Crocodylian fossils are well documented from Upper Cretaceous and lower to middle Paleogene deposits in the mid-high latitudes of the Western Interior, whereas the only extant North American taxon, Alligator mississippiensis, is restricted to the lower-latitude wetlands of the southeastern United States. The departure of crocodylians from the Western Interior has been inferred to represent a major shift from more equable, warmer, wetter climates in the Paleogene to more seasonal, cooler, drier climates in the Neogene. The timing of further geographic range shifts during the Neogene, including the local extinction (extirpation) of crocodylians from the Great Plains, is poorly constrained. We document the Neogene crocodylian fossil record of the Central Great Plains (CGP) in order to constrain the timing of mid-continental crocodylian extinctions against a backdrop of climatic and environmental changes. The Neogene CGP crocodylian fossil record consists of mostly incomplete specimens, likely referable to the extant genus Alligator, and appears to document multiple latitudinal range shifts that are spatiotemporally consistent with regional climatic and environmental changes inferred from independent proxy evidence. The last appearance datum (LAD) for crocodylians in the CGP is ∼6 Ma, which suggests that climatic and environmental conditions in the region were unfavorable to crocodylians after this time. In general, Neogene crocodylian fossils throughout the Great Plains are not abundant. Barring taphonomic biases or sampling issues, this could imply low population densities, and/or that the fossil-bearing areas in this region were close to the northernmost limits of crocodylian (cf. Alligator) distributions during the Neogene.

鳄鱼化石在西部内陆中高纬度地区的上白垩统和古近纪中到下至中部沉积物中有很好的记录，而北美现存的唯一分类群是鳄鱼密西西比仅限于美国东南部的低纬度湿地。鳄鱼从西部内陆的离开被认为代表了从古近纪的更均衡，更温暖，更湿润的气候向新近纪的更季节性，更凉爽，更干燥的气候的重大转变。新近纪进一步地理范围变化的时机，包括大平原鳄鱼的局部灭绝（灭绝），受到了严格的限制。我们记录了中部大平原（CGP）的新近纪鳄鱼化石记录，目的是在气候和环境变化的背景下，限制中部大陆鳄的灭绝时间。Neogene CGP鳄鱼化石记录主要由不完整的标本组成，可能与现存的短吻鳄属有关，并且似乎记录了多个纬度范围变化，这些变化时空与根据独立代理人证据推断出的区域气候和环境变化一致。CGP中鳄鱼的最后一次出现数据（LAD）约为6 Ma，这表明该时间之后该地区的气候和环境条件不利于鳄鱼。通常，整个大平原的新近纪鳄鱼化石并不丰富。除非存在系统偏倚或采样问题，否则可能意味着人口密度低，并且/或者该地区的化石承载区域接近新近纪时期鳄鱼（见鳄鱼皮）分布的最北端。