A NEW LOWER VALANGINIAN AMMONITE FAUNA FROM SW SICILY

1. A new lower Valanginianammonite fauna fromSW Sicily
3° Palaeontological VirtualCongress, 1st – 15th December 2021
Antonello D'Alessandro1, *, Johannes Pignatti2
* Corresponding author email: antonellodalessandro78@gmail.com
1Via Caprareccia, 23, 02034, Montopoli di Sabina (RI) Italy
2Department of Earth Sciences, “La Sapienza” University, P.le Aldo Moro 5, 00185 – Roma

2. Introduction
During an excursion to an active quarry in the Province of Agrigento, the richest italian ammonite
fauna of the lower Valanginian of the Lattimusa Formation, belonging to the Saccense Domain, was
discovered. This allows to describe systematically, for the first time, ammonites from the Lower
Cretaceous of Sicily. This fauna is interesting for the finding of species never mentioned from the
island, some never recorded from Italy, and for a genus and a species of Olcostephanidae new for
science.
Geographical and geological contexts
Contrada Diesi quarry.Mod. from Marino et al. (2004)
UpperTriassic
Lower Jurassic
Middle – UpperJurassic UpperJurassic
Lower Cretaceous
Geographical location.FromGoogle Maps (Access 12-2020)

3. Layer A: 270 specimens
23 species, 14 genera, 6 family
Layer A2: 17 specimens
10 sp., 9 gen., 6 fam.
Layer B: 9 specimens.
4 sp., 4 gen., 3 fam.
Total specimens:296.
25 species, 15 genera, 7 families
The faunal composition
1) Marly limestone, 2) Calcareous marl

4. The new genus and species
1) Olcostephanidae nov. gen. nov. sp.
(m) D = 10,5 mm;
2) Olcostephanidae nov. gen. nov. sp.
(M) D = 18.0 mm
1 2 3 4 5
1 2
4
3
5
6 7
Species never cited from
Sicily
1) Vergoliceras salinarium (Uhlig,
1887) D = 21.0 mm;
2) "Thurmanniceras" pertransiens
(Sayn, 1907) D = 14.0 mm;
3) Kilianella roubaudiana
(d'Orbigny, 1850) D = 19.2 mm;
4) Neocomites premolicus Sayn,
1907 D = 19.4 mm;
5) Bochianites sp. Length = 9.0
mm;
6) Protancyloceras bicostatum
Arnould-Saget, 1951 Length =
11.6 mm;
7) Protancyloceras punicum
Arnould-Saget, 1951 Length =
17.5 mm
Species never cited from Italy
1) Protetragonites cf. juilleti (d’Orbigny,
1841) D = 37.0 mm;
2) Kilianella lucensis (Sayn, 1907) D =
34.2 mm;
3) Kilianella grossouvrei (Sayn, 1889) D =
20.7 mm;
4) Sarasinella cf. eucyrta (Sayn, 1907) D
= 41.0 mm;
5) Protancyloceras sp. Length = 6.5 mm;
6) Protancyloceras cristatum Arnould-
Saget, 1951 Length = 9.0 mm
1 2
3 4
5 6
The accompanying fauna
1) Scleractinia indet. D = 12.2 mm;
2) Pholadomya sp. Height = 25.2 mm;
3) Lamellaptychus sp. Length = 22.2 mm;
4) Pygites diphyoides (d'Orbigny, 1849) Height =
27.9 mm;
5) Duvalia sp. Length = 77.4 mm
1 2
The fauna

5. Biostratigraphy
All the species found, listed in the chart below, appear to be coeval. The composition of the fauna, expecially the presence of "T."
pertransiens and N. premolicus, indicates the Neocomites premolicus Subzone, the base of the "Thurmanniceras" pertransiens Standard
Zone of the basal Valanginian.
"Thurmanniceras"pertransiens
(Sayn, 1907)
D = 18.2 mm
Standard zones Subzone
Paleobiogeography
The fauna clearly belongs to the Tethyan
Realm for the abundance of
Phylloceratoidea, Lytoceratoidea and
Neocomitidae, and for the lack of Boreal
taxa.
NeocomitespremolicusSayn, 1907
D = 19.4 mm