Archaeopteryx + dsungaripterid pterosaur from Russia + teleosauroid carcasses seafloor arrival position + alligator osteoderm development
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Ben Creisler
Jul 7, 2025, 2:44:26 PM7/7/25
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Ben Creisler
Recent papers:
Jingmai O’Connor (2025)
Archaeopteryx
Current Biology 35(13): R643-R644
doi: https://doi.org/10.1016/j.cub.2025.02.019
https://www.cell.com/current-biology/abstract/S0960-9822(25)00153-8
https://www.sciencedirect.com/science/article/abs/pii/S0960982225001538
Archaeo-who? Archaeopteryx lithographica — a small, feathered dinosaur found in the ∼150 million year old Solnhofen limestones located in Bavaria (Figure 1). The Solnhofen deposits record a tropical marine archipelago, with fossils of sharks, bony fishes, ichthyosaurs, marine crocodilians, turtles, crustaceans, echinoderms, ammonites and bivalves. In addition, the rocks occasionally preserve terrestrial island inhabitants, such as pterosaurs, rhynchocephalians and theropod dinosaurs. Archaeopteryx was first described from an isolated feather in 1861 (Figure 1B), when the only organisms known to have feathers were birds. Thus, Archaeopteryx was identified as an ‘Urvogel’ (‘primordial bird’). While not truly the first bird, Archaeopteryx is the oldest known bird — the pectoral structure of a newly discovered bird from the Jurassic Zhenghe avifauna strongly suggests that birds originated more than 150 million years ago. As such, Archaeopteryx provides the earliest piece of evidence regarding the unique evolutionary history of this fascinating lineage.
Archaeopteryx
Current Biology 35(13): R643-R644
doi: https://doi.org/10.1016/j.cub.2025.02.019
https://www.cell.com/current-biology/abstract/S0960-9822(25)00153-8
https://www.sciencedirect.com/science/article/abs/pii/S0960982225001538
Archaeo-who? Archaeopteryx lithographica — a small, feathered dinosaur found in the ∼150 million year old Solnhofen limestones located in Bavaria (Figure 1). The Solnhofen deposits record a tropical marine archipelago, with fossils of sharks, bony fishes, ichthyosaurs, marine crocodilians, turtles, crustaceans, echinoderms, ammonites and bivalves. In addition, the rocks occasionally preserve terrestrial island inhabitants, such as pterosaurs, rhynchocephalians and theropod dinosaurs. Archaeopteryx was first described from an isolated feather in 1861 (Figure 1B), when the only organisms known to have feathers were birds. Thus, Archaeopteryx was identified as an ‘Urvogel’ (‘primordial bird’). While not truly the first bird, Archaeopteryx is the oldest known bird — the pectoral structure of a newly discovered bird from the Jurassic Zhenghe avifauna strongly suggests that birds originated more than 150 million years ago. As such, Archaeopteryx provides the earliest piece of evidence regarding the unique evolutionary history of this fascinating lineage.
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A. O. Averianov & A. V. Lopatin (2025)
Dsungaripterid Pterosaur from the Lower Cretaceous of Transbaikalia, Russia
Doklady Earth Sciences 523: 18
doi: https://doi.org/10.1134/S1028334X25607035
https://link.springer.com/article/10.1134/S1028334X25607035
A proximal fragment of tibiotarsus (fused tibia and fibula) from the Lower Cretaceous Murtoi Formation at the Mogoito locality in Buryatia, Russia, is attributed to a pterosaur Dsungaripteridae indet. on the base of a relatively large cnemial crest and considerable bone thickness of the tibia shaft. The pterosaurs from the Mogoito locality had previously been identified based on isolated teeth attributed to Ornithocheiridae. The described tibiotarsus represents the second record of Dsungaripteridae in Russia and the second pterosaur bone known from the Lower Cretaceous of Russia.
