First skeletal microfauna from the Cambrian Series 3 of the Jordan Rift Valley (Middle East)

OLAF ELICKI

CAMBRIAN successions are spectacularly exposed in the Jordan Rift Valley. Outcrops along the eastern (Jordanian) shoreline of the Dead Sea and a little south in the northern Wadi Araba yield fossiliferous deposits of shallow and marginal marine origin (Burj Formation). In the south-western Wadi Araba (Israel) equivalent Cambrian sediments also occur locally (Timna Formation). Cambrian trilobites have been known from the region for about a century (Dienemann 1915; King 1923; Richter & Richter 1941). More recent work on trilobites and substantial investigation on other fossil groups including brachiopods, hyoliths and trace fossils have been completed (Parnes 1971; Cooper 1976; Bandel 1986; Seilacher 1990a, b; Rushton & Powell 1998). A summary of the history of palaeontological, petrographical, palaeogeographical and facies investigations in this region is provided by Elicki (2007a) and Shinaq & Elicki (2007).

Much of the previous palaeontological work concentrated on the stratigraphic position and correlation of the Dead Sea Cambrian succession. As such, there was often focus on macrofossils. Micropalaeontological sampling has been lagging behind in this region. This paper documents the first skeletal microfauna of Cambrian age from this region.

In the course of several joint research projects between the Freiberg working group and colleagues from Yarmouk University (Irbid) and the Natural Resources Authority (Amman) has resulted in bulk collections of carbonate, siliciclastic and mixed lithological successions along measured stratigraphic sections from Jordanian Cambrian surface outcrops. These have undergone palaeontological and sedimentological analyses (Elicki & Shinaq 2000; Elicki et al. 2002; Elicki 2007a; Shinaq & Elicki 2007; Geyer & Elicki submitted; Hofmann et al. submitted).

ELICKI, O., 2011:12:23. First skeletal microfauna from the Cambrian Series 3 of the Jordan Rift Valley (Middle East). Memoirs of the Association of Australasian Palaeontologists 42, 153-173. ISSN 0810-8889.

For the first time, a Cambrian microfauna is reported from the Jordan Rift Valley. The fauna comes from low-latitude carbonates of the Numayri Member (Burj Formation, Jordan) and to a lesser degree the equivalent Nimra Member (Timna Formation, Israel). Co-occuring with trilobite, brachiopod and hyolith macrofossils, the microfauna is represented mostly by disarticulated poriferid (mostly hexactinellids) and echinoderm remains (eocrinoids and edrioasteroids). Among the hexactinellids, Rigbyella sp., many isolated triactins and tetractins, as well as a few pentactins and rare hexactins occur. Additional poriferid spicules come from heteractinids (Eiffelia araniformis [Missarzhevsky, 1981]) and polyactinellids (?Praephobetractinia). Chancelloriids (Archiasterella cf. hirundo Bengtson, 1990, Allonnia sp., Chancelloria sp., ?Ginospina sp.) are a rather rare faunal element. Micromolluscs are represented mainly by an indeterminable helcionellid. The probable octocoral spicule Microcoryne cephalata (Bengtson, 1990), torellellid and hyolithellid hyolithelminths, and a bradoriid arthropod occur as very few or single specimens. The same is the case with a probable siphogonuchitid. The occurrence of a cornulitid related microfossil may extend the stratigraphic range of this fossil group significantly.

The rather low-diversity microfauna is overwhelmingly dominated by sessile epibenthic biota. The preferred feeding habit seems to have been suspension feeding and minor deposit feeding. The microfauna from the Jordan Rift Valley is typical for low-latitude carbonate environments of Cambrian Series 3 age that corresponds to the traditional late early to middle Cambrian. Some taxa indicate a closer relation to the equatorial Gondwanan Iran and Australia. Some connection to the European shelf of Perigondwana may also have existed.

O. Elicki (elicki@geo.tu-freiberg.de), Freiberg University, Geological Institute, Bernhard-von-Cotta Street 2, 09599 Freiberg, Germany. Received 9 August 2011.

Keywords: Small shelly fossils, poriferids, echinoderms, Cambrian, Jordan, Israel, Dead Sea.

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The systematic and detailed field work led to the discovery of sections largely unaffected by the heavy diagenetic overprint typical of the region, and facilitated detailed micropalaeontological investigation of skeletonised body-microfossils. For the first time, this paper focuses on description and documentation of Cambrian microfossils from this palaeogeographic region.

The palaeontological specimens figured in this paper, are housed at the Geological Institute of Freiberg University, Germany (archive numbers FG 595 and FG 619).

GEOLOGICAL AND STRATIGRAPHIC BACKGROUNDThe field area is situated along the eastern shoulder of the Jordan Rift Valley in the Dead Sea area, and the northeastern Wadi Araba south of the Dead Sea (Jordan). The Timna region (Israel), from where some microfauna was kindly provided for investigation by Professor Michael Bassett (Cardiff), represents the only locality investigated from southwestern Wadi Araba (Fig. 1).

The Cambrian sediments nonconformably overlie Precambrian basement rocks of the Arabo-Nubian Shield (Aqaba Complex) or, locally, Neoproterozoic volcanoclastics and conglomerates (Araba Complex; Bender 1974;

Powell 1989; Teimeh et al. 1990; Bandel & Shinaq 2003). The oldest Cambrian sedimentary rocks (part of Umm Gaddah Formation and Salib Formation, about 200 m thick; Fig. 2) are continental, fluvial to alluvial siliciclastics (Powell 1989; Amireh et al. 1994; Makhlouf 2003; Amireh et al. 2008). The overlying Burj Formation represents a marine maximum stage transgression (Amireh et al. 1994; Rushton & Powell 1998; Schneider et al. 2007). The start of transgression is indicated by some trace-fossil content in the lower Burj Formation (Tayan Member: Elicki 2007a), pointing to an early Cambrian age of these siliciclastics. The conformably succeeding Numayri Member (limestones, dolostones, minor siliciclastics) includes a variety of marginal-marine environments including open and restricted marine areas, shoals, lagoons, sabkhas (Shinaq & Bandel 1992; Rushton & Powell 1998; Elicki et al. 2002; Shinaq & Elicki 2007). The Numayri Member yields various macrofossils including trilobites, brachiopods and hyolithids, but also trace fossils (Richter & Richter 1941; Parnes 1971; Cooper 1976; Seilacher 1990a; Rushton & Powell 1998). The upper portion of the Burj Formation is represented by the siliciclastic Hanneh Member containing a rich marine ichnofauna (Seilacher 1990a, b; Mángano et al. 2007; Hofmann et al. 2008; Elicki et al. 2010, Hofmann et al. submitted) and some trilobites (Elicki & Geyer, submitted). The package is conformably overlain by the siliciclastic Umm Ishrin Formation which contains trilobites and trace fossils only at its base, but generally indicates regression and return of continental conditions (Makhlouf & Abed 1991; Hofmann et al. submitted).

