Citation:

Maréchal, A., Rotatori F. M., Merella M., Puértolas-Pascual E., Sequero C., Pereira R., Nsungani P., & Mateus O. (2025).  A new Maastrichtian hyposaurine dyrosaurid (Crocodylomorpha) from Namibe province, Angola. 204(4), zlaf092., 2025/08/01

Abstract:

Dyrosauridae are one of the few clades of large marine vertebrates that survived the Cretaceous/Palaeogene (K–Pg) extinction event. The early diversification of this clade, dated to the Cretaceous, is still poorly understood. We describe a new specimen of Dyrosauridae from the Late Cretaceous of Bentiaba, Angola, represented by a posterior portion of the skull, a left ectopterygoid fragment, and a tooth. Comparative morphological analysis reveals a unique combination of characters distinguishing it from known dyrosaurid taxa but due to the fragmentary nature of the specimen and the absence of key diagnostic features, we assign it to Hyposaurinae indet.. Phylogenetic relationships were tested through maximum parsimony and Bayesian inference, using the SFBD model with time-binning criteria for the K–Pg boundary. Both of our phylogenetic analyses recover this new specimen as Hyposaurinae, which is consistent with our comparative study. Evolutionary rates accelerated during the latest stages of the Cretaceous, although the fossil bias prevents the ability to appreciate their impact on cladogenetic events. We estimated diversification, fossilization, and extinction rates, and we did not find evidence of radiation after the K–Pg in this clade. Biogeographically, this discovery supports hypotheses of longirostrine crocodyliform dispersal in Africa leading to hyposaurine diversification during the Maastrichtian.

Notes:

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