Dinosaur eggshells from Lance Formation of Wyoming + pan-trionychid turtle from Cretacous of China + Bunostegos (pareiasaur) osteoderms + more
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Ben Creisler
Sep 18, 2025, 5:12:26 PM (10 days ago) Sep 18
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Ben Creisler
Tom T.P. Van Der Linden, Jonathan J.W. Wallaard, Maarten De Rijke, and René H.B. Fraaije (2025)
The first description of dinosaurian eggshell from the Maastrichtian Lance Formation, Wyoming, North America
Acta Palaeontologica Polonica 70(3): 573-579
doi:10.4202/app.01211.2024
https://www.app.pan.pl/article/item/app012112024.html
Free pdf:
https://www.app.pan.pl/archive/published/app70/app012112024.pdf
Although numerous fossils have been excavated and described from the Upper Cretaceous (Maastrichtian) Lance Formation, eggs and eggshell remains are rare and have yet to be described in detail. Here, we provide the first description of an eggshell found in the Lance Formation in eastern Wyoming. The eggshell can be attributed to the oofamily Ovaloolithidae, and is most comparable to the oogenus Ovaloolithus based on the smooth outer surface, the eggshell thickness, the closely packed shell units, and the presence of two layers. The eggshell can tentatively be ascribed to either ornithopod or non-avian theropod dinosaurs. This new eggshell expands our understanding of the geographical distribution of ovaloolithid ootaxa throughout the uppermost Cretaceous of North America, having been previously described from the Maastrichtian North Horn Formation of Utah.
Yuzheng Ke, Fenglu Han, and Walter G. Joyce (2025)
The first pan-trionychid turtle from the Upper Cretaceous of southern China, with a summary of the turtle succession in the Ganzhou Basin
Acta Palaeontologica Polonica 70 (3): 607-612
doi:10.4202/app.01263.2025
https://www.app.pan.pl/article/item/app012632025.html
Free pdf:
https://www.app.pan.pl/archive/published/app70/app012632025.pdf
Pan-trionychids are a group of aquatic turtles with a geological occurrence from the Early Cretaceous to the present. Here, we report a small pan-trionychid specimen from the Upper Cretaceous Zhoutian Formation of the Ganzhou Basin of Jiangxi Province, China, which consists of a nearly complete carapace and several associated fragments. The specimen is the first definitive pan-trionychid record from the Upper Cretaceous of southern China. Its general skeletal features are comparable with those of other pan-trionychids from the mid Cretaceous of Asia. However, because the specimen appears to be a juvenile and lacks sufficient anatomical details, we refrain from naming a new species or hypothesizing phylogenetic relationships. Upper Cretaceous sediments in the Ganzhou Basin document a succession of turtle faunas ranging from aquatic pan-trionychids to semi-aquatic lindholmemydids to possibly terrestrial nanhsiungchelyids, but the relationship between this succession and paleoclimate remains ambiguous.
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Xavier Delclòs, Enrique Peñalver, Carlos Jaramillo, Edwin Cadena, César Menor-Salván, José Luís Román, Rafael Francisco Castaño-Cardona, David Peris, Marcelo Carvalho, Daniela Quiroz-Cabascango, Mónica R. Carvalho, Patrick Blomenkemper, Fabiany Herrera, Patricio Santamarina, Maxime Santer, Galo Carrera & Mónica M. Solórzano-Kraemer (2025)
Cretaceous amber of Ecuador unveils new insights into South America’s Gondwanan forests
Communications Earth & Environment 6: 745
doi: https://doi.org/10.1038/s43247-025-02625-2
https://www.nature.com/articles/s43247-025-02625-2
Amber, a fossilised resin, became widespread during the Barremian ( ~ 122 Ma), marking the onset of the Cretaceous Resinous Interval (125–72 Ma). While common in the Northern Hemisphere, amber containing terrestrial arthropod inclusions had not previously been reported from the Mesozoic of South America. Here, we report the major occurrence of such amber from the early Albian ( ~ 112 Ma) Hollín Formation in Ecuadorian Napo region. Discovered at the Genoveva quarry, the amber is associated with coeval pollen and plant macrofossils deposited in fluvio-lacustrine environments. Geochemical analyses suggest araucariacean trees as the resin source, while palynological and macrofloral data indicate moderately diverse forests and the earliest known angiosperm leaf assemblage from north-western South America. Arthropods (hexapods and arachnids) representing at least six orders are well preserved. These findings provide direct evidence of a humid, resinous forest ecosystem and its arthropod fauna in equatorial Gondwana during the Cretaceous Resinous Interval.
