[讨论]og12第二篇文章

winnemashi

        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

(5)   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.

(10)   

                  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

(15) 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

(20) 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.

(25) 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.

 (20) 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.

(20) 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.

(25) 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.

 (20) 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.

(25) 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.

 

        文中画线的地方不是矛盾的吗？第一段说灭绝的两个种类裂缝平率更高（breakage frequencies in the extinct species），第二段里面又说在这两种已灭绝的种类中没有裂缝（a total absence of breakage in two extinct species ）好奇怪啊

[此贴子已经被作者于2009/9/15 14:50:04编辑过]

lxhf0406

Because "the extinct species" are carnivores

However "two extinct species" are not the same species mentioned before. Maybe they are not carnivores. Just to explain that it's not the problem of preservation