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Published online 22 October 2007 |
Nature
| doi:10.1038/news.2007.184
Updated online: 13 February 2008
News
Ancient bat flew without echolocation (Updated)
Researchers scrounge to get their hands on samples of 20-clawed bat.
The most primitive bat ever discovered is finally being scientifically reported, years after the first fossil was found and snapped up by a private collector.
The 52.5-million-year-old bat unusually had a claw on all five digits of each limb, earning it the nickname '20-clawed bat'.
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In my opinion, the authors' conclusions on the lack of echolocation in this fossil bat is a stretch as wide and as deep as the Grand Canyon. From the article, it appears they advanced this theory on the lifestyle of the bat solely on the presence of additional claws on the bat. Their formula: Additional claws = no echolocation. What made bats all of a sudden decide that they needed echolocation to survive as a species?
The lack of echolocation is reasonable given the limited distribution of echolocation in modern megabats (flying foxes)--being limited to Rousettus. The date is too late for an ancestral species, but it was probably a relict during Green River time. Echolocation is generally associated with capture of aerial prey, but bat ancestors were probably dietary generalists (fruit and insects) or gleaners (capturing prey from substrates), so lack of echolocation in a primitive bat is not surprising.
Attn: William Burnett: I suggest you reread the article. The conclusion about lack of echolocation was based on the anatomy of the skull. The article states, "Features in the sinuses and skull revealed that the bat could not echolocate."
Very exciting find, but as to the claim of being primitive or a relict of an ancestral population, that must remain speculation for now. In any other area of science, a claim of such significance would require demonstration, observation, or elimination of other possibilities. This case may simply represent a new, specialized form of bat. It wouldn't be the first time that a supposed primitive relict turned out to be something else. This also reminds me of the Cambrian "explosion" and the apparent (fossil) rapid radiation of avian and mammalian orders in the early Cenozoic.
Still most fruit bats, use their eyes and smell organs to locate food and not echolocation like insectivour bats. So I think the finding goes well with the ancesstral tree dwelling origins of Bats. Tesfaye Mengesha
i think echo vision came first, because they would have died without it.