Revision of the Middle Triassic coelacanth Ticinepomis Rieppel 1980 (Actinistia, Latimeriidae) with paleobiological and paleoecological considerations

• Published in: Swiss journal of palaeontology Vol. 142; no. 1; pp. 18 - 33
• Main Authors: Ferrante, Christophe, Furrer, Heinz, Martini, Rossana, Cavin, Lionel
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-12-2023; Springer; Springer Nature B.V; SpringerOpen
• Subjects: 100 years of scientific excavations at UNESCO world heritage site Monte San Giorgio and global research on Triassic marine Lagerstaetten; 20th century; Actinistia; Analysis; Besano Formation; Coelacanth; Coelacanthiformes; Earth and Environmental Science; Earth Sciences; Historic sites; Latimeriidae; Limestone; Monte San Giorgio; Morphology; Museums; New species; Paleoecology; Paleontology; Pasta; Research Article; Species diversity; Stratigraphy; Taxonomic revision; Ticinepomis; Triassic; World Heritage Areas; Germany; Davos Switzerland; Italy; Southern Alps; Switzerland; Monte San Giorgio; Middle Triassic; Coelacanth; New species; Prosanto Formation; Actinistia; Besano Formation
• ISSN: 1664-2376; 1664-2384
• DOI: 10.1186/s13358-023-00276-4

Coelacanths form today an impoverished clade of sarcopterygian fishes, which were somewhat more diverse during their evolutionary history, especially in the Triassic. Since the first description of the coelacanth
Ticinepomis peyeri
from the Besano Formation of the UNESCO World Heritage Site of Monte San Giorgio (Canton Ticino, Switzerland), the diversity of coelacanths in the Middle Triassic of this area of the western Paleo-Tethys has been enriched with discoveries of other fossil materials. At Monte San Giorgio, two specimens of
Heptanema paradoxum
and several specimens of the unusual coelacanth 
Rieppelia
heinzfurreri
, have been reported from the Meride Limestone and the Besano Formation, respectively. Another unusual coelacanth,
Foreyia maxkuhni
, and two specimens referred to
Ticinepomis
cf.
T. peyeri
have been described from the isochronous and paleogeographical close Prosanto Formation at the Ducanfurgga and Strel sites (near Davos, Canton Graubünden). In the framework of the revision of the coelacanth material from the Besano Formation kept in the collection of the Paläontologisches Institut und Museum der Universität Zürich (Switzerland), we reviewed the genus
Ticinepomis
on the basis of the holotype and four new referred specimens. Several morphological traits that were little and/or not understood in
T. peyeri
are here clarified. We re-evaluate the taxonomic attribution of the material of
Ticinepomis
cf.
T. peyeri
from the Prosanto Formation. Morphological characters are different enough from the type species,
T. peyeri
, to erect a new species,
Ticinepomis ducanensis
sp. nov., which is shown to be also present in the Besano Formation of Monte San Giorgio, where it is represented by fragmentary bone elements. The recognition of a new coelacanth species indicates that the diversity of this slow-evolving lineage was particularly high in this part of the Western Tethys during the Middle Triassic, especially between 242 and 240 million years ago.