Phylogenetic dataset contained 282 characters and 74 OTUs from “A new large ‘silesaur’ specimen from the ?Late Triassic of Zambia; Taxonomic, ecological and evolutionary implications”

Phylogenetic dataset contained 282 characters and 74 OTUs from “A new large ‘silesaur’ specimen from the ?Late Triassic of Zambia; Taxonomic, ecological and evolutionary implications”

Femoral measurements from a selection of early diverging avemetatarsalian taxa used to generate a regression equation for estimating femoral length in “A new large ‘silesaur’ specimen from the ?Late Triassic of Zambia; Taxonomic, ecological and evolutionary implications”

Femoral measurements from a selection of early diverging avemetatarsalian taxa used to generate a regression equation for estimating femoral length in “A new large ‘silesaur’ specimen from the ?Late Triassic of Zambia; Taxonomic, ecological and evolutionary implications”

The upper Madumabisa Mudstone Formation is a richly fossiliferous rock formation exposed in the Luangwa Basin in Zambia, with well-documented upper Permian vertebrate assemblages comparable to those of coeval basins in Tanzania and South Africa. The tetrapod communities of the upper Madumabisa Mudstone include 20 species of dicynodonts. Although most Permian dicynodont clades are represented in the upper Madumabisa Mudstone assemblages, the ornamented clade Geikiidae, which occurs in both the Karoo and Ruhuhu basins, has yet to be reliably reported in the Luangwa Basin; historical reports likely represent other cryptodont taxa. We report a new species of geikiid, Aulacephalodon kapoliwacela, sp. nov., known from both the lower and upper assemblages of the upper Madumabisa Mudstone Formation. This species closely resembles the abundant South African taxon Aulacephalodon bainii, including bearing robust tusks, bosses on the squamosals, and a tall ascending process of the jugal, but differs in the absence of a pineal boss and differing ontogenetic trajectories of the postfrontal and postcaniniform crests. We also provisionally rediagnose A. bainii using only characters visible in the holotype, and for the first time provide a diagnosis for the genus. Phylogenetic analysis supports a close relationship between Zambian and South African geikiids. Multiple juvenile individuals of A. kapoliwacela help clarify ontogenetic trends within Geikiidae, including differences in development and fusion of the postfrontal between geikiid species. Large wear facets on the tusks of some individuals indicate substrate-focused foraging behavior in Aulacephalodon.

The upper Madumabisa Mudstone Formation is a richly fossiliferous rock formation exposed in the Luangwa Basin in Zambia, with well-documented upper Permian vertebrate assemblages comparable to those of coeval basins in Tanzania and South Africa. The tetrapod communities of the upper Madumabisa Mudstone include 20 species of dicynodonts. Although most Permian dicynodont clades are represented in the upper Madumabisa Mudstone assemblages, the ornamented clade Geikiidae, which occurs in both the Karoo and Ruhuhu basins, has yet to be reliably reported in the Luangwa Basin; historical reports likely represent other cryptodont taxa. We report a new species of geikiid, Aulacephalodon kapoliwacela, sp. nov., known from both the lower and upper assemblages of the upper Madumabisa Mudstone Formation. This species closely resembles the abundant South African taxon Aulacephalodon bainii, including bearing robust tusks, bosses on the squamosals, and a tall ascending process of the jugal, but differs in the absence of a pineal boss and differing ontogenetic trajectories of the postfrontal and postcaniniform crests. We also provisionally rediagnose A. bainii using only characters visible in the holotype, and for the first time provide a diagnosis for the genus. Phylogenetic analysis supports a close relationship between Zambian and South African geikiids. Multiple juvenile individuals of A. kapoliwacela help clarify ontogenetic trends within Geikiidae, including differences in development and fusion of the postfrontal between geikiid species. Large wear facets on the tusks of some individuals indicate substrate-focused foraging behavior in Aulacephalodon.

The stratigraphic record of the whaitsiid therocephalian Theriognathus in the Karoo basins of southern Africa is reviewed, with special emphasis on biostratigraphic correlations of the Ruhuhu (Tanzania) and Luangwa (Zambia) basins. Historically, tetrapod-bearing horizons in the Usili Formation of Tanzania and upper Madumabisa Mudstone of Zambia have been inconsistently correlated to the Cistecephalus Assemblage Zone (AZ), Daptocephalus AZ, or have not been conclusively subdivided to the level of the Karoo biozonation. Recent collecting in the main Karoo Basin reference section helps to resolve the first (FAD) and last (LAD) appearance datum of Theriognathus and may reconcile the differing opinions on these formation’s age assignments. The relative abundance of Theriognathus peaks in the middle third of its range in the Daggaboersnek Member of the Balfour Formation (lower Daptocephalus AZ), but a new specimen collected from the Oukloof Member in 2020 and a review of prior records confirms the FAD of Theriognathus in the middle Cistecephalus AZ. Refinements to the FAD partly help to reconcile inconsistent age assignments for Theriognathus in the literature, especially for its occurrences in the Ruhuhu and Luangwa basins which have been most recently interpreted as Cistecephalus AZ-equivalent. We suggest that the well-documented genus Theriognathus provides a reliable biostratigraphic index for the Usili Formation and upper Madumabisa Mudstone Formation, and, in conjunction with its associated dicynodont fauna, is most consistent with the upper Cistecephalus to lower Daptocephalus AZ which has been dated as late Wuchiapingian in age (ca. 256–253 Ma).

