The Cambrian genus Onaraspis Öpik, 1968 (Trilobita), in Spain

MARÍA EUGENIA DIES ÁLVAREZ, ELADIO LIÑÁN & RODOLFO GOZALO

THE GENUS Onaraspis was originally described by Öpik (1968) from the Ordian Stage of Australia. Sdzuy (1971) noted the presence of a genus similar to Onaraspis in the Bilbilian Stage (late Early Cambrian) of Spain. Jell (1974) reported Onaraspis from the early Middle Cambrian of Israel.

Several species, assigned to different genera but similar to Onaraspis, were defined in the same period: ?Jakutus kielcensis Bednarcyzk, 1970 from Poland, Myopsolenus palmeri Parnes, 1971 from Israel, and Perrector? altus Liñán & Gozalo, 1986 from Spain. They have very similar morphological features to Onaraspis, both in the cranidium and the pygidium.

Jell (in Bentgson et al. 1990) described Onaraspis rubra from the Lower Cambrian of South Australia; this species is older than those described by Öpik (see Bentgson et al. 1990, p. 15).

Gozalo & Liñán (1997a, b) revised the Spanish material of Perrector? altus, and reassigned the species to Onaraspis; they also proposed to include Myopsolenus palmeri within Onaraspis. Subsequently, Rushton & Powell (1998), in their description of a trilobite fauna from the Lower Cambrian of Jordan, figured Jordanian material of Myopsolenus palmeri and concluded that the species belonged to Onaraspis.

Recently, Geyer & Landing (2004) postulated a clade composed of the genera Onaraspis and Myopsolenites. They assigned only species from Australia to Onaraspis, and transferred the morphologically comparable species from Israel, Jordan, Spain, Morocco and Poland to Myopsolenites. They therefore disagreed with the use of Onaraspis to accommodate Perrector? altus, as suggested by Gozalo & Liñán (1997a, b), and also Myopsolenus palmeri, following Gozalo & Liñán (1997a, b) and Rushton & Powell (1998). We believe the differences between species assigned to Onaraspis and Myopsolenites are insufficient to permit the recognition of two genera; we thus consider Myopsolenites to be a junior subjective synonym of Onaraspis.

GEOLOGICAL AND STRATIGRAPHIC SETTINGThe material studied herein has been found in Murero (Zaragoza province; Iberian Chains) and Valdoré (León province; Cantabrian Mountains) in northern Spain (Fig. 1).

In the Iberian Chains, Onaraspis altus (Liñán & Gozalo, 1986) occurs in the Rambla de Valdemiedes 1 and 2 sections (see Liñán & Gozalo 1986; Liñán et al. 1993a; Dies et al. 2004). The material is recorded in the upper part of the Valdemiedes Formation (Liñán et al.

DIES ÁLVAREZ, M.E., LIÑÁN, E. & GOZALO, R., 2007:12:21. The Cambrian genus Onaraspis Öpik, 1968 (Trilobita), in Spain. Memoirs of the Association of Australasian Palaeontologists 34, 419-429. ISSN 0810-8889.

Spanish material of the Cambrian trilobite genus Onaraspis is revised. Onaraspis altus from the Cadenas Ibéricas is redescribed, and O. aff. kielcensis is documented for the first time from the Cantabrian Mountains. The genus Myopsolenites Geyer & Landing, 2004 is considered as a junior subjective synonym of Onaraspis. Onaraspis is considered to be a useful genus for the correlation of traditional Lower–Middle Cambrian successions in Australia, the Mediterranean region and Poland.

M.E. Dies Álvarez (medies@unizar.es, M.dies-alvarez@nhm.ac.uk) Palaeontology Department, Natural History Museum. Cromwell Road SW7 5BD, UK and Área y Museo de Paleontología, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, E–50009 Zaragoza, Spain; E. Liñán, Área y Museo de Paleontología, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, E–50009 Zaragoza, Spain; R. Gozalo (rodolfo.gozalo@uv.es), Departamento de Geología, Universitat de València. Calle Dr. Moliner 50. E–46100 Burjasot, Spain. Received 24 October 2007.

Keywords: Lower–Middle Cambrian, Trilobita, Iberian Chains, Cantabrian Mountains, Spain, systematic, correlation.

AAP Memoir 34 (2007)420

1992), and the trilobite assemblage in these levels is composed of Protolenus jilocanus (Liñán & Gozalo, 1986), P. pisidianus Dean in Dean & Özgul, 1994, Hamatolenus (H.) ibericus Sdzuy, 1958, Sdzuyia sanmamesi Liñán & Gozalo, 1999, and Tonkinella sequei Liñán & Gozalo, 1999; this assemblage belongs to the Protolenus jilocanus Zone, formerly the Hamatolenus (H.) ibericus Zone (upper Bilbilian age).

