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| Bakiribu waridza Pêgas, Aureliano, Holgado, Almeida, Santos & Ghilardi, 2025 Artwork by Julio Lacerda |
Abstract
The Santana Group in Northeast Brazil has yielded a remarkable discovery: the first filter-feeding pterosaur from the tropics, named Bakiribu waridza gen. et sp. nov. This new taxon provides key insights into the evolutionary history and ecological diversity of Ctenochasmatidae, a clade known for its specialized feeding adaptations. Bakiribu exhibits extremely elongated jaws and dense, brush-like tooth rows, similar to Pterodaustro but distinct in tooth cross-section and spacing. Paleohistological analysis of the teeth revealed well-preserved dentine and pulp cavities. Phylogenetic analysis recovers Bakiribu as the sister taxon to Pterodaustro, forming a clade more closely related to Ctenochasma than to Gegepterus, which is reinterpreted as a non-ctenochasmatine. Regarding some specific traits such as tooth density, elongation, and count, Bakiribu is intermediate between Ctenochasma and Pterodaustro, thus partially bridging a key evolutionary gap within Ctenochasmatinae. Taphonomic features support the interpretation of the fossil assemblage as a regurgitalite. This discovery brings crucial data for understanding biogeographic dispersal and ecological specialization within Ctenochasmatinae during the Early Cretaceous, and offers rare evidence of predator-prey interactions in the Romualdo Formation paleoecosystem. Together, these findings further underscore the importance of the Araripe Basin as a window into the Early Cretaceous biodiversity.
Keywords: Pterodactyloidea, Ctenochasmatidae, Araripe basin, Romualdo formation, Paleohistology, Regurgitalite
Pterosauria Owen 1842.
Pterodactyloidea Plieninger 1901.
Ctenochasmatidae Kuhn 1967.
Ctenochasmatinae Nopcsa 1928.
Pterodaustrini Andres, Clark and Xu 2014.
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| Overview of the concretion containing the remains of Bakiribu waridza gen. et sp. nov. (holotype and paratype) and four associated fishes. A, Part (MCC 1271.1-V). B, Counterpart (MPSC 7312). C and D, Schematic drawings of MCC 1271.1-V and MPSC 7312, respectively. Scale bar equals 50 mm. |
Bakiribu waridza gen. et sp. nov.
Diagnosis. Ctenochasmatine pterosaur with the following combination of features, including autapomorphies (marked with an asterisk): jaws extremely elongate (estimated rostral index of ~ 12–16); teeth closely packed together (interdental gaps under tooth diameter); high tooth density (17.6 teeth/cm); high tooth count (between 110 and 142 per jaw, per side, as preserved; total estimate = between 440 and 568); teeth long and slender (elongation index surpassing 1:60); acrodont-like tooth implantation on both jaws*; and tooth crowns subquadrangular in cross-section*.
Holotype. MCC 1271-Va/MPSC 7312a (Figs. 2 and 3A and B), a partial rostrum. Based on position and orientation, fragments b, c, and d most likely belong to the same individual (Fig. 3B).
Horizon and Locality. This fossil was preserved in a calcareous concretion of the Romualdo Formation, Araripe Basin, Northeast Brazil. This unit is late Aptian-early Albian in relative age31. The precise locality of this concretion is unknown, but the Romualdo Formation outcrops east-west along the Araripe Plateau between the states of Pernambuco, Ceará, and Piauí.
Etymology. The generic epithet comes from bakiribú (Kariri word for ‘comb’), in allusion to the typical comb-like dentition of ctenochasmatids. The specific epithet comes from waridzá (Kariri word for ‘mouth’). Together, the binomial name not only highlights the distinctive dental morphology of the taxon but also honors the cultural heritage of the Kariri people, Indigenous inhabitants of the region where the fossil was discovered.
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| Reconstruction of the type specimens of Bakiribu waridza gen. et sp. nov. A, close view of MCC 1271.1-V (main part). B, simplified schematic reconstruction of the holotype based on fragments a, b, c, and d. C, simplified schematic reconstruction of holotype based on fragments e, f, and g. Scale bar equals 10 mm. |
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| Artistic reconstruction of the filter-feeding pterosaur Bakiribu waridza gen. et sp. nov. in the Early Cretaceous Romualdo Formation environment. The spinosaurid in the background represents the putative predator that produced the regurgitalite described herein. Artwork by Julio Lacerda. |
R. V. Pêgas, Tito Aureliano, Borja Holgado, William B. S. Almeida, Claude L. A. Santos and Aline M. Ghilardi. 2025. A regurgitalite reveals A New filter-feeding Pterosaur from the Santana Group. Scientific Reports. 15, 37336. DOI: doi.org/10.1038/s41598-025-22983-3 [10 November 2025]