Dinanomodon guoi, new dicynodont from Permian of China + small reptiles from Carboniferous-Permian of Utah + early amniote phylogeny
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Ben Creisler
Dec 15, 2025, 2:54:10 PM (3 days ago) Dec 15
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Ben Creisler
Recent tetrapod papers:
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Dinanomodon guoi sp. nov.
Yu-Tai Shi & Jun Liu (2025)
A new Chinese dicynodont and the frequent dispersal of tetrapods between Northern and Southern Pangaea during the late Permian
Cladistics (advance online publication)
doi: https://doi.org/10.1111/cla.70019
https://onlinelibrary.wiley.com/doi/10.1111/cla.70019
The dispersal pattern of tetrapods across Pangaea is a crucial problem for understanding Permian terrestrial ecosystems. This study describes a rare cross-equatorial record of a dicynodont genus. New fossil material from China can be referred to Dinanomodon, a genus formerly only known from South Africa, although it represents a new species—D. guoi. To investigate the divergence of Bidentalia, a newly assembled dataset was employed to perform maximum parsimony analysis, Bayesian inference and the first tip-dating analysis within the anomodonts. Considering other tetrapod occurrences, we suggest that frequent cross-equatorial dispersal of tetrapods occurred during the Lopingian (late Permian). Based on tetrapod distribution and paleoclimate data, precipitation, rather than temperature, probably represents the major ecological factor influencing corridors for dispersal along the eastern margin of Pangaea.
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Cladistics (advance online publication)
doi: https://doi.org/10.1111/cla.70019
https://onlinelibrary.wiley.com/doi/10.1111/cla.70019
The dispersal pattern of tetrapods across Pangaea is a crucial problem for understanding Permian terrestrial ecosystems. This study describes a rare cross-equatorial record of a dicynodont genus. New fossil material from China can be referred to Dinanomodon, a genus formerly only known from South Africa, although it represents a new species—D. guoi. To investigate the divergence of Bidentalia, a newly assembled dataset was employed to perform maximum parsimony analysis, Bayesian inference and the first tip-dating analysis within the anomodonts. Considering other tetrapod occurrences, we suggest that frequent cross-equatorial dispersal of tetrapods occurred during the Lopingian (late Permian). Based on tetrapod distribution and paleoclimate data, precipitation, rather than temperature, probably represents the major ecological factor influencing corridors for dispersal along the eastern margin of Pangaea.
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Adam K. Huttenlocker, Amy C. Henrici, Xavier A. Jenkins, Zachary Lyons-Weiler, Jason D. Pardo & Bryan J. Small (2025)
New records of diverse small reptiles with thecodont implantation from the Carboniferous–Permian Halgaito Formation (Cutler Group) of southeastern Utah, U.S.A.
Journal of Vertebrate Paleontology e2564788
doi: https://doi.org/10.1080/02724634.2025.2564788
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2564788
Carboniferous–Permian (C–P) amniotes and stem-amniotes were historically well documented in the southwestern U.S.A., but Carboniferous reptile diversity and abundance was relatively low compared with other groups (e.g., synapsids). Here, we describe new microvertebrate material collected from the C–P Halgaito Formation (Cutler Group) in southeastern Utah, U.S.A., consisting of small reptile jaws and teeth with distinctive tooth implantation and replacement patterns. Recent insights into fossil reptile tooth implantation and replacement suggest clade-specific patterns in major C–P reptile groups, making micro-computed tomography and histology useful in the identification of cryptic, small reptile diversity during this time. Two new taxa demonstrating thecodont tooth implantation and replacement are shown to be represented in the upper Halgaito Formation: (1) a small bolosaurid-like taxon with bulbous, faceted tooth crowns, and (2) another small amniote with simple, medio-laterally compressed conical teeth with wide, bilobed roots that are replaced from within the pulp cavity directly beneath the functional tooth. Both taxa lack plicidentine, which has variable distribution in early amniote and stem-amniote clades. Based on comparisons to other small C–P amniotes, we suggest the first of these may represent an early-branching bolosaurian that had not yet evolved the “talon-and-heel” morphology indicative of later Permian bolosaurids, whereas the second represents another distinct small amniote in the Halgaito Formation. These new microvertebrate records add to the taxonomic composition of the Halgaito fauna and underscore the diversity of small reptiles in the southwestern U.S.A. during the C–P geologic transition.
