Chanaresuchus (Triassic archosauriform) tarsus + Patagoniaemys (Cretaceous meiolaniform turtle) postcranial anatomy + New Miocene turtles Helianthochelys and Manouria morla
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Ben Creisler
Oct 3, 2025, 2:06:12 PM10/3/25
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Ben Creisler
New reptile papers:
New insights on the tarsus of Chanaresuchus bonapartei Romer, 1971 (Archosauriformes) and its evolutionary implications
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70061
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70061
Chanaresuchus bonapartei is a species of proterochampsid archosauriform found in the late Landinian–early Carnian aged Chañares Formation of Triassic Argentina. In spite of the fact that its anatomy is relatively well-known, the tarsus remains poorly understood. Here, we describe and compare in detail the astragalus and calcaneum of newly recovered Chanaresuchus specimens. The new material shows a combination of characters previously unknown in other basal archosauriforms including a reduced anterior hollow, contiguous crural facets, a concave anterior surface and convex posterior surface on the astragalus, an anteromedially acute corner, and a mediolaterally constricted calcaneal tuber which is posterolaterally oriented by about 45°. In addition, it possesses a convex articular surface for the fibula in the calcaneum and a subvertically oriented perforating astragalocalcaneal canal, features currently unknown in other proterochampsids, and which may be autapomorphic for the species. Furthermore, we found a functional mesotarsal tarsus, as in the closely related Tropidosuchus. The presence in the astragalus of a reduced anterior hollow located under the fibular facet, an acute anteromedial corner, added to the presence of an ascending process, a dorsally concave medial surface for the tibia, a concave anterior surface and convex posterior surface on the astragalus, an astragalus anteroposteriorly thicker medially than laterally, and a mediolaterally constricted calcaneal tuber are features shared with Ornithodira.
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Carolina Oriozabala, Marcelo S. de la Fuente & Juliana Sterli (2025)
The meiolaniform Patagoniaemys gasparinae from the Upper Cretaceous La Colonia Formation (Chubut, Argentina), Part 1: Postcranial anatomy and paleoecology
Journal of Vertebrate Paleontology e2554253
doi: https://doi.org/10.1080/02724634.2025.2554253
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2554253
Patagoniaemys gasparinae is a non-meiolaniid meiolaniform turtle from the Upper Cretaceous La Colonia Formation in Chubut, Argentina. Aside from Meiolania platyceps, no other almost completely preserved meiolaniform turtle has been described in detail to date. This manuscript describes the postcranial anatomy of Pa. gasparinae based on several specimens, including a nearly complete associated skeleton. This makes Pa. gasparinae the most complete Cretaceous meiolaniform known from Gondwana. This detailed description expands the known postcranial anatomy for Pa. gasparinae, originally described in 2011 based on limited remains. Based on the postcranial anatomy, the manuscript explores the paleoecology of this extinct turtle. Analyses of forelimb proportions suggest that Pa. gasparinae would have been terrestrial or amphibious. The amphibious habitat of Pa. gasparinae is also supported by the proportion of stylopodial elements and the plastral morphology. On the other hand, the terrestrial habitat of Pa. gasparinae is supported by the presence of osteoderms. Furthermore, the finding of specimens of different sizes allows for discussing anatomical changes throughout the ontogeny of Pa. gasparinae.
