rare olenid trilobites resembling Parabolina from the Furongian stages 9 and 10. The record of late Cambrian trilobites from ‘El Fabar Beds’ was briefly mentioned by Gutiérrez-Marco and Bernárdez (2003) and Albani et al. (2006), but the material was never studied in detail. For the present work, we have examined all the specimens collected during the excavation of the “Túnel Ordovícico del Fabar” in the A-8 highway 7 km west of Ribadesella (Asturias). Our results confirm the preliminary identification of complete but poorly preserved olenid trilobites, adding the occurrence of several cranidia of the idahoiid Maladioidella cf. colcheni Shergold, Liñán and Palacios, 1983. This constitutes a probable further record of a species defined from the lower member of the Najerilla Formation of the Sierra de la Demanda, which was considered part of a trilobite assemblage of possible early Franconian age as suggested by Shergold et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,trilobite biozone of eastern Newfoundland (basal Cambrian Stage 10 of the Furongian series: see Rushton et al., 2011). In adition to the palynoflora, macrofossils from the El Fabar beds include some obolid brachiopods, phyllocarid crustaceans and rare olenid trilobites resembling Parabolina from the Furongian stages 9 and 10. The record of late Cambrian trilobites from ‘El Fabar Beds’ was briefly mentioned by Gutiérrez-Marco and Bernárdez (2003) and Albani et al. (2006), but the material was never studied in detail. For the present work, we have examined all the specimens collected during the excavation of the “Túnel Ordovícico del Fabar” in the A-8 highway 7 km west of Ribadesella (Asturias). Our results confirm the preliminary identification of complete but poorly preserved olenid trilobites, adding the occurrence of several cranidia of the idahoiid Maladioidella cf. colcheni Shergold, Liñán and Palacios, 1983. This constitutes a probable further record of a species defined from the lower member of the Najerilla Formation of the Sierra de la Demanda, which was considered part of a trilobite assemblage of possible early Franconian age as suggested by Shergold et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,et al., 2011). In adition to the palynoflora, macrofossils from the El Fabar beds include some obolid brachiopods, phyllocarid crustaceans and rare olenid trilobites resembling Parabolina from the Furongian stages 9 and 10. The record of late Cambrian trilobites from ‘El Fabar Beds’ was briefly mentioned by Gutiérrez-Marco and Bernárdez (2003) and Albani et al. (2006), but the material was never studied in detail. For the present work, we have examined all the specimens collected during the excavation of the “Túnel Ordovícico del Fabar” in the A-8 highway 7 km west of Ribadesella (Asturias). Our results confirm the preliminary identification of complete but poorly preserved olenid trilobites, adding the occurrence of several cranidia of the idahoiid Maladioidella cf. colcheni Shergold, Liñán and Palacios, 1983. This constitutes a probable further record of a species defined from the lower member of the Najerilla Formation of the Sierra de la Demanda, which was considered part of a trilobite assemblage of possible early Franconian age as suggested by Shergold et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,Parabolina from the Furongian stages 9 and 10. The record of late Cambrian trilobites from ‘El Fabar Beds’ was briefly mentioned by Gutiérrez-Marco and Bernárdez (2003) and Albani et al. (2006), but the material was never studied in detail. For the present work, we have examined all the specimens collected during the excavation of the “Túnel Ordovícico del Fabar” in the A-8 highway 7 km west of Ribadesella (Asturias). Our results confirm the preliminary identification of complete but poorly preserved olenid trilobites, adding the occurrence of several cranidia of the idahoiid Maladioidella cf. colcheni Shergold, Liñán and Palacios, 1983. This constitutes a probable further record of a species defined from the lower member of the Najerilla Formation of the Sierra de la Demanda, which was considered part of a trilobite assemblage of possible early Franconian age as suggested by Shergold et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,et al. (2006), but the material was never studied in detail. For the present work, we have examined all the specimens collected during the excavation of the “Túnel Ordovícico del Fabar” in the A-8 highway 7 km west of Ribadesella (Asturias). Our results confirm the preliminary identification of complete but poorly preserved olenid trilobites, adding the occurrence of several cranidia of the idahoiid Maladioidella cf. colcheni Shergold, Liñán and Palacios, 1983. This constitutes a probable further record