Michela M. Johnson, Eudald Mujal, Samuel L.A. Cooper & Erin E. Maxwell (2025)
Criteria for inferring seafloor arrival position in teleosauroid carcasses (Crocodylomorpha: Thalattosuchia) and comparison with other marine vertebrates
Geological Magazine 162: e19
DOI: https://doi.org/10.1017/S0016756825100058
https://www.cambridge.org/core/journals/geological-magazine/article/criteria-for-inferring-seafloor-arrival-position-in-teleosauroid-carcasses-crocodylomorpha-thalattosuchia-and-comparison-with-other-marine-vertebrates/1B793ED1775F77E76F65BBF0025FB9F8
The Lower Jurassic (Toarcian) Posidonienschiefer Formation of southwestern Germany is a classic konservat lagerstätte, yielding some of the world’s best-preserved fossils of marine vertebrates, including ichthyosaurs, thalattosuchian crocodylomorphs, plesiosaurs and fishes. Despite numerous studies concentrating on the taphonomy of ichthyosaurs in this formation, less taphonomic work has focussed on the thalattosuchians of the assemblage. Multiple thalattosuchian species displaying a wide range of body sizes have been recovered. We investigated indicators for seafloor arrival position in thirteen Macrospondylus bollensis and one Platysuchus multiscrobiculatus specimens representing various body sizes using three-dimensional (3D) photogrammetric models. False-colour depth maps were used to interpret the relative topography (depth level) of bone penetration into the sediment and were aligned on the XY plane, making them parallel to the stratigraphic plane. Our results show both headfirst and non-headfirst seafloor arrivals in observed specimens, with headfirst seafloor arrivals exhibiting deeply buried skulls, displacement of select cervical vertebrae and/or characteristic fractures in the cranium and mandible. We (1) interpret seafloor landing types in teleosauroids; (2) recognize and list specific characteristics that are consistently attributed to either a headfirst or non-headfirst seafloor arrival; (3) discuss possible factors that may have contributed to these features, such as body shape and size, substrate and velocity; and (4) provide a new definition for headfirst seafloor arrival that can be readily attributed to other marine vertebrates from various formations. Lastly, our results show that observers must carefully consider how historical specimens might have been prepared, as this may influence taphonomic interpretations.
Dsungaripterid Pterosaur from the Lower Cretaceous of Transbaikalia, Russia
Doklady Earth Sciences 523: 18
doi: https://doi.org/10.1134/S1028334X25607035
https://link.springer.com/article/10.1134/S1028334X25607035
A proximal fragment of tibiotarsus (fused tibia and fibula) from the Lower Cretaceous Murtoi Formation at the Mogoito locality in Buryatia, Russia, is attributed to a pterosaur Dsungaripteridae indet. on the base of a relatively large cnemial crest and considerable bone thickness of the tibia shaft. The pterosaurs from the Mogoito locality had previously been identified based on isolated teeth attributed to Ornithocheiridae. The described tibiotarsus represents the second record of Dsungaripteridae in Russia and the second pterosaur bone known from the Lower Cretaceous of Russia.
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Free pdf:
Michela M. Johnson, Eudald Mujal, Samuel L.A. Cooper & Erin E. Maxwell (2025)
Criteria for inferring seafloor arrival position in teleosauroid carcasses (Crocodylomorpha: Thalattosuchia) and comparison with other marine vertebrates
Geological Magazine 162: e19
DOI: https://doi.org/10.1017/S0016756825100058
https://www.cambridge.org/core/journals/geological-magazine/article/criteria-for-inferring-seafloor-arrival-position-in-teleosauroid-carcasses-crocodylomorpha-thalattosuchia-and-comparison-with-other-marine-vertebrates/1B793ED1775F77E76F65BBF0025FB9F8
The Lower Jurassic (Toarcian) Posidonienschiefer Formation of southwestern Germany is a classic konservat lagerstätte, yielding some of the world’s best-preserved fossils of marine vertebrates, including ichthyosaurs, thalattosuchian crocodylomorphs, plesiosaurs and fishes. Despite numerous studies concentrating on the taphonomy of ichthyosaurs in this formation, less taphonomic work has focussed on the thalattosuchians of the assemblage. Multiple thalattosuchian species displaying a wide range of body sizes have been recovered. We investigated indicators for seafloor arrival position in thirteen Macrospondylus bollensis and one Platysuchus multiscrobiculatus specimens representing various body sizes using three-dimensional (3D) photogrammetric models. False-colour depth maps were used to interpret the relative topography (depth level) of bone penetration into the sediment and were aligned on the XY plane, making them parallel to the stratigraphic plane. Our results show both headfirst and non-headfirst seafloor arrivals in observed specimens, with headfirst seafloor arrivals exhibiting deeply buried skulls, displacement of select cervical vertebrae and/or characteristic fractures in the cranium and mandible. We (1) interpret seafloor landing types in teleosauroids; (2) recognize and list specific characteristics that are consistently attributed to either a headfirst or non-headfirst seafloor arrival; (3) discuss possible factors that may have contributed to these features, such as body shape and size, substrate and velocity; and (4) provide a new definition for headfirst seafloor arrival that can be readily attributed to other marine vertebrates from various formations. Lastly, our results show that observers must carefully consider how historical specimens might have been prepared, as this may influence taphonomic interpretations.