The meiolaniform Patagoniaemys gasparinae from the Upper Cretaceous La Colonia Formation (Chubut, Argentina), Part 1: Postcranial anatomy and paleoecology
Journal of Vertebrate Paleontology e2554253
doi: https://doi.org/10.1080/02724634.2025.2554253
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2554253
Patagoniaemys gasparinae is a non-meiolaniid meiolaniform turtle from the Upper Cretaceous La Colonia Formation in Chubut, Argentina. Aside from Meiolania platyceps, no other almost completely preserved meiolaniform turtle has been described in detail to date. This manuscript describes the postcranial anatomy of Pa. gasparinae based on several specimens, including a nearly complete associated skeleton. This makes Pa. gasparinae the most complete Cretaceous meiolaniform known from Gondwana. This detailed description expands the known postcranial anatomy for Pa. gasparinae, originally described in 2011 based on limited remains. Based on the postcranial anatomy, the manuscript explores the paleoecology of this extinct turtle. Analyses of forelimb proportions suggest that Pa. gasparinae would have been terrestrial or amphibious. The amphibious habitat of Pa. gasparinae is also supported by the proportion of stylopodial elements and the plastral morphology. On the other hand, the terrestrial habitat of Pa. gasparinae is supported by the presence of osteoderms. Furthermore, the finding of specimens of different sizes allows for discussing anatomical changes throughout the ontogeny of Pa. gasparinae.
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Cenozoic turtles:
Free pdf:
Helianthochelys redondita gen. et sp. nov.
Juliana Sterli, Evangelos Vlachos, José Ignacio Cuitiño, Ignacio A. Cerda, and Mónica Romina Buono (2025)
Southernmost dermochelyid turtle from the Miocene
Ameghiniana 62(4): 1–19
doi: 10.5710/AMGH.29.08.2025.3635
https://www.ameghiniana.org.ar/index.php/ameghiniana/libraryFiles/downloadPublic/149
Dermochelyids are a unique lineage of turtles where the primary carapace underwent an extreme reduction, with its maximum expression in the extant Dermochelys coriacea. Above the primary carapace (thecal), a secondary (epithecal) carapace formed by thousands of ossicles appeared in the late Paleocene. In general, the fossil record of dermochelyids is incomplete, fragmentary, and patchy. Besides, no in-depth and detailed studies on their anatomy led to a poorly resolved alpha taxonomy. In this contribution, we present one of the most complete dermochelyids in the world. Our new turtle was found in the Gaiman Formation (Lower Miocene) in Chubut, Argentina. This Burdigalian record of Patagonia represents the southernmost species in the fossil record of dermochelyid turtles in the Southern Hemisphere in the Miocene. The histological analysis of long bones shows a highly remodeled cortex, a unique condition in turtles. The tissue compaction recorded in this new turtle would suggest it was a very old individual. The phylogenetic analysis recovered the new species in a clade characterized by longitudinal ridges in the carapace and ossicles arranged in a “sunflower” pattern. Exploring the diversity patterns of dermochelyids, we recognize two peaks of diversity and three extinction events, comparable with those observed in other marine tetrapods (e.g., cetaceans, penguins).
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Free pdf:
Manouria morla sp. nov.
Milan Chroust, Tomasz Szczygielski & Àngel H. Luján (2025)
Manouria morla sp. nov., the Ancient One: an Early Miocene large tortoise from the Swamps of Ahníkov, Czechia
Swiss Journal of Palaeontology 144: 63
doi: https://doi.org/10.1186/s13358-025-00400-6
https://link.springer.com/article/10.1186/s13358-025-00400-6
Tortoises (Testudinidae) are a clade of turtles highly specialized to terrestrial environments, mainly living in semi-arid conditions. Herein, we present Manouria morla sp. nov., a new species of the genus Manouria, which is considered to be the most basal extant testudinid genus. The studied material comes from the Ahníkov I fossil site, formerly known as Merkur or Merkur-North, located in the Most Basin in NW Bohemia (Czechia), dated to the Early Miocene (Burdigalian, MN 3). Manouria morla sp. nov. is the oldest member of the Manouria lineage, which nowadays inhabits SE Asia only, and therefore its biogeography and plausible European origin are discussed. The specific type of multiplication of plastral scutes in the inguinal region is discussed as a new morphological character diagnostic for the genus. Based on zoological studies, specific environmental requirements of the genus Manouria allow us to use this taxon as a proxy for the paleoclimate reconstruction of the Ahníkov I fossil site which suggests a broadleaf evergreen tropical wet forest. The simplified use of fossil testudinids as a proxy for reconstructing semi-arid palaeoclimate is therefore disproven.
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