Mecaster fourneli (Deshayes, 1847)

Mohamed Abdelhamid, Marouf Abdel-Aty & Moustafa Azab, Mahmoud, 2012, Turonian-Santonian echinoids from Egypt, Geodiversitas 34 (3), pp. 575-615 : 606-607

Mecaster fourneli (Deshayes, 1847) ( Figs 15L, M; 17D, E )

Hemiaster fourneli Deshayes in Agassiz & Desor, 1847: 123. — Abdelhamid 1997: 154, fig. 7 (4). — Abdelhamid & El Qot 2001: 25, fig. 7C, D.

Periaster fourneli – Desor 1858: 383, pl. 42, fig. 5.

Hemiaster (Mecaster) fourneli – Abdel-Gawad etal. 2004: pl. 10, figs 12, 13. — El Qot 2006: 152, pl. 34, figs 2, 3. — Abdel-Gawad et al. 2007: pl. 6, figs 9, 10.

Mecaster fourneli – Smith & Bengston 1991: 61, pls 14A-M, 15A-L, 16E, F, figs 45K, L, 47, 48B, 50. — El Qot 2010: 280, pl. VI, figs 8, 9.

MATERIAL EXAMINED. — 16 measured specimens and numerous non measured from the Coniacian- Santonian of Abu Roash (Ostrea and Plicatula unit), ASUARE136-151, Abu Roash echinoid horizons 3-5 ( REH 3-5), four specimens and numerous non measured from the Coniacian-Santonian of Wadi Dakhl (Matulla Formation), ASUDLE183-186, Wadi Dakhl echinoid horizon 2 ( DEH 2), and one specimen from the Turonian (Wata Formation) of Wadi Abu Qaada, ASUAQE157, Wadi Abu Qaada echinoid horizon 2 ( QEH 2) and 12 from the Coniacian-Santonian (Matulla Formation), ASUAQE158-169, Wadi Abu Qaada echinoid horizon 5 ( QEH 5).

MEASUREMENTS. — See Table 14.

DESCRIPTION

Test size variable. Outline sub-hexagonal, and narrow at posterior. Anterior margin with conspicuous furrow. Apical disc semi-ethmolytic, transverse, centric to slightly eccentric backwards. Frontal ambulacrum nonpetaloid, wide, deep, and notching the ambitus until peristome. Pore pairs with small, oval, equal, nonconjugate, and oblique pores. Paired ambulacra petaloid, deep. Posterior paired petals shorter and less divergent than the anterior paired petals. Fascioles are composed of a wide band of peripetalous parafasciole (sensu Néraudeau et al. 1998).

Figures

FIG. 17. — Camera lucida drawings: A, phyllode and plastron plating in Toxaster dakhlensis n. sp. from the Turonian of Wadi Dakhl; B, C, Mecaster turonensis (Fourtau,1921) from the Turonian of Wadi Dakhl;B, apical disc;C, phyllode and plastron plating;D, E, Mecaster fourneli (Deshayes,1847) from the Coniacian-Santonian of Wadi Abu Qaada;D, apical disc;E, phyllode and plastron plating;F, phyllode and plastron plating in Mecaster duncani (Fourtau, 1906) n. comb. from the Turonian of Wadi Abu Qaada. Abbreviations: a, first half of the ambulacrum; b, second half of the ambulacrum; f, direction of enlargement of the scrobicules on the sternal plates (indicated by the arrows); V, ambulacrum no. 5. Scale bars: A, C, 2 mm; B, 0.36 mm; D, 0.4 mm; E, 1.4 mm; F, 1.3 mm.