In the Cantabrian Mountains, Onaraspis aff. kielcensis (Bednardcyzk, 1970) is preserved in reworked rounded clasts of limestone within the base of the upper member of the Láncara Formation. The Valdoré section has been studied by Zamarreño (1972) and Álvaro et al. (2000). The base of the upper member of the Láncara Formation is erosive (Álvaro et al. 2000) and the lowest strata (50 cm) are composed of pink packstones with rounded clasts of limestone at the base. Liñán et al. (2003) found the trilobite species Kingaspis campbelli (King, 1923) in the rounded clasts; Geyer & Landing (2004) questioned their identification, but Gozalo et al. (2007, p. 364-365) rebutted that query. In the latter paper they recorded a cranidium of Onaraspis sp. in the same rounded clasts, and here it is identified as O. aff. kielcensis. The trilobites in these rounded clasts are indicative of an upper Bilbilian age, but specimens of Acadoparadoxides

mureroensis (Sdzuy, 1958) have been found at this level, marking the first zone of the Leonian stage (early Middle Cambrian).

Onaraspis altus and O. aff. kielcensis have been found in the upper Bilbilian stage, which is considered the last stage in the lower Cambrian of Spain (see Liñán et al. 1993a, b, 2002; Sdzuy et al. 1999; Gozalo et al. 2007).

SYSTEMATIC PALAEONTOLOGYThe material studied herein is housed in the Museo Paleontológico de la Universidad de Zaragoza-Gobierno de Aragón at Zaragoza (Spain) under references MPZ 838-839, MPZ 841-848, MPZ 99/510-562, MPZ 99/582-597, MPZ 99/599 and MPZ 2005/297.

The abbrevia t ions employed in the measurements (in mm) (Appendix 1 and Fig. 4) are: Cw = Cranidial width, Cl = Cranidial length (sag.), Gw = Glabellar width (at occipital furrow), Gl = Glabellar length (sag.), Pw = Pygidial width (at anterior margin), Pl = Pygidial length (sag.), Rw = Pygidial axial width (at anterior margin), and Rl = Pygidial axial length (sag.).

Order REDLICHIIDA Richter, 1932Suborder REDLICHIINA Richter, 1932Family SAUKIANDIDAE Hupé, 1953Subfamily RESSEROPINAE Chang, 1966

Remarks. Öpik (1968) included Onaraspis in the family Metadoxididae based on the cranidial morphology. This proposal was followed by Jell (in Bentgson et al. 1990), by Chang et al. (1997) with some uncertainty, and by Rushton & Powell (1998). Geyer & Landing (2004) considered the Onaraspis clade as being of uncertain familial assignment, but in discussing the morphology of the group, considered the pygidial morphology to be closer to the Resserops clade.

The thoracic morphology, the position of the macropleural segment and the pygidial morphology are similar to the genera Perrector Richter & Richter, 1940 and Richterops Hupé, 1953, which are representative of the subfamily Resseropinae. We consider that the morphology of the cranidium, the position of the genal spines near the middle of the lateral cephalic margin, the thorax of 12 to 14 segments with a posteriorly located macropleural segment, and a relatively large subcircular pygidium permits placement

Fig. 1. Geographical situation of the studied sections.

Fig. 2. A, Onaraspis somniurna Öpik, 1968, holotype, plaster cast. B, Onaraspis adusta Öpik, 1968, holotype, plaster cast. C-G, Onaraspis altus (Liñán & Gozalo, 1986), all the specimens occur in shales, RV1 section, Iberian Chains. C, latex cast of two complete exoskeletons and a cephalon, MPZ 99/515 (left) and MPZ 99/586 (right). D, holotype, internal mould of a complete specimen, MPZ 840. E, internal mould of an incomplete specimen, MPZ 99/589. F, internal mould of a complete specimen, MPZ 99/594. G, internal mould of a complete specimen, MPZ 99/590. All scale bars 2 mm.

AAP Memoir 34 (2007) 421

AAP Memoir 34 (2007)422

AAP Memoir 34 (2007) 423

of Onaraspis in the subfamily Resseropinae in accordance with the diagnosis of this subfamily by Chang et al. (1997).

Onaraspis Öpik, 1968

Type species. Onaraspis somniurna Öpik, 1968.

Original diagnosis. “Onaraspis gen. nov. refers to species of Metadoxididae distinguished by a relatively small number of segments in the thorax (twelve in the type species), well developed pygidium with concave flange, and only slightly tapering glabella; in the type species the tenth segment is macropleural” (Öpik 1968, p. 151).