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Some recent papers:
Free pdf:
Tom T.P. Van Der Linden, Jonathan J.W. Wallaard, Maarten De Rijke, and René H.B. Fraaije (2025)
The first description of dinosaurian eggshell from the Maastrichtian Lance Formation, Wyoming, North America
Acta Palaeontologica Polonica 70(3): 573-579
doi:10.4202/app.01211.2024
https://www.app.pan.pl/article/item/app012112024.html
Free pdf:
https://www.app.pan.pl/archive/published/app70/app012112024.pdf
Although numerous fossils have been excavated and described from the Upper Cretaceous (Maastrichtian) Lance Formation, eggs and eggshell remains are rare and have yet to be described in detail. Here, we provide the first description of an eggshell found in the Lance Formation in eastern Wyoming. The eggshell can be attributed to the oofamily Ovaloolithidae, and is most comparable to the oogenus Ovaloolithus based on the smooth outer surface, the eggshell thickness, the closely packed shell units, and the presence of two layers. The eggshell can tentatively be ascribed to either ornithopod or non-avian theropod dinosaurs. This new eggshell expands our understanding of the geographical distribution of ovaloolithid ootaxa throughout the uppermost Cretaceous of North America, having been previously described from the Maastrichtian North Horn Formation of Utah.
====
Free pdf:
Yuzheng Ke, Fenglu Han, and Walter G. Joyce (2025)
The first pan-trionychid turtle from the Upper Cretaceous of southern China, with a summary of the turtle succession in the Ganzhou Basin
Acta Palaeontologica Polonica 70 (3): 607-612
doi:10.4202/app.01263.2025
https://www.app.pan.pl/article/item/app012632025.html
Free pdf:
https://www.app.pan.pl/archive/published/app70/app012632025.pdf
Pan-trionychids are a group of aquatic turtles with a geological occurrence from the Early Cretaceous to the present. Here, we report a small pan-trionychid specimen from the Upper Cretaceous Zhoutian Formation of the Ganzhou Basin of Jiangxi Province, China, which consists of a nearly complete carapace and several associated fragments. The specimen is the first definitive pan-trionychid record from the Upper Cretaceous of southern China. Its general skeletal features are comparable with those of other pan-trionychids from the mid Cretaceous of Asia. However, because the specimen appears to be a juvenile and lacks sufficient anatomical details, we refrain from naming a new species or hypothesizing phylogenetic relationships. Upper Cretaceous sediments in the Ganzhou Basin document a succession of turtle faunas ranging from aquatic pan-trionychids to semi-aquatic lindholmemydids to possibly terrestrial nanhsiungchelyids, but the relationship between this succession and paleoclimate remains ambiguous.
