How does evolution actually happen

Discussion in 'Biology & Genetics' started by Dudeyhed, Mar 2, 2003.

  1. Deist27 Registered Senior Member

    Messages:
    61
    Darwin believed that the little variations we see between one person and another, one fish and another, when chosen by natural selection, could build up in an unlimited way. You could breed guppies, selecting for large tails. By allowing only the guppies with the largest tails to breed you are able to get guppies with tails more than twice as big as the ones started with. This would correspond in nature, but because of genetic limits it is impossible to develop either a breed of guppies with tails as big as a whale, or develop whales from guppies by selective breeding. Genetic limits are real! They are real for natural selection as well as for selective breeding.

    Changing works to a point, but don't do like John the book keeper who was good at math and knew that his son John Junior was five feet tall and was now growing about an inch a year. Junior had outgrown his bed, and John wanted to get him one he could use all the rest of his life, so John did the arithmetic. Figuring the inch a year on out into the future, if Junior lived another 60 years it should add another 60 inches, he should be 10 feet tall! So John special ordered a bed just over ten feet long. He did not take into account a genetic limit that permits growth for a period, and then stops it.

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  3. Deist27 Registered Senior Member

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    Why so they always resort to name calling when logic faisl them?:m:
     
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  5. Persol I am the great and mighty Zo. Registered Senior Member

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    5,946
    Originally posted by Deist27
    This would correspond in nature, but because of genetic limits it is impossible to develop either a breed of guppies with tails as big as a whale, or develop whales from guppies by selective breeding. Genetic limits are real! They are real for natural selection as well as for selective breeding.
    You say this based on a very small number of selective breeding exercises over 'maybe' 20 generations. Natural selection had a much larger time frame.

    ...but don't do like John the book keeper who was good at math and knew that his son John Junior was five feet tall and was now growing about an inch a year... 10 feet tall. He did not take into account a genetic limit that permits growth for a period, and then stops it.

    This is a different case. Within an individual there may be a genetic limit to traits like height. However, you can selectivly bread so that the 'genetic limit' increases. This is like the butterfly argument, in that it completely argues around the point.
     
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  7. Persol I am the great and mighty Zo. Registered Senior Member

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    Because do to your posting habits it appeared as if you are not thinking for youself but just taking from other source.

    Here is one such source:
    http://www.creationism.org/heinze/Method.htm

    At the very least quote your sources and don't supply it as your own
     
  8. Deist27 Registered Senior Member

    Messages:
    61
    Over time, the guppies with the longest tails become the guppies least likely to survive because they are not the optimum size tails for guppies. What happens in nature is the guppies change BACK to their original size tails. Changes occur in nature up to a certain point, but circumstances change yet again and the guppies turn into their nominal size tails again. Thus no evolutionary change happens due to genetic alterations.

    .
    You can NOT selectivly bread so that the 'genetic limit' increases beyond a certain point. If you brred too far, say with guppies or dogs, you kill off the species. Like an over-bred poodle that is weak and frail

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  9. pumpkinsaren'torange Registered Senior Member

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    exactly! and, that's what's going to happen with human cloning as well...they are going to be weak, unhealthy and eventually die-off. it's "akin" to over-breeding, if you will.
     
  10. Persol I am the great and mighty Zo. Registered Senior Member

    Messages:
    5,946
    You are correct in that there are limits applied by physical circumstances which prevent certain sizes from being worthwhile to evolution. However, the sizes we are discussing are obviously possible due to their existance in nature. Another problem is that this does not take mutations into account, as this has the ability to introduce new gene variations and thus increase diversity. (Even if 999 out of 1000 mutations result in death or no effect, you have a huge number of individuals to work with)
     
  11. Deist27 Registered Senior Member

    Messages:
    61
    The sizes we are discussing are obviously impossiblre. Therfor they must have been created due to their existance in nature.

    Mutations further weaken genetic diversity. Since 999 out of 1000 mutations result in death, mutations can potentially destroy all ike on earth. Mutations cause Genetic information to be reduced. natural selection acts as a sieve which eliminates weaklings or those with incomplete structures (arms, legs, eyes, etc.) that may have arisen because of mutations. An arm becoming a wing, for example, would be a bad arm and discarded by natural selection before becoming a good wing.
     
