Itapeuasaurus taphonomic study in Brazil + Neuquensaurus dominated bone accumulation in Argentina
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Ben Creisler
Sep 19, 2026, 10:10:07 PM (2 days ago) Sep 19
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Ben Creisler
New papers:
Free pdf:
Ana Carolina Nunes de Moraes Rego, Hermínio Ismael de Araújo-Júnior, Fernando Henrique de Souza Barbosa & Manuel Alfredo Medeiros (2026)
Biostratinomic aspects of Itapeuasaurus cajapioensis (Dinosauria, Diplodocoidea) from the Alcântara Formation, Cenomanian of the São Luís Basin, Northeast of Brazil
Cretaceous Research 106495
doi: 10.1016/j.cretres.2026.106495
https://www.sciencedirect.com/science/article/pii/S0195667126001849
Bullet Points
First detailed taphonomic study of Itapeuasaurus cajapioensis
Assemblage deposited in a transitional estuarine setting
Diverse biostratinomic modifications in vertebrate remains
Taphonomic patterns reflect marginal-marine depositional dynamics
Provides a framework for vertebrate taphonomy in marginal-marine systems
Abstract
The Alcântara Formation (Cenomanian, São Luís Basin, northeastern Brazil) preserves one of the most significant Cretaceous vertebrate assemblages in South America, yet taphonomic studies of its fauna remain scarce. Here, we present the first detailed biostratinomic analysis of Itapeuasaurus cajapioensis, a diplodocoid sauropod from Itapeua Beach, Maranhão State. Twenty-two skeletal elements attributed to a single individual were analyzed using established methods for assessing taphonomic attributes. The assemblage is characterized by complete skeletal disarticulation and spatially restricted distribution, with the remains occurring in three spatially associated groups within an area of slightly more than 9 m2. Fluvial Transport Index (FTI) values indicate moderate to high transportability of the skeletal elements, although these values do not provide direct evidence of hydraulic transport. Abrasion was recorded in all analyzed specimens, predominantly at low to moderate intensity. Weathering stages 2 and 3, desiccation features, and insect-related bioerosion indicate subaerial exposure prior to final burial, whereas the predominance of biostratinomic fracture patterns supports pre-burial mechanical modification. Deformation and corrosion provide evidence of additional post-burial mechanical and chemical alteration, while bone coloration may reflect interactions with iron and manganese oxides and/or organic matter in the surrounding sediment. The combined taphonomic evidence indicates a complex history involving complete disarticulation, limited spatial redistribution, mechanical abrasion, subaerial exposure, bioerosion, fragmentation, and subsequent diagenetic modification. Although the transitional to marginal-marine depositional context may have favored hydrodynamic reworking, including tidal processes, the available evidence does not allow a specific transport mechanism to be established. This study contributes to the understanding of vertebrate preservation in transitional to marginal-marine settings and expands the taphonomic record of Cretaceous vertebrates from the Alcântara Formation and the São Luís Basin.
Free pdf:
Ana Carolina Nunes de Moraes Rego, Hermínio Ismael de Araújo-Júnior, Fernando Henrique de Souza Barbosa & Manuel Alfredo Medeiros (2026)
Biostratinomic aspects of Itapeuasaurus cajapioensis (Dinosauria, Diplodocoidea) from the Alcântara Formation, Cenomanian of the São Luís Basin, Northeast of Brazil
Cretaceous Research 106495
doi: 10.1016/j.cretres.2026.106495
https://www.sciencedirect.com/science/article/pii/S0195667126001849
Bullet Points
First detailed taphonomic study of Itapeuasaurus cajapioensis
Assemblage deposited in a transitional estuarine setting
Diverse biostratinomic modifications in vertebrate remains
Taphonomic patterns reflect marginal-marine depositional dynamics
Provides a framework for vertebrate taphonomy in marginal-marine systems
Abstract
The Alcântara Formation (Cenomanian, São Luís Basin, northeastern Brazil) preserves one of the most significant Cretaceous vertebrate assemblages in South America, yet taphonomic studies of its fauna remain scarce. Here, we present the first detailed biostratinomic analysis of Itapeuasaurus cajapioensis, a diplodocoid sauropod from Itapeua Beach, Maranhão State. Twenty-two skeletal elements attributed to a single individual were analyzed using established methods for assessing taphonomic attributes. The assemblage is characterized by complete skeletal disarticulation and spatially restricted distribution, with the remains occurring in three spatially associated groups within an area of slightly more than 9 m2. Fluvial Transport Index (FTI) values indicate moderate to high transportability of the skeletal elements, although these values do not provide direct evidence of hydraulic transport. Abrasion was recorded in all analyzed specimens, predominantly at low to moderate intensity. Weathering stages 2 and 3, desiccation features, and insect-related bioerosion indicate subaerial exposure prior to final burial, whereas the predominance of biostratinomic fracture patterns supports pre-burial mechanical modification. Deformation and corrosion provide evidence of additional post-burial mechanical and chemical alteration, while bone coloration may reflect interactions with iron and manganese oxides and/or organic matter in the surrounding sediment. The combined taphonomic evidence indicates a complex history involving complete disarticulation, limited spatial redistribution, mechanical abrasion, subaerial exposure, bioerosion, fragmentation, and subsequent diagenetic modification. Although the transitional to marginal-marine depositional context may have favored hydrodynamic reworking, including tidal processes, the available evidence does not allow a specific transport mechanism to be established. This study contributes to the understanding of vertebrate preservation in transitional to marginal-marine settings and expands the taphonomic record of Cretaceous vertebrates from the Alcântara Formation and the São Luís Basin.
