Holothurian sclerites from the Triassic of Jordan and their stratigraphic importance

Holothurian selerites are some of the most stratigraphically important microfossils of the middle Triassic of Jordan. Stratigraphically and palaeogeographically important faunas have been obtained by dissolving Triassic carbonate rocks with a dilute acetic acid. The oldest forms, Acanthotheelia jordanica Sadeddin, Priscopedatus quadratus Kozur & Mostler, and Tetravirga perforata Mostler, occur in the Hisban Formation (Anisian) in the area of the northeast corner of the Dead Sea and Wadi Abu Oneiz. North of this area in Wadi Salit, Ladinian holothurian faunas are especially characterized by the mass occurrence of Schizotheelia jordanica and Schizotheelia multiporata Kozur & Sadeddin in the lower part of the section (Fassanian) and Theelia tubercula Kristan-Tollmann in the upper part (Longobardian). In spite of some differences, the Jordanian Middle Triassic holothurian faunas are similar to those from the Northern Alps and Germanic Basin, and the Himalayas. As yet, no holothurian selerites have been recovered from Jordanian Lower or Upper Triassic deposits.


Adasiah (Area 2! of
) Samples N 8 (NTS) and NY were collected from the Hisban Formation (lower part of the Hisban Limestone Member) at Wadi Abu Oneiz 2.5 km SW o f Adasiah (Fig. Ib). Both samples were taken from the massive, thick bedded grey limestone (N9 is 5 m above N8). They yielded rich holothurian sclerite faunas containing Teirauirgu perforuta Mostler, C'alclum~na

Wadi Hisban section (Fig. l a )
Based on conodonts (belonging to Nrogonr/olella hiilgaric~a), a middle Anisian (Pelsonian) age is warranted for the lower part o f this section. The presence of Parrigondolrllrr htitihirlogi in sample 7b, C;ontlolellrr constrictrr in sample Xb, and accompanying macrofossils such a s ammonites (Heneckeitr Irvuntinu) and brachiopods (Coenothyris vidgnris) indicate an upper Anisian (Illyrian) age for the middle and upper part of this succession.
The lower and middle part of thc Jalda section can be correlated with the section of Wadi Hisban, whereas strata referred to the upper part of the Jalda section are not exposed in Wadi Hisban.

Ahu Oneiz section (Fig. lb)
No age diagnostic microfossils have been found in the basal part of this section. Based on lithostratigraphic correlation with analogous sequences in area I , a lower Anisian age is justiticd for this part. In the middle and upper part of this section which represents the Hisban Limestone Member, holothurian faunas have been found (samples N3, N7, N8. NY, and Nx) that are especially characterized by the oldest Acanthorheelia (Acunthothrdia jordanica Sadeddin. 1YYl). A Pelsonian (middle Anisian) age (well dated by a conodont fauna collccted by the author with Nicoraella gerrnanicu, Nicoruella kockeli and Neogondolella hrdgarica) is warranted for the middle and upper part of Abu Oneiz sequence.

Wadi Salit section (Fig. lc)
The basal portion of this and the uppermost portion of the Jalda section are very similar . Samples 15. IS', IS" and IS"' contain abundant holothurians that are also especially characterized by Schizotheelia jordanica and Schizothedia tizirltiporatu. The accompanying conodonts collected by the author (P,~eiidofitrnishiii.s priscirs) are analogous to those of the upper portion of Jalda section, indicating a Fassanian (early Ladinian) age. No holothurian sclerites have been found in the samples directly above samples 14, 13, 12. I I . from the lowcr part of this section. The presence of Budrrrovignuthu.s triienipyi Hirsch in sample 12 indicates an uppermost Fassanian (Fassanian/ Longbardian) age for this part of the section. In samples 10. 8. 7, 7",h, 6 , 5, S", 4, 4' and 4" holothurian sclerites have been recorded that are characterized by the frequent occurrence of Theelia tuhc,rciila which appears in all samples except sample 7 and 7". Samples 10 and 8 contain conodonts belonging to P.seirdofiirni.shiiis sosioensis which Gullo & Kozur (1 989) placed in the lower Longobardian: macrofossils have also been reported comprising Trigonodits sp. (sample lo), and Posidonicr wengensis (sample 8). P1uciinopsi.s fiubelliinz has been found in the horizon from which samples 7 and 7" were collected. These samples and samples 6, h', 6". 5 and 5" have yielded highly evolved representatives of Pseudofiimishiirs tiiirrcicrriiis (biplatform type) and a middle Longobardian age is indicated for this part of the succession. In samples 4. 4' and 4 which contain frequent Therlia tiiherciila, conodont:s comprising Psc.iidoji*rnishiiis micrciunii.~ (exclusively rnionoplatform type) and Biidurovignuthirs miingoensis, partly transitional to Biulicrouignathiis dieheli, have been found. This level (4, 4', 4") belongs to the higher Longobardian-Ladinian/Carnian boundary. The next higher beds which consist of dolomite, gypsum, cellular dolomite are analogous to the germanic lower 'Gipskeuper' and the adjacent areas. Based on lithostratigraphic correlation with these sequenca, an early Carnian age is indicated for these beds.

