Turtles from Lower Cretaceous of Transbaikalia, Russia + Eoscapherpeton skull anatomy + coprolites and neodiapsid humeri from Early Triassic of India + Upper Cretaceous bromalites from Mexico
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Ben Creisler
Apr 29, 2026, 2:59:28 PM (5 days ago) Apr 29
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Ben Creisler
Recent papers:
Sofia D. Shvets, Alexander O. Averianov, Pavel P. Skutschas, Ekaterina M. Obraztsova & Igor G. Danilov (2026)
Turtles from the Lower Cretaceous of Transbaikalia, Russia, with insights on relationships of sinemydid/macrobaenid turtles and palaeobiogeography of Early Cretaceous turtles of Asia
Journal of Systematic Palaeontology 24(1): 2642426
doi: https://doi.org/10.1080/14772019.2026.2642426
https://www.tandfonline.com/doi/full/10.1080/14772019.2026.2642426
This paper is devoted to the description of turtle material from the Early Cretaceous (Valanginian) Murtoi Formation of the Republic of Buryatia, Transbaikalia, Russia, including new material and the revision of previously described material referred to the sinemydid/macrobaenid turtle Kirgizemys dmitrievi Nessov and Khosatzky, Citation1981a, as well as to several indeterminate stem cryptodires. New material of Kirgizemys dmitrievi, including a partial shell, shell fragments and some appendicular bones, revealed new details of its morphology and variation, allowing us to assign all previously described turtle material from the Murtoi Formation to this species. To determine the phylogenetic position of Kirgizemys dmitrievi and the main taxa of sinemydid/macrobaenid turtles, we performed four phylogenetic analyses based on the global taxon-character matrix of turtles. These analyses, which included more sinemydid/macrobaenid taxa than previous analyses, new anatomical observations and different inference methods (parsimony and Bayesian), differed in their placement of xinjiangchelyids, sinemydids and macrobaenids among stem turtles or stem cryptodires, and in the monophyly or paraphyly of traditional concepts of Xinjiangchelyidae and Macrobaenidae. In addition, these analyses allow the composition of the clades Sinemydidae and Macrobaenidae to be refined and suggest new phylogenetic hypotheses for them, including the placement of Undjulemys platensis one step above Ordosemys and the placement of Wuguia in a single clade with Manchurochelys within Sinemydidae; the monophyly or paraphyly of Kirgizemys (including Jeholochelys and Changmachelys or only the former); the placement of Osteopygis and Borealochelys within one clade; and the different positions of Macrobaena and Gallica within Macrobaenidae. An updated analysis of the palaeobiogeography of Early Cretaceous turtles of Asia supports a split pattern, in which more derived basal stem cryptodires (Sinemydidae and Macrobaenidae) occupied isolated (lacustrine) inland basins, while early branching cryptodires (pan-trionychians) inhabited surrounding coastal areas. Kirgizemys spp., distributed in both inland and coastal areas, retain a primitive, homogeneous distribution pattern, probably inherited from their Jurassic ancestors. A review of the palaeobiology of xinjiangchelyids, sinemydids and macrobaenids shows that, although unevenly studied, they demonstrate a wide range of aquatic adaptations, including neck retraction abilities, feeding mechanics and diet.