Emended diagnosis. A genus of the Resseropinae characterised by trapezoidal cranidium with anterior dorsal outline slightly concave to slightly convex; slightly tapering glabella with transglabellar S1 and no transglabellar S2 and S3; anterior border narrow and preglabellar field lacking; narrow preocular field. Thorax with twelve to fourteen segments, the antepenultimate is macropleural. Pygidium well developed with a long axis with three to eight ring furrows developed.

Remarks. The original diagnosis by Öpik (1968) made reference to thorax, pygidium and glabella. In the emended diagnosis above, cranidial characters are given more weight.

Geyer & Landing (2004) considered the genus Myopsolenites, based on Myopsolenus palmeri Parnes, 1971, to be a valid genus. While they gave a diagnosis of Myopsolenites, they did not discuss the differences between it and Onaraspis. For a discussion on the availability of the name Myopsolenites see Żylińska (in Żylińska & Masiak 2007, p. 676-677).

Rushton & Powell (1998) asserted that the morphological differences between the Australian species of Onaraspis and Myopsolenus palmeri from Jordan were more likely of specific significance. We agree with this assertion and believe that the relatively slight morphological differences in the cranidium, thorax and pygidium between these species are insufficient to separate

them generically. As a consequence, all of the species assigned to Myopsolenites by Geyer & Landing (2004) should be included in Onaraspis. Therefore, in addition to the type species, the following species should be included in Onaraspis: O. adusta Öpik, 1968; ?Jakutus kielcensis Bednarcyk, 1970; Myopsolenus palmeri Parnes, 1971; Perrector? altus Liñán & Gozalo, 1986; O. rubra Jell, 1990; and Myopsolenites boutiouiti Geyer & Landing, 2004.

Onaraspis altus (Liñán & Gozalo, 1986) (Figs 2C-G, 3A-B, D, F-K)

v 1986 Perrector? altus n. sp.; Liñán & Gozalo, p. 44-45, pl. 3, figs 1-6, pl. 4, figs 1-2.

v 1986 Neoredlichiidae? sp. indet.; Liñán & Gozalo, p. 45, pl. 4, figs 3, 5-6.

v 2004 Onaraspis altus (Liñán & Gozalo, 1986); Dies Álvarez, p. 32-35, pl. 2, figs 3-7, pl. 3, pl. 4, figs 1-4.

v 2007 Onaraspis altus (Liñán & Gozalo, 1986); Gozalo et al., fig. 5c.

Material. Thirty complete specimens, eleven cranidia, ten cephalothoraces, eight pygidia, six thoracopyga, four incomplete thoraces, three hypostomes, several librigenae and two axial rings. All specimens have suffered tectonic deformation to some degree. They are preserved as internal and external moulds in green, yellow and pink lutites and yellow, fine-grained sandstones.

Emended diagnosis. Species of Onaraspis with long palpebral lobes (more than two thirds of the glabellar length) and genal spines beginning in an advanced position and extending to the eighth thoracic segment. Border of the pygidium marked.

Description. Cranidium subrectangular; with straight or slightly curved anterior margin; narrow, rounded (sag.) anterior border, slightly narrower axially. Fine terrace ridges parallel or almost parallel to the anterior margin in larger specimens. Deep anterior border furrow. Preglabellar field absent. Glabella subcylindrical

Fig. 3. A-B, D, F-K, Onaraspis altus (Liñán & Gozalo, 1986), Iberian Chains. A, internal mould of a complete specimen, 99/588, RV1 section. B, internal mould of hypostome, MPZ 847, RV1 section. D, internal mould of axial ring, 99/582, RV1 section. F, internal mould of an incomplete cephalon with several partially articulated thoracic segments, 99/593, RV1 section. G, internal mould of hypostome, MPZ 99/591, RV1 section. H, internal mould of hypostome, MPZ 99/592, RV1 section. I, internal mould of pygidium, MPZ 99/585, RV1 section. J, internal mould of pygidium, MPZ 99/583, RV1 section. K, internal mould of pygidium, MPZ 848, RV2 section. C, E, Onaraspis aff. kielcensis (Bednarczyk, 1970), Valdoré 1 section, Cantabrian Mountains. C, partially exfoliated testate cranidium, MPZ 2005/297 . E, detail of C showing the ornamentation. All scale bars 2 mm, except F, scale bar is 5 mm.

AAP Memoir 34 (2007)424

The posterior border of the hypostome is narrower and less convex than the lateral borders. The maculae are crescent shaped and are located in the posterior part of the hypostome.