of a species defined from the lower member of the Najerilla Formation of the Sierra de la Demanda, which was considered part of a trilobite assemblage of possible early Franconian age as suggested by Shergold et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,Maladioidella cf. colcheni Shergold, Liñán and Palacios, 1983. This constitutes a probable further record of a species defined from the lower member of the Najerilla Formation of the Sierra de la Demanda, which was considered part of a trilobite assemblage of possible early Franconian age as suggested by Shergold et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,et al. (1983) or, alternatively, correlated with the Iverian or Sunwaptan regional stages (Alvaro et al., 2007). The widespread genus Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus,Maladioidella has numerous local synonyms and ‘sister taxa’ (Kuruktagella, Iranella, Cedarellus, Saratogia p.p., Elrathiella p.p., Lakella p.p., among others), and in Wales it ranges from the Parabolina spinulosa to thep.p., Elrathiella p.p., Lakella p.p., among others), and in Wales it ranges from the Parabolina spinulosa to the Peltura scarabaeoides trilobite zones (late Cambrian stages 9 and 10). Elsewhere it has been recorded from Furongian siliciclastic and carbonate rocks extending from northern Australia through South Korea and northern China into Siberia, Iran, Turkey and Europe (Wales, France, Spain and Sardinia): see Shergold et al. (1983), Shergold and Sdzuy (1984), Rushton and Hughes (1996), and Alvaro et al. (2003). From a palaeobiogeographical point of view, the record in the Cantabrian Zone of the undetermined Parabolinalike olenid plus Maladioidella cf. colcheni is interesting because the second form belongs to a special group of trilobites that in the late Cambrian migrate into temperate, peri-Gondwanan platforms in intermediate paleolatitudinal settings. Also, according to Alvaro et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).trilobite zones (late Cambrian stages 9 and 10). Elsewhere it has been recorded from Furongian siliciclastic and carbonate rocks extending from northern Australia through South Korea and northern China into Siberia, Iran, Turkey and Europe (Wales, France, Spain and Sardinia): see Shergold et al. (1983), Shergold and Sdzuy (1984), Rushton and Hughes (1996), and Alvaro et al. (2003). From a palaeobiogeographical point of view, the record in the Cantabrian Zone of the undetermined Parabolinalike olenid plus Maladioidella cf. colcheni is interesting because the second form belongs to a special group of trilobites that in the late Cambrian migrate into temperate, peri-Gondwanan platforms in intermediate paleolatitudinal settings. Also, according to Alvaro et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).et al. (1983), Shergold and Sdzuy (1984), Rushton and Hughes (1996), and Alvaro et al. (2003). From a palaeobiogeographical point of view, the record in the Cantabrian Zone of the undetermined Parabolinalike olenid plus Maladioidella cf. colcheni is interesting because the second form belongs to a special group of trilobites that in the late Cambrian migrate into temperate, peri-Gondwanan platforms in intermediate paleolatitudinal settings. Also, according to Alvaro et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).et al. (2003). From a palaeobiogeographical point of view, the record in the Cantabrian Zone of the undetermined Parabolinalike olenid plus Maladioidella cf. colcheni is interesting because the second form belongs to a special group of trilobites that in the late Cambrian migrate into temperate, peri-Gondwanan platforms in intermediate paleolatitudinal settings. Also, according to Alvaro et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).Parabolinalike olenid plus Maladioidella cf. colcheni is interesting because the second form belongs to a special group of trilobites that in the late Cambrian migrate into temperate, peri-Gondwanan platforms in intermediate paleolatitudinal settings. Also, according to Alvaro et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).Maladioidella cf. colcheni is interesting because the second form belongs to a special group of trilobites that in the late Cambrian migrate into temperate, peri-Gondwanan platforms in intermediate paleolatitudinal settings. Also, according to Alvaro et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).et al. (2007) this group includes Australasian invaders not only restricted to peri-Gondwanan margins, but co-occurring with cosmopolitan genera like Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).Maladioidella, Prochuangia, Onchonotellus, Olentella and others. This is a contribution to Project CGL2009-07073 from the Spanish Ministry of Economy and Competitiveness (MINECO).