The thickness of the Burj Formation in the Dead Sea region varies from about 190 m in the north (Wadi Zerqa Ma’in) to approximately 120 m in the (southern) Safi region (Powell 1989), thinning to zero in the basement area of southern Wadi Araba.

Evidence for the stratigraphic position of the Cambrian succession comes from trilobites. These have been found in the marine carbonates (Numayri Member) over the last hundred years (Dienemann 1915; King 1923; Richter & Richter 1941) and were recently summarised and reviewed by Rushton & Powell (1998). New discoveries of abundant, well preserved specimens by the Freiberg working group from the carbonate Numayri Member and the Hanneh Member siliciciclastics, enabled a critical review of the Cambrian trilobite fauna and confirmed a stratigraphic position within the traditional Early–Middle Cambrian boundary interval, probably equivalent to parts of Series 3, stage 5 (Rushton

Figure 1. Geographical map of the Jordan Rift Valley. Working areas are indicated (for detailed location of the sampled sections see Elicki 2007a).

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& Powell 1998; Geyer & Landing 2004; Geyer & Elicki submitted).

MATERIALS AND METHODSThe fossiliferous carbonates were investigated by thin-section analysis and also preparated by laboratory chemical work. Best results have been attained by careful chemical solution of the carbonate rocks using formic acid (about 15%) and in some cases acetic acid (about 15%). In some cases, concentrated acetic acid with added anhydrous copper sulphate (5 g per 100

ml acid) has been used, a method which utilises the absorption of water by crystals of calcium acetate (Nötzold 1965). Sieving procedure was executed using sieves of mesh size 0.3 mm and 0.1 mm. Microscopic work has been achieved using a ZEISS SV-11 polarisation light-microscope. SEM investigation was undertaken at the Geological Institute of Freiberg University with the field emission scanning electron microscope JEOL JSM-7001 F. For related compositional identification of the microbiota, an energy dispersive X-ray spectroscopy (edx) BRUKER

Figure 2. Generalised composite stratigraphic column of the Cambrian in the Dead Sea area (left; Salib Formation and Umm Ishrin Formation are only partially illustrated). Lithostratigraphic range of the Numayri Member in the investigated sections at the right (Numayri Member without fill pattern; Tayan Member and Hanneh Member with cross fill pattern and only partially illustrated). Lithostratigraphic position of the described microfaunas are indicated by bars.

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device with software ESPRIT 1.9 was utilised.

SYSTEMATIC PALAEONTOLOGYPoriferan spiculesSponge spicules were recovered in only a few samples, but normally in very large numbers. Lithotypes from the southern Dead Sea region (Wadi Umm Jafna, Wadi Uhaymir, unnamed valley south of Wadi At Tayan) contained the majority of these microfossils. Dominating types include triactine, tetractine and pentactine hexactinellid remains (c. thousands of spicules per kilogram of rock). Heteractinid spicules, in contrast, are of limited quantity. Some spicules could not be assigned systematically (see below). Nearly all remains are siliceous and come mostly from the lower portion of the Numayri Member (Burj Formation).

Phylum PORIFERA Grant, 1836Class HEXACTINELLIDA, Schmidt, 1870Order AMPHIDISCOSA Schrammen, 1924Family STIODERMATIDAE Finks, 1960

Rigbyella Mostler & Mosleh-Yazdi, 1976

Type species. Rigbyella ruttneri Mostler & Mosleh-Yazdi, 1976.

Rigbyella sp. (Fig. 3A-S)

Material. About 450 isolated siliceous spicules.

Description. Stiodermatiid (sensu Hooper & Van Soest 2002, p. 1214) pinnules with dramatically swollen vertical ray perpendicular to a generally four-rayed stauractine-like cross built by ‘basal’ spicules lying in same plane (Fig. 3B2). Swelling

Figure 3. Hexactinellid spicules of Rigbyella sp. from the lower part of the Numayri Member at the unnamed valley immediately south of Wadi At Tayan. All scale bars 100 µm. A, FG 619/13-133; B, FG 619/14-133; B2, detail of basal part of same specimen FG 619/14-133; C, FG 619/15-133; D, FG 619/16-133; E, FG 619/17-133; F, FG 619/21-133; G, FG 619/33-133; H, FG 619/32-133; I, FG 619/34-133; J, FG 619/22-133; K, FG 619/12-133; L, FG 619/31-133; M, FG 619/29-133; N, FG 619/24-133; O, FG 619/25-133; P, FG 619/27-133; Q, FG 619/23-133; R, FG 619/28-133; S, FG 619/26-133.

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of the vertical ray begins some distance above the ‘basal’ rays so that there is a bottle-neck-like transition. In a few cases, the ‘basal’ cross is tilted up to about 45° relative to the vertical ray (e.g., Fig. 3C, F). The swollen vertical ray is always many times the length of the other rays; its diameter is also generally larger than the length of the other rays (up to five times). There are two morphotypes occurring in the sample: the first and most common type is rather elongate and rice-grain shaped (Fig. 3A-M). The second morph is not as tall, commonly about two-thirds the length of the first morphotype, but with distinctly larger diameter and teardrop-shaped (Fig. 3N-S). The distal portion of the spicules is cuspid, and especially in the second morphotype, well developed, (e.g., Fig. 3P, S).

Discussion. All specimens come from one thin bioclastic limestone horizon near the base of the Numayri Member (unnamed adjacent valley south of Wadi At Tayan) immediately on top of basal, laminated and stromatolitic dolomites of the lowermost Numayri Member. Accompanying fauna consists of small trilobite hash, fragmented brachiopod shells, and isolated eiffeliid and rare ‘normal’ hexactinellid spicules.

Spicules of similar form are only rarely reported from Cambrian rocks. Rigby (1975) described sponge spicules from Late Cambrian-Early Ordovician limestones of Texas with pentactins that have a distinctly swollen vertical ray. Unfortunately, no photographs are included by Rigby, but, simplified drawings indicate these specimens are of very similar morphology (Rigby, 1975: text-fig. 1, H-N). Rigby (1975) also reported an association of ‘normal’ and acanthose hexactines and pentactines, and presented a reconstruction of the spicule scleritome, interpreting the swollen spicules as specialised morphs that form a dermal pavement surrounding the interior of the sponge.

