Saccocoma vernioryi Manni and Nicosia, 1984

Brodacki, Michał, 2006, Functional anatomy and mode of life of the latest Jurassic crinoid Saccocoma, Acta Palaeontologica Polonica 51 (2), pp. 261-270 : 268-269

publication ID	https://doi.org/ 10.5281/zenodo.13643883
persistent identifier	https://treatment.plazi.org/id/038F7D2E-FF8D-FFF1-CA13-F6CD3AD1FB05
treatment provided by	Felipe
scientific name	Saccocoma vernioryi Manni and Nicosia, 1984
status

Treatment

Figs. 3F–I View Fig , 4F View Fig , 5G View Fig , 6D View Fig .

1972 Saccocoma sp. indet.; Hess 1972: 639, pl. 2: 24.

1972 Non−identifiable elements; Hess 1972: 639, pl. 2: 26.

1979 Saccocoma cf. quenstedti Verniory, 1961 ; Pisera and Dzik 1979: 811–813, fig. 4a, c–e.

1979 Saccocoma sp. ; Pisera and Dzik 1979: 812, fig. 4b.

1984 Saccocoma vernioryi Manni and Nicosia, 1984: 91–97 , figs. 1–16.

1987 Saccocoma cf. quenstedti ; Głuchowski 1987: 40–41, pl. 17: 2, 3, fig. 13: 11.

Material.—More than 50 radials, about 15 brachials and many broken−off radial spines.

Description.—Radials ( Fig. 3F–I View Fig ) as in Saccocoma tenella , but equipped with two pairs of spines, one projecting upward and the other downward, at the base of the articulation facet. The spines may branch, but are usually broken in the studied material. The second primibrachial or primaxillary (IBr2 = IAx; Fig. 4F View Fig ) is small (about 1 mm wide and long), triangular in outline, with a sloping non−muscular articulation facet on the proximal and two muscular facets on the distal side. The wings have a distinctive bell−shaped profile, different from dish−like wings of S. tenella . The second secundibrachial (IIBr2; Fig. 5G View Fig ) generally resembles the IBr2, but it has only one distal articulation facet (muscular) and the wings are asymetrical. The only identified distal secundibrachial of higher order (IIBr5, IIBr6 or IIBr7) has muscular articulations at both ends and low, but distinct oral projections.

Remarks.—Although no articulated specimens of this species are known, the spiny radials can be unequivocally considered conspecific with the bell−shaped brachials, as Manni and Nicosia (1984) found such radials in strata where no other species of Saccocoma occurred. They described all types of ossicles, including the wingless IBr1, IIBr1, and IIBr3 which seem to correspond to their equivalents in S. tenella (except that, in my opinion, the first secundibrachial in both species must have been similar to the first primibrachial, not to the third secundibrachial, as I have explained earlier in this paper). The present material is not as rich; I identified only about a dozen very small and delicate IBr2 and IIBr2, evidently belonging to juvenile individuals ( Figs. 4F View Fig , 5G View Fig ), and a single poorly preserved secundibrachial of higher order (IIBr5, IIBr6 or IIBr7; Fig. 6D View Fig ). Nevertheless, broken radials of this species are quite common; usually only the area around the articulation facet (with damaged spines attached) is preserved. There is also an abundance of broken−off spines.

A large second secundibrachial (IIBr2) and presumably two other brachials of this form have been illustrated by Pisera and Dzik (1979: 812, fig. 4c–e) under the name Saccocoma cf. quenstedti . These ossicles were attributed by Manni and Nicosia (1984) to S. vernioryi . They apparently represent adult individuals as opposed to the juvenile ones here described. However, in the present material there were no such elements.

Saccocoma aff. vernioryi Manni and Nicosia, 1984 Figs. 4D, E View Fig , 5E, F View Fig , 6G View Fig .

Material.—About 10 brachials.

Description.—This group of ossicles includes second primibrachials or primaxillaries (IBr2 = IAx; Fig. 4D, E View Fig ) with relatively short wings which extend distally but not proximally. The large, sloping non−muscular proximal articulation facet projects beyond the proximal margin of the wings, as in S. vernioryi . However, the wings are not bell−shaped as in this species but flat or slightly concave, as in S. tenella. On the aboral side, there is a more or less pronounced depression at the base of each wing ( Fig. 4D View Fig 2 View Fig ), which may be overgrown by a broad lamella that extends from the central part of the ossicle to the sides ( Fig. 4E View Fig 2 View Fig ) and leaves only narrow fissures visible in lateral views ( Fig. 4E View Fig 3 View Fig ). This lamella has some small perforations and shows traces of reticulate sculpture. The oral side bears three large processes. The distal end of this ossicle is high, with two conspicuous muscular articulation facets ( Fig. 4E 4 View Fig ). The corresponding ligament fossae are large and well−visible in the aboral view ( Fig. 4E View Fig 2 View Fig ). With a developed aboral lamella, the ossicle has a compact and massive general appearance. The second secundibrachial (IIBr2; Fig. 5E, F View Fig ) is similar to the IBr2, but has only one distal articulation facet and no median processus.

The only identified secundibrachial of higher order (IIBr5, IIBr 6, IIBr 7 or more; Fig. 6G View Fig ) is short, broad, has small wings and well−developed proximal and distal muscular articulation facets with large ligament fossae. Its aboral side has a broad lamella and the oral surface shows roots of two presumably large processes.

Remarks.—The brachials described here resemble the brachials of adult Saccocoma vernioryi with regard to the protruding proximal articulation facet, high distal end and general outline. However, the wings are not bell−shaped, but flat or slightly concave. Additionally, on the aboral side there is a lamellar overgrowth that extends laterally and makes the elements look more robust and massive than those of S. vernioryi . A single broken radial with very massive spines ( Pisera and Dzik 1979: 812, fig. 4b) may match these brachials. They either represent a species closely related to S. vernioryi , or simply belong to senior, highly calcified individuals. At the moment, there are not enough such elements to settle this issue.

Kingdom	Animalia
Phylum	Echinodermata
Class	Crinoidea
Order	Roveacrinida
Family	Saccocomidae
Genus	Saccocoma