Thorax composed of thirteen segments. Axis narrows posteriorly, while the pleurae are of equal width up to the tenth thoracic segment. Axial rings are convex (sag., tr.) and each possesses a median node. Pleurae possess a deep pleural furrow dividing each pleura into two triangular bands. Most pleurae terminate in wide, short, pleural spines. Tenth thoracic segment is macropleural with a thin, long spine extending to the pygidium.

Pygidium semicircular. Axis well defined, strongly tapering posteriorly, reaching the pygidial border; with at least five axial rings. Border flat or slightly convex. Pleural field elevated above border. Smaller specimens show a narrower border that is difficult to distinguish from the pleural field.

Measurements . Appendix 1 shows the measurements of the best preserved specimens collected. The bivariate method has been applied in the morphometric analysis of this data. Following the methods of Hughes & Jell (1992),

to slightly tapering, narrowing anteriorly. Three transglabellar furrows slightly curved backwards. Deep occipital furrow curved anteriorly. Occipital lobe wider axially. Preocular field very short, triangular in shape and slightly convex. Thin, curved palpebral lobe, almost reaching the posterior border of the cranidium. It is longer in the smaller specimens and becomes shorter, more curved and wider in larger specimens. Palpebral furrow marked. Palpebral area flat, wide and subtriangular in shape. Small postocular area. Narrow, deep posterior furrow. Posterior border narrow, rounded (sag.). Straight posterior margin. Opisthoparian suture. Very short anterior and posterior branches of the suture. “S” parameter (Liñán Guijarro 1978, p. 158, fig. 3) convergent and secant.

Narrow librigena with a very small librigenal field. Wide (tr.) and flat lateral border. Genal spine long (reaching eighth thoracic segment), narrow, with base anterior of the posterior border.

Hypostome fused with the rostral plate; boundary represented by a very fine furrow (Liñán & Gozalo 1986). This furrow is deeper in smaller specimens. The central part and lateral borders of the hypostome are strongly convex. Lateral furrows deep, more marked in larger specimens.

Cl-Gly = 0,8844x - 0,0666

R2 = 0,9985

0

5

10

15

20

25

30

0 5 10 15 20 25 30

Cl

Gl

A Cw-Gwy = 0,4618x + 0,526

R2 = 0,8519

0

4

8

12

16

0 2 4 6 8 10 12 14 16

Cw

Gw

B

Pw-Rw y = 0,4176x - 0,0034

R2 = 0,9347

0

4

8

12

16

0 5 10 15 20 25 30

Pw

Rw

DPl-Rl y = 0,7266x + 1,1744

R2 = 0,9831

0

5

10

15

20

25

30

0 5 10 15 20 25 30 35

Pl

Rl

C

Fig. 4. Bivariate scatterplots showing relationships between cranidial length and glabellar length (A), cranidial width and glabellar width (B), pygidial length and pygidial axis length (C), pygidial width and pygidial axis width (D), in Onaraspis altus.

AAP Memoir 34 (2007) 425

Labandeira & Hughes (1994), Hughes (1994) and Chirivella et al. (2003), we have used the measurements obtained in the same direction (i.e., width versus width and length versus length) in order to avoid low correlation coefficients due to tectonic distortion (Fig. 4A-D); the Pearson coefficients (R2) are high (>0.85) in all bivariate plots, and the regression lines show clearly that all specimens belong to a single species.

Remarks. Liñán & Gozalo (1986) defined Perrector? altus in the lower Cambrian of Murero. They noted that this species shows clear differences from the type species of the genus in having a straight anterior margin and a very thin anterior border at a lower level than the glabella and the fixigenae. Gozalo & Liñán (1997a, b) considered Perrector? altus (Liñán & Gozalo, 1986) to belong to the genus Onaraspis. In addition, the specimens referred to Neoredlichiidae? sp. indet. by Liñán & Gozalo (1986) are here considered to belong to Onaraspis altus.

Onaraspis altus has a longer palpebral lobe than other congeners. Its postocular field is very narrow or absent, its genal spine considerably longer and more advanced than in other species.

Stratigraphic distribution. Levels 4, 5 and 6 from the Rambla de Valdemiedes-1 section and levels 4, 5 and 6 from the Rambla de Valdemiedes-2 section. Protolenus jilocanus Zone (Upper Bilbilian).

Onaraspis aff. kielcensis (Bednarczyk, 1970) (Fig. 3C, E)

v 2007 Onaraspis sp.; Gozalo et al., fig. 4E, I.

Material. One incomplete, partially exfoliated cranidium.