Mostler & Mosleh-Yazdi (1976) described spicules from the Furongian of Iran (Mila Formation), including hexactine spicules with swollen vertical ray as well as swollen lateral rays. Sometimes the rays are drop-shaped or cap shaped and pointed. The authors erected the taxon Rigbyella ruttneri which includes (1) swollen hexactins, (2) hexactins with rays of unequal length, and (3) hexactins with rays with split ends. Some of the figured specimens (e.g., p. 34: plate III figure 6) are very similar to the material from Jordan. The specimens from Jordan generally do not have swollen lateral rays (which are quite common in the Iranian fauna). However, in cases where only the vertical ray is swollen in the Iranian material, these are very similar to

the spicules from Jordan. Whereas hexactins are exclusively mentioned in the original diagnosis of the genus Rigbyella, the current Treatise (Finks et al. 2004) also reports pentactins and includes the spicules described by Rigby (1975) from the Wilberns Formation (see above) in this genus.

Siliceous pentactins with swollen, spindle-shaped vertical ray and tetraradially symmetrical morphology are also described by Bengtson (1986) from Furongian carbonates from western Queensland (Australia). The author mentioned also records similar and very abundant spicules with smooth and acanthose surface ornament. He further noted that specimens with excessively swollen rays similar to those as published by Rigby (1975, compare explanations above) are not present in the spicule microfauna from Queensland. Indeed, the spicules from Jordan described here, commonly have a distinctly more swollen vertical ray, but, their overall construction is otherwise very close to the spicule morphs figured by Bengtson (1986: Fig. 9C).

Bengtson also discussed spicules from the early Cambrian of Kazakhstan (referred to Azyrtalia), published by Nazarov (1973, cited by Bengtson 1986) and suggests these may be synonymous with Rigbyella. If this assumption is correct, then Azyrtalia would represent an older synomym and would have taxonomic priority. However, reinvestigation of the cited material is needed to clarify this aspect.

From the middle Cambrian Georgina Basin in central northern Australia (Northern Territory), Mehl (1995, 1998) described Thoracospongia follispiculata with typical hexactins and pentactins characterised by having a distinctly swollen vertical ray. These forms are quite similar to the specimens from Jordan. Differences consist in the occurrence of distinct longitudinally ribs along the swollen ray and in the lack of a bottle-neck-like transition to the “basal” rays in the material from Australia. Unfortunately, the preservation of the spicules from Jordan is always very coarse-grained (diagenetic replacement by coarse quartz crystals), so that the original surface structure can only be suspected at best. In some cases it cannot be excluded that (faint) primarily longitudinally ribs may have been present in the Jordanian spicules. The Australian spicule fauna also consists of hexactinellid, demosponge and calcarea spicules (e.g. Eiffelia), similar to the association recovered from Jordan.

Considering the morphological variability of the sclerites from all these regions, the close affinity of the described spicules to Rigbyella is most reasonable. Minor morphological differences from the only species of this genus (R. ruttneri) and the strong diagenetic overprint

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Figure 4. Unassigned hexactinellid spicules: triactins (A-G), tetractins (H-J’), pentactins (K’-R’), hexactins (S’). Specimens come from the lower portion of the Numayri Member at Wadi Uhaymir (A-D, I-W, Y-Z, A’-B’, E’-G’, K’-O’, Q’-R’) and Wadi Umm Jafna (E-F, X, C’-D’, H’-J’, P’, S’-S’1), as well as from upper portion of the upper Numayri Member at Wadi Zerqa Ma’in (G-H). All scale bars 100 µm. A, FG 619/3-398 B, FG 619/13-398; C, FG 619/18-398; D, FG 619/33-398; E, FG 619/53-398; F, FG 619/65-398; G, FG 619/23-451; H, FG 619/29-451; I, FG 619/2-398; J, FG 619/4-398; K, FG 619/7-398; L, FG 619/8-398; M, FG 619/9-398; N, FG 619/14-398; O, FG 619/17-398; P, FG 619/15-398; Q, FG 619/16-398; R, FG 619/19-398; S, FG 619/20-398, T, FG 619/23a-398; U, FG 619/25-398; V, FG 619/30-398; W, FG 619/29-398; X, FG 619/63-398; Y, FG 619/28-398; Z, FG 619/31-398; A’, FG 619/37-398; B’, FG 619/44-398; C’, FG 619/50-398; D’, FG 619/51-398; E’, FG 619/40-398; F’, FG 619/42-398; G’, FG 619/32-398; H’, FG 619/54-398; I’, FG 619/59-398; J’, FG 619/61-398; K’, FG 619/24-398; L’, FG 619/38-398; M’, FG 619/45-398; N’, FG 619/47-398; O’, FG 619/48-398; P’, FG 619/62-398; Q’, FG 619/5-137; R’, FG 619/28-398; S’1, FG 619/57-398; S’2, detail of same specimen FG 619/57-398.

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in the spicules from Jordan may lead to some uncertainty.

Unassigned hexactinellid spicules. Unassigned isolated triactins, tetractins and pentactins represent the vast majority of the hexactinellid spicule microfauna. Tetractins are often represented by calthrops and triaenes, and less common by stauractins. Hexactins are rare. Almost all spicules have a smooth surface (Fig. 4A-Z, A’-R’). Acanthose ornamentation is extremely rare (Fig. 4S’1, S’2).

The majority of spicules occur in huge numbers (mass occurrences within distinct layers) which yield only few other fossils: trilobite and hyolith remains. Taxonomic assignment is not useful for these specimens because of the huge morphological variability of the group. Nevertheless, it can be argued that (1) the huge number, (2) the nearly exclusive occurrence of the spicules in distinct limestone layers, and (3) the content within the taphocoenosis from different localities, suggests the spicules derived from the same scleritome.

Most of the spicules come from carbonate horizons in the middle to upper portion of the Numayri Member of Wadi Umm Jafna and Wadi Uhaymir, as well as from a loose boulder at Wadi Uhaymir and from the upper Numayri Member of Wadi Zerqa Ma’in. The variability of spicules from Jordan is illustrated in Figure 4.

Class CALCAREA Bowerbank, 1864Order HETERACTINIDAE Hinde, 1888Family EIFFELIIDAE Rigby, 1986

Eiffelia Walcott, 1920

Type species. Eiffelia globosa Walcott, 1920.