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Turtles from the Lower Cretaceous of Transbaikalia, Russia, with insights on relationships of sinemydid/macrobaenid turtles and palaeobiogeography of Early Cretaceous turtles of Asia
Journal of Systematic Palaeontology 24(1): 2642426
doi: https://doi.org/10.1080/14772019.2026.2642426
https://www.tandfonline.com/doi/full/10.1080/14772019.2026.2642426
This paper is devoted to the description of turtle material from the Early Cretaceous (Valanginian) Murtoi Formation of the Republic of Buryatia, Transbaikalia, Russia, including new material and the revision of previously described material referred to the sinemydid/macrobaenid turtle Kirgizemys dmitrievi Nessov and Khosatzky, Citation1981a, as well as to several indeterminate stem cryptodires. New material of Kirgizemys dmitrievi, including a partial shell, shell fragments and some appendicular bones, revealed new details of its morphology and variation, allowing us to assign all previously described turtle material from the Murtoi Formation to this species. To determine the phylogenetic position of Kirgizemys dmitrievi and the main taxa of sinemydid/macrobaenid turtles, we performed four phylogenetic analyses based on the global taxon-character matrix of turtles. These analyses, which included more sinemydid/macrobaenid taxa than previous analyses, new anatomical observations and different inference methods (parsimony and Bayesian), differed in their placement of xinjiangchelyids, sinemydids and macrobaenids among stem turtles or stem cryptodires, and in the monophyly or paraphyly of traditional concepts of Xinjiangchelyidae and Macrobaenidae. In addition, these analyses allow the composition of the clades Sinemydidae and Macrobaenidae to be refined and suggest new phylogenetic hypotheses for them, including the placement of Undjulemys platensis one step above Ordosemys and the placement of Wuguia in a single clade with Manchurochelys within Sinemydidae; the monophyly or paraphyly of Kirgizemys (including Jeholochelys and Changmachelys or only the former); the placement of Osteopygis and Borealochelys within one clade; and the different positions of Macrobaena and Gallica within Macrobaenidae. An updated analysis of the palaeobiogeography of Early Cretaceous turtles of Asia supports a split pattern, in which more derived basal stem cryptodires (Sinemydidae and Macrobaenidae) occupied isolated (lacustrine) inland basins, while early branching cryptodires (pan-trionychians) inhabited surrounding coastal areas. Kirgizemys spp., distributed in both inland and coastal areas, retain a primitive, homogeneous distribution pattern, probably inherited from their Jurassic ancestors. A review of the palaeobiology of xinjiangchelyids, sinemydids and macrobaenids shows that, although unevenly studied, they demonstrate a wide range of aquatic adaptations, including neck retraction abilities, feeding mechanics and diet.
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Veniamin V Kolchanov & Pavel P Skutschas (2026)
Skull anatomy of the Late Cretaceous salamander Eoscapherpeton asiaticum (Caudata: Cryptobranchidae) based on computed tomography, and implications for cryptobranchid cranial evolution
Zoological Journal of the Linnean Society 206(4): zlag042
doi: https://doi.org/10.1093/zoolinnean/zlag042
https://academic.oup.com/zoolinnean/article-abstract/206/4/zlag042/8663725
The salamander Eoscapherpeton asiaticum from the Upper Cretaceous of Uzbekistan is one of the most basal cryptobranchids and provides important information on the early evolution of Cryptobranchidae. We describe the cranial anatomy of E. asiaticum based on computed tomography of several specimens. The skull is not as dorsoventrally flattened as in extant cryptobranchids. The skull is further characterized by: ventrolaterally oriented suspensorium; extensive squamosal–parietal contact; long vomeral process of the premaxilla; septum in the olfactory region, formed by the dorsal processes of the vomers; complex system of neurovascular canals in the premaxillae, maxillae, frontals, and mandible; extensively ossified hyobranchial apparatus; presence of lacrimals, anterior coronoids, and large pterygoids; and absence of anteromedial fenestra in the palate. The cranial structure (ossified hyobranchial apparatus; complex system of neurovascular canals; subhorizontal ridge on labial surface of premaxilla and maxilla; and lack of anteromedial fenestra) suggests that E. asiaticum was an active aquatic predator that used the well-developed lateral line system in its head as a unique adaptation for locating prey. The acquisition of large body size in derived species of Cryptobranchidae, together with retaining the neotenic state, led to the flattening of the skull and the origin of a complex suction-feeding mechanism characteristic of extant cryptobranchids.
