Paleoecological and biomechanical inferences regarding the paleoichthyofauna of the Romualdo Formation, Aptian-Albian of the Araripe Basin, state of Pernambuco, northeastern Brazil

• Published in: Journal of South American earth sciences Vol. 111; p. 103444
• Main Authors: Barbosa Lopes, Gabriel Levi, Franca Barreto, Alcina Magnólia
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2021
• Subjects: Cluster analysis; Fish; Paleoautecological; Similarity index; Cluster analysis; Fish; Paleoautecological; Similarity index
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2021.103444

The Romualdo Formation, Aptian-Albian of the Araripe Basin, is known for the extraordinary preservation of its paleoichthyofauna. The majority of the studies performed on the basin are descriptive, so this study aims to analyze morphological adaptations in the paleoichthyofauna of the Romualdo Formation, seeking to understand how they influenced the life habits of fishes. To conduct the paleoecological study, 117 specimens were selected among 13 different taxa and used for the investigation of types of dentition, mouth orientation, and body morphology. A cluster analysis was carried out using morphometric data of body morphology, resulting in three groups based on the similarity index among the species. The morphology of most of the paleoichthyofauna, like Rhacolepis buccalis and Vinctifer comptoni, was adapted to swimming in high-energy environments and continuous swimming. Others, such as Araripelepidotes temnurus, presented a morphology adapted to surviving in low-energy environments, and few, like Brannerion sp. and Neoproscinetes penalvai, could perform maneuverability moves due to a deep, laterally flattened body and well-developed fins. The mouth orientation, as well as the body morphology, was of great importance to the inferences about the living zone and feeding habits of the fishes, suggesting that most inhabited the middle of the water column and were generalists regarding their feeding zone. Moreover, the types of dentition or lack thereof helped to infer food diversity and a possible food web. Therefore, the ecomorphological attributes showed some degree of morphological variations in the paleoichthyofauna, reflecting different swimming habits in environments of varied energy. The study also revealed a range of explored food resources, and the association among the fishes allowed the proposition of a rather complex food web.
•New analysis of morphological characteristics of the paleoichthyofauna of the Romualdo formation, state of Pernambuco.•Cluster analysis applied in paleoecological studies.•New interpretations about the position of the fish in the water column.•New contributions about the ecological interactions in the paleoichthyofauna of the Romualdo Formation, state of Pernambuco.