In article <c2fnha$1nn$0@pita.alt.net>, noway@jose.com [Uncle Davey] wrote...
[snip]
>> I'm not sure that we should really expect that the currently-known
>> fossil record of Loricariidae [or Callichthyiidae] should be any
>> better than it is.
>>
>> First, it seems that there aren't any large number of South American
>> freshwater fossil sites of the right age range that have been
>> extensively explored so far. How many fossil catfish experts are
>> currently working to actually study whatever remains have been found
>> to date? For all we know, there may in fact be many more fossil
>> armored-catfish specimens already on museum storage shelves but
>> still waiting to be described and named.
>>
>> Then, there are the obvious taphonomic questions:
>>
>> Don't many loricariids prefer to live in rocky stream habitats, not in
>> places with deeply accumulating sediment? I vaguely remember
>> something of the sort. If it's the case that living loricariids tend
>> to avoid those places that favor fossil preservation, then it may not
>> be so surprising that the known fossils of their relatives are
>> relatively few.
>>
>> From what I've seen so far about the loricariid and callichthyiid
>> fossil record, it sounds like members of both families often tend to
>> disintegrate into a jumble of loose plates and spines after death.
>> [An aquarist might confirm if this often happens to ones that die
>> several days before being discovered and removed?] Even if the
>> scattered bits of armor do preserve well, the hypothetical overworked
>>
>> South American paleoichthyologists might be forgiven for not spending
>> much time classifying the fragmentary remains. I'm reminded of that
>> earlier-cited paper which mentioned layers with concentrations of
>> abundant Corydoras plates and spines, but evidently didn't bother to
>> name any new fossil Corydoras species from the remains. The literature
>> already cited of fossil loricariids and callichthyiids do seem to
>> largely involve descriptions of loose bones [other than your one very
>> complete Corydoras fossil].
>>
>> Anyway, it seems to me that the currently-known existence of even a
>> few fossil speciments and species of these fish strongly implies the
>> existence of many more individuals [and additional related species]
>> that aren't yet known as fossils. Presumably, that fossil Corydoras
>> species known only from a single specimen must represent only one of
>> a very large number of individuals that ever lived of that species.
>> [But I suppose a believer in special creationism might argue that that
>> one fossil fish may well have been the only individual ever created of
>> its species, and a true believer in omphalism might even suggest that
>> it was specially created as a fossil, already in place in the rocks]
>>
>> Even an adherent of inclusive separately-created "kinds" would need
>> to argue that there are many "gaps" in the fossil record between say,
>> the remarkable modern diversity of Corydoras catfishes and the
>> hypothetical originally-created single ancestral form of their "kind".
>> The explanation will be much the same as the "evolutionist" one-- all
>> the required gradual-intermediate forms must have existed in the past,
>> but most are as yet unknown as fossils.
>My Omphalism Lite is still tending to believe that the fossils are from the
>Flood and not from being placed there, as full omphalism would suggest.
>
>Omphalism Lite is like a cross between Full Omphalism and YEC, taking the
>strongest bits of each idea.
Okay. And Last Thursdayism is the straight vodka version of Omphalism?
>The way that a huge group of fishes like the armoured catfishes, and we can
>also look at doradid catfishes which also have hefty plates, leave so little
>trace in the record really needs some explanation by evolutionists.
Well, it seems to me that the problem would just be one of you
expecting there to be more fossils than there are, since all of these
groups are reportedly known from at least _some_ fossils.
I quite
>appreciated your argument about loricariids preferring upstream locations,
>but this is far from the case with all types. The peruvian Pseudosturisoma
>is a good example of the type you mentioned (picture of mine
>http://www.jbc.nildram.co.uk/DCAM0307.JPG ) As you can probably see it is
>very flattened and adapted to the upstream niche. The problem I had was even
>that it preferred a much lower temperature than the 27 degrees I couldn't
>get below in that tank over the summer, and in due course I lost the fish.
>
>This is actually not such a typical loricariid, and in consequence harder to
>keep unless you can refrigerate your tank all summer...
>
>In fact the world's leading expert on Loricariids, Hans-Georg Evers, whom I
>once about twelve years ago had the priviledge of visiting with and seeing
>his fine collection of fish and tree frogs also, (he seemed to have enough
>Dendrobates to put out the population of Hamburg,
He'd probably need Phyllobates terribilis for that [but I hear that
captive ones lose the toxicity, that it's dependent on their natural
diet]
but I'm sure he didn't
>mean anything by it, and of course if he had we'd have known about it by
>now) and Ingo Seidel (whom I don't know personally - yet anyway) write in
>the standard work Mergus Wels Atlas Band 1 ISBN 3-88244-062-7 on page 31 the
>following: "Es ist keine leichte Aufgabe, im eng gesetzten Rahmen dieses
>Buches [yeah right, it's only 816 pages on half a family] alle Lebensraeume
>der Harnischwelse vorzustellen. Die verschiedenen Mitglieder der Familie
>haben im Laufe der Evolution die meisten der bekannten Lebensraeume in der
>Neotropis besiedelt.
