Dr. Eliseu Vieira Dias of the State University of Western Paraná (UNIOESTE) has announced the discovery of a new species of deep-bodied fish that prowled ancient rivers and lakes in the South American part of Gondwana during Permian period.
A paper in the journal Zootaxa describes a new species of deep-bodied fossil fish, called Paranaichthys longianalis, which also represents a new genus belonging to the Actinopterygii (the largest subclass of ray-finned fishes).
A single fossilized specimen of P. longianalis was collected from the Rio do Rasto Formation in Paraná Basin, Brazil.
“As mentioned in the paper, the single specimen of this fossil fish was discovered in 1989 by Dr. Rosemarie Rohn of the State University of Paulista,” Dr. Dias explained in the interview with Sci-News.com. “Dr. Rohn found the specimen in waste pile of a small mine. The fossil was preserved in the collection of the Museum of Science and Technology in Porto Alegre, Brazil.”
“The discovery was for the first time presented in 1996. Now, some features of the new fish have been revised and appeared in Zootaxa.”
The researcher noted that this fossil fish lived in freshwater habits in the southwestern part of Gondwana about 268-260 million years ago (the Upper Permian).
“P. longianalis is a deep-bodied fish that has an elongated anal fin (deep-bodied fishes are those of laterally compressed body shapes, usually as tall as long),” Dr. Dias said. “The cranial features are poorly preserved in the specimen. However, the presence of crushing dentition indicates a hard-food diet for this species.”
“This crushing dentition presents a small cap of an enameloid tissue known as verruciform acrodin”, Dr. Dias explained. “The scales are ganoid with a three layer organization, in which the inner layer is composed of bone tissue, the intermediate is dentine and the external is enamel (ganoine). The flank scales are high, a pattern common in deep-bodied fishes.”
P. longianalis measured about 8.5 inches (21.5 cm) and had remarkably large and long anal fin, a feature unknown in all other deep-bodied actinopterygians.
The name of the species refers to this remarkable fin, while the genus name refers to the Paraná sedimentary Basin, where the fossil was found.
This fossil fish probably lived together with other actinopterygians, amphibian temnospondyls such as Australerpeton cosgriffi, chondrichthyans and dipnoans. It would have been able to develop short fast movements using its strong caudal peduncle and well-developed caudal fin.
“This is the second actinopterygian species, described from the Rio do Rasto Formation in Paraná Basin, and the first deep-bodied”, Dr. Dias concluded. “This geological formation is in the focus of several researches and many new fossil taxa described, including the discovery of carnivorous dinocephalian by Cisneros et al. in 2012, which is not cited in my paper. The knowledge of this fossil fauna can provide a more complete reconstruction of the Middle-Upper Permian in the western Pangea paleoenvironments.”