Data from: High overlap of extant mammal ranges with sediment sinks indicates high fossilization potential of total diversity

Mammalian species richness is commonly highest at mid- to high-elevations,
but the accumulation of sediment that might bury and preserve skeletal
remains generally occurs at lower elevations, leading to concerns that
fossil assemblages are biased towards low-elevation taxa. Here, I use
extant mammals as an analogue to test the basin-scale spatial overlap
between species ranges and sediment sinks where burial and fossilization
would be possible. Sediment sinks are estimated within five
topographically complex regions in western North America by identifying
areas with both a low slope and a high contributing area of runoff and are
compared with point occurrences of mammals compiled from the Global
Biodiversity Information Facility (GBIF). I find that, among the test
areas, 82-96% of all species have occurrences that overlap with a sediment
sink, despite common offsets in the elevations of maximum sink area and
maximum species richness: summed across all test areas, 83% of species and
87% of total sediment sink area are found in the lowest 1000 m of the test
areas. Although many other factors can act against the fossilization of
terrestrial mammals, these results indicate that the spatial distribution
of mammal species with respect to sediment sinks should not in itself
impose a major bias at the basin scale.

哺乳动物物种丰富度通常在中高海拔区域达到峰值，但可掩埋并保存骨骼遗骸的沉积物汇（sediment sinks）的堆积过程一般发生在低海拔区域，由此引发了一个担忧：化石组合存在偏向低海拔类群的偏差。本研究以现生哺乳动物作为类比模型，检验物种分布范围与可发生掩埋和石化作用的沉积物汇之间的流域尺度空间重叠情况。研究通过识别坡度低且径流贡献面积大的区域，在北美西部5个地形复杂的区域内估算沉积物汇的分布，并将其与从全球生物多样性信息设施（Global Biodiversity Information Facility, GBIF）整合得到的哺乳动物点位出现记录进行对比。本研究发现，尽管沉积物汇面积峰值与物种丰富度峰值的海拔存在普遍偏移，但在所有研究区域中，82%~96%的哺乳动物物种的出现记录均与沉积物汇存在空间重叠；在所有研究区域汇总后，83%的物种和87%的沉积物汇总面积均分布在研究区域最低的1000米海拔范围内。尽管存在诸多其他不利于陆生哺乳动物化石形成的因素，但本研究结果表明，就沉积物汇而言，哺乳动物物种的空间分布本身并不会在流域尺度上造成显著的采样偏差。