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Kelsey M Jenkins, Dalton L Meyer & Bhart-Anjan S Bhullar (2025)
Phylogenetic paradigm shifts in early amniote evolution
Systematic Biology, syaf087
doi: https://doi.org/10.1093/sysbio/syaf087
https://academic.oup.com/sysbio/advance-article-abstract/doi/10.1093/sysbio/syaf087/8379424
The dichotomy within Amniota (mammals and reptiles) was recognized early in the history of phylogenetic systematics, and with it developed a canonical understanding of the evolutionary relationships of early-diverging clades. In recent years, the relationships of these clades have shifted dramatically among studies, which has profound effects on how researchers interpret evolutionary patterns in early amniotes. To gain a fuller understanding of the early evolution of amniotes, we compiled one of the largest amniote-wide phylogenetic datasets, including 590 fully illustrated characters and 150 taxa representing all the major clades of “pelycosaurian” stem mammals, pan-reptiles, and several outgroups. We analyzed this dataset under Bayesian and Parsimony frameworks, which resulted in different topologies, particularly among stem mammals and near-crown and within-crown Reptilia. To explore the effect sampling has on tree topology, we conducted three series of exclusion experiments, each consisting of ten analyses, each with ten fewer OTUs than the previous, as well as 26 exclusion analyses removing one major clade of early diverging amniote or individual OTU at a time. This experiment showed that taxon sampling has a major effect on early amniote tree topology, and many of the topologies we found bear striking similarities to those reported in recent publications. Furthermore, we identify and discuss several unique effects that taxon exclusion may have on phylogenies. To address poorly resolved (i.e., polytomies) and unstable portions of amniote phylogeny, where branches frequently move or dismantle depending on sampling and choice of analytical technique, we encourage more detailed anatomical work on early amniotes, particularly stem mammals, and expansion of morphological phylogenetic datasets.
Phylogenetic paradigm shifts in early amniote evolution
Systematic Biology, syaf087
doi: https://doi.org/10.1093/sysbio/syaf087
https://academic.oup.com/sysbio/advance-article-abstract/doi/10.1093/sysbio/syaf087/8379424
The dichotomy within Amniota (mammals and reptiles) was recognized early in the history of phylogenetic systematics, and with it developed a canonical understanding of the evolutionary relationships of early-diverging clades. In recent years, the relationships of these clades have shifted dramatically among studies, which has profound effects on how researchers interpret evolutionary patterns in early amniotes. To gain a fuller understanding of the early evolution of amniotes, we compiled one of the largest amniote-wide phylogenetic datasets, including 590 fully illustrated characters and 150 taxa representing all the major clades of “pelycosaurian” stem mammals, pan-reptiles, and several outgroups. We analyzed this dataset under Bayesian and Parsimony frameworks, which resulted in different topologies, particularly among stem mammals and near-crown and within-crown Reptilia. To explore the effect sampling has on tree topology, we conducted three series of exclusion experiments, each consisting of ten analyses, each with ten fewer OTUs than the previous, as well as 26 exclusion analyses removing one major clade of early diverging amniote or individual OTU at a time. This experiment showed that taxon sampling has a major effect on early amniote tree topology, and many of the topologies we found bear striking similarities to those reported in recent publications. Furthermore, we identify and discuss several unique effects that taxon exclusion may have on phylogenies. To address poorly resolved (i.e., polytomies) and unstable portions of amniote phylogeny, where branches frequently move or dismantle depending on sampling and choice of analytical technique, we encourage more detailed anatomical work on early amniotes, particularly stem mammals, and expansion of morphological phylogenetic datasets.
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