SGER: A Novel Dinosaurian Tissue Exhibiting Unusual Preservation

SGER：一种表现出不寻常保存的新型恐龙组织

• 批准号: 0435626
• 负责人: Mary Schweitzer
• 金额: --
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0435626&HistoricalAwards=false
• 关键词: SGER; Novel; Dinosaurian; Tissue; Exhibiting

ABSTRACTThe Museum of the Rockies 2003 summer field season yielded a Tyrannosaurus rex that is full of surprises. This dinosaur possesses a novel tissue type on the internal (endosteal) surface of the femur that has potential physiological and phylogenetic significance. It is structurally distinct from other fossil bone types, and may be the functional analogue of avian medullary bone, a specialized bone type that serves as short term storage for calcium reserves used in the formation of eggshells. This ephemeral bone tissue is not produced by extant reptiles or mammals, but forms in response to increased estrogen levels produced by ovulating female birds. If subsequent analyses confirm that this novel tissue is analogous to avian medullary bone, it will be the first objective means of assigning gender to a dinosaur, and provides additional information regarding the reproductive phase of the animal.The hypothesis regarding the origin of this new tissue will be tested by subjecting samples to various chemical, microscopic and molecular analyses, as avian medullary bone tissue is distinct from other bone types in living birds both structurally and chemically. For example, extant medullary bone has increased concentrations of acid mucopolysaccharides and sulfated glucosaminoglycans over other bone types, and responds in a distinct manner to high iron diamide (HID) staining.However, the presence of this novel tissue is not the only surprise observed in this dinosaur specimen. Upon demineralization of the bone, characteristics were revealed that were utterly unexpected, and again, never reported for bone tissues of this age. The demineralized matrix of the new tissue was elastic and stretchy, and had the capacity to be dehydrated and rehydrated many times without losing this characteristic. Demineralization of cortical bone also revealed the matrix to be fibrous and highly oriented, consistent with demineralized collagen in extant bone. Additionally, upon complete demineralization, pliable branching vessels were revealed within the cortical bone that are indistinguishable from those similarly recovered from extant bone after demineralization and collagenase digestion. The dinosaur vessels possessed microstructures consistent with red blood cells retained in treated vessels from ostrich bone, and these microstructures contained internal contents reminiscent of nucleated red blood cells. Finally, demineralization of the cortical bone liberated microstructures possessing external projections similar to filipodia, which are virtually identical to osteocytes observed after demineralization of cortical bone from extant birds. These microstructures also possess internal contents.This project will pursue chemical, molecular and microstructural analyses of these exceptional tissues. These dinosaur tissues have great potential to elucidate previously unsuspected aspects of molecular diagenesis, tissue/molecular preservation and processes of fossilization, not to mention the potential to independently test existing phylogenetic hypotheses and evolution. The risk of this project is more than balanced by the potential, and therefore seems to fall well within the intent of SGER funds.

摘要2003年夏季，落基山脉博物馆发现了一只充满惊喜的霸王龙雷克斯。这种恐龙在股骨的内部（骨内膜）表面具有一种新的组织类型，具有潜在的生理和系统发育意义。它在结构上与其他化石骨类型不同，可能是鸟类髓骨的功能类似物，这是一种专门的骨类型，用于短期储存蛋壳形成中使用的钙储备。这种短暂的骨组织不是由现存的爬行动物或哺乳动物产生的，而是在排卵的雌性鸟类产生的雌激素水平增加时形成的。如果随后的分析证实这种新组织类似于鸟类的髓骨，这将是确定恐龙性别的第一个客观手段，并提供有关动物生殖阶段的更多信息。关于这种新组织起源的假设将通过对样品进行各种化学、显微镜和分子分析来检验，因为鸟类的髓骨组织在结构上和化学上都不同于活鸟类中的其它骨类型。例如，现存的髓骨中酸性粘多糖和硫酸化葡糖胺聚糖的浓度高于其他骨类型，并且对高铁二酰胺（HID）染色有独特的反应。然而，这种新组织的存在并不是在这个恐龙标本中观察到的唯一惊喜。在骨脱矿后，发现了完全出乎意料的特征，并且在该年龄段的骨组织中从未报道过。新组织的脱矿物质基质是有弹性和伸展性的，并且具有多次脱水和再水化而不失去这种特性的能力。皮质骨脱矿也显示基质为纤维状且高度定向，与现存骨中的脱矿胶原一致。此外，在完全脱矿后，在皮质骨内发现柔韧的分支血管，这些血管与脱矿和胶原酶消化后从现存骨中类似回收的血管无法区分。恐龙血管的显微结构与鸵鸟骨处理血管中保留的红细胞一致，这些显微结构含有让人联想到有核红细胞的内部内容物。最后，脱矿的皮质骨解放的微观结构具有外部的预测类似于filipodia，这是几乎相同的骨细胞后，从现存的鸟类皮质骨脱矿观察。这些微观结构也具有内在的内容。本项目将对这些特殊组织进行化学、分子和微观结构分析。这些恐龙组织有很大的潜力，以阐明以前未知的方面的分子成岩作用，组织/分子保存和石化过程，更不用说独立测试现有的系统发育假说和进化的潜力。该项目的风险超过了潜力的平衡，因此似乎完全符合SGER基金的意图。