A recent study has provided clues to predator-prey dynamics in the late Pleistocene era. Researchers compared the number of tooth fractures in present-day carnivores with tooth fractures in carnivores that lived 36,000 to 10,000 years ago and that were preserved in the Rancho La Brea tar pits in Los Angeles. The breakage frequencies in the extinct species were strikingly higher than those in the present-day species.
In considering possible explanations for this finding, the researchers dismissed demographic bias because older individuals were not overrepresented in the fossil samples. They rejected preservational bias because a total absence of breakage in two extinct species demonstrated that the fractures were not the result of abrasion within the pits. They ruled out local bias because breakage data obtained from other Pleistocene sites were similar to the La Brea data. The explanation they consider most plausible is behavioral differences between extinct and present-day carnivores—in particular, more contact between the teeth of predators and the bones of prey due to more thorough consumption of carcasses by the extinct species. Such thorough carcass consumption implies to the researchers either that prey availability was low, at least seasonally, or that there was intense competition over kills and a high rate of carcass theft due to relatively high predator densities.
According to the passage, if the researchers had NOT found that two extinct carnivore species were free of tooth breakage, the researchers would have concluded that
the difference in breakage frequencies could have been the result of damage to the fossil remains in the La Brea pits
the fossils in other Pleistocene sites could have higher breakage frequencies than do the fossils in the La Brea pits
Pleistocene carnivore species probably behaved very similarly to one another with respect to consumption of carcasses
all Pleistocene carnivore species differed behaviorally from present-day carnivore species
predator densities during the Pleistocene era were extremely high
此讲解的内容由AI生成,还未经人工审阅,仅供参考。
正确答案是 A。
在文中,研究人员考虑了一些可能的解释来解释这一发现,包括人口偏差,保存偏差和当地偏差。由于他们发现两种灭绝的食肉动物物种没有齿痕损坏,因此他们排除了保存偏差这一可能性。如果这些研究人员没有发现两种灭绝的食肉动物没有牙齿损坏,他们就会得出结论,即差异可能是由于拉布雷亚泥坑中化石需要经历的损坏而导致的。
这道题问的是如果研究者没有发现那两个species免于破损,会怎样
文中提到,研究者排除preservational bias,是因为a total absence of breakage in two extinct species
那这道题问的就是相反的情况,
因此,研究者不能草率排除preservational bias
其实不太明白这道题,既然比较的就是牙齿破损率,结果原文却说两个样本完好无损,证明没有保存上得偏差。但起码应该牙齿破损了啊,不然这买比较得出结论“古代的食肉动物牙齿破损频率大于现代”
错在没有正确定位到原文——要相信所有的细节题和推断题还是可以定位到原文的
They rejected preservational bias because a total absence of breakage in two extinct species demonstrated that the fractures were not the result of abrasion within the pits.
.>>如果had NOT found that two extinct carnivore species were free of tooth breakage ,那麼fractures were the result of abrasion within the pits.
=A: breakage frequencies could have been the result of damage to the fossil remains in the La Brea pits
that the fractures were not the result of abrasion within the pits. —— abrasion within the pits坑中的磨损