Description. Cranidium ornamented with tubercles of different sizes. Anterior margin slightly concave medially. Anterior border rounded, widens abaxially, exhibiting terrace lines. Anterior furrow wide and shallow. Preglabellar field absent. Glabella slightly tapering, with three pairs of glabellar furrows. Preocular field subrectangular and depressed. Ocular ridge is wide and intercepts the glabella in front of the first glabellar furrow. Palpebral field wide, slightly narrower than glabella. Posterior furrow deep and wide.

Remarks. This specimen is similar to Onaraspis kielcensis (Bednarczyk, 1970), but differs in that the “S” parameter, which is secant and strongly

convergent in the Polish species, is outer and moderately convergent in the Spanish cranidium. They also differ in that the anterior margin in Onaraspis aff. kielcensis is slightly concave, while in Onaraspis kielcensis (see Żylińska in Żylińska & Masiak 2007, fig. 10a-d, f) it is convex.

Both this specimen and Onaraspis kielcensis have the same pattern of ornamentation (dense tuberculation on the surface of the cranidium and terrace ridges on the anterior border), similar to that illustrated in one specimen of Onaraspis somniurna (Öpik 1968, pl. 19, fig. 1).

Stratigraphic distribution. Rounded clasts of limestone in base of Level 6b from the Valdore-1 section, upper Bilbilian (see Gozalo et al. 2007).

BIOSTRATIGRAPHY AND BIOGEOGRAPHY OF ONARASPISThe genus Onaraspis has been recorded from five localities in Australia, all of them assigned to the Xystridura templetonensis–Redlichia chinensis Zone (Ordian/Early Templetonian). Onaraspis somniurna and O. sp. indet. from the Northern Territory, and O. adusta from Western Australia were described by Öpik (1968); Onaraspis sp. was reported by Shergold (1986) from the Amadeus Basin; and O. rubra Jell, 1990 was recorded from the Moodlatana Formation near Wirrealpa (South Australia) and is considered to be of early Cambrian age (pre-Redlichia chinensis Zone) (see Bengtson et al. 1990, p. 15). Jago (in Brock et al. 2000) and Jago et al. (2006) considered the level with Onaraspis rubra as equivalent to the latest Toyonian (lower Cambrian).

Onaraspis kielcensis (Bednarczyk, 1970) was found near Brzechów village, in the western part of the Svietokryskie Mountains, Poland, in the lower Paradoxides oelandicus layers (Middle Cambrian). Orłowski (1985, fig. 1) located this species in the lower part of the Paradoxides insularis Zone in the Holy Cross Mountains.

Onaraspis palmeri (Parnes, 1971) occurs in the Timna and Burj Formations in Israel and Jordan (Parnes 1971; Rushton & Powell 1998). Rushton & Powell (1998) suggested a correlation with the Bilbilian stage for this material; Liñán et al. (2003) and Gozalo et al. (2007) subsequently refined this assignment to the upper Bilbilian.

The two species found in Spain and described above also belong to the upper Bilbilian.

Onaraspis boutiouiti (Geyer & Landing, 2004) is recorded from the base of the Jbel Wawrmast Formation, Brèche à Micmacca Member, in the Cephalopyge notabilis Zone (Middle Cambrian).

AAP Memoir 34 (2007)426

Figure 5 shows a correlation chart of the levels with Onaraspis based on Gozalo et al. (2007), and uses the zonation proposed for the Holy Cross Mountains by Orłowski (1985, 1992) and Żylińska & Masiak (2007).

The tentative correlation proposed by Geyer & Landing (2004, fig. 3) is in error. They located the level with Onaraspis altus (M in the Iberia Column) at the base of Acadoparadoxides mureroensis Zone (Middle Cambrian), but O. altus is recorded from the last zone of the Bilbilian in the Protolenus jilocanus Zone, formerly the Hamatolenus (H.) ibericus Zone (see Liñán & Gozalo 1986; Liñán et al. 1993a; Dies et al. 2004). Similarly, in the Israel/Jordan column, Geyer & Landing (2004, fig. 3) marked the occurrence of Schistocephalus (in reference to Palaeolenus antiquus) and Kingaspis campbelli at different stratigraphic positions. They also referred to Schistocephalus juvenis as a zonal species, but this taxon has not been reported from Israel and Jordan. Rushton & Powell (1998, p. 136, fig. 6) described Palaeolenus antiquus together with Kingaspis campbelli in the same stratigraphic

level of the Wadi Zarqa Ma’in section. Finally, we agree with Rushton & Powell

(1998), Liñán et al. (2003) and Gozalo et al. (2007) in considering the levels with Onaraspis spp. and/or Kingaspis campbelli in the Middle East and Spain as late Early Cambrian in the traditional sense. Those levels may be correlated with the Onaraspis spp. from Australia. On the other hand, Onaraspis spp. from Poland and Morocco belong to the base of the traditional Middle Cambrian in that they are associated with paradoxidids. Thus, Onaraspis is a useful biostratigraphic tool for correlation between Australia, peri-Gondwana areas and Baltica during the lower–middle Cambrian interval.