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Paolo Citton, Ignacio A. Cerda, Virginia L. Zurriaguz, Martina Caratelli, Jonatan Kaluza, José Aravena & Federico Guzmán (2026)
Genesis of a Neuquensaurus australis (Dinosauria: Sauropoda) dominated bone accumulation (Anacleto Formation, Campanian, Patagonia): burial process, preliminary biostratinomic insights and palaeoecological implications
Cretaceous Research 106496
doi: 10.1016/j.cretres.2026.106496
https://www.sciencedirect.com/science/article/abs/pii/S0195667126001850
Highlights
Near monospecific subadult-dominated assemblage with minimal transport evidence.
Possible non-catastrophic mortality on a floodplain setting is suggested.
Minor attritional input is represented by rare non-Neuquensaurus remains.
Event-driven Neuquensaurus australis accumulation buried rapidly by dense flood flow.
Massive deposition ensured rapid burial and skeletal preservation.
Abstract
A bone-bearing assemblage dominated by the saltasaurine Neuquensaurus australis from the Anacleto Formation (Campanian, Patagonia, Argentina) is analysed from a biostratinomic and sedimentological perspective. The assemblage comprises a minimum of six individuals (five subadults and one juvenile), with rare remains referable to Titanosauria indet. and teeth of Theropoda indet. Biostratinomic evidence, including low weathering, negligible abrasion, rare bioerosion, and a balanced representation of elements with different transport susceptibilities, indicates limited exposure, minimal reworking, and short transport prior to burial. The near-monospecific composition, preservation of fragile elements, lack of preferred orientation and hydraulic sorting collectively support a rapid burial, likely triggered by a dense, sediment-laden flow associated with an episodic flooding event. The assemblage is interpreted as an event-dominated accumulation, most likely reflecting a non-catastrophic mortality event involving multiple individuals belonging to two ontogenetic categories (one juvenile and five subadult individuals), followed by rapid entombment. Rare non-Neuquensaurus remains are regarded as a minor attritional background signal, indicating limited time-averaging of the assemblage.
====
Genesis of a Neuquensaurus australis (Dinosauria: Sauropoda) dominated bone accumulation (Anacleto Formation, Campanian, Patagonia): burial process, preliminary biostratinomic insights and palaeoecological implications
Cretaceous Research 106496
doi: 10.1016/j.cretres.2026.106496
https://www.sciencedirect.com/science/article/abs/pii/S0195667126001850
Highlights
Near monospecific subadult-dominated assemblage with minimal transport evidence.
Possible non-catastrophic mortality on a floodplain setting is suggested.
Minor attritional input is represented by rare non-Neuquensaurus remains.
Event-driven Neuquensaurus australis accumulation buried rapidly by dense flood flow.
Massive deposition ensured rapid burial and skeletal preservation.
Abstract
A bone-bearing assemblage dominated by the saltasaurine Neuquensaurus australis from the Anacleto Formation (Campanian, Patagonia, Argentina) is analysed from a biostratinomic and sedimentological perspective. The assemblage comprises a minimum of six individuals (five subadults and one juvenile), with rare remains referable to Titanosauria indet. and teeth of Theropoda indet. Biostratinomic evidence, including low weathering, negligible abrasion, rare bioerosion, and a balanced representation of elements with different transport susceptibilities, indicates limited exposure, minimal reworking, and short transport prior to burial. The near-monospecific composition, preservation of fragile elements, lack of preferred orientation and hydraulic sorting collectively support a rapid burial, likely triggered by a dense, sediment-laden flow associated with an episodic flooding event. The assemblage is interpreted as an event-dominated accumulation, most likely reflecting a non-catastrophic mortality event involving multiple individuals belonging to two ontogenetic categories (one juvenile and five subadult individuals), followed by rapid entombment. Rare non-Neuquensaurus remains are regarded as a minor attritional background signal, indicating limited time-averaging of the assemblage.
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