Comparative morphology between extinct and extant forms provides evidence for earlier radiation in istiophorid billfishes (Teleostei, Istiophoriformes).
- Author(s)
- Carlos Fernando De Gracia, Felix Rodriguez, Orangel Antonio Aguilera Socorro, Carlos Jaramillo, Jürgen Kriwet
- Abstract
Billfishes include some of the largest pelagic teleostean species, but several aspects
about their morphology, paleobiology and evolution remains ambiguous. Their fossil
record is very fragmentary and mostly represented by rostral and skull remains. Here,
we present a comparative study of the caudal vertebral morphology of extant
istiophorid species and we use this information to describe two fossil vertebrae from
the Gatun and Chagres formations, both from the late Miocene of Panama. The caudal
vertebra from the Gatun Fm. is characterized by the presence of a lateral apophysis
and accordingly identified as Makaira sp., while the vertebra from the Río Indio Member of Chagres Fm. lacks this structure and its morphology indicates a different genus. The estimated total length of the Makaira sp. specimen from Gatun Fm. is about 5.18 m, the largest size calculated for a marlin, while the Rio Indio specimen was about 2.56 m long. The phylogenetic analysis conducted here demonstrates that crown istiophorids lack lateral apophyses on the caudal vertebrae. Loss of this feature most likely evolved in the Pliocene when crown istiophorids diverged from its closest relative. However, the fossil vertebra from Río Indio proves that the lateral apophysis already had been lost in some istiophorids during the late Miocene, ~8.3 – 7.1 Ma. Our results highlight that both Makaira ssp. and taxa lacking the lateral apophysis already occurred during the late Miocene, indicating that the radiation of crown istiophorids most likely occurred earlier.- Organisation(s)
- Department of Palaeontology
- External organisation(s)
- Smithsonian Tropical Research Institute, Universidade do Estado do Rio de Janeiro
- Volume
- 142
- Pages
- 17
- No. of pages
- 1
- Publication date
- 09-2021
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105118 Palaeontology
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/2baa2499-f6b2-4df7-83a7-f40ccae4569f