The stratigraphic record of the whaitsiid therocephalian Theriognathus in the Karoo basins of southern Africa is reviewed, with special emphasis on biostratigraphic correlations of the Ruhuhu (Tanzania) and Luangwa (Zambia) basins. Historically, tetrapod-bearing horizons in the Usili Formation of Tanzania and upper Madumabisa Mudstone of Zambia have been inconsistently correlated to the Cistecephalus Assemblage Zone (AZ), Daptocephalus AZ, or have not been conclusively subdivided to the level of the Karoo biozonation. Recent collecting in the main Karoo Basin reference section helps to resolve the first (FAD) and last (LAD) appearance datum of Theriognathus and may reconcile the differing opinions on these formation’s age assignments. The relative abundance of Theriognathus peaks in the middle third of its range in the Daggaboersnek Member of the Balfour Formation (lower Daptocephalus AZ), but a new specimen collected from the Oukloof Member in 2020 and a review of prior records confirms the FAD of Theriognathus in the middle Cistecephalus AZ. Refinements to the FAD partly help to reconcile inconsistent age assignments for Theriognathus in the literature, especially for its occurrences in the Ruhuhu and Luangwa basins which have been most recently interpreted as Cistecephalus AZ-equivalent. We suggest that the well-documented genus Theriognathus provides a reliable biostratigraphic index for the Usili Formation and upper Madumabisa Mudstone Formation, and, in conjunction with its associated dicynodont fauna, is most consistent with the upper Cistecephalus to lower Daptocephalus AZ which has been dated as late Wuchiapingian in age (ca. 256–253 Ma).

Captorhinidae are a diverse group of early or stem amniotes that were dominant components of early Permian terrestrial ecosystems, and one of the first reptiliomorphs to experiment with high-fiber herbivory. Moradisaurinae is a clade of large-bodied captorhinids that evolved by the middle Kungurian (∼280 Ma) and that possess multiple tooth rows on the maxilla and dentary. Here, we describe Amenoyengi mpunduensis gen. et sp. nov., a diminutive moradisaurine captorhinid from the Lopingian upper Madumabisa Mudstone Formation of the Luangwa Basin, Zambia and therefore one of the geologically youngest captorhinids. Amenoyengi bears a mosaic of cranial features including few maxillary tooth rows, a maxillary diastema, and caniniform teeth in the maxilla and dentary. An updated phylogenetic analysis places Amenoyengi mpunduensis as the sister taxon of Gansurhinus, a relationship supported by five unambiguous characters including a low number of maxillary tooth positions and tooth rows and the presence of a maxillary diastema. Our results indicate that moradisaurine interrelationships are influenced by ontogenetically variable characters, in agreement with recent studies. We review other late occurrences of Captorhinidae, and find that several, unnamed post-Cisuralian and small-bodied captorhinids can be referred to Moradisaurinae, and note that captorhinid specimens are unknown from later than the Wuchiapingian stage of the late Permian, and therefore the clade is not necessarily a victim of the end-Permian Mass Extinction.

Captorhinidae are a diverse group of early or stem amniotes that were dominant components of early Permian terrestrial ecosystems, and one of the first reptiliomorphs to experiment with high-fiber herbivory. Moradisaurinae is a clade of large-bodied captorhinids that evolved by the middle Kungurian (∼280 Ma) and that possess multiple tooth rows on the maxilla and dentary. Here, we describe Amenoyengi mpunduensis gen. et sp. nov., a diminutive moradisaurine captorhinid from the Lopingian upper Madumabisa Mudstone Formation of the Luangwa Basin, Zambia and therefore one of the geologically youngest captorhinids. Amenoyengi bears a mosaic of cranial features including few maxillary tooth rows, a maxillary diastema, and caniniform teeth in the maxilla and dentary. An updated phylogenetic analysis places Amenoyengi mpunduensis as the sister taxon of Gansurhinus, a relationship supported by five unambiguous characters including a low number of maxillary tooth positions and tooth rows and the presence of a maxillary diastema. Our results indicate that moradisaurine interrelationships are influenced by ontogenetically variable characters, in agreement with recent studies. We review other late occurrences of Captorhinidae, and find that several, unnamed post-Cisuralian and small-bodied captorhinids can be referred to Moradisaurinae, and note that captorhinid specimens are unknown from later than the Wuchiapingian stage of the late Permian, and therefore the clade is not necessarily a victim of the end-Permian Mass Extinction.