HUMEROCYRTIIDAE, Dumitrică, 2024

Dumitrică, Paulian, 2024, New Middle Triassic Bell-Shaped Nassellarian Radiolaria From Alpine And Carpathian Areas, Acta Palaeontologica Romaniae 20 (1), pp. 51-75 : 64-65

Family HUMEROCYRTIIDAE n. fam. Type genus: Humerocyrtis n. gen.

Diagnosis. Shell dicyrtid, bell-shaped with the proximal part of the thorax laterally expanded forming a kind of shoulder. Cephalis simple with initial spicule without dorsal ray, and primary and secondary lateral rays not extended outside shell surface. Apical and ventral rays extended outside into spines of different sizes and structures, usually three-bladed or conical and never hollow. Thorax latticed, perforated by circular or polygonal pores and usually wide open distally.

Remarks. The species of this new family differ from those of the family Gorispelidae n. fam. by not having hollow apical and ventral horns and by having the proximal part of the thorax laterally extended forming a kind of shoulder. It seems that, by some of its species such as Humerocyrtis gracilis n. sp. and others, this family, together with some species of the genus Goestlingella Kozur & Mostler (see Dumitrica 1917), marks the first appearance in the paleontological record of nassellarians with simple wall and circular pores arranged in a quincuncial manner, a type of arrangement common in many Jurassic, Cretaceous and especially Cenozoic species.

The species of this genus can be grouped in three subgroups:

1. Species with bigger skeletons, apical and ventral spines three-bladed and pores of the distal part of thorax disposed in circumferential rows: Humerocyrtis superba n. sp., H. deweveri n. sp., H. lahmi n. sp. and H. avirostrum n. sp., Humerocyrtis n. sp.

2. Species with smaller skeleton, apical horn three bladed and well developed, ventral spine very small, and thorax with pores arranged irregularly or quincuncially in oblique rows; H. jekeli n. sp., H. contraria n. sp., H. conica n. sp.

3. Species with apical horn conical and not hollow, and ventral spine three-bladed or conical.

Stratigraphic range. Middle Anisian (Pelsonian) to lower Ladinian so far as known.