High-precision body mass predictors for small mammals: A case study in the Mesozoic

Body mass is a pivotal quantity in palaeobiology but must be estimated from an imperfect fossil record. We analyse the precision of skeletal predictors of mammalian body mass as a mean to inform the Mesozoic mammal record, including a new eutriconodont from North America. We focus on the critical small end of the size spectrum – critical because the earliest mammals were small, because small size persisted onto the stems of the major extant radiations, and because small mammals compose a large proportion of crown diversity. Linear regressions based on extant small mammals indicate a universal correlation of body mass with observed measurements, but with clear differences in precision. Postcranial predictors outperform jaw and dental metrics, with certain femoral joint dimensions providing surprisingly precise estimations. Overall, our data indicate small-mammal evolution during the Mesozoic unfolded in patterns of underappreciated complexity. Studying these dynamics is only possible whe..., For extant samples, craniodental measurements were taken using Paleo-Tech Dental Caliper with a Mitutoyo 0-150 mm digital scale to the nearest 0.01mm. Limb measurements and measurements of the specimens from KUNHM were taken with a SPI Dial Caliper Model 31-415-3 to the nearest 0.05 mm. If specimens had both left and right sides, we used measurements from the more complete side and supplemented from the contralateral side if necessary. For fossil specimens, we recorded measurements from literature. For specimens lacking published measurements of preserved predictors, we used published figures and ImageJ to add measurements where possible. This approach included calibrating the line tool with the published scale bar and then using this tool for measurement. Where possible, we also compared our figure-based measurements with published values to ensure accuracy. Because we could not verify the angle of the limb elements in specimens preserved in slabs, we measured the midshaft diameter of ..., , # Data from: High-precision body mass predictors for small mammals: a case study in the Mesozoic One collection of extant therian dentoskeletal measurments, one collection of Eutriconodonta dentoskeletal measurments, and one collection of Eutriconodonta body mass predictions. ## Description of the data and file structure 'data.csv' is the csv file containing measurements of extant therians, 'eutridata.csv' is the csv file containing measurements of Eutriconodonta and 'allmass.csv' is the file for plotting the figure of fossil mass prediction. 'pgls.tre' and 'pglstime.tre' are tree files in Newick format required to run the below R markdown file. For data.csv, NA represents missing values due to either the absence or immeasurability of the structure. For eutridata.csv, the associated specimen for a measurement is either next to the measurement in the 'name' column, or the first one above in that column; the same is true for the associated publication in the 'Publication' column. ...体质量是古生物学研究中的关键参数，但只能通过残缺不全的化石记录来估算。本研究以哺乳动物体质量的骨骼预测指标（skeletal predictors）的估算精度为研究对象，旨在为中生代哺乳动物化石记录提供参考，其中包含一件产自北美的新三尖齿兽类（Eutriconodonta）标本。我们聚焦于体型谱系中至关重要的小型类群——这一聚焦的意义在于：最早的哺乳动物体型小巧，小型特征延续至各大现生类群的茎群阶段，且小型哺乳动物在冠群多样性中占据极高比例。基于现生小型哺乳动物的线性回归分析显示，体质量与实测骨骼指标普遍存在相关性，但估算精度存在显著差异。躯干后肢骨骼预测指标的表现优于颌骨与牙齿指标，特定股骨关节维度的估算精度甚至出人意料地高。综合来看，我们的数据表明，中生代小型哺乳动物的演化过程蕴含着此前未被充分认知的复杂模式。对这些演化动态的研究，唯有依托稳健且标准化的测量框架方可实现。 对于现生标本，我们使用搭载三丰（Mitutoyo）0-150 mm数字标尺的Paleo-Tech牙科游标卡尺开展颅齿部测量，测量精度可达0.01 mm。针对肢体骨骼指标以及昆明自然历史博物馆（KUNHM）馆藏标本的相关测量，我们采用SPI Dial Caliper Model 31-415-3型游标卡尺，测量精度可达0.05 mm。若标本同时保存左右两侧结构，我们优先选用保存更完整一侧的测量数据，必要时则以对侧结构的测量数据作为补充。 对于化石标本，我们从已发表文献中提取测量数据。若已发表文献未提供该标本保存的预测指标的测量值，我们将借助已发表的标本图像与ImageJ软件尽可能补全测量数据。该方法需先以文献中给出的比例尺对直线测量工具进行校准，再开展测量工作。若条件允许，我们还会将通过图像获取的测量值与已发表的数值进行比对，以确保数据准确性。由于无法确认扁平保存标本中肢体骨骼的摆放角度，我们仅测量了其骨干中部直径…… # 数据集来源：《小型哺乳动物高精度体质量预测指标：以中生代类群为例》（High-precision body mass predictors for small mammals: a case study in the Mesozoic） 本数据集包含三类数据：一套现生兽类齿骨骼测量数据集、一套三尖齿兽目（Eutriconodonta）齿骨骼测量数据集，以及一套三尖齿兽目体质量预测数据集。 ## 数据与文件结构说明 `data.csv` 为包含现生兽类测量数据的CSV文件；`eutridata.csv` 为包含三尖齿兽目测量数据的CSV文件；`allmass.csv` 用于绘制化石体质量预测结果图。`pgls.tre` 与`pglstime.tre` 为Newick格式的系统发育树文件，是运行下文R Markdown文档所需的依赖文件。 在`data.csv` 中，NA代表因结构缺失或无法测量而产生的缺失值。 在`eutridata.csv` 中，某一测量指标对应的标本要么紧邻该指标所在的`name`列条目，要么为该列中位于其上方的首个条目；`Publication` 列中关联的文献来源遵循相同的对应规则。 ...