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Filip Novak, Oumarou Amadou Ide & Christian A. Sidor (2025)
The vertebrate fauna of the upper Permian of Niger—XII. The osteoderms of Bunostegos akokanensis (Parareptilia: Pareiasauria)
Journal of Vertebrate Paleontology e2532707
doi: https://doi.org/10.1080/02724634.2025.2532707
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2532707
Bunostegos akokanensis is an early diverging pareiasaur known from the Moradi Formation of northern Niger. Most of its osteology has been described in detail, although the occurrence of osteoderms has been noted only in passing. Here, we present a detailed analysis of the morphology and arrangement of the osteoderms of B. akokanensis based on a large, presumably osteologically mature, individual. Articulated osteoderms are present in the cervical and dorsal regions, consisting of four longitudinal rows. Autapomorphically, these osteoderms are sutured together into patterned groups of six or eight, exhibiting varying degrees of ornamentation. In addition, the lateral spinous osteoderms are doubled in the cervicodorsal region. Although relatively small, many of the osteoderms possess subtle radiating ridges and a high degree of suturing to their neighbors. Above the posterior dorsal vertebrae, the osteoderms are reduced to small, underdeveloped elements. Overall, the arrangement of osteoderms in Bunostegos conforms to its phylogenetic position as currently understood, being nested between basally branching bradysaurs, which possess dorsal rows of relatively small, minimally ornamented osteoderms that lack sutural contacts, and the more derived clade of velosaurs, which show suturing, extensive osteoderm body coverage, and more complex ornamentation. Unique traits of Bunostegos, such as an even number of osteoderm rows, lead us to introduce several novel characters that may enhance future phylogenetic analyses of pareiasaurs. Other material from the Moradi Formation, which shows more extensive osteoderm cover, could represent a second species of pareiasaur in the formation, although this conclusion is necessarily tentative.
The vertebrate fauna of the upper Permian of Niger—XII. The osteoderms of Bunostegos akokanensis (Parareptilia: Pareiasauria)
Journal of Vertebrate Paleontology e2532707
doi: https://doi.org/10.1080/02724634.2025.2532707
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2532707
Bunostegos akokanensis is an early diverging pareiasaur known from the Moradi Formation of northern Niger. Most of its osteology has been described in detail, although the occurrence of osteoderms has been noted only in passing. Here, we present a detailed analysis of the morphology and arrangement of the osteoderms of B. akokanensis based on a large, presumably osteologically mature, individual. Articulated osteoderms are present in the cervical and dorsal regions, consisting of four longitudinal rows. Autapomorphically, these osteoderms are sutured together into patterned groups of six or eight, exhibiting varying degrees of ornamentation. In addition, the lateral spinous osteoderms are doubled in the cervicodorsal region. Although relatively small, many of the osteoderms possess subtle radiating ridges and a high degree of suturing to their neighbors. Above the posterior dorsal vertebrae, the osteoderms are reduced to small, underdeveloped elements. Overall, the arrangement of osteoderms in Bunostegos conforms to its phylogenetic position as currently understood, being nested between basally branching bradysaurs, which possess dorsal rows of relatively small, minimally ornamented osteoderms that lack sutural contacts, and the more derived clade of velosaurs, which show suturing, extensive osteoderm body coverage, and more complex ornamentation. Unique traits of Bunostegos, such as an even number of osteoderm rows, lead us to introduce several novel characters that may enhance future phylogenetic analyses of pareiasaurs. Other material from the Moradi Formation, which shows more extensive osteoderm cover, could represent a second species of pareiasaur in the formation, although this conclusion is necessarily tentative.
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Shilong Guo, Wang Ma, Liang Chen, Yunyu Tang, Mengfei Li, Yanchen Zhao, Xinru Deng, Jialiang Zhuang, Yingjie Qiao, Hui Fang, Chungkun Shih, Zhigang Guo, Conrad C. Labandeira & Dong Ren (2025)
The effects of sensitive environmental indicators in interpreting faunas of the past: a case study from the Jurassic of China
Palaeontology 68(5): e70023
doi: https://doi.org/10.1111/pala.70023
https://onlinelibrary.wiley.com/doi/10.1111/pala.70023
The Yanliao Biota is a key Mesozoic terrestrial Lagerstätte in China. It is dominated by invertebrates, particularly clam shrimp, water boatmen and mosquitoes. Vertebrates are rare, with occasional sturgeons and salamanders. Most Chinese researchers suggest that there may be a spatiotemporal and physical association between fragmentation and erosion of the North China Craton (NCC) circumscribing the evolution of the Middle Jurassic Yanliao and Early Cretaceous Jehol faunas that are separated by c. 40 million years. However, recent research has primarily focused on the broad relationships between the tectonic behaviour of the North China Craton and events involving biodiversity and macroevolutionary expansion of these faunas whilst simultaneously neglecting quantitative analyses of community structure and the effects of environmental factors. By integrating species abundances and community co-occurrence networks with geochemical data, we identified salinity as being strongly associated with differentiation among the fossil communities of the Early Yanliao fauna during the late Middle Jurassic interval. Furthermore, our results ruled out humidity, temperature, water carbon-to-nitrogen ratio, and water oxidation conditions as factors with strong correlations, indirectly reinforcing the hypothesis that structural alteration of the North China Craton significantly influenced development and extinction of the Yanliao biota.
