Mature titanosaur dorsal ribs growth pattern from Upper Cretaceous of Texas
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Ben Creisler
Oct 16, 2025, 11:28:01 AM (3 days ago) Oct 16
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Ben Creisler
A new paper:
John A. Fronimos & Holly N. Woodward (2025)
Ontogenetic assessment from dorsal ribs in a mature titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Texas
Journal of Vertebrate Paleontology e2559012
doi: https://doi.org/10.1080/02724634.2025.2559012
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2559012
Osteohistology has provided significant insights into the ontogeny and life history of the sauropod dinosaurs. However, the Titanosauria, which include Earth’s largest terrestrial vertebrates, exhibit intense appendicular bone remodeling that obscures these details. Inspired by findings of well-preserved growth histories in sauropod dorsal ribs, we sampled a titanosaur specimen from the latest Cretaceous of Texas, one of the largest known from North America. The specimen preserved an almost complete set of dorsal ribs, many in articulation, from which five were sectioned near their proximal ends to allow comparisons between anterior, middle, and posterior positions. Results show that the high degree of remodeling characteristic of titanosaurs is also present in the dorsal ribs. Despite this, some primary bone persists in the outer cortex, where up to 12 lines of arrested growth were found. An external fundamental system, a sign of skeletal maturity, was seen only in posterior dorsal ribs despite the periosteal surface surviving in others. This could indicate that growth did not cease simultaneously in all parts of the skeleton. Pneumatic chambers interacted dynamically with remodeling, indicating multiple cycles of resorption and deposition that may have allowed the chambers to change size and shape through ontogeny. Taphonomic processes also hinder life history reconstruction, because the primary bone in which lines of arrested growth are preserved showed greater diagenetic alteration than secondary bone. The best preservation was found on surfaces protected from diagenetic fluids by clay matrix and which did not undergo preparation, which may guide future sampling strategies.
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Ontogenetic assessment from dorsal ribs in a mature titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Texas
Journal of Vertebrate Paleontology e2559012
doi: https://doi.org/10.1080/02724634.2025.2559012
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2559012
Osteohistology has provided significant insights into the ontogeny and life history of the sauropod dinosaurs. However, the Titanosauria, which include Earth’s largest terrestrial vertebrates, exhibit intense appendicular bone remodeling that obscures these details. Inspired by findings of well-preserved growth histories in sauropod dorsal ribs, we sampled a titanosaur specimen from the latest Cretaceous of Texas, one of the largest known from North America. The specimen preserved an almost complete set of dorsal ribs, many in articulation, from which five were sectioned near their proximal ends to allow comparisons between anterior, middle, and posterior positions. Results show that the high degree of remodeling characteristic of titanosaurs is also present in the dorsal ribs. Despite this, some primary bone persists in the outer cortex, where up to 12 lines of arrested growth were found. An external fundamental system, a sign of skeletal maturity, was seen only in posterior dorsal ribs despite the periosteal surface surviving in others. This could indicate that growth did not cease simultaneously in all parts of the skeleton. Pneumatic chambers interacted dynamically with remodeling, indicating multiple cycles of resorption and deposition that may have allowed the chambers to change size and shape through ontogeny. Taphonomic processes also hinder life history reconstruction, because the primary bone in which lines of arrested growth are preserved showed greater diagenetic alteration than secondary bone. The best preservation was found on surfaces protected from diagenetic fluids by clay matrix and which did not undergo preparation, which may guide future sampling strategies.
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