Compsemys (Cretaceous/Paleocene turtle) re-evaluation + squamate lung evolution + rhea hindlimb morphology
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Ben Creisler
Aug 13, 2026, 6:04:49 PMAug 13
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Ben Creisler
Barbara de Godoi Champini, Ray Brasil Bueno de Souza & Wilfried Klein (2026)
Phylogenetic Reconstruction of Lung Evolution in Extant Squamata
Journal of Zoology (advance online publication)
doi: https://doi.org/10.1111/jzo.70151
https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/jzo.70151
Free pdf:
https://zslpublications.onlinelibrary.wiley.com/doi/epdf/10.1111/jzo.70151
The Squamata group exhibits remarkable diversity in lung structure. However, a comprehensive understanding of how this variation evolved within the clade is still lacking. To reconstruct the evolutionary history of lungs of living squamates, we conducted comparative phylogenetic analyses using categorized lung traits, such as lung type, respiratory epithelium type, and distribution of parenchyma, obtained from literature-derived morphological data. Stochastic character mapping on an amniote phylogeny revealed uncertainties regarding the ancestral lung type at the amniote root, whereas strong support for a unicameral lung was found at the base of Lepidosauria, Squamata, Toxicofera, Iguania, and Anguimorpha. Correlation analysis revealed a small but significant association between epithelium type and distribution, suggesting a degree of correlated evolution among these traits.
Some recent non-dino papers:
Free pdf:
Steven E. Jasinski, Asher J. Lichtig, Sebastian G. Dalman and Spencer G. Lucas (2026)
Re-Evaluation of Compsemys and North American Compsemydids (Testudinata)
Taxonomy 6(3): 48
doi: https://doi.org/10.3390/taxonomy6030048
https://www.mdpi.com/2673-6500/6/3/48
Compsemys is an enigmatic turtle first described over 160 years ago. Its taxonomic position has been uncertain, as many of the species placed in the genus have since been removed from it. For the last 30+ years, Compsemys victa has been the only recognized North American fossil species. New fossil specimens collected from the Paleocene in the United States necessitate a re-evaluation of the taxonomy of these turtles and call into question the long-held belief that only one species of Compsemys is valid in North America. Specimens from the Paleocene are far more complete than the holotype of C. victa, and all have been referred to this species based on a similar surface texture. Differences between material from the Cretaceous and Paleocene suggest multiple species of Compsemys are valid. In addition to the genotypic species Compsemys victa, C. puercensis, and C. torrejonensis are both valid species from the Paleocene. Beyond surface sculpturing and texture, features of the carapace and plastron can be used to help differentiate the three species. North American Compsemys survived the Cretaceous–Paleogene mass extinction. Rather than being a monospecific genus, Compsemys diversified in the Paleocene. Not only does this suggest an increase in the diversity of North American compsemydids, but it also leads to the possibility of asymmetric or budding cladogenesis among Compsemys species during the Late Cretaceous and Paleocene, at least in the American Southwest.
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Steven E. Jasinski, Asher J. Lichtig, Sebastian G. Dalman and Spencer G. Lucas (2026)
Re-Evaluation of Compsemys and North American Compsemydids (Testudinata)
Taxonomy 6(3): 48
doi: https://doi.org/10.3390/taxonomy6030048
https://www.mdpi.com/2673-6500/6/3/48
Compsemys is an enigmatic turtle first described over 160 years ago. Its taxonomic position has been uncertain, as many of the species placed in the genus have since been removed from it. For the last 30+ years, Compsemys victa has been the only recognized North American fossil species. New fossil specimens collected from the Paleocene in the United States necessitate a re-evaluation of the taxonomy of these turtles and call into question the long-held belief that only one species of Compsemys is valid in North America. Specimens from the Paleocene are far more complete than the holotype of C. victa, and all have been referred to this species based on a similar surface texture. Differences between material from the Cretaceous and Paleocene suggest multiple species of Compsemys are valid. In addition to the genotypic species Compsemys victa, C. puercensis, and C. torrejonensis are both valid species from the Paleocene. Beyond surface sculpturing and texture, features of the carapace and plastron can be used to help differentiate the three species. North American Compsemys survived the Cretaceous–Paleogene mass extinction. Rather than being a monospecific genus, Compsemys diversified in the Paleocene. Not only does this suggest an increase in the diversity of North American compsemydids, but it also leads to the possibility of asymmetric or budding cladogenesis among Compsemys species during the Late Cretaceous and Paleocene, at least in the American Southwest.
