Understanding the evolution of the earliest primates

在大约6500万年前，非鸟类恐龙灭绝后不久，我们自己所属的灵长类动物就出现了。在哺乳动物时代的早期，这些原始灵长类动物蓬勃发展，产生了令人印象深刻的不同形式的多样性。目前的项目试图从三个不同的角度更好地了解灵长类起源和多样化的过程。*首先，怀俄明州和蒙大拿州的田野工作将寻求发现鲜为人知的早期灵长类动物群体的新标本。在怀俄明州Bighorn盆地约5400万年前的沉积物中挖掘，将寻找稀有的鳞甲科的新材料，该科仅从11个标本中已知。这个家族包括有记录以来最小的灵长类动物之一(Pmicroomys Petersonorum)，它只有10克左右重，是现存最小灵长类动物的三分之一。在多西溪采石场的工作，为这个难以捉摸的家庭提供了最好的材料，将寻求增加我们对这种微小灵长类动物的了解。对蒙大拿州疯狂山脉盆地更古老的沉积物(~62英里)的研究也将扩大我们对灵长类动物中最原始的家族之一--帕拉希通科的了解。作为首批多样化的灵长类物种之一，扩大我们对这个家族的了解是理解我们这个目后来丰富的多样性的核心。这两个地点的工作将集中在显著气候变化的时期，揭示这种变化如何影响哺乳动物动物，这与模拟未来气候变化的影响有关。*第二，将对最大的干状灵长类动物样本进行研究，其中包括1500多个已知年龄的样本，以记录一个家族--小食蟹科--的进化模式。这一大样本提供了一个独特的机会，不仅记录了进化变化的发生，而且潜在地解释了这种变化的原因。用于量化牙齿形状方面的尖端牙齿地形图方法将使我们有可能考虑气候变化时期与这一群体饮食变化的关系。*最后，高分辨率X射线计算机断层扫描(CT)数据将用于重建灵长类化石以及我们的近亲和近亲，包括啮齿动物和兔子的内铸型(反映大脑解剖的头骨内部模型)。这项研究将更好地了解灵长类动物大脑的大小和形状方面的原始情况，并更好地描述异常巨大的人脑发育的最早阶段。总而言之，这个项目旨在更好地了解灵长类动物进化的早期阶段，帮助描述人类最终进化的进化背景。

The first members of our own Order, the Primates, appear shortly after the extinction of the non-avian dinosaurs, some 65 million years ago. In the early years of the Age of Mammals these primitive primates flourished, producing an impressive diversity of different forms. The current project seeks to better understand the processes by which primates originated and diversified from three different perspectives. ***First, fieldwork in Wyoming and Montana will seek to uncover new specimens of poorly known groups of early primates. Excavations in approximately 54 million year old deposits in the Bighorn Basin of Wyoming will seek new material of the rare Picromomyidae, a family known from only 11 specimens. This family includes one of the smallest primates ever documented (Picromomys petersonorum), which only weighed around 10g, making it a third the size of the smallest living primate. Work at Dorsey Creek Quarry, the site that has produced the best material for this elusive family, will seek to add to our knowledge of this tiny primate. Research in older deposits (~62 mya) in the Crazy Mountains Basin of Montana will also expand what we know about one of the most primitive families of primates, the Palaechthonidae. As one of the first primate groups to diversify, expanding our knowledge of this family is central to understanding the later rich diversity of our Order. Work in both locations will focus on periods of significant climate change, shedding light on how such changes can affect the mammalian fauna, which is relevant to modeling the effects of future climate change. ***Second, the largest single sample of stem primates, including more than 1500 specimens of known age, will be studied to document patterns of evolution in one family, the Microsyopidae. This large sample provides a unique opportunity to not only document evolutionary change as it happened, but to potentially explain the causes of that change. Cutting edge dental topographic methods for quantifying aspects of the tooth shape will make it possible to consider how periods of climate change related to shifting diets in this group. ***Finally, high resolution X-ray computed tomography (CT) data will be used to reconstruct endocasts (internal models of the skull which reflect brain anatomy) from fossil primates and from our close living and fossil relatives, including rodents and rabbits. This research will provide a better understanding of what is primitive for Primates in terms of the size and form of the brain, and better characterize the very earliest stages in the development of the exceptionally large human brain. ***In sum, this project aims to provide a better understanding of the early phases of primate evolution, helping to characterize the evolutionary backdrop against which humans ultimately evolved.********