Eiffelia araniformis (Missarzhevsky, 1981) (Fig. 5A-D)

1981 Lenastella araniformis; Missarzhevsky in Missarzhevsky & Mambetov, p. 76, pl. 12, figs 1, 10.

1981 Lenastella aculeata; Missarzhevsky in Missarzhevsky & Mambetov, p. 76, pl. 12, figs 2-4.

1981 Lenastella mucronata; Missarzhevsky in Missarzhevsky & Mambetov, p. 77, pl. 12, figs 8, 9, 11.

1981 Lenastella umbonata; Missarzhevsky in Missarzhevsky & Mambetov, p. 77, pl. 12, fig. 12.

1984 Actinoites universalis; Duan, p. 167, pl. 4, figs 11, 13-14.

1984 Actinoites simplex; Duan, p. 167, pl. 4, fig. 6.

1984 Niphadus xihaopingensis; Duan, p. 168, pl. 4, fig. 17.

1984 Niphadus complanatus; Duan, p. 168, pl. 4, fig. 8.

1986 Lenastella sp.; Laurie, p. 447, fig. 10C.1990 Eiffelia araniformis (Missarzhevsky);

Bengtson et al., p. 27, figs 12, 13.1994 Eiffelia araniformis (Missarzhevsky);

Elicki, p. 73, figs 14-15.1996 Eiffelia araniformis (Missarzhevsky);

Culver et al., p. 4, fig. 5.13.2001 Eiffelia cf. araniformis (Missarzhevsky);

Sarmiento et al., p. 120, pl. 2, figs 10-11. 2004 Eiffelia araniformis (Missarzhevsky);

Wrona, p. 18, fig. 5H.2005 Eiffelia araniformis (Missarzhevsky);

Elicki, p. 163.2006 Eiffelia araniformis (Missarzhevsky);

Elicki, p. 9.2006 Eiffelia araniformis (Missarzhevsky);

Skovsted et al., p. 1098, figs 7.23, 7.24.2007b Eiffelia araniformis (Missarzhevsky);

Elicki, p. 146.

Material. About 10 isolated secondary silicified spicules from 2.5 m above the base of the Numayri Member at the valley immediately south of Wadi At Tayan.

Description. The specimens are regularly six-rayed. Angle between rays is about 60°. No vertical ray (as sometimes reported for this taxon) is observed. All rays are arranged in the same plane. The length of the rays varies: in some cases all six rays seem to have the same length (often they are broken), in other cases the length differs. This is also the case regarding the width of the rays. Most specimens have one ray distinctly elongate (double to triple the length of the others).

Discussion. A full discussion of this species was provided by Bengtson et al. (1990). Here, the opinion of Bengtson et al. (1990) is followed concerning the assignment of the genus Lenastella Missarzhevsky, 1981, to the synonymy of Eiffelia Walcott, 1920, and in interpreting the various Lenastella species erected by Missarzhevsky (1981) as belonging to the morphological range of Eiffelia araniformis.

The specimens from Jordan come from bioclastic, oncolitic limestone with accompanying small trilobite and brachiopod hash, Rigbyella (see above), and rare hyolithid, chancelloriid and echinoderm remains. In most cases, the bioclasts are oncolitic.

Eiffelia araniformis is known from the early and middle Cambrian interval almost worldwide.

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Unassigned sponge spicules. One specimen of a polyactinellid, triradiate spicule (Fig. 5E) was observed along with Rigbyella near the base of the Numayri Member at the valley immediately south of Wadi At Tayan (see above). The spicule has Mg-calcareous mineralogy. Two of the rays (lower rays according to Finks et al. 2004) are dichotomously branched into two secondary rays; branching begins close to the point of divergence of the main rays. The third main ray (upper first-order ray) is distinctly longer, straight, and not branched, but clearly more tilted. Between the lower rays (originated by branching), the original presence of a now broken additional ray is indicated by a round breaking suture. This ray arrangement and branching clearly point to the systematic affiliation close to the calcisponge Praephobetractinia Kozur, 1991, known from

the early Cambrian to early Ordovician (Mostler 1985, 1996; Kozur 1991). Some similarity exists with Dodecaactinella Reif, 1968. However, a distinct difference to Dodecaactinella is in the presence of the unbranched and clearly elongate third main ray, and in the angles between rays in the specimen from Jordan. These characters can be observed despite the broken preservation and are consistent with the diagnostic features of Praephobetractinia. These characters are also present in specimens from Greenland (Skovsted 2006) and Pennsylvania (Skovsted & Peel 2010), erroneously reported as Dodecaactinella. A specimen from Sardinia figured by Mostler (1985, pl. 3, fig. 3 = “phobetractine spicule”) and Finks et al. (2004, p. 760. fig. 7a) is most similar to the specimen described here.

A few spicules were recovered from limestone

Figure 5. Heteractinids (A-D), ?polyactinellids (E-O), chancelloriids (P-Z), and other spicules (A’) from the Numayri Member (A-Z, A’) and the equivalent Nimra Member (Israel, W-Z). Scale bars D-V = 100 µm, A-C, W-X = 1 mm. A-D, Eiffelia araniformis (Missarzhevsky, 1981); A, FG 619/1-133; B, FG 619/2-133; C, FG 619/3-133; D, FG 619/4-133; E, polyactinellid praephobetractinid spicule, FG 619/11-133; F-O, ?polyactinellid spicules; F, FG 619/6-398; G, FG 619/12-451; H, FG 619/21-398; I, FG 619/34-398; J, FG 619/35-398; K, FG 619/39-398; L, FG 619/43-398; M, FG 619/46-398; N, FG 619/56-398; O, FG 619/60-398; P-Q, Archiasterella cf. hirundo Bengtson, 1990; P, FG 619/10-133; Q, FG 619/6-133; R-T, Allonnia sp.; R, FG 619/5-133; S, FG 619/9-133; T, FG 619/52-133; U, ?Ginospina sp., FG 619/8-133; U1, lateral view; U2, plan view; V-Z, Chancelloria sp.; V, FG 619/7-133; W, FG 619/19-200; X, FG 619/20-200; Y, FG 619/21-200; Z, FG 619/23-200; A’, Microcoryne cephalata (Bengtson, 1990), FG 619/40-133.

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samples of the lower portion in the Numayri Member at Wadi Umm Jafna and Wadi Uhaymir. Most specimens come from a loose boulder sampled in the latter region (Fig. 5F-O).

The spicules illustrated here are characterised by conspicuous irregularity in the pattern of branching, ray arrangement and ray symmetry. The composition of the spicules appears to be siliceous, but it is difficult to be sure this reflects the original composition because of the strong diagenetic overprint of silification in these sections. An axial canal is not visible and this may be the result of diagensis as well. The polyactinellid or dodecaactinellid nature (Calcarea, Heteractinida) of some spicules is possible (Reitner personal communication 2011). One of the spicules (Fig. 5M) has a ray configuration similar to phobetractins, but with an additional ray in a third plane. Mehl (1998 p. 1167, figs 7, 8, 10, and personal communication 2011) figured demospongid specimens from the middle Cambrian of the Georgina Basin (Australia) which resembles some of the material from Jordan (e.g. Fig. 5H).

The coeval fauna consists of abundant hexactinellid spicules and a few trilobite and hyolith remains.