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Skull anatomy of the Late Cretaceous salamander Eoscapherpeton asiaticum (Caudata: Cryptobranchidae) based on computed tomography, and implications for cryptobranchid cranial evolution
Zoological Journal of the Linnean Society 206(4): zlag042
doi: https://doi.org/10.1093/zoolinnean/zlag042
https://academic.oup.com/zoolinnean/article-abstract/206/4/zlag042/8663725
The salamander Eoscapherpeton asiaticum from the Upper Cretaceous of Uzbekistan is one of the most basal cryptobranchids and provides important information on the early evolution of Cryptobranchidae. We describe the cranial anatomy of E. asiaticum based on computed tomography of several specimens. The skull is not as dorsoventrally flattened as in extant cryptobranchids. The skull is further characterized by: ventrolaterally oriented suspensorium; extensive squamosal–parietal contact; long vomeral process of the premaxilla; septum in the olfactory region, formed by the dorsal processes of the vomers; complex system of neurovascular canals in the premaxillae, maxillae, frontals, and mandible; extensively ossified hyobranchial apparatus; presence of lacrimals, anterior coronoids, and large pterygoids; and absence of anteromedial fenestra in the palate. The cranial structure (ossified hyobranchial apparatus; complex system of neurovascular canals; subhorizontal ridge on labial surface of premaxilla and maxilla; and lack of anteromedial fenestra) suggests that E. asiaticum was an active aquatic predator that used the well-developed lateral line system in its head as a unique adaptation for locating prey. The acquisition of large body size in derived species of Cryptobranchidae, together with retaining the neotenic state, led to the flattening of the skull and the origin of a complex suction-feeding mechanism characteristic of extant cryptobranchids.
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Saurabh Pal, Ajoy K. Bhaumik, Sayan Tikadar, Sudip K. Mahato & Anjali Pal (2026)
Coprolites and Neodiapsida remains from the Early Triassic Panchet Formation, India
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2026.2654073
https://www.tandfonline.com/doi/full/10.1080/08912963.2026.2654073
The Permo-Triassic mass extinction event was one of the most catastrophic events in Earth’s history, with a few disaster taxa that survived this extinction event. During the Early Triassic, ecosystems began to recover as a few surviving lineages diversified to fill the vacant niches. Thus, the study of Early Triassic biota is significant to understand the ecosystem recovery and the evolutionary paths of the surviving clades. In India, the Early Triassic non-marine biota has been recorded within the Panchet and Kamthi formations. In this study, we report an assemblage of vertebrate coprolites within the Early Triassic sandstone beds belonging to the Panchet Formation, India. Based on their external features, presence/absence of biotic inclusions, and chemical nature, the recovered coprolite ichnofossils have been characterised into ichnotaxa and different morphotypes. Several of these coprolites showcase well-preserved inclusions of ganoid fish scales and conchostracan valves, suggesting that the producer(s) practised carnivory with a dominant piscivorous diet. In addition, this study describes Neodiapsida humeri from the same horizon and tentatively attributed to Archosauromorpha.
urn:lsid:zoobank.org:pub:7BF6A7FA-6D96-4A68-894F-9B4D5457A964
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P. E. Mungarro-González, C. I. Serrano-Brañas, B. Espinosa-Chávez, M. C. Peñalba, I. R. Espinoza-Encinas & A. Varela-Romero (2026)
Exploring the paleoecology and taphonomy of Upper Cretaceous bromalites from the Cerro del Pueblo Formation, Northern Mexico
Ichnos (advance online publication)
doi: https://doi.org/10.1080/10420940.2026.2659169
https://www.tandfonline.com/doi/full/10.1080/10420940.2026.2659169
In this study, 252 bromalite specimens from the paleontological collection of the Benemérita Escuela Normal de Coahuila were examined. These specimens were collected in the Cerro del Pueblo Formation (Upper Campanian) in the state of Coahuila, Mexico, and analyzed to obtain paleoecological and, for the first time, taphonomic data. A total of 18 morphotypes were classified and assigned to various potential producers, including teleosts, basal actinopterygians, elasmobranchs, crocodilians, testudines, amphibians, reptiles, theropod dinosaurs, and possibly other groups of omnivorous vertebrates. A multivariate analysis supported relationship between morphotypes and their associated potential producers. Additionally, some specimens present macroscopic and microscopic inclusions, such as bone remains and plant fragments, suggesting that these could represent predator-prey and herbivore-plant interactions. In contrast, traces of bioerosion in some specimens suggest coprophagy. The oxidized/reduced colorations, fragmentation, and biostratinomic alterations in the specimens indicate that they were likely deposited in floodplain environments. Furthermore, the ichnogenera Alococopros isp., Eucopros isp., and Struocopros isp. were identified within the collection, thus representing the first coprolite ichnotaxonomic records for northern Mexico from the Late Cretaceous. The biotic interactions inferred from the inclusions in the bromalites, their associated potential producers, and their distinct taphonomic histories suggest the presence of a diverse fauna that inhabited the various types of terrestrial and transitional environments within the Cerro del Pueblo Formation at the end of the Cretaceous.
