Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis
Author
Sandoval, José
text
Geodiversitas
2022
2022-09-15
44
27
801
851
journal article
10.5252/geodiversitas2022v44a27
835cc227-e5c4-4453-a956-07a154f8fa5f
1638-9395
7150329
urn:lsid:zoobank.org:pub:E4896081-9312-4EA6-AE33-AAC44201748E
Dorsetensia
? sp.
[M]
(
Fig. 14T
)
MATERIAL
EXAMINED. —
JAC22.57.3
.
MEASUREMENTS. — See
Table 27.
DESCRIPTION
Moderately evolute, whorl section compressed subrectangular with a low umbilical wall that almost matches the rounded umbilical edge. The flanks are gently convex and the ventral area is weakly tabulated with a moderately developed keel. The ribs, arising near the umbilical edge, somewhat irregular in thickness, are mainly simple but some tend to join in pairs near their base. Radial or only barely sinuous, they bend forward at the ventral edge. The ribbing weakens but does not disappear in the BC. The suture is not preserved.
TABLE 27. — Measurements of
Dorsetensia
? sp. [M].
| Specimen |
D |
U |
u |
H |
H |
W |
w |
Remarks |
Biostratigraphy
|
| JAC22.57.3 |
65.0 46.0 |
22.0 15.5 |
0.34 0.34 |
23.0 18.5 |
0.35 0.40 |
– – |
– – |
Almost complete |
Laeviuscula Subzone |
TABLE 28. — Measurements of
Dorsetensia regrediens
(
Haug, 1893
)
[m].
| Specimen |
D |
U |
u |
H |
h |
W |
w |
Remarks |
Biostratigraphy
|
| JRi3.28.1 |
27.0 |
11.0 |
0.41 |
9.0 |
0.33 |
12.0 |
0.36 |
Romani Subz. |
REMARKS
The specimen described above displays common characters with
Witchellia
gr.
laeviuscula
(J. de C.
Sowerby, 1824
)
and some primitive
Dorsetensia
such as
D. pinguis
(
Roemer, 1836
)
,
D.
hannoverana
(
Hiltermann, 1939
)
, and
D. hebridica
Morton.
W. laeviuscula
has a similar ribbing style, but is more involute and has greater whorl expansion. Also, the section is subtriangular instead of subrectangular.
Dorsetensia
gr.
pinguis
specimens have similar coiling, but usually have more developed ribbing.
DISTRIBUTION
This specimen is from the upper part of the Laeviuscula Zone, and is therefore older than
D
. gr.
pinguis
, from the JAC22 section, Campillo de Arenas (Jaén Province).