Phylum unassignedClass COELOSCLERITOPHORA Bengtson &

Missarzhevsky, 1981Order CHANCELLORIIDA Missarzhevsky, 1989Family CHANCELLORIIDAE Walcott, 1920

Archiasterella Sdzuy, 1969

Type species. Archiasterella pentactina Szduy, 1969.

Archiasterella cf. hirundo Bengtson, 1990 (Fig. 5P-Q)

2001 Archiasterella cf. hirundo Bengtson; Fernández-Remolar, p. 59, figs 3e-f, 8c-d, f.

2001 Archiasterella cf. hirundo Bengtson; Sarmiento et al., p. 120, pl. 2, fig. 5.

2010 ?Archiasterella hirundo Bengtson; Moore et al., p. 1053, figs 11.1-11.3, 11.6, 11.7.

Material. 3 spicules, numerous probably related single rays; from lower Numayri Member of the valley south of Wadi At Tayan.

Discussion. The typical rays, the characteristic arrangement and curvature, and canal openings (foramina) on the lower side, identifies these spicules as chancelloriid and archiasterellid (Szduy 1969; Bengtson et al. 1990). The number

of rays (4+0), ray configuration and proportions suggest the affiliation with A. hirundo from South Australia (Bengtson in Bengtson et al. 1990). The original spicule surface pattern is not visible due to coarse recrystallisation. Because of this poor preservation of the material, the spicules from Jordan are referred to Archiasterella cf. hirundo. Archiasterella hirundo is known from the late early Cambrian of South Australia, Germany, Spain and probably from southern China (Bengtson et al. 1990; Elicki 1994; Fernández-Remolar 2001; Sarmiento et al. 2001; Moore et al. 2010).

Allonnia Doré & Reid, 1965

Type species. Allonnia tripodophora Doré & Reid, 1965.

Allonnia sp. (Fig. 5R-T)

Material. Only few spicules, probably large number of related single rays; from lower Numayri Member of the valley south of Wadi At Tayan and from the higher Numayri Member of Wadi Umm Jafna.

Discussion. The arrangement and number of rays (4+0) in these specimens are in the range of the genus Allonnia. Jiang (in Luo et al. 1982) erected Onychia tetrathallis from southern China for four-rayed spicules, which were assigned later to the genus Allonnia by Qian & Bengtson (1989). The specimens from Jordan are poorly preserved, so that species determination is difficult. Nevertheless, the number, arrangement and orientation of the four rays point to a systematic affiliation with the species A. tetrathallis.

Allonnia is known from Cambrian strata worldwide and A. tetrathallis also has a worldwide distribution in the early and middle Cambrian.

Chancelloria Walcott, 1920

Type species. Chancelloria eros Walcott, 1920.

Chancelloria sp. (Fig. 5V-Z)

Material. About 20 spicules, but many probably related single rays; from lower Numayri Member of the valley south of Wadi At Tayan and from Timna area (upper Nimra Member of Timna Formation, which is more or less equivalent to the Numayri Member in Jordan).

Description. Rosette-like sclerites with 5-6 rays of very similar length and shape. Openings on the

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lower side are round to slightly oval. Rays only slightly bent upwards; no vertical ray present.

Discussion. The preservation of the sclerites is poor, so that detailed systematic affiliation cannot be determined. Many accompanied unassigned specimens with chancelloriid characteristics possibly belong this genus. For some specimens, the foramen on the lower side of the sclerite can faintly be seen. The shape and organisation of the spicule suggests affinity with the genus Chancelloria, a genus which is extremely common in Cambrian microfaunas worldwide.

Family SISSOSPINIDAE Missarzhevsky, 1989

Ginospina Missarzhevsky, 1989

Type species. Ginospina araniformis Missar-zhevsky, 1989.

?Ginospina sp. (Fig. 5U1-U2)

Material. One specimen from the lower Numayri Member of the valley south of Wadi At Tayan.

Discussion. This secondarily silicified, poorly preserved chancelloriid sclerite has 7 upright rays of variable length. Rudimentary foramina are visible on the lower side. A conspicuous character is the remarkable, somewhat elliptical arrangement of the rays. This kind of ray-arrangement in chancelloriids is similar to the genus Ginospina from the early Cambrian (Tommotian) of Siberia (Missarzhevsky 1989).

Phylum, class, order & family unassigned

Microcoryne Bengtson, 1990

Type species. Microcoryne cephalata Bengtson, 1990.

Microcoryne cephalata (Bengtson, 1990) (Fig. 5A’)

1990 Microcoryne cephalata; Bengtson in Bengtson et al., p. 35, fig. 19.

1994 Microcoryne cephalata Bengtson; Elicki, p. 74, pl. 2, figs 6.10-6.16.

2010 Microcoryne cephalata Bengtson; Elicki &

Geyer, p. 107, fig. 2.13.

Material. One spicule from a loose boulder of the middle Numayri Member sampled at the mouth of the Wadi Qunai.

Discussion. Sclerites with this characteristic mace-shaped morphology were described by Bengtson (in Bengtson et al. 1990) who grouped them into the new genus Microcoryne (type species: M. cephalata Bengtson, 1990). The morphological variability of the spicules from Australia is quite large. The phosphate mineralogy is assumed to be a secondary replacement. The Jordanian material coincides fully with spicules of M. cephalata described from the late early Cambrian of Germany (Elicki 1994; Elicki & Geyer 2010). The only difference is in the type of preservation which is distinctly coarser in the Jordanian material due to different diagenetic overprint.

As discussed by Bengtson (1990), Microcoryne seems to be closest to the sclerites of octocorals.

In Jordan, Microcoryne is a very rare constituent in bioclastic carbonates which also yield trilobite hash. Besides the specimen from Jordan described here, M. cephalata is hitherto reported from the higher early Cambrian of South Australia and Germany.

Echinoderm remainsEchinoderm remains are represented by isolated plates and ossicles of diagenetically altered, secondarily phosphatised or silified composition. They occur in bioclastic limestones in various levels within the whole Numayri Member. The majority of the ossicles described here come from the Wadi Zerqa Ma’in section which represents the uppermost part of the Numayri Member (Shinaq & Elicki 2007). The limestones of this section are interpreted as deposited within a shallow, open-marine, occasionally storm-influenced environment (Shinaq & Bandel 1992; Shinaq & Elicki 2007).

