Ferromirum, Dwykaselachus and Stethacanthus

Ferromirum oukherbouchi (Frey et al. 2020; Late Devonian; PIMUZ A/I 4806; est. 33cm overall) is closest toDwykaselachus in the LRT. Preserved with impressions of soft tissue this is a rare 3D specimen. The large size of the palatoquadrate (= lacrimal) erased the temporal fenestrae. Note the hyomandibular is a distinct 'bone'. Teeth were individually sharp, but coiled to lay each point alongside each side. As the jaws opened the mandibles rotated outwardly to expose more teeth.

Dwykaselachus oosthuizeni (Oelofsen 1986, Coates et al. 2018; Middle Permian) is a larger, later version of Ferromirum.

Coates MI et al. (4 co-authors) 2018. A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes. Nature 541:208–211.

Frey L et al. (4 co-authors) 2020. A symmoriiform from the Late Devonian of Morocco demonstrates a derived jaw function in ancient chondrichthyans. Nature Communications Biology 3:681 https://doi.org/10.1038/s42003-020-01394-2 www.nature.com/commsbio

Oelofsen BW 1986. A fossil shark neurocranium from the Permo-Carboniferous (lowermost Ecca Formation) of South Africa. Indo-Pacific fish biology: Proceedings of the Second International Conference on Indo-Pacific Fishes: 107–124.

Zangerl R 1984. On the microscopic anatomy and possible function of the spine-"brush" complex of Stethacanthus (Elasmobranchii: Symmoriida). Journal of Vertebrate Paleontology. 4 (3): 372–378.

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Chondrichthyes

Manta

Ozarcus

Chlamydoselachus

Xenacanthus