ACKNOWLEDGEMENTSThe authors acknowledge the helpful suggestions made by Drs. J. Laurie, G. Geyer and A.W.A. Rushton for the improvement of the manuscript.

Financial support has been received from the Spanish Dirección General de Investigación and FEDER, Project CGL2006-12975/BTE, and Museo Paleontológico Group (E-17, Gobierno de

Fig. 5. Tentative correlation chart among the sequences containing Onaraspis (*) based on Rushton & Powell (1998), Liñán et al. (2003) and Gozalo et al. (2007). Stratigraphic units for Poland adopted from Orłowsky (1985, 1992) and Żylińska & Masiak (2007). Abbreviations: O. i. FAD, first appearance datum of Oryctocephalus indicus; O. g. FAD, first appearance datum of Ovatoryctocara granulata.

AAP Memoir 34 (2007) 427

Aragón). María Eugenia Dies Álvarez gratefully acknowledges a postdoctoral fellowship (ref. EX2005-1019) from the Spanish Ministry of Education.

We also pay tribute to the late John Shergold for his important palaeontological contributions and his friendship.

REFERENCES Álvaro, J.J., vennin, e., Moreno-eiris, e., PereJón, a.

& Bechstädt, t., 2000. Sedimentary patterns across the Lower-Middle Cambrian transition in the Esla nappe. (Cantabrian Mountains, northern Spain). Sedimentary Geology 137, 43-61.

Bednarczyk, W., 1970. Trilobites Fauna of the Lower Paradoxides oelandicus Stage from the Brzechów Area in the Western Part of the Świętokrzyskie Mts. Bulletin de l’Académie Polonaise des Sciences, Série des sciences géologique et géographiques, 18, 29-35.

Bengtson, s., conWay Morris, s., cooPer, B.J., Jell, P. a. & runnegar, B.n., 1990. Early Cambrian fossils from South Australia. Memoirs of the Association of Australasian Palaeontologists 9, 1-364.

Brock, g.a., engelBretsen, M.J., Jago, J.B., kruse, P.d., laurie, J.r., shergold, J.h., shi, g.r. & sorauf, J.e., 2000. Palaeobiogeographic affinities of Australian Cambrian faunas. Memoirs of the Association of Australasian Palaeontologists 23, 1-61.

chang, W.t., 1966. The classification of Redlichiacea with description of new families and new genera. Acta Palaeontologica Sinica 14, 135-184.

chang, W.t., rePina, l.n. & geyer, g., 1997. Introduction to the Suborder Redlichiina. 429-470 in Kaesler, R. (ed.), Treatise on invertebrate paleontology Part O, Arthropoda 1, Trilobita 1 (Revised). Geological Society of America, Boulder and University of Kansas Press, Lawrence.

chirivella Martorell, J.B., gozalo, r. & liñÁn, e., 2003. Estudio taxonómico y biometrico de Badulesia tenera (Hartt in Dawson, 1868), Trilobita. Caesaraugustiense (Cámbrico Medio) de las Cadenas Ibéricas (NE de España). Revista Española de Paleontología 18, 83-101.

dean, W.t. & Özgul, n., 1994. Cambrian rocks and faunas, Hüdai area, Taurus Mountains, southwestern Turkey. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre 64, 5-20.

dies, M.e., gozalo, r. & liñÁn, e., 2004. Zonación del límite Bilbiliense-Leoniense (Formación Valdemiedes, Cámbrico Inferior-Medio) en las Cadenas Ibéricas. Geo-Temas 6(2), 283-286.

dies Álvarez, M.e., 2004. Bioestratigrafía y Paleoecología de la Formación Valdemiedes (límite Cámbrico Inferior-Medio) en las Cadenas Ibéricas. Unpublished Ph.D. thesis, Universidad de

Zaragoza, 147 p.geyer, g. & landing, e., 2004. A unified Lower-Middle

Cambrian chronostratigraphy for West Gondwana. Acta Geologica Polonica 54, 179-218.

gozalo, r. & liñÁn, e., 1997a. Revision of the genus Onaraspis Öpik 1968 and its biostratigraphic and biogeographic significance. 24-25 in Second International Trilobite Conference, Brock University, St. Catharine’s, Ontario, August 22-25, Abstracts with Program.

