Papacrinus avignonensis, Roux & Philippe, 2021

Roux, Michel & Philippe, Michel, 2021, Early Miocene stalked crinoids (Echinodermata) from the southern Rhodanian basin (southeastern France). Paleoenvironments and taxonomy, Zootaxa 5052 (3), pp. 301-331 : 323

Papacrinus avignonensis n. gen., n. sp.

Fig. 12D–F .

Type material. A single isolated nodal as holotype ( MHNL 20.062726 ) .

Etymology. From Avignon (reference to the type locality).

Diagnosis. As in description.

Type stratum. Late Burdigalian.

Type locality. Place du Palais des Papes in Avignon .

Description. Nodal with subcircular to pentalobate facets, H: 1.43 mm, D: 4.65 mm, H/D 0.31, identical symplexy on each facet ( Fig. 12D–E ) with pyriform to triangular closed petaloid zones, 12 Cr/PZ of variable size including 6 marginal ones, weak crenularium relief, massive protuberance curved proximally prolonging PZ ( Fig. 12E ); deep, subcircular cirrus sockets much lower than the nodal height, nearly tangent to the distal N facet border, with two strong triangular culminae ( Fig. 12F ).

Remarks. The symplexial crenularium of Papacrinus avignonensis n. gen. n., sp. is of balanocrine-type (see Fig. 2D ). Such side protuberances are unknown in extant and fossil Isocrinida . The particular morphology of this nodal justifies the creation of a new genus. Its size and relative thickness suggest that it belongs to the distal stalk of a young individual. The absence of a cryptosymplexy is usually a paedomorphic character of the proximal nodals without phylogenetic significance. It is retained in the distal stalk of Proisocrinus . In this genus, symplexies differ from those of Papacrinus n. gen. in having always open PZ; moreover, rudimentary cirri are restricted to proxistele and in mid to distal stalk there are only nudinodals (Bourseau et al. 1991). Pending new discoveries allowing a more complete description, the symplexial characters lead us to place Papacrinus n. gen. provisionally in the subfamily Balanocrininae .

Occurrence. Only known from Avignon (Palais des Papes), Late Burdigalian.

Figures

FIGURE 2. Morphology of crinoid ossicles. A–D in isocrinid stalk, A: side view of a stalk segment (Ci: cirrus, IN: internodal, N: nodal, D: diameter, H: columnal height, Lnd: noditaxis length), B: symplexial facet of metacrinine type (IPZ: interpetaloid zone, PZ: petaloid zone, icr: inner crenularium, igr: interpetaloid groove, lg; ligament area, mdcr: middle crenularium, mgcr: marginal crenularium, pl: perilumen), C: symplexial facet of diplocrinine type (opz: open petaloid zone), C: symplexial facet of balanocrinine type (cpz: close petaloid zone); E–F: in isocrinid arm, E: proximal arm pattern in Metacrinus (IBr: primibrachials, IIBr: secundibrachials, R: radial, s1: synostosis at IBr1+2, s2: synostosis at IBr4+5); F: facet of muscular synarthry (al: aboral ligament depression, il: inner ligament area, m: muscular area, ps:pinnule socket); G–H: in rhizocrinid columnal, G: distal view, H: side view (fr: fulcral ridge, ri: rhizoid insertion). Measured parameters, D: greatest diameter including insertion of rhizoid, D’: greatest articular facet diameter without rhizoid insertion, d: smallest articular facet diameter, H: columnal height, ri: rhizoid insertion).

FIGURE 12. Isocrinid and rhizocrinid columnals. A–K: from Palais des Papes in Avignon; A–C: Metacrinus berthei (MHNL 20.062719), A–B: symplexies with anomalous 4-symmetry, C: distal internodal from a young individual; D–F: Papacrinus avignonensis n. gen., n. sp. (MHNL 20.062726), D: oblique distal view, E–F: oblique proximal view, F: close up of cirrus socket; G–K: Paraconocrinus rhodanicus n. sp. (MHNL 20.062727), G–H: columnal from dististele, G: proximal view, H: close up of fulcral ridge, oblique view, I: columnal from middle mesistele, J: columnal from proximal dististele, proximal view, K: columnal from proximal dististele, side distal view; L: Gastecrinus viticolis n. gen., n. sp. from Vigne Gaste (Istres), aboral cup (MHNL 20.062729). Scale bar equals 1 mm in A–F and L, 0.5 mm in G and I–K, 0.1 mm in H.