Phylum ECHINODERMATA Klein, 1734Class, order & family unassigned

gen. et sp. indet. (Fig. 6A-Z, A’-E’)

Material. Hundreds of ossicles from Wadi Zerqa

Figure 6. Echinoderm ossicles. All scale bars 100 µm. A, FG 619/7-115; B, FG 619/13-559; C, FG 619/2-115; D, FG 619/8-559; E, FG 619/3-559; F, FG 619/18-115; G, FG 619/1-115; H, FG 619/7-137; I, FG 619/2-559; J, FG 619/8-362; K, FG 619/13-362; L, FG 619/17-362; M, FG 619/1-559; N, FG 619/1-477; O, FG 619/9-559; P, FG 619/11-137; Q, FG 619/11-559; R, FG 619/12-559; S, FG 619/12b-362, T, FG 619/16-362; U, FG 619/3-115; V, FG 619/4-115; W, FG 619/11-362; X, FG 619/8-115; Y, FG 619/20-115; Z, FG 619/15-137; A’, FG 619/15-559; B’, FG 619/19-115; C’, FG 619/5-115; D’, FG 619/8-115; E’, FG 619/6-115.

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Ma’in (uppermost Numayri Member); usual components in bioclastic limestones of various stratigraphic levels of the Numayri Member.

Description. A wide range of morphology is represented by disarticulated plates with micro-porous stereom ultrastructure. But, there are more or less three characteristic morphological types: (1) plates with very distinct epispires (Fig. 6A-L), (2) pentamerous and irregular to slightly rounded plates (Fig. 6M-W), and (3) irregular brick-like segments (Fig. 6X-Z, A’-E’).

Discussion. The value of echinoderm residues preserved as isolated ossicles is generally limited. Only in some cases it is possible to suggest systematic affinity. Nevertheless, such remains have been mentioned from carbonates of many early to middle Cambrian successions worldwide such that echinoderms have obviously represented an important constituent of shallow marine carbonate habitats at this time.

The morphologies mentioned above are typical for edrioasteroids and eocrinoids, but some of them do also occur in cincta. Ossicles of type 3 morphology (Fig. 6X-Z, A’-E’) may represent brachiole or ambulacral parts of an eocrinoid or ring elements surrounding the central platform of an edrioasteriod. Plates of types 1 and 2 (Fig. 6A-W) are probably edrioasteroid interambulacral or cover plates, or eocrinoid thecal elements (compare Smith 1985, p. 718, text-fig. 2, p. 722, text-fig. 5). Interestingly, no columnal (barrel-shaped) stem elements, no typical cinctan plates, and also no stylocone segments have been recovered from the huge number of remains; different from other Gondwanan occurrences of comparative age (e.g., Elicki et al. 2003; Clausen 2004; Elicki 1994, 2006; Shinaq & Elicki 2007; Elicki & Gürsu 2009; Clausen & Smith 2008; Zamora et al. 2009; Zamora 2010).

The echinoderm remains from the Jordanian successions suggest eocrinoid and edrioasteroid affinity. Internal ultrastructure of some of the remains seems to be identical to those reported by Kruse et al. (2004) from the Ord Basin (Australia) and by Clausen & Álvaro (2006) from the Cantabrian Mountains and interpreted by the latter authors as non-echinoderm problematicum (?lobopodian Cantabria labyrinthica Clausen & Álvaro, 2006). As stated by these authors, the

main arguments for a non-echinoderm relation are the occurrence of hollow tubes instead of non-hollow trabeculae, in two apatitic layers, and in non-phosphatisation of echinoderm ossicles within the same sample. However, these arguments are rather weak regarding the complex diagenetic alteration of such remains. The hollow tubes (which can be observed also on ‘true’ echinoderm remains, e.g. with epispires) may very well represent coating processes which can be observed not only in echinoderms, but also on many Cambrian shelly microfossils from Jordan and elsewhere (e.g. Shinaq & Elicki 2007, p. 266 fig. 7.14; Zamora et al. in press, fig. 5B-C; from Turkey by personal observation of the author). It is quite common that microfossils from the same horizon and sample show very different preservation: shell-pseudomorphs, phosphatic coatings and steinkerns. The preservation reported by Clausen & Álvaro (2006) is also known from many other localities, and is observed in the material from Jordan. It is interpreted here as a diagenetic phenomenon.

Phylum MOLLUSCA Cuvier, 1797Class HELCIONELLOIDA Peel, 1991Order HELCIONELLIDA Geyer, 1994Family HELCIONELLIDAE Wenz, 1938

gen. et sp. indet. (Fig. 7A-O)

Material. Dozens of silicified specimens exclusively from Timna area (higher Nimra Member of Timna Formation). The specimens have kindly been provided by Professor Mike Bassett (Cardiff University).

Description. Cap-shaped, cyrtoconic, planspiral univalves with wide aperture. Aperture is somewhat elliptical in outline due to slightly compressed shape of cap. The apex is distinctly coiled (but less than a complete whorl), not only tilted or bent. The apex is partly isolated by a weak constriction. The margin of the shell is planar and slightly curved posteriorly. Ornamentation consists of numerous fine radiating ridges; faint grow lines are occasionally preserved.

Discussion. The preservation of the specimens is poor. The coarsely silicified material does not allow a detailed determination. In only few cases

Figure 7. Helcionellid gen. et sp. indet. from the Nimra Member of the Timna Formation (Israel). All scale bars 100 µm. A1, FG 619/7-200; A2, oblique lateral view of same specimen FG 619/7-200; A3, half-lateral view of apical area of same specimen FG 619/7-200; B, FG 619/1-200; C, FG 619/5-ISR3B; D, FG 619/2-ISR3; E, FG 619/3-ISR3; F, FG 619/1-ISR3; G, FG 619/13-200; H, FG 619/6-ISR3B; I, FG 619/6-200; J, FG 619/12-200; K1, FG 619/4-200; K2, half-lateral view of apical area of same specimen FG 619/4-200; L, FG 619/8-200; M1; FG619/10-200; M2, detail of same specimen FG 619/10-200; N1, FG 619/17-200; N2, FG 619/17-200; O, FG 619/18-200.

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very faint radiating rugae and growth lines can be observed. The general shape and kind of coiling indicate a helcionellid affinity.

The remarkable radiating ridges are also reported from other Cambrian univalved molluscs. Runnegar & Jell (1976) erected a species of Latouchella with such characteristics (L. penecyrano), but Latouchella has a stronger coiling and a more elongate ventral margin than the specimens from Israel. Regarding the general shape and ornamentation, there is also some similarity to the genera Kutanjia (middle Cambrian of the Northern Territory, Australia; Kruse 1991), Kalbyella (middle Cambrian of Denmark and Australia; figured by Berg-Madsen & Peel 1978, and by Runnegar in Bengtson et al. 1990) and to Yochelcionella (as in Atkins & Peel 2004). Nevertheless, distinct further differences in shell morphology do not allow suggestion of any closer affinity of the specimens described here.

The systematic position of monoplacophorans and helcionellids is under debate and they are affiliated to various higher taxonomic groups by different authors. For major discussion of the systematics and on the palaeobiological aspects see Bengtson et al. (1990), Peel (1991), Runnegar (1996), Gubanov & Peel (2000) and Parkhaev (2002).