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The effects of sensitive environmental indicators in interpreting faunas of the past: a case study from the Jurassic of China
Palaeontology 68(5): e70023
doi: https://doi.org/10.1111/pala.70023
https://onlinelibrary.wiley.com/doi/10.1111/pala.70023
The Yanliao Biota is a key Mesozoic terrestrial Lagerstätte in China. It is dominated by invertebrates, particularly clam shrimp, water boatmen and mosquitoes. Vertebrates are rare, with occasional sturgeons and salamanders. Most Chinese researchers suggest that there may be a spatiotemporal and physical association between fragmentation and erosion of the North China Craton (NCC) circumscribing the evolution of the Middle Jurassic Yanliao and Early Cretaceous Jehol faunas that are separated by c. 40 million years. However, recent research has primarily focused on the broad relationships between the tectonic behaviour of the North China Craton and events involving biodiversity and macroevolutionary expansion of these faunas whilst simultaneously neglecting quantitative analyses of community structure and the effects of environmental factors. By integrating species abundances and community co-occurrence networks with geochemical data, we identified salinity as being strongly associated with differentiation among the fossil communities of the Early Yanliao fauna during the late Middle Jurassic interval. Furthermore, our results ruled out humidity, temperature, water carbon-to-nitrogen ratio, and water oxidation conditions as factors with strong correlations, indirectly reinforcing the hypothesis that structural alteration of the North China Craton significantly influenced development and extinction of the Yanliao biota.
====
====
Free pdf:
Xavier Delclòs, Enrique Peñalver, Carlos Jaramillo, Edwin Cadena, César Menor-Salván, José Luís Román, Rafael Francisco Castaño-Cardona, David Peris, Marcelo Carvalho, Daniela Quiroz-Cabascango, Mónica R. Carvalho, Patrick Blomenkemper, Fabiany Herrera, Patricio Santamarina, Maxime Santer, Galo Carrera & Mónica M. Solórzano-Kraemer (2025)
Cretaceous amber of Ecuador unveils new insights into South America’s Gondwanan forests
Communications Earth & Environment 6: 745
doi: https://doi.org/10.1038/s43247-025-02625-2
https://www.nature.com/articles/s43247-025-02625-2
Amber, a fossilised resin, became widespread during the Barremian ( ~ 122 Ma), marking the onset of the Cretaceous Resinous Interval (125–72 Ma). While common in the Northern Hemisphere, amber containing terrestrial arthropod inclusions had not previously been reported from the Mesozoic of South America. Here, we report the major occurrence of such amber from the early Albian ( ~ 112 Ma) Hollín Formation in Ecuadorian Napo region. Discovered at the Genoveva quarry, the amber is associated with coeval pollen and plant macrofossils deposited in fluvio-lacustrine environments. Geochemical analyses suggest araucariacean trees as the resin source, while palynological and macrofloral data indicate moderately diverse forests and the earliest known angiosperm leaf assemblage from north-western South America. Arthropods (hexapods and arachnids) representing at least six orders are well preserved. These findings provide direct evidence of a humid, resinous forest ecosystem and its arthropod fauna in equatorial Gondwana during the Cretaceous Resinous Interval.
====
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