Early Miocene stalked crinoids (Echinodermata) from the southern Rhodanian basin (southeastern France). Paleoenvironments and taxonomy
Author
Roux, Michel
Muséum national d’Histoire naturelle, UMR 7205 ISYEB MNHN-CNRS-UPMC-EPHE, Département Systématique et Évolution, CP
Author
Philippe, Michel
0000-0002-4582-8990
Centre “ Louis Lortet de conservation et d’étude des collections (Musée des Confluences, Lyon) 13 A, rue Bancel - 69007 Lyon, France. https: // orcid. org / 0000 - 0002 - 4582 - 8990
text
Zootaxa
2021
2021-10-15
5052
3
301
331
journal article
4004
10.11646/zootaxa.5052.3.1
7903d074-a590-48ba-b7e6-b515a0f1c65d
1175-5326
5572077
1EB14EF1-E205-4E37-85F9-DFD97BE93058
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.