?Siphogonuchitids (Fig. 8A-E)

Material. From limestone of the Wadi Zerqa Ma’in section (uppermost Numayri Member) come about ten fragments grouped together here as probable siphogonuchitids.

Description. All specimens are fragmentary. The remains are asymmetrical and of phosphatic mineralogy (EDX analysis data). Their cross-section is angled to irregularly subtriangular with rounded corners. No distinct keel is visible. A characteristic feature is the ornamentation of transverse, densely spaced lineations (of about 5-10 µm). A basal opening (rounded and slightly elongate) can be seen in a few cases (Fig. 8C-D). The apex is unknown due to poor preservation.

Discussion. Skovsted (2006) described very similar microfossils from the upper lower Cambrian Bastion Formation of eastern Greenland as “siphogonochitids?”. Skeletal elements from southern China and northern Iran determined as Siphogonuchites and Lopochites (Qian & Bengtson 1989; Hamdi 1995; Steiner et al. 2004) are also similar to the remains from Jordan, but the preservation of the latter is much too poor for more detailed determination.

Siphogonuchitids are typical elements of the

early Cambrian skeletal fauna and mostly grouped within the class Coeloscleritomorpha Bengtson & Missarzhevsky (1981). They are known mainly from Asia (China, Mongolia, Siberia), but have been reported from France, Australia, Iran and Greenland (Luo et al. 1984; Missarzhevsky 1989; Qian 1989; Kerber 1988; Qian & Bengtson 1989; Bengtson et al. 1990; Hamdi 1995; Eskova & Zhegallo 1996; Steiner et al. 2004; Skovsted 2006). Whilst most occurrences are from the lower portion of the early Cambrian, some siphogonuchitids (especially from the occurrences outside Asia, see citations above) are reported from younger strata, up to the traditional Early-Middle Cambrian boundary interval. However, this stratigraphic phenomenon could rather reflect the occurrence of special palaeoecological conditions and lithofacies than a true palaeogeographic migration pattern.

Hyolithelminths (Fig. 8F-J)

Material. Six incomplete specimens. All come from bioclastic limestones of the higher portion of the Wadi Zerqa Ma’in section (uppermost Numayri Member).

Discussion. The palaeobiology, taxonomy and systematic affiliation of hyolithelminths (interpreted as annelids or cnidarians) is not clear and is still controversial (compare e.g. Landing 1988, Brasier in Cowie & Brasier 1989, Bengtson in Bengtson et al. 1990, Paterson et al. 2007; Topper et al. 2009; Skovsted & Peel 2011). The original diagnostic definition of the only two families (torellellids and hyolithellids) is rather imprecise and highly controversial too. Specimens mentioned here, are formally related in the ‘classical’ sense into those with circular cross-sections (hyolithellid) and those with flattened cross-sections (torellellid). Preservation is in phosphatic mineralogy, but mostly in steinkerns.

Hyolithellid hyolithelminths (Fig. 8H-J) have been recognised by three fragmentary preserved steinkerns of regular, nearly straight (extremely low angle of widening) tubes with circular cross-section. No tapering is visible. The most conspicuous character is the prominent growth annulations (regularly perpendicular to the tube direction) which occur in distances of commonly 40–50 µm, but sometimes this distance is reduced to 20 µm (Fig. 8H-I). In one specimen (Fig. 8J), very fine longitudinal corrugation can be observed between the growth lines. However, it has to be stressed that this specimen represents a steinkern and that these features reflect the inner surface of the tube.

Torellellid hyolithelminths (Fig. 8F-G) have

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been identified by two fragments of phosphatic tubular steinkerns. The features are mostly identical to hyolithellids except in cross-section and angle of divergence. Here, the tube is flattened so the cross-section is elliptical. The ellipticity is variable when comparing both specimens, but also within the same specimen, and illustrates the large morphological variability of these hyolithelminths.

?Cornulitids (Fig. 8K-L)

Material. Two incomplete specimens from the uppermost Numayri Member of the Wadi Zerqa Ma’in section. Shinaq & Elicki (2007, p. 266, fig 7.23-7.24) referred them to Torellella and stressed the problematic taxonomy because of some anomalous characters in the specimens from Jordan.

Discussion. The two tube fragments are of phosphatic mineralogy (EDX analysis data). The

conical, thick-walled tubes have flattened cross-sections, but in early growth stages it is more circular. The only larger fragment shows distinct and irregular sinuosity. The angle of tube widening is very low and not constant. Outer surface is ornamented by pronounced transverse annulations (rings), running characteristically irregular so that they often come closer until fusion, producing a somewhat cellular wall structure (Fig. 8K-L). Longitudinally, distinct and densely arranged striae between the rings are remarkable (Fig. 8K2). These characters coincides in some extant to torellellid hyolithelminths (mineralogy, cross-section, general shape). The transition from circular to elliptical cross-section is already known from such specimens (e.g. Rozanov 1982; Missarzhevsky 1989). In contrast, the very special structure of the characteristic annulations which led to a kind of cellular appearance of the outer wall, and the sturdy striation between these rings is not known from hyolithelminths in general. Additionally, although some sinuosity

Figure 8. Unassigned small shelly fossils from Wadi Zerqa Ma’in section (uppermost Numayri Member). All scale bars 100 µm. A-E, ?Siphogonuchitids; A, FG 619/32133-451; B, FG 619/32150-451; C, FG 619/19-362; D, FG 619/20-362; E, FG 619/22-115; F-G, torellellid hyolithelminths; F, FG 619/31-451; G1, FG 619/21-451; G2, lateral view of same specimen FG 619/21-451; H-J, hyolithellid hyolithelminths; H, FG 619/7-362; I, FG 619/20-451; J, FG 619/6-362; K-L, ?cornulitids; K1, FG 619/32092-362; K2, detail of same specimen FG 619/32092-362; L, FG 619/32148-451; M-O, opercula of hyoliths; M, FG 619/45-133; N, FG 619/46-133; O, FG 619/50-133; P, bradoriid, FG 619/7-115; P1, lateral view; P2, posterolateral view.

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is already described for Torellella (e.g. Rozanov 1982; Missarzhevksy 1989; Elicki 1994), such a high degree as in the material from Jordan has not previously been recorded. However, these characteristics are typical for cornulitids, a problematic group described from the Ordovician to Carboniferous and controversial interpreted as annelids, tentaculitids, microconchids, cnidarians, molluscs, bryozoans or phoronids (Fisher 1962; Morris & Mollins 1971; Morris & Felton 2003; Herringshaw et al. 2007; Zhan & Vinn 2007). The only rather problematic feature in the specimens from Jordan is their comparatively small size. Until more material is available, the specimens described here are classified as problematica with probable cornulitid affinity. If the assumed affinity is confirmed, the material from Jordan would represent the oldest occurrence of this fossil group.

