Giants and dwarves: Reconstructing the evolution of size and life histories within Myriapoda

多足动物群的代表，即蜈蚣，千足虫和它们的亲戚，通常被认为是生活在土壤和落叶中的相当小的动物。尽管千足虫的种类远少于昆虫，但蜈蚣和千足虫是现代动物群的重要组成部分。它们发挥着重要的生态作用，例如，仅举两个例子，它们是分解者或令人印象深刻的捕食者。虽然大多数现代多足动物的身体大小在毫米范围内，但更大的多足动物生活在热带地区，最大长度略超过30厘米。因此，更令人惊讶的是，在晚古生代，特别是在石炭纪（约。3.59 - 2.99亿年前），这一群体的化石代表达到了两米的身体大小。在多足动物的身体大小方面，特别令人感兴趣的是比较最大的代表，唯一的化石代表Arthropleuridae，和最小的代表，刚毛千足虫（Polyxenida）。后者既出现在现代动物群中，也作为化石保存在不同年龄（从1.3亿到1500万年前）的琥珀中。尽管它们的体型差异很大，但这两个群体被认为是姐妹群体，因此在体型上发生了明显的进化变化。我们探讨两个方面：支持Arthropleaseridea和Polyxenida之间的姐妹群关系，以及刚毛千足虫的大小随时间的变化。化石大小比较的一个挑战是，小的代表可能只是不成熟的。因此，我们将把这些阶段包括在我们的比较中，这些阶段还没有完整的段号。这种不成熟的阶段可以被认为是现代的，也可以被认为是某些谱系的化石代表（例如石生目或Polyxenidae），并以此被识别为不同的阶段。当比较这些阶段时，个体发育变异，即个体发育期间的变异，可以得到纠正。对这些从1.3亿年前到今天的发现进行调查和分析，将有助于更好地了解生态功能随时间的变化。

Representatives of the group Myriapoda, i.e. centipedes, millipedes, and their relatives, are generally known as rather small animals living in the soil and leaf litter. Even though the group Myriapoda comprises far less species than, for example, the group Insecta, centipedes and millipedes are important components of the modern fauna. They fulfil important ecological roles, for example, as decomposers or impressive predators to name just two examples. While the majority of modern representatives of Myriapoda has a body size within the millimetre range, much larger ones live in the tropics, with a maximum length of slightly more than 30 centimetres. Hence, it is even more astonishing that during the late Palaeozoic, especially in the Carboniferous (ca. 359–299 million years ago), fossil representatives of this group reached body sizes of up to two metres. Of special interest in the context of body size in Myriapoda is the comparison of the largest representatives, the exclusively fossil representatives of Arthropleuridea, and the smallest representatives, bristly millipedes (Polyxenida). The latter occur both in the modern fauna and as fossils preserved in ambers of different ages (from 130 to 15 million years ago). Despite their significant size difference, both groups have been suggested to be sister groups, hence apparently strong evolutionary changes in body size occurred. We explore two aspects: the support for a sistergroup relationship between Arthropleuridea and Polyxenida, and the size changes of bristly millipedes through time. A challenge in the comparison of size in fossils is that small representatives could simply be immatures. Therefore, we will include those stages into our comparisons which do not yet have the full segment number. Such immature stages can be recognised for modern and also for fossil representatives of certain lineages (e.g. Lithobiomorpha or Polyxenidae) and with this be identified to distinct stages. When these stages are compared, the ontogenetic variation, i.e. the variation during individual development, can be corrected. The investigations and analyses of these finds from 130 million years ago to today will provide for a better understanding of the changes in ecological functions through time.