Research projects

Prof. Dr. Marcelo Sánchez

The fossil record and evolution of the neotropical fish fauna

Leadership/contacts

Duration

January 2025 to December 2029

Funding sources

SNF, Personen- und Projektförderung, SNF 320030-231714

Collaborations

Summary

Greater Amazonia, including Orinoco and Amazon river basins, is home of more than 3000 fish species. What is the origin and evolution of this hyperdiversity? The fossil record offers the chance to provide clues on this question, and document how extinctions have affected the group in the past.
Fossil freshwater fishes have been understudied, with hundreds of undescribed specimens from sites across the neotropics available for study in this project. Intensive search for fossils of diverse small vertebrates using screen-washing in the Urumaco region of Venezuela will surely also provide results. Urumaco is rich in fossils across more than 5000 meters of sediments documenting change for a period of 20 million years – a reference site to compare fossil sites across Greater Amazonia. Other sites to be intensively studied for fossil fishes are La Venta in Colombia and Iquitos in Peru.
We will investigate the systematic affinities of fossils of apex predators such as arowanas, arapaimas, and lungfishes, as well as piranhas, cichlids and catfishes.
We will explore if fishes experienced faunal turnovers reported for other neotropical faunal groups during the last 20 million years.
The location and connections of rivers have changed over geological time, in part as a result of the rise of the Andes and climate change. We will examine if the distribution of fossils we find correspond with models of the changes of connections across river basins in the last 20 million years, and study the extent of the mega-wetland area called Pebas that covered large areas of Greater Amazonia for millions of years.
Taxonomic assignments will be based on comparative osteology, using non-invasive imaging and histological studies when needed. We will synthesize information across the continent for the open access paleobiology database. We will assess how patterns of taxon longevity relate to the current extinction crisis and examine the hypothesis of Urumaco as cradle and museum of diversity. The digitalization of fossils will increase accessibility and the long-term impact of the project.

Keywords

Fish, Neotropics, Paleontology, Evolution, Extinction