Hyolith opercula (Fig. 8M-O)

Material. Five, partly corroded specimens from the Numayri Member of the Wadi Umm Jafna section.

Discussion. Three different morphotypes of hyolith opercula were found. The specimens are preserved as very fragile phosphatic moulds of different morphology.

The first type (Fig. 8O) has a rather circular outline with relatively narrow but long and rather straight to slightly outwardly curved clavicles (indicated by the ridge-like elevations of the phosphate envelope). The clavicles enclose an angle of about 50°. The second type (Fig. 8N) has a subrounded to slightly triangular outline. Clavicles are well developed and are slightly curved comarginally. They are closer to the margin of the operculum as in the first morphotype and seemingly broader and shorter. The angle between the clavicles is about 80°. The third type (Fig. 8M) has a quite different, distinctly triangular outline. The ventral side is rather flat and the two flanks enclose an angle of about 120° meeting each other by a pointed peak. Clavicles are rather short and run comarginally.

The general outline and clavicle configuration of type 1 correspond to Hyolithes kingi, the very common and only described hyolith of the Numayri Member.

Bradoriids (Fig. 8P1-P2)

Material. One specimen from limestone of the Wadi Zerqa Ma’in section (uppermost Numayri Member).

Discussion. The specimen is of phosphate composition (EDX analysis data) and has a bivalved preplete carapace of asymmetrical, sub-semicircular outline. Valves gape anteriorly a little. The dorsal margin is straight and has rounded, but angular corners anteriorly and posteriorly (Fig. 8P1). The anterodorsal area of the carapace is slightly flattened close to the margin. Outer surface is smooth to somewhat corrugate; no lobes, ridges or other ornamentation is visible. The large depression of the carapace (Fig. 8P1) is a secondary feature due to compaction, which is interpreted here as an indication of some organic constituent in a non-calcitic carapace reacting flexibly. Due to the limited morphological features, a detailed determination is problematic.

CONCLUSIONSFor the first time, the Cambrian carbonates o f the Jordan Ri f t Va l ley have been micropalaeontologically investigated. During the last few years, several research projects focusing on the Cambrian successions of Jordan (Burj Formation) have been initiated (Elicki et al. 2002; Elicki 2007a; Shinaq & Elicki 2007; Elicki submitted; Geyer & Elicki submitted; Hofmann et al. submitted). This paper presents the micropalaeontological outcomes of this research and the first microfauna published from this region.

The carbonates have been deposited in a structured complex of shallow marine environments under tropical/subtropical conditions (Shinaq & Elicki 2007; Elicki et al. 2002; Elicki submitted). The development of the carbonate platform (Numayri Member) in the early Series 3 of the Cambrian (near the traditional Early-Middle Cambrian boundary interval) begins and ends with stromatolitic fabrics. Carbonate facies types in between are rather diversified and yield a lot of shelly macro- and microbiota. Whereas the former are represented by trilobites, brachiopods and hyoliths, the microfauna contains poriferids, echinoderms, helcionellid molluscs, chancelloriids, hyolithelminths, bradoriids and some problematica, as well as very rare (?)octocorals, (?)siphogonochitids and (?)cornulitids. Because of the diagenetic overprint and related large mineral replacement, as well as due to the lack of knowledge on the morphological diversity of some skeletal taxa (e.g., poriferids, echinoderms), a detailed taxonomic determination is not possible in several cases. Nevertheless, two genera and one species of poriferids, four genera and one species of chancellorrids, and one probable octocoral species have been identified.

By far the most of the microfossils belong to echinoderms and poriferids. Isolated

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echinoderm ossicles could be identified as eocrinoid and edrioasteroid elements. Among poriferids, hexactinellid spicules (Rigbyella sp. and triactins, tetractins, pentactins, and hexactins) are predominant. Heteractinids (Eiffelia araniformis [Missarzhevsky, 1981]) and polyactinellids (?Praephobetractinia) are rather rare. Chancelloriids are not very common and are represented by Archiasterella cf. hirundo Bengtson, 1990, Allonnia sp., Chancelloria sp., and ?Ginospina sp. Molluscs are known from the microfossil content of Jordan by only few opercula of hyoliths. From the Nimra Member of the Timna area in Israel (which coincides to the Numayri Member of Jordan), a poorly preserved helcionellid mollusc has been identified in large numbers. Microcoryne cephalata (Bengtson, 1990) – a probable octocoral sclerite – is represented by one specimen. Few specimens of torellellid and hyolithellid hyolithelminths were able to be determined. Bradoriid arthropods are represented by one specimen. Some rare and broken microfossils point to a siphogonuchitid affinity. The occurrence of a probably cornulitid related problematicum is reported; if correct, this would represent the oldest occurrence of this fossil type so far.

The diversity of the microfossil assemblage is not very large. The fauna is clearly dominated by sessile (and minor mobile) epibenthic forms. Few representatives may have realised a necto-benthic life-style. Most organisms seem to have been suspension feeders with fewer deposit feeders.

Such type of microfauna is well known from many late early to middle (Series 3) Cambrian low-latitude carbonate environments. Nevertheless, some taxa from the Jordan Rift Valley may support a somewhat closer relation to Iran and Australia (e.g., Rigbyella, Archiasterella cf. hirundo Bengtson, 1990) which were part of equatorial Gondwana. Some connection may have existed to the European shelf of Perigondwana, too, as suggested by the shared occurrence of Microcoryne cephalata (Bengtson, 1990) and again of Archiasterella cf. hirundo Bengtson, 1990.

ACKNOWLEDGEMENTSI thank Michael Bassett (Cardiff, UK) and Leonid Popov (Cardiff, UK) for making available microfossils from their own field work in Israel. Important suggestions in poriferan investigation came from Joachim Reitner (Göttingen, Germany) and Dorte Mehl (Frankfurt/Main, Germany). Pierre Kruse (Adelaide, Australia) kindly helped in discussing helcionellids. Glenn A. Brock (Sydney, Australia) is deeply thanked for help with English. He and Christian B. Skovsted

(Uppsala, Sweden) provided important comments and suggestions which improved the paper. Rafie Shinaq (Irbid, Jordan), Thomas Wotte (Münster, Germany) and Thomas Biener (Ludwigsfelde, Germany) helped significantly during field work in Jordan. Jan Fischer (Freiberg, Germany) is thanked for technical assistance. Field work would not have been possible without the generous assistance provided by the Natural Resources Authority of Jordan (Amman, Jordan). Their long-lasting and fruitful cooperation is greatly appreciated. Investigations have received significant support from the German Research Foundation (DFG, Germany).

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