New cichlid fossils from the middle-late Miocene alkaline lakes of Africa

By Kevrekidis, Charalampos & Bernhard Ruthensteiner, Alexander F. Cerwenka, Stefanie B. R. Penk & Bettina Reichenbacher

Journal of Vertebrate Paleontology, (n. e1805621 ), 2020. DOI: 10.1080/02724634.2020.1805621


" The African Cichlidae Oreochromis (Alcolapia) and Oreochromis amphimelas can survive in extremely alkaline environments and represent the only known modern alkaliphilic cichlid fish found in Africa. The presence of fossil cichlids from the Miocene of central Kenya (Tugen Hills) that are morphologically similar to Oreochromis (Alcolapia) has been noted in previous works, but the conclusions remained tentative. The purpose of this study is to examine newly discovered fossil cichlids from the Tugen Hills and to compare their osteology with that of extant Oreochromis (Alcolapia). This is performed based on a comprehensive collection of comparative material, using microscopy and computed microtomography (μCT). We provide a revised diagnosis for the genus †Rebekkachromis, and revise its systematic relationships by assigning it to the Oreochromini (rather than to the Etiini). Two new species of †Rebekkachromis are described, i.e., †R. valyricus, sp. nov., and †R. vancouveringae, sp. nov., and a morphologically diverse assemblage of co-occurring †Rebekkachromis specimens is documented. Moreover, we found that †Rebekkachromis had three sensory canal pores (instead of four) on the lower arm of the preopercle, a feature that distinguishes both the modern Oreochromis (Alcolapia) and our fossil specimens from almost all other modern African cichlid fish. Our new data indicate that alkaliphile cichlids similar to Oreochromis (Alcolapia) were present in Central Kenya about 10–13 Ma ago and that the ability of African cichlid fishes to thrive in highly alkaline waters had already developed by that time "

Classification: Evolution.

Language: English

Kevrekidis, Charalampos & Bernhard Ruthensteiner, Alexander F. Cerwenka, Stefanie B. R. Penk & Bettina Reichenbacher. 2020. "New cichlid fossils from the middle-late Miocene alkaline lakes of Africa". Journal of Vertebrate Paleontology. (n. e1805621 ),. DOI: 10.1080/02724634.2020.1805621 (crc09908) (abstract)