New insights into the evolution of billfishes (Teleostei, Istiophoridae)
- Autor(en)
- Carlos Fernando De Gracia, Jürgen Kriwet
- Abstrakt
Extant billfishes represent some of the largest fishes in the open ocean in tropical to subtropical latitudes. They are at the top of oceanic food webs and contribute to their functioning and stability. Their distribution, population genomics and phylogeny have been extensively studied because of their ecological and fishery importance. Conversely, their fossil record and its evolution still remain poorly understood. The major obstacles in the study of fossil billfishes are the absence of well-preserved specimens combined with the poor stratigraphic constraints. Research in progress about the axial skeletal morphology and the phylogenetic relationships between fossil and living species shows that gigantism is a pattern associated with specific skeletal structures in the cranium and vertebral column. However, the role and origin of such morphological traits and the plesiomorphic state of crown billfishes remain ambiguous. In this work we present an unusual billfish association from Austria that was recovered from the early Miocene (~23 Ma) Konservat – Lagerstätten cropping out in Pucking (Ebelsberg Formation). The billfish assemblage includes the latest record of †Aglyptorhynchus (Paleorhynchidae), a new swordfish (Xiphiidae) species, and the earliest fossil record of the family Istiophoridae represented by two new species. This billfish fauna includes stem forms †Aglyptorhynchus co-occurring with the crown family Istiophoridae reported here for first time. The presence of †Aglyptorhynchus close a 5 Ma temporal gap between the first appearance of all extant billfish genera and the last appearance of any extinct billfish. The new xiphiid displays a previously unrecognized shape with large sail-like dorsal fins, elongated upper and lower jaws and large body size combined with an unusual morphology in precaudal vertebrae. This specimen with a protrusible sail – like dorsal fin and elongated upper and lower jaws demonstrate that both traits are plesiomorphic for extant billfishes. The new fossil marlins shows that istiophorids were smaller during the early Miocene and that gigantism appeared later during the evolution in this family. The fossil marlins also show that associated skeletal structures such as the lateral apophysis and one additional caudal vertebra can be gained or lost secondarily playing a key function in the diversification and gigantism of istiophorid billfishes. The first appearance of each billfish family occurred in the region of the Tethys Sea (or Paratethys) and our new evidence strengthens the hypothesis that this region is an origination point for Istiophoriformes.
- Organisation(en)
- Institut für Paläontologie
- Seiten
- 36-36
- Anzahl der Seiten
- 1
- Publikationsdatum
- 03-2022
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105118 Paläontologie
- Sustainable Development Goals
- SDG 14 – Leben unter Wasser
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/fcee0d8b-4487-4f2e-8abf-21865c9e2602