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Free pdf:
Barbara de Godoi Champini, Ray Brasil Bueno de Souza & Wilfried Klein (2026)
Phylogenetic Reconstruction of Lung Evolution in Extant Squamata
Journal of Zoology (advance online publication)
doi: https://doi.org/10.1111/jzo.70151
https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/jzo.70151
Free pdf:
https://zslpublications.onlinelibrary.wiley.com/doi/epdf/10.1111/jzo.70151
The Squamata group exhibits remarkable diversity in lung structure. However, a comprehensive understanding of how this variation evolved within the clade is still lacking. To reconstruct the evolutionary history of lungs of living squamates, we conducted comparative phylogenetic analyses using categorized lung traits, such as lung type, respiratory epithelium type, and distribution of parenchyma, obtained from literature-derived morphological data. Stochastic character mapping on an amniote phylogeny revealed uncertainties regarding the ancestral lung type at the amniote root, whereas strong support for a unicameral lung was found at the base of Lepidosauria, Squamata, Toxicofera, Iguania, and Anguimorpha. Correlation analysis revealed a small but significant association between epithelium type and distribution, suggesting a degree of correlated evolution among these traits.
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M. B. J. Picasso, C. Acosta Hospitaleche & B. Quaggia (2026)
Reassessing hindlimb morphology in greater and lesser rheas (Aves, Palaeognathae, Rheidae): New insights for fossil rheid identification
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70315
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70315
Correct identification of Rhea americana and Rhea pennata in the fossil record has important paleoenvironmental implications; however, the strong similarity between their postcranial skeletons complicates taxonomic assignments. This study analyzes hindlimb morphology in both species to identify diagnostic characters useful for fossil and archaeological material and to reassess previously reported remains. Femora, tibiotarsi, and tarsometatarsi of adult and juvenile R. americana and R. pennata, comprising a total of 37 specimens, were comparatively analyzed using qualitative morphology and linear measurements. Several osteological differences were identified, particularly in distal tibiotarsal and tarsometatarsal morphology, including trochlear configuration and divergence patterns. Some differences are maintained in juvenile specimens, although ontogenetic variation may complicate identification in certain cases. Reevaluation of fossil and archaeological specimens supported revised taxonomic interpretations for several specimens, whereas poorly preserved or morphologically ambiguous materials were conservatively assigned to Rheidae indet. Although hindlimb bones of R. americana and R. pennata are broadly similar, distal tibiotarsal and especially tarsometatarsal morphology provide useful diagnostic characters. Trochlear configuration and divergence appear to be among the most consistent features, whereas other traits are affected by ontogenetic, intraspecific, and preservational variation. These results contribute to a more robust framework for identifying fossil rheids and highlight the importance of evaluating multiple characters when dealing with fragmentary material.
Reassessing hindlimb morphology in greater and lesser rheas (Aves, Palaeognathae, Rheidae): New insights for fossil rheid identification
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70315
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70315
Correct identification of Rhea americana and Rhea pennata in the fossil record has important paleoenvironmental implications; however, the strong similarity between their postcranial skeletons complicates taxonomic assignments. This study analyzes hindlimb morphology in both species to identify diagnostic characters useful for fossil and archaeological material and to reassess previously reported remains. Femora, tibiotarsi, and tarsometatarsi of adult and juvenile R. americana and R. pennata, comprising a total of 37 specimens, were comparatively analyzed using qualitative morphology and linear measurements. Several osteological differences were identified, particularly in distal tibiotarsal and tarsometatarsal morphology, including trochlear configuration and divergence patterns. Some differences are maintained in juvenile specimens, although ontogenetic variation may complicate identification in certain cases. Reevaluation of fossil and archaeological specimens supported revised taxonomic interpretations for several specimens, whereas poorly preserved or morphologically ambiguous materials were conservatively assigned to Rheidae indet. Although hindlimb bones of R. americana and R. pennata are broadly similar, distal tibiotarsal and especially tarsometatarsal morphology provide useful diagnostic characters. Trochlear configuration and divergence appear to be among the most consistent features, whereas other traits are affected by ontogenetic, intraspecific, and preservational variation. These results contribute to a more robust framework for identifying fossil rheids and highlight the importance of evaluating multiple characters when dealing with fragmentary material.
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