Bown T M, Holroyd P A, Rose K D
U.S. Geological Survey, Federal Center, Denver, CO 80225.
Proc Natl Acad Sci U S A. 1994 Oct 25;91(22):10403-6. doi: 10.1073/pnas.91.22.10403.
There is a general inverse relationship between the natural logarithm of tooth area (a body size indicator) of some fossil mammals and paleotemperature during approximately 2.9 million years of the early Eocene in the Bighorn Basin of northwest Wyoming. When mean temperatures became warmer, tooth areas tended to become smaller. During colder times, larger species predominated; these generally became larger or remained the same size. Paleotemperature trends also markedly affected patterns of local (and, perhaps, regional) extinction and immigration. New species appeared as immigrants during or near the hottest (smaller forms) and coldest (larger forms) intervals. Paleotemperature trend reversals commonly resulted in the ultimate extinction of both small forms (during cooling intervals) and larger forms (during warming intervals). These immigrations and extinctions mark faunal turnovers that were also modulated by sharp increases in sediment accumulation rate.
在怀俄明州西北部大角盆地约290万年的始新世早期，一些化石哺乳动物的牙齿面积（一种身体大小指标）的自然对数与古温度之间存在普遍的反比关系。当平均温度变暖时，牙齿面积往往会变小。在较冷时期，较大的物种占主导地位；这些物种通常变得更大或保持相同大小。古温度趋势也显著影响了局部（或许还有区域）灭绝和迁徙模式。新物种在最热（较小形态）和最冷（较大形态）时期或接近这些时期时作为移民出现。古温度趋势的逆转通常导致小形态物种（在降温时期）和大形态物种（在升温时期）最终灭绝。这些迁徙和灭绝标志着动物群的更替，而这种更替也受到沉积物堆积速率急剧增加的调节。
