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| Ferganoceratodus edwardsi Challands, Cavin, Zondo, Munyikwa, Choiniere & Barrett, 2024 |
ABSTRACT
The lungfish, the extant sister group of the tetrapods, have an evolutionary history illustrated by a fossil record extending for ∼420 million years. The post-Paleozoic fossil record of the clade is almost exclusively restricted to sediments deposited in freshwater paleoenvironments and is characterized by an abundance of highly mineralized tooth plates, whereas cranial and postcranial remains are scarce. Here, we report a sample of isolated tooth plates found in the Upper Triassic Pebbly Arkose Formation of the Mid-Zambezi Basin, Zimbabwe. It consists of pterygoid and prearticular tooth plates from adult individuals, plus some dental plates referred to juvenile individuals, which we refer to a new species of Ferganoceratodus. This discovery provides an opportunity to review briefly the tooth plates of the ‘ptychoceratodontid morphotype’ reported from around the world. We discuss how various occurrences previously referred to Ptychoceratodus may be more appropriately referred, with caution, to Ferganoceratodus. We also describe the histology of the tooth plates of the new species and note similarities with other Mesozoic taxa. The scarcity of histological data for Mesozoic lungfish tooth plates compounds the problem of assigning isolated tooth plates to genus and species level. Ferganoceratodus and closely related taxa arose in the Early Triassic in southern Gondwana and diversified worldwide in the Late Triassic. The genus then became more common in Laurasia during the Jurassic and Early Cretaceous and declined thereafter with relict Late Cretaceous occurrences in Madagascar and South America.
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| Ferganoceratodus edwardsi. A-E, upper tooth plates; F-J, lower tooth plates. A-B, NHMZ 2432(9), holotype in labial and occlusal views. Arrowhead indicates the surface for a potential symphyseal contact; C, NHMZ 2432(6); D, NHMZ 2432(13); E, NHMZ 2432(5); F, NHMZ 2432(1), juvenile; G, NHMZ 2432(2), juvenile; H, NHMZ 2432(12); I, NMHZ 2432(11); J, NHMZ 2432(14); K, NHMZ 2432(4), juvenile. Scale bars equal 10 mm. |
Subclass SARCOPTERYGII Romer, Citation1955
Order DIPNOI Müller, Citation1845
Suborder CERATODONTOIDEI Nikolski, Citation1954 sensu Kemp et al., Citation2017
Family incertae sedis
Genus FERGANOCERATODUS Nessov and Kaznyshkin, Citation1985
FERGANOCERATODUS EDWARDSI sp. nov.
Etymology—Named in honor of Mr. Steve Edwards, discoverer of ‘The Dentists’ and other Late Triassic field sites in Matusadona National Park, who collected the specimens described herein.
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| Geographic and stratigraphic distributions of Ferganoceratodus spp. and Ptychoceratodus serratus. |
Tom J. Challands, Lionel Cavin, Michel Zondo, Darlington Munyikwa, Jonah N. Choiniere and Paul M. Barrett. 2024. A New Lungfish from the Upper Triassic of the Mid-Zambezi Basin, Zimbabwe. Journal of Vertebrate Paleontology. e2365391. DOI: doi.org/10.1080/02724634.2024.2365391