Paleontological Data Reveals Unexpected Biogeographic Histories of Extant Organisms: Bonytongue Fishes (Teleostei: Osteoglossomorpha) as a Case Study

• Main Author: Capobianco, Alessio
• Other Authors: Friedman, Matt, Rabosky, Daniel, Lopez-Fernandez, Hernan, Smith, Stephen A, Wilson, Jeffrey A
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: Paleontology; Biogeography; Ichthyology; Fossil; Osteoglossomorpha; Systematics; Geology and Earth Sciences; Science; Arctic; Greenland
• Online Access: https://hdl.handle.net/2027.42/170076; https://doi.org/10.7302/3121

Paleontological data are invaluable for reconstructing the biogeographic history of living organisms. Nonetheless, information from present-day species (neontological data) dominates biogeographic studies of extant clades, due to either incompleteness of the fossil record or challenges in integrating it into evolutionary inference. In this dissertation, I explore the paleontological record of the freshwater fish clade Osteoglossomorpha (bonytongues) to derive a deep-time perspective on the biogeographic history of this ancient and iconic group of fishes. The complex geographic distribution of extant bonytongues, coupled with their abundant fossil record when compared to other tropical freshwater fishes, makes this group an ideal target for biogeographic investigation through a paleontological lens. I first consider the temporal and geographic distribution of the fossil record of seven extant freshwater fish groups – including bonytongues – to derive confidence intervals on their times of origin and test the plausibility of vicariant scenarios in which continental break-ups shaped their modern distributions. I find that, even when fish groups are old enough to have been affected by continental fragmentation during the Mesozoic, successive dispersals and regional extinction tend to erase or confound vicariant patterns and shape the geographic distributions that we see today. The middle portion of my dissertation involves the description of two bonytongue fossil specimens from early Cenozoic marine deposits in Greenland and Morocco. The Greenland specimen extends the geographic range of the group to the Arctic and represents one of their earliest records in marine deposits, few million years after the Cretaceous–Paleogene mass extinction. The Moroccan specimen represents a new genus with cranial adaptations related to feeding ecology previously unknown in these fishes. I show how bonytongues reached a surprising ecomorphological diversity in marine settings during the early Cenozoic, and identify key anatomical ...