HIGHLIGHTS
Bromalite specimens from the Cerro del Pueblo (Late Cretaceous) were classified into 18 morphotypes.
The morphological and morphometric analyses and their inclusions suggest these morphotypes were produced by marine and non-marine fauna.
The examination of the bromalite morphotypes indicates the presence of one marine ichnogenus and two terrestrial ichnogenera.
Ecological interactions were preserved within the inclusions found in the bromalites and their associated potential producers.
The bromalites could have undergone different taphonomic histories based on the biostratinomic and diagenetic alterations identified in the specimens.
Exploring the paleoecology and taphonomy of Upper Cretaceous bromalites from the Cerro del Pueblo Formation, Northern Mexico
Ichnos (advance online publication)
doi: https://doi.org/10.1080/10420940.2026.2659169
https://www.tandfonline.com/doi/full/10.1080/10420940.2026.2659169
In this study, 252 bromalite specimens from the paleontological collection of the Benemérita Escuela Normal de Coahuila were examined. These specimens were collected in the Cerro del Pueblo Formation (Upper Campanian) in the state of Coahuila, Mexico, and analyzed to obtain paleoecological and, for the first time, taphonomic data. A total of 18 morphotypes were classified and assigned to various potential producers, including teleosts, basal actinopterygians, elasmobranchs, crocodilians, testudines, amphibians, reptiles, theropod dinosaurs, and possibly other groups of omnivorous vertebrates. A multivariate analysis supported relationship between morphotypes and their associated potential producers. Additionally, some specimens present macroscopic and microscopic inclusions, such as bone remains and plant fragments, suggesting that these could represent predator-prey and herbivore-plant interactions. In contrast, traces of bioerosion in some specimens suggest coprophagy. The oxidized/reduced colorations, fragmentation, and biostratinomic alterations in the specimens indicate that they were likely deposited in floodplain environments. Furthermore, the ichnogenera Alococopros isp., Eucopros isp., and Struocopros isp. were identified within the collection, thus representing the first coprolite ichnotaxonomic records for northern Mexico from the Late Cretaceous. The biotic interactions inferred from the inclusions in the bromalites, their associated potential producers, and their distinct taphonomic histories suggest the presence of a diverse fauna that inhabited the various types of terrestrial and transitional environments within the Cerro del Pueblo Formation at the end of the Cretaceous.
HIGHLIGHTS
Bromalite specimens from the Cerro del Pueblo (Late Cretaceous) were classified into 18 morphotypes.
The morphological and morphometric analyses and their inclusions suggest these morphotypes were produced by marine and non-marine fauna.
The examination of the bromalite morphotypes indicates the presence of one marine ichnogenus and two terrestrial ichnogenera.
Ecological interactions were preserved within the inclusions found in the bromalites and their associated potential producers.
The bromalites could have undergone different taphonomic histories based on the biostratinomic and diagenetic alterations identified in the specimens.
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