gozalo, r. & liñÁn, e., 1997b. Revision del género Onaraspis Öpik 1968 (Trilobita) y sus implicaciones biostratigráficas y paleobiogeográficas para el Bilbiliense (Cámbrico Inferior). 75-76 in XII Jornadas de Paleontología. V Reunión Internacional Proyecto 351 PICG. A Coruña 16-18 de Octubre, 1997. Libro de Resúmenes y excursiones.

gozalo, r., liñÁn, e., dies, M.e., gÁMez vintaned, J.a & Mayoral, e., 2007. The Lower-Middle Cambrian boundary in the Mediterranean subprovince. Geological Society of America Special Paper 423, 359-373.

hughes, n.c., 1994. Ontogeny, intraspecific variation, and systematics of the Late Cambrian trilobite Dikelocephalus. Smithsonian Contributions to Paleobiology 79, 89 p.

hughes, n.c. & Jell, P.a., 1992. A statistical/computer-graphic technique for assessing variation in tectonically deformed fossils and its application to the Cambrian trilobites from Kashmir. Lethaia 25, 317-330.

huPé, P., 1953. Contributions à l’étude du Cambrien inférieur et du Précambrien III de L’Anti-Atlas marocain. Notes et Memoirers du Service Gélogique du Maroc 103, 1-402.

Jago, J.B., zang W.-l., sun, X., Brock, g.a., Paterson, J.r. & skovsted, c.B., 2006. A review of the Cambrian biostratigraphy of South Australia. Palaeoworld 15, 406-423.

Jell, P.a., 1974. Faunal provinces and possible planetary reconstruction of the Middle Cambrian. Journal of Geology 82, 319-350.

king, W.B.r., 1923. Cambrian fossils from the Dead Sea. Geological Magazine 60, 507-514.

laBandeira, c.c. & hughes, n.c., 1994. Biometry of the Late Cambrian trilobite genus Dikelocephalus and its implications for trilobite systematics. Journal of Paleontology 68, 492-517.

liñÁn, e., dies, M. e. & gozalo, r., 2003. A review of the genus Kingaspis (Trilobita, Lower Cambrian) from Spain and its biostratigraphical consequences for correlation in the mediterranean subprovince. Revista Española de Paleontología 18, 2–14.

liñÁn, e., fernÁndez-nieto, c., gÁMez, J.a., gozalo, r., Mayoral, e., Moreno-eiris, e., Palacios, t. & PereJón, a., 1993a. Problemática del límite Cámbrico Inferior-Medio en Murero (Cadenas Ibéricas, España). Revista Española de

AAP Memoir 34 (2007)428

Paleontología no. extraordinario, 26–39.liñÁn, e. & gozalo, r., 1986. Los trilobites del

Cámbrico Inferior y Medio de Murero (Cordillera Ibérica). Memorias del Museo Paleontológico de la Universidad de Zaragoza 2, 1-104.

liñÁn, e. & gozalo, r., 1999. Nuevos trilobites del Cámbrico Inferior de Aragón. 255-261 in Gámez Vintaned, J.A. & Liñán, E. (eds), 25 años de Paleontología Aragonesa, Homenaje al Prof. Leandro Sequeiros. Institución “Fernando el Católico”, Zaragoza.

liñÁn, e., gozalo, r., gÁMez, J. a. & Álvaro, J., 1992. Las Formaciones del Grupo Mesones (Cámbrico Inferior-Medio) en las Cadenas Ibéricas. III Congreso Geológico de España y VIII Congreso Latinoamericano de Geología, Salamanca, Actas 1, 517-523.

liñÁn, e., gozalo, r., Palacios, t., gÁMez vintaned, J. a., ugidos, J.M. & Mayoral, e., 2002. Cambrian. 17–29 in Gibbons, W. & Moreno, T. (eds.), The Geology of Spain. The Geological Society, London.

liñÁn, e., PereJón, a. & sdzuy, k., 1993b. The Lower-Middle Cambrian stages and stratotypes from the Iberian Peninsula: a revision. Geological Magazine 130, 817-833.

liñÁn guiJarro, e., 1978. Biostratigrafía de la Sierra de Córdoba. Tesis doctorales de la Universidad de Granada 191, 212 p.

ÖPik, A.A., 1968. The Ordian Stage of the Cambrian and its Australian Metadoxididae. Bureau of Mineral Resources, Geology and Geophysics, Bulletin 92, 133-169.

OrłOwski, S., 1985. New data on the Middle Cambrian trilobites and stratigraphy in the Holy Cross Mts. Acta Geologica Polonica 35, 251-263.

OrłOwski, S., 1992. Cambrian stratigraphy and stage subdivision in the Holy Cross Mountains, Poland. Geological Magazine 129, 471-474.

