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Vascularised endosteal bone tissue in armoured sauropod dinosaurs.

ABSTRACT: The presence of well-vascularised, endosteal bone in the medullary region of long bones of nonavian dinosaurs has been invoked as being homologous to medullary bone, a specialised bone tissue formed during ovulation in birds. However, similar bone tissues can result as a pathological response in modern birds and in nonavian dinosaurs, and has also been reported in an immature nonavian dinosaur. Here we report on the occurrence of well-vascularised endosteally formed bone tissue in three skeletal elements of armoured titanosaur sauropods from the Upper Cretaceous of Argentina: i) within the medullary cavity of a metatarsal, ii) inside a pneumatic cavity of a posterior caudal vertebra, iii) in intra-trabecular spaces in an osteoderm. We show that considering the criteria of location, origin (or development), and histology, these endosteally derived tissues in the saltasaurine titanosaurs could be described as either medullary bone or pathological bone. Furthermore, we show that similar endosteally formed well-vascularised bone tissue is fairly widely distributed among nondinosaurian Archosauriformes, and are not restricted to long bones, but can occur in the axial, and dermal skeleton. We propose that independent evidence is required to verify whether vascularised endosteal bone tissues in extinct archosaurs are pathological or reproductive in nature.

SUBMITTER: Chinsamy A

PROVIDER: S-EPMC4845056 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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Vascularised endosteal bone tissue in armoured sauropod dinosaurs.

Chinsamy Anusuya A Cerda Ignacio I Powell Jaime J

Scientific reports 20160426

The presence of well-vascularised, endosteal bone in the medullary region of long bones of nonavian dinosaurs has been invoked as being homologous to medullary bone, a specialised bone tissue formed during ovulation in birds. However, similar bone tissues can result as a pathological response in modern birds and in nonavian dinosaurs, and has also been reported in an immature nonavian dinosaur. Here we report on the occurrence of well-vascularised endosteally formed bone tissue in three skeletal ...[more]

PMID: 27112710

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Project description:BackgroundTooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates.Methodology/principal findingsWe present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days). Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section.Conclusions/significanceDifferences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size), and derived titanosaurs and diplodocoids independently evolved the highest known tooth replacement rates among archosaurs.

Project description:The establishment of bone metastasis remains one of the most frequent complications of patients suffering from advanced breast cancer. Patients with bone metastases experience high morbidity and mortality caused by excessive, tumor-induced and osteoclast-mediated bone resorption. Anti-resorptive treatments, such as bisphosphonates, are available to ease skeletal related events including pain, increased fracture risk, and hypercalcemia. However, the disease remains incurable and 5-year survival rates for these patients are below 25%. Within the bone, disseminated breast cancer cells localize in "metastatic niches," special microenvironments that are thought to regulate cancer cell colonization and dormancy as well as tumor progression and subsequent development into overt metastases. Precise location and composition of this "metastatic niche" remain poorly defined. However, it is thought to include an "endosteal niche" that is composed of key bone cells that are derived from both, hematopoietic stem cells (osteoclasts), and mesenchymal stromal cells (osteoblasts, fibroblasts, adipocytes). Our knowledge of how osteoclasts drive the late stage of the disease is well-established. In contrast, much less is known about the interaction between osteogenic cells and disseminated tumor cells prior to the initiation of the osteolytic phase. Recent studies suggest that mesenchymal-derived cells, including osteoblasts and fibroblasts, play a key role during the early stages of breast cancer bone metastasis such as tumor cell homing, bone marrow colonization, and tumor cell dormancy. Hence, elucidating the interactions between breast cancer cells and mesenchymal-derived cells that drive metastasis progression could provide novel therapeutic approaches and targets to treat breast cancer bone metastasis. In this review we discuss evidences reporting the interaction between tumor cells and endosteal niche cells during the early stages of breast cancer bone metastasis, with a particular focus on mesenchymal-derived osteoblasts and fibroblasts.

Dataset Information

Vascularised endosteal bone tissue in armoured sauropod dinosaurs.

Publications

Vascularised endosteal bone tissue in armoured sauropod dinosaurs.

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