jelkind@ruby.berkeley.edu.UUCP (04/02/87)
All of this discussion on mass extinctions has raised a question in my mind, which I haven't seen discussed much. Do any of the catastrophist models of mass extinction explain why the ichthyosaurs became extinct but the sharks didn't? Richard Schultz -------------------------------------------------------------- | To sit in solemn silence in a dull, dark, dock, | | In a pestilential prison, with a life-long lock, | | Awaiting the sensation of a short, sharp, shock, | | From a cheap and chippy chopper on a big black block! | | -- W. S. Gilbert | --------------------------------------------------------------
agranok@udenva.UUCP (04/04/87)
In article <3003@jade.BERKELEY.EDU> jelkind@ruby.berkeley.edu (The Unexpected Tiger) writes: > >All of this discussion on mass extinctions has raised a question in my mind, >which I haven't seen discussed much. > >Do any of the catastrophist models of mass extinction explain why the >ichthyosaurs became extinct but the sharks didn't? > > Richard Schultz > As far as I can tell, the reason for the sharks surviving while the ichthyo- saurs all died has nothing to do with the model itself, but probably lies somewhere in the area of adaptability. When the food sources ran out, the sharks could make use of other types, whereas the marine dinosaurs couldn't. It's the same sort of thing with coyotes and wolves today. -- Alex Granok hao!udenva!agranok "Wait a minute. Strike that. Reverse it."
mrh@cybvax0.UUCP (04/06/87)
In article <3366@udenva.UUCP> agranok@udenva.UUCP (Alexander Granok) writes: > As far as I can tell, the reason for the sharks surviving while the ichthyo- > saurs all died has nothing to do with the model itself, but probably lies > somewhere in the area of adaptability. When the food sources ran out, the > sharks could make use of other types, whereas the marine dinosaurs couldn't. While these just-so stories are mere speculation, "adaptability" may have nothing to do with it, while preadaptation might. An asteroidial winter scenario proposes a general famine. Sharks, with their extremely low metabolic rate, are pre-adapted to survive famines. Ichthyosaurs might not have been. Many surviving lineages of once-predominant groups (such as lizards, snakes, turtles, lampreys, lungfish, nautalus, [coelocanth?], and salamanders) are notable for having very low metabolic rates and the ability to survive long periods without food. If there was a nuclear winter, we might well expect whales and dolphins to become extinct because of their high metabolic rate, while sharks might survive unchanged. > It's the same sort of thing with coyotes and wolves today. No it's not. Wolves have been exterminated by humans, because when their normal food sources were swept aside to make room for domesticated animals, they adapted by eating the domesticated animals. It has been cost effective for humans to wipe out wolves (for assorted reasons), but not coyotes. -- "An important scientific innovation rarely makes its way by gradually winning over and converting its opponents... What does happen is that its opponents gradually die out, and that the growing generation is familiarized with the ideas from the beginning." Max Planck -- Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh
pmk@prometheus.UUCP (04/07/87)
In article <1415@cybvax0.UUCP> mrh@cybvax0.UUCP (Mike Huybensz) writes: >In article <3366@udenva.UUCP> agranok@udenva.UUCP (Alexander Granok) writes: >> It's the same sort of thing with coyotes and wolves today. >No it's not. Wolves have been exterminated by humans, because when their >normal food sources were swept aside to make room for domesticated animals, >they adapted by eating the domesticated animals. It has been cost effective >for humans to wipe out wolves (for assorted reasons), but not coyotes. Actually, fences discrimminated in this process of eliminating food sources from wolves. Cattle used to be grazed in SMALL fenced pastures, and now are fed in feed lots and barns. In the past, rotated pasture/cropland were all fenced. Those fences have come out, and the farmers plow the ground from ditch to ditch. The open range has allowed the wolves back in. I ran into my first wolf while hunting in Iowa! Impressive! Very long legged, huge feet, teeth as long as fingers all crowded toward the business end of a very long mouth. I took a theatening stance, and backed out of his path. Beastie took what seemed like a few leisurely loping steps and was gone into a thicket a half mile (1 kilometer) away. It stopped momentarily and looked back, and then vanished from sight. A solitary "outer limits" experience that I will never forget. It was in an area about three or four miles north of the line between Fayette and Wadena along the Volga River, in Fayette county, just in case any one has some time to kill and wants to see a zone where wilderness has returned in just a decade or two. +---------------------------------------------------------+--------+ | Paul M. Koloc, President: (301) 445-1075 | FUSION | | Prometheus II, Ltd.; College Park, MD 20740-0222 | this | | {mimsy | seismo}!prometheus!pmk; pmk@prometheus.UUCP | decade | +---------------------------------------------------------+--------+
agranok@udenva.UUCP (04/12/87)
In article <621@prometheus.UUCP> pmk@prometheus.UUCP (Paul M. Koloc) writes: >In article <1415@cybvax0.UUCP> mrh@cybvax0.UUCP (Mike Huybensz) writes: >>In article <3366@udenva.UUCP> agranok@udenva.UUCP (Alexander Granok) writes: > >>> It's the same sort of thing with coyotes and wolves today. > >>No it's not. Wolves have been exterminated by humans, because when their >>normal food sources were swept aside to make room for domesticated animals, >>they adapted by eating the domesticated animals. It has been cost effective >>for humans to wipe out wolves (for assorted reasons), but not coyotes. I disagree. I *know* that for many years, ranchers out here in Colorado and New Mexico (where I am from) have been out to eliminate the "coyote problem." The only reason that it is cost ineffective to wipe out coyotes, when compared to wolves (as far as I can tell) is that it just can't seem to be done. In fact, in many areas where coyotes were hunted, they actually thrived! They were attacked for just the same reason you gave for the wolves. We now know that this just isn't the case. Though I have seen many coyotes in the wild, I have never seen a wolf. I would like to, someday. I have heard them when I was camping, and it was one of the most chilling sounds that I have ever heard. Let's hope that the sound doesn't disappear forever. -- Alex Granok hao!udenva!agranok "A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!"