Parnes, A., 1971. Late Lower Cambrian trilobites from the Timna area and Haar’Amran (Southern

Negev, Israel). Israel Journal of Earth Sciences 20, 179-205.

richter, R., 1932. Crustacea (Paläontologie). 840-864 in Dittler, R., Joos, G., Korschelt, E., Linek, G., Oltmanns, F. & Schaum, K. (eds), Handwörterbuch der Naturwissenschaften, 2nd edition. Gustav Fisher, Jena.

richter, r. & richter, e., 1940. Die Saukianda-Stufe von Andalusien, eine fremde Fauna in europäischen Ober-Kambrium. Abhandlungen der senckenbergische naturforschenden Gessellschaft 450, 1-88.

rushton, a.W.a. & PoWell, J.h., 1998. A review of the stratigraphy and trilobite faunas from the Cambrian Burj Formation in Jordan. Bulletin of The Natural History Museum (Geology Series) 54, 131–146.

sd z u y , K., 1958. Neue Trilobiten aus dem Mittelkambrium von Spanien. Seckenbergiana lethaea 39, 235-253.

sdzuy, k., 1971. Acerca de la correlación del Cámbrico inferior de la Península Ibérica. I Congreso Hispano-Luso-Americano de Geología Económica, Sección 1 Geología 2, 753–768.

sdzuy, k., liñÁn, e. & gozalo, r., 1999. The Leonian Stage (early Middle Cambrian): a unit for Cambrian correlation in the Mediterranean subprovince. Geological Magazine 136, 39–48.

shergold, J.h., 1986. Review of the Cambrian and Ordovician palaeontology of the Amadeus Basin, central Australia. Bureau of Mineral Resources, Geology and Geophysics, Report 276, 1–21.

zaMarreño, I., 1972. Las litofacies carbonatadas del Cámbrico de la Zona Cantábrica (NW de España) y su distribución paleogeográfica. Trabajos de Geología, Universidad de Oviedo 5, 1–118.

Żylińska, a. & Masiak, M., 2007. Cambrian trilobites from Brzechów, Holy Cross Mountains (Poland) and their significance in stratigraphic correlation and biogeographic reconstructions. Geological Magazine 164, 661-686.

AAP Memoir 34 (2007) 429

99/536 10 6.5 6.5 5.7 7.5 3.5 4.5 4

MPZ Cw Gw Cl Gl Pw Rw Pl Rl MPZ Cw Gw Cl Gl Pw Rw Pl Rl

840 (Holo.) 15 8 9.1 8 8.5 4 7.5 7 99/538 3.5 8.5 799/586 5.5 4.5 4 6.2 3 3.1 3 99/546 3.8 9.8 8.7 1.2 8 7.899/515 11 5.5 3.5 99/553 5 6 5.5 5 1.599/512 9 4.7 7.5 6.5 5 2.5 4.8 4 99/554 9 10.5 9.399/587 10 5 99/558 12 11.5 10.599/510 7.5 3.5 6.8 99/561 6.5 5.7 599/588 3 3.2 1.6 5.5 5 99/562 20 17.399/590 13 6.5 5.5 4.7 7 3.3 4 3 99/594 5.5 3.2 7 699/593 23 28 25 99/595 6 8.5 7.599/583 6.5 3.4 6.2 5.5 99/599 6.5 6.5 5.5

843 8 8 7 99/583 17 6.3 7.3 7844 13 5.3 99/584 9 16.5 14846 25 23 20 848 22 7.5 9 8

99/516a 3 7.2 6.5 99/585 14 32 2399/516b 12 5.7 841a 5.5 2.5 7 6.599/517 3.5 841b 5 1.7 7 6.699/521 5.2 2.9 6.5 5.6 99/542 6 2.5 8.2 799/522 6 2.3 3.5 3 99/543 24.5 12 20 1799/524 5.5 5.2 4.3 99/547 4 1.8 6.599/530 6 8.3 7.5 99/550 6 2.3 6 599/531 3.8 3.7 3.2 4.3 1.2 99/552 15.5 6.5 6.8 6.5

APPENDIXMeasurements of specimens housed in the Museo Paleontológico de la Universidad de Zaragoza-Gobierno de Aragón at Zaragoza (MPZ). The abbreviations employed in the measurements (in mm) are: Cw = Cranidial width, Cl = Cranidial length (sag.), Gw = Glabellar width (at occipital furrow), Gl = Glabellar length (sag.), Pw = Pygidial width (at anterior margin), Pl = Pygidial length (sag.), Rw = Pygidial axial width (at anterior margin), and Rl = Pygidial axial length (sag.).