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Brooke H. Dubansky, Jacob Raney, Stevie Bordelon, Katie Black, Peyton Cagle & Benjamin Dubansky (2025)
Mechanical stress may initiate osteoderm development in the American alligator (Alligator mississippiensis)
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70015
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70015
Osteoderms are bones that form in the dermis of several species, but their development and function are not well understood. Comparing cellular and molecular events that initiate and drive pathologies similarly characterized by ossification of soft tissues (heterotopic ossification) may provide insight into how osteoderms develop. It is thought that the origin of some heterotopic ossification lesions is mediated through mechanotransduction, or the conversion of mechanical forces on the extracellular matrix (ECM) to biochemical signals that initiate bone formation. Discrete osteoderm developmental stages in alligators were previously established based on morphology; however, questions remain regarding the type of collagen, the identity of cell precursors, and factors that initiate their development. In this study, we investigated changes in the ECM in different stages of osteoderm development. We found that in dorsal cervical scales, an organized reticulin fiber scaffold precedes bone formation, and that before and during ossification, collagen fibers are under tension in specific planes of the body. These tensed collagen fibers correspond to attachments of the superficial and deep cervical fasciae and the tendons of some muscles of the jaws, neck, and shoulders. Osteoderms are therefore exoskeletal elements that likely distribute mechanical forces to the skin during normal body movements, and we hypothesize that these mechanical forces play a role in stimulating ossification at these sites via mechanotransduction. This developmental mechanism may be comparable to the development of some trauma-induced heterotopic ossification lesions that are similarly initiated by mechanotransduction.
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Mechanical stress may initiate osteoderm development in the American alligator (Alligator mississippiensis)
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70015
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70015
Osteoderms are bones that form in the dermis of several species, but their development and function are not well understood. Comparing cellular and molecular events that initiate and drive pathologies similarly characterized by ossification of soft tissues (heterotopic ossification) may provide insight into how osteoderms develop. It is thought that the origin of some heterotopic ossification lesions is mediated through mechanotransduction, or the conversion of mechanical forces on the extracellular matrix (ECM) to biochemical signals that initiate bone formation. Discrete osteoderm developmental stages in alligators were previously established based on morphology; however, questions remain regarding the type of collagen, the identity of cell precursors, and factors that initiate their development. In this study, we investigated changes in the ECM in different stages of osteoderm development. We found that in dorsal cervical scales, an organized reticulin fiber scaffold precedes bone formation, and that before and during ossification, collagen fibers are under tension in specific planes of the body. These tensed collagen fibers correspond to attachments of the superficial and deep cervical fasciae and the tendons of some muscles of the jaws, neck, and shoulders. Osteoderms are therefore exoskeletal elements that likely distribute mechanical forces to the skin during normal body movements, and we hypothesize that these mechanical forces play a role in stimulating ossification at these sites via mechanotransduction. This developmental mechanism may be comparable to the development of some trauma-induced heterotopic ossification lesions that are similarly initiated by mechanotransduction.
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