Marzanoptera tersillae, Bisconti & Damarco & Pavia & Sorce & Carnevale, 2021

Bisconti, Michelangelo, Damarco, Piero, Pavia, Marco, Sorce, Barbara & Carnevale, Giorgio, 2021, Marzanoptera tersillae, a new balaenopterid genus and species from the Pliocene of Piedmont, north-west Italy, Zoological Journal of the Linnean Society 192, pp. 1253-1292 : 1277-1278

MARZANOPTERA TERSILLAE SP. NOV.

( FIGS 3–16)

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: F3B4AA64-BEBC-47FA-8DE5-19B777B75BB1

Etymology: The fossil skeleton was discovered by Tersilla Argenta, for whom it was named.

Holotype: Specimen 207.13307 of the inventory of EGPPA-MPTA institution in Asti. The specimen includes most of the skull, with one periotic in articulation, seven vertebrae and nine ribs.

Horizon and locality: The holotype skeleton was discovered near San Marzanotto d’Asti (~ 6 km South from Asti, Piedmont, northern Italy). The geographical coordinates of the site of the discovery are 44°51′54.36″N and 8°13′13.33″E ( Fig. 1; Boni & Casnedi, 1970). The specimen was found in a hilly area in Asti Province, a site previously known because of the discovery of several marine mammals, including an almost complete, 9-m-long skeleton of a large balaenopterid whale assigned to ‘ Balaenoptera acutorostrata cuvieri ’ by Caretto (1970), which was discovered in Valmontasca (Vigliano d’Asti). That skeleton was subsequently regarded as a new taxon (still to be described formally) by Bisconti (2009). In this area, Caretto (1970) described a stratigraphic sequence ~ 53 m thick. At the bottom of this sequence, there are 5 m of clayey sediments in Piacenzian facies, overlapped by ~ 48 m of sands alternating with silty sand. In this second part, there are two layers with abundant molluscs, dominated by bivalves (Supporting Information, Table S1; Fig. S1). Polychaete tubes ( Ditrupa cf. cornea ) are also abundant in this fossil community lying beneath and near the bones. The particular diagenetic conditions associated with the water circulation in the sediments did not allow the preservation of the calcareous tests of foraminiferans except in a few cases. The few foraminiferans found showed worn tests and unrecognizable morphological features. Therefore, the study of the foraminiferans found at the site did not allow an accurate stratigraphic reconstruction. To obtain a more accurate chronostratigraphic assessment of the site, the mollusc assemblage was compared with assemblages from other sites of the Asti area where foraminiferans were more abundant ( Scarselli, 1990). This comparison resulted in the conclusion that the whale-bearing horizon corresponds approximately to the higher part of the Argille Azzurre Formation, close to the overlying Sabbie d’Asti Formation ( Carraro, 1996). The mollusc assemblage and the overall stratigraphic data support the hypothesis that the estimated age of the whale-bearing horizon is earliest Piacenzian, MPL4a foraminiferal zone of Rio et al. (1997) (between ~3.6 and 3.2 Mya).

Diagnosis: Given that in the text it is suggested that ‘ Balaenoptera ’ bertae Boessenecker, 2013 is to be assigned to Marzanoptera , a diagnosis of the new species is provided here. In proportion to the length of the supraoccipital (from the superior

border of the foramen magnum to the anterior border), Marzanoptera tersillae differs from Marzanoptera bertae in having transversely wider intertemporal region of the frontal, transversely s h o r t e r s u p r a o r b i t a l p r o c e s s e s o f t h e f r o n t a l, slightly shorter and stockier zygomatic process of the squamosal, and dorsal surface of the skull less rounded in lateral view.