>
>Evers and Seidel then goes on for another 160 pages talking about all the
>different niches of the Loricariidae all over S. America, with copius
>illustrations.
>
><puts book back on shelf>.
>
>So, I still think that science has a long way to go to illustrate the
>evolution of Loricariidae, and in particular the eye.
They do have some interesting funny-shaped pupils [but I prefer some
geckos' weird ones that close in bright light to make a vertical row
of diamond-shaped pinholes].
>The books I have are silent on the fossil record of the family, so what you
>have told me is all I know about it, and it certainly seems that we have too
>fragmentary knowledge to state in a scientific manner that the family
>loricariidae, with its 650 odd species, some of them extremely odd, by the
>way, actually evolved from anything.
But is the absence of known fossil evidence really evidence of absence?
It sounds like there are still only a few suitable fossil sites. For
evidence of their common ancestry with other armored catfishes, we may
have to rely on evidence from comparative studies of the living forms.
>I would also like to know how people posit the evolution of the
>characteristic 'omega eye' of the loricariids looked like, along with the
>intermediate forms.
Eyes being soft tissue, the best approach would probably be the
comparative one among living forms. Do all Loricariidae have identical
eyes? If so, do any other loricarioid catfishes approach them at all?
>From a Creationist perspective, I would say that in all probability there
>were six kinds; Astroblebidae, Neoplecostominae, Loricarinae, Ancistrinae,
>Hypostominae and Hypoptopomatinae, but if Jonathan Armbruster, the leading
>ichthyologist in the field, comes up with other findings I will be the first
>to wanna take those into account, since obviously the claims of science are
>not to be waived aside whenever they are really based on solid evidence.
This is based on your criterion that a kind should be a group that you
can imagine might have evolved from a common ancestor on a YEC [or YEC
Lite?] timetable?
It's commendably consistent with its premises, but of course many
others would doubt that much speciation at all would have occurred
during just a few thousand years [so that the kinds might as well be
the same as the extant species].
If your timetable were extended, then would you be able to accept
much more inclusive kinds?
Here's a thought, and a semi-"gotcha"! moment:
If as you suppose the loricariid groups Astroblebidae, Neoplecostominae,
Loricarinae, Ancistrinae, Hypostominae and Hypoptopomatinae are indeed
the relevant separately-created "kinds", and if the currently-known
fossil record should in fact be considered reasonably complete [which
claim is implicit in the usual creationist argument about fossil record
"gaps"], then there really ought to be some known fossils of each of
Astroblebidae, Neoplecostominae, Loricarinae, Ancistrinae, Hypostominae
and Hypoptopomatinae.
I suspect that several of them, probably most of them, aren't yet known
from fossils.
Therefore, the gaps in the fossil record will need explaining by
Flood/Kind creationists, just as much as they do by evolutionists.
No doubt the explanations will have to be closely similar: the early
members of the groups must have existed, but any fossils they may have
produced haven't yet been found.
Thus, both creationists and evolutionists must agree that the fossil
record is simply incomplete after all. QED
A more basic problem I have with this whole thing is, if those
subfamilies are the separately-created "kinds", then what does
Loricariidae [or Loricarioidea or Siluriformes or Ostariophysi or
Teleostei or Vertebrata] even mean? Why should there be any clearly
recognizable higher-than-kind groups, let alone ones as compellingly
"real" as Loricariidae?
Are they just coincidental, random resemblances? Why are within-kind
patterns of similarities not obviously different in kind [so to speak]
from higher-than-kind similarities among different kinds? Why do they
seem to fall naturally into treelike nested hierarchies? Common-descent
theory offers one clear explanation; the creationist alternative needs
to come up with an equally good one.
[enjoying the discussion!]
cheers
|
| Follow-ups: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 |
| 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 |
| 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 |
| 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114 | 115 | 116 | 117 | 118 | 119 |
| 120 | 121 | 122 | 123 | 124 | 125 | 126 | 127 | 128 | 129 | 130 | 131 | 132 | 133 | 134 | 135 | 136 | 137 | 138 | 139 | 140 | 141 | 142 | 143 | 144 | 145 | 146 | 147 | 148 | 149 |
| 150 | 151 | 152 | 153 | 154 | 155 | 156 | 157 | 158 | 159 | 160 | 161 | 162 | 163 | 164 | 165 | 166 | 167 | 168 | 169 | 170 | 171 | 172 | 173 | 174 | 175 | 176 | 177 | 178 | 179 |
| 180 | 181 |
|