Wadi Huni section (Fig. Id)
Based on the 'conodonts Budiii~ouigtznthit.~ nzungoensis and B. nzostlt~ri an uppermost Longobardian-lowest Cordevolian age (I,andiniam/Carnian boundary) is indicated for the holothurian-bearing lower part o f this section. The middle and upper part of this section (gypsum and shale members of Abu Ruwais Formation) overlaying the carbonate member, is correlatable with the top part of the Salit section (shale member is missing) and analogous to the lower 'Giipskeuper' of the Germanic Basin and the adjacent areas (lower member of Mohilla Formation, Israel). On the basis of i.he lithostratigraphic co'rrelation with the aforcmentioned sequences, an early Carriian age is warranted for the middle and upper part of Wadi Huni section.

DISCUS,SION
The Triassic of Jordan belonge'd to a marginal sea south of the southern Tethys. In Skythian sediments which are exposed at the eastern rim of the Dead Sea (twenty samples have been studied), no holothurian sclerites have been found as yet. The first association appears in Anisian carbonate rocks from Wadi Siyala (area 1, Fig. 1 Mostler. These associations are characterired by the frequent occurrerice of Acanthothec~lia jorrlunicn Sadeddin which appears in thc Pelsonian of Jordan. According to Mostler (1970Mostler ( , 1973) Acanthotheelia Frizzell & Exline appears in the Illyrian (Upper Anisian) of the northern calcareous Alps, Hungary and western Carpathians. Kozur (1969) and Kozur & Mostler (1970) did not report Acanthothrelia in the holothurian sclerite associations from the Pelsonian (Middle Anisian) of thc Germanic Basin.
The early Middle Triassic I( Anisian) holothurians from Jordan are, with some differences, similar to thosc o f North Tethyan faunas known from the northern Alps, western Carpathians and the Germanic Basin (Sadeddin, 1991) In the Illyrian (Upper Anisian) from Wadi Hisban and Wadi Siyala (Fig.1 a ) Kozur,77ierlia sp., Acliistriini monochorriata Hodson, Harris and Lawson arc present.
The Fassanian (early Ladinian) holothurian sclerite associations from Wadi Siyala (top of Jalda section, Fig.la) and from Wadi Salit section (Fig.lc) Mostlcr, 1971) late Middle Triassic (Ladinian ) rocks yield the same holothurian species that occur in other rcgions o f this province .
Thcdia tiibm-iilu which has been regarded so far as an index species for thc Cordevolian (early Carnian) was found in the early Longbardian (early late Ladinian) o f Jordan together with the conodont species P,teiitlofiirniJhiiis .so.sioensis Gull0 & Kozur. I t occurs in shallow-water sediments as well as in pelagic sediments. is regarded as a palaeogeographic indicator for the southern Tethys and its marginal seas, and has the same distribution as the conodont genus ~.seiidofiirni.shiii.s , see also Kozur & Simon (1972. Kozur ct (11. (1985). In the higher sediments (Wadi Salit and Wadi Huni, Fig.lc, d) which belong most probably to the early Carnian. no holothurian sclerites have been found.
In addition to holothurian sclerites crinoid debris. echinoids, conodonts, ostracods, foraminiferans, microbivalves, microgastropods and fish remains are present in most studied samples. No relationship could be discerned between the presence or abundance of holothurians with any o f these fossil groups.

SYSTEMATIC PALAEONTOLOGY
Thc classification followed is that of Frizzell & Exline (1955h), which is based on the morphology of the sclerites. and has an artificial character.  Material. 14 specimens.
Occurrence. Pelsonian of Jordan (in the lower part of Hisban Limestone) 25 m below the 'Terebratel beds' with Beneckeia spp. Description. Wheel-like large sclerite with 7-9 spokes and subcircular t o polygonal outline. Periphery always with one large spine opposite to every interspoke space. Distal ends of spines often expanded knob-like. Rim moderately broad, its inner margin not or only slightly bent inward. Spokes moderately long, straight, mostly broad but some times narrow, of equal width throughout. Hub small to medium-sized. llpper surface of hub convex and sometimes higher than upper margin of rim. Lower surface slightly convex to plane.

Theelia zapfei
Theelia cf. T . zawidzkae Kozur & Mock. 1972 (PI. 2, fig. 5  Description. Hub round. small, lies slightly elevated above the plane of the sclerite on both sides or at the same level, with flat or slightly concave centre. From the hub emanate 7-1 1, predominantly 9-10 narrow spokes of the same width throughout. Interspoke spaces drop-like, pointing inwards, always larger than outer pores. Spokes are multi-furcated whereby the adjoining branches produce dilferent-sized pores, which generally become smaller outwards. The pores are irregularly shaped: rounded, oval, or drop-like and may be elongated either parallel or perpendicular to the periphery.  Remarks. Schizoacanthotheelia spiniperforata Zawidzka, 1971 from the upper Anisian of west Carpathian and from Cordevolian of Spain, differs from Schizotheelia jordunica by having distally uni-or bi-furcated spokes. Schizotheelia schizomata Kristan-Tollmann, 1973 from Carninan of the southern Alps, has lancet shaped, proximally and distally pointed interspoke spaces and pores. Schizotheelia multiporata Kozur & Sadeddin has small or unequally sized interspoke spaces. Kozur & Sadeddin,19Y2 (PI. 2, fig. 8