Postdoctoral Fellowship: EAR-PF: Is there a taphonomic clock? Assessing the progression of terrestrial bone alterations across environments and time

雷切尔·莱克博士被授予美国国家科学基金会地球科学博士后奖学金，在辛辛那提大学约书亚·米勒博士的指导下开展研究和专业发展活动，并在萨拉·基南博士的指导下在南达科他州矿业学院开展研究和专业发展活动。在这项研究中，Laker博士将研究与有机胶原蛋白的腐烂和丢失时间有关的骨骼上丝裂损伤(裂缝、微生物通道和其他在死后但在埋葬前发生的损伤)的积累和形态。在比较不同年龄或不同地区的动物群时，骨骼上的丝裂学损伤通常被用来估计不同的骨骼和化石积累所代表的时间，这是至关重要的信息。攻丝损失累积的速度在很大程度上是未知的。实际实验通常在有限的时间内(几周到几十年)进行评估，并且经常产生与在自然景观中发现的骨骼的观察相冲突的破坏率，这种情况可能持续数年到数千年。为了更好地了解蚕食损伤是如何形成的，并量化其发生的速度，莱克博士将测量驯鹿鹿角上累积的蚕食损伤，这些鹿角在几千年的时间里一直在腐烂(使用放射性碳测年进行评估)。为了增加科学参与和文化联系，莱克博士将定期与与北极国家野生动物保护区接壤的Gwich‘in土著阿拉斯加社区进行虚拟接触。莱克博士将继续通过本科生指导和专业服务为地球科学界服务，倡导归属感、可获得性、正义、公平、多样性和包容性价值观。这个项目的目的是限制我们对几年到几千年的时间尺度上骨骼的物理表现和破损率的理解。Laker博士将(1)定义单一环境环境下的细胞学变化的表达和变异，包括与胶原蛋白保存和骨骼结构差异相关的变异性，然后(2)测试这些发现的一致性，包括纬度梯度上的细胞学变化的比率和形态。通过整合微观和宏观分析尺度来提高我们对普遍存在但知之甚少的攻丝特征形成的理解，这项工作将解决攻丝实验室和现场实验中的不足，以有助于更全面地理解时间和攻丝特征之间的联系。这项研究将产生一个工具包，用于评估不同环境的动物组合所代表的时间，加强古生物记录的古生态比较。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Rachel Laker has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out research and professional development activities at the University of Cincinnati under the mentorship of Dr. Joshua Miller and at South Dakota School of Mines under the mentorship of Dr. Sarah Keenan. In this fellowship, Dr. Laker will investigate the accumulation and morphology of taphonomic damage (cracks, microbial tunnels, and other damage that occurs after death but before burial) on bones as related to the time of decay and loss of the organic collagen. Taphonomic damage on bones is often used to estimate how much time is represented by different bone and fossil accumulations, which is critical information when comparing faunas from different ages or localities. The rates at which taphonomic damage accumulates are largely unknown. Actualistic experiments are generally evaluated over limited amounts of time (weeks to perhaps decades) and frequently yield rates of destruction that conflict with observations from bones found on natural landscapes, which can persist from years to millennia. To better understand how taphonomic damage forms, and quantify the rates at which it occurs, Dr. Laker will measure the taphonomic damage accumulated on caribou antlers that have been decaying across several millennia (evaluated using radiocarbon dating). To increase science engagement and cultural connectivity, on a regular basis Dr. Laker will virtually engage with the Gwich’in Native Alaskan community bordering the Arctic National Wildlife Refuge. Dr. Laker will continue to serve the geosciences community as an advocate for belonging, accessibility, justice, equity, diversity, and inclusion values through undergraduate mentorship and professional service. This project aims to constrain our understanding of the physical manifestation and rates of taphonomic damage of bone on timescales ranging from years to millennia. Dr. Laker will (1) define the expression and variation of taphonomic alterations of a single environmental setting, including variability associated with collagen preservation and differences in bone construction, then (2) test the consistency of these findings, including the rates and morphologies of taphonomic alterations, across a latitudinal gradient. By integrating microscopic and macroscopic scales of analysis to improve our understanding of the formation of ubiquitous but poorly understood taphonomic features, this work will address shortcomings in taphonomic laboratory and field experiments to contribute to a more comprehensive understanding of the links between time and taphonomic degradation of bone. This research will generate a toolkit for assessing the time represented by faunal assemblages of different environments, enhancing paleoecological comparisons of paleontological records.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.