Pantanellium squinaboli (Tan, 1927)

Dumitrica, Paulian, Dieni, Iginio & Massari, Francesco, 2022, Valanginian Radiolarians Of Ne Sardinia (Italy) In The Frame Of The Weissert Event, Acta Palaeontologica Romaniae 18 (2), pp. 97-159 : 109

Pantanellium squinaboli (Tan, 1927)

Figs. 7j , l-n1

1927 Stylosphaera squinaboli Tan , p. 35, pl. 6, figs. 9a-d. 1981 Sphaerostylus lanceola (Parona, 1890) group – Schaaf, p. 438, pl. 7, fig. 6; pl. 16, figs. 5-a-b.

1981 Sphaerostylus lanceola (Parona) – Kanie et al., pl. 1, fig. 6.

1994 Pantanellium squinaboli (Tan) – Jud, p. 90, pl. 15, figs. 10-12.

1995 Pantanellium squinaboli (Tan) part. – Baumgartner et al., p. 372, pl. 5067, figs. 1, 2, 4, not 3, 5-7.

1997b Pantanellium corriganensis Pessagno , p. 33, pl. 3, figs. 5, 6.

2014 Pantanellium squinaboli Tan – Robertson et al., fig. 10(B), 2.

2017 Pantanellium squinaboli Tan – Xu & Luo, figs. 3 P, Q.

Dimensions. Diameter 122-135µm, length without spines 130-150 µm, length of spines 75-100 µm.

Remarks. What is very characteristic of this species in the S’Ozzastru fauna, besides its general morphology with wide pores, nodes at vertices and a very thick cortical shell, is the ornamentation of the internal faces of pores, which have numerous tiny pustules disposed in radial and circular rows ( Figs. 7m 1 , 7n 1 ). These pustules are nothing else than remains of a dense spongy meshwork that infilled the pore cavities and the surface of the cortical shell. Such a spongy meshwork is common in an unpublished pantanellid species occurring in the very well-preserved lower Tithonian radiolarian fauna of the sample Mo 22 from the Solnhofen area partly published by Zügel ( 1997), Dumitrică & Zügel (1998, 2003, 2008) and Dumitrică (2013a, 2013b). In the Solnhofen species, this spongy meshwork, when very well preserved, is so thick that the species determination is almost impossible.

Range and occurrence. Tithonian to late Barremian.

Figures

Fig. 7 a - Praeconosphaera sphaeroconus (Rüst OZ826. b-d - Praeconosphaera antiqua (Parona): b - OZ834, c - OZ838, d - OZ825. e - Tritrabs ewingi (Pessagno), arm in lateral view, OZ836. f-h - Emiluvia chica Foreman, OZ836; f - face view, g - lateral view from a spine, h - lateral view of a broken specimen showing the medullary test. i - Pantanellium sp. 1, OZ825. j, l-n1 - Pantanellium squinabolli (Tan): j - OZ834; l, m - OZ834, n - OZ836; m1, n1, details of inner wall of pores. k - Pantanellium sp. 2, OZ834. o – Pantanellium cf. squinaboli (Tan), OZ836; p - Praeconocaryomma copiosa Wu, OZ836. r - Praeconocaryomma thurowi Dumitrică n. sp., OZ836. s, t - Triactoma tithonianum Rüst, side views; s - OZ834, broken off specimen showing medullary shell; t - OZ825, equatorial view, t1 – face view; s1, t2 - detail of the base of spines of figs. s and t, respectively, x800. Figs. a-h, l-n x200; i-k, o-r x300; s, t x400, m1, n1 x500.

Fig. 1 Geologic map of the Siniscola area, NE Sardinia (from Dieni & Massari, 1971, updated in 1986). Legend: a - Recent and present alluvial deposits (Holocene). b - Scree deposits (Würm-Holocene). c - Detrital cones mostly composed of gelifraction limestone clasts (“éboulis ordonnés”) (Würm-Holocene). d - Uncemented alluvial cones mostly consisting of limestone clasts (Würm-Holocene). e - Terraced alluvial deposits composed of clasts of basement rocks (Riss?). f - Tightly cemented and dismembered alluvial cones mostly made up of gelifraction limestone clasts (Riss?). g - Cuccuru ’e Flores Conglomerate: polymict, chaotic and thick-bedded breccia and stratified sandstone (middle Eocene). h - Siniscola Marl: grey and grey-yellow marl and, in the upper part, alternating marl/marly limestone with ammonites and very abundant radiolarians and sponge spicules (late Valanginian). i - Schiriddè Limestone: light-brown cherty limestone and limestone with marly interbeds, containing ammonites, radiolarians, sponge spicules and calpionellids (early Valanginian). j - Monte Bardia Limestone: thick-bedded to massive white limestone in places bioconstructed, with corals, nerineids, etc. (early Tithonian - late Berriasian). k - S’Adde Limestone: light-brown to grey fine-grained, well-bedded limestone, condensed with hardgrounds near the base, cherty in the upper part, with ammonites and belemnites in the uppermost part (latest Bathonian - earliest Tithonian). l - Dorgali Formation: well bedded quartz-arenitic and locally ooidal brown dolostone (middle-late Bathonian). m - Crystalline basement (phyllite, micaschist, paragneiss, quartzite, etc.) (Palaeozoic). n - Fault. o - Attitude of beds and schistosity planes. p - Limits of slumped masses of Jurassic formations (Quaternary). q - Concave-upward slip surfaces delimiting rotational slumps (Quaternary). r - Edge of fluvial terrace. s - Quarry. A-A’ Trace of the geological section of Fig. 2. (extracted from Bottini et al., 2018).