  12. Persol I am the great and mighty Zo. Registered Senior Member

    Messages:
    5,946
    Originally posted by Deist27
    The sizes we are discussing are obviously impossiblre. Therfor they must have been created due to their existance in nature.
    No... if something exists then it is not impossible. Even if it was created, it's not impossible.

    Mutations further weaken genetic diversity.

    No they increase diversity. When you say 'weaken genetic diversity' that implies that diversity is lessening. Mutations may kill some, but those who survive are more diverse.

    Since 999 out of 1000 mutations result in death

    I didn't say this. I said death or no effect.

    mutations can potentially destroy all ike on earth

    Mutations do not affect every individual, and they don't kill every individual they affect, so this comment has no basis.

    Mutations cause Genetic information to be reduced.

    See above

    natural selection acts as a sieve which eliminates weaklings or those with incomplete structures (arms, legs, eyes, etc.) that may have arisen because of mutations.

    Then the resemblance of species physically and genetically, and the transitory fossils found are all because god didn't want to start over from scratch on each new creature?

    An arm becoming a wing, for example, would be a bad arm and discarded by natural selection before becoming a good wing.

    No. An arm with a web still functions for short gliding. Add feathers and you have insulation. Add both and you have a bird's wing.
     
  13. Deist27 Registered Senior Member

    Messages:
    61
    Mutations further weaken genetic diversity resulting in death or no change
    mutations can potentially destroy all ike on earth[/b]
    Mutations do not affect every individual becuse not all have mutations. They don't kill every individual they affect,because most mutations result in no change. Mutations thus cause Genetic information to be reduced if they hav an effect.

    natural selection acts as a sieve which eliminates weaklings or those with incomplete structures (arms, legs, eyes, etc.) that may have arisen because of mutations.
    Transitory fossils have NEVER been found. Show us a single one.

    An arm becoming a wing, for example, would be a bad arm and discarded by natural selection before becoming a good wing.
    Yes. Mutations (rare and random changes in complex living systems) do not provide new traits to be selected. They merely rearrange the traits that already exist in a species, sometimes repeating, sometimes deleting what is already there. As expected…most mutations are either lethal or harmful to the organism experiencing them. Perhaps one mutation out of a thousand might be neutral.

    an eye or wing coming into being) has ever been found in either living or fossil specimens. Natural selection is a conservation mechanism, not one of innovation as required by evolution. Evolution requires new traits. Natural selection does not provide any; it merely selects what is already present.]
     
  14. pumpkinsaren'torange Registered Senior Member

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    2,159

    actually, that is quite true...in a nut-shell, evolution is ALL ABOUT creating new traits...in order for future survival.
     
  15. Deist27 Registered Senior Member

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    Good point Pumpkin...

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  16. Persol I am the great and mighty Zo. Registered Senior Member

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    Originally posted by Deist27
    natural selection acts as a sieve which eliminates weaklings or those with incomplete structures (arms, legs, eyes, etc.) that may have arisen because of mutations.
    Once again... just repeating yourself

    Transitory fossils have NEVER been found. Show us a single one.

    How about these?

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    taken from here
    This link has other ape->human skulls and shows that even creationists can not tell decide if the transitional fossils are more ape or more human.

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    taken from here

    And finally from here :

    <ul>
    Transition from primitive jawless fish to sharks, skates, and rays:
    <ul>
    <li>
    Cladoselachians (e.g., <i>Cladoselache</i>).
    <li>
    Hybodonts (e.g. <i>Hybodus</i>)
    <li>
    Heterodonts (e.g. <i>Heterodontus</i>)
    <li>
    Hexanchids (e.g. <i>Chlamydoselache</i>)
    </ul>
    Transition from primitive bony fish to holostean fish:
    <ul>
    <li>
    Palaeoniscoids (e.g. <i>Cheirolepis</i>); living chondrosteans such as
    <i>Polypterus</i> and <i>Calamoichthys</i>, and also the living acipenseroid
    chondrosteans such as sturgeons and paddlefishes.
    <li>
    Primitive holosteans such as <i>Semionotus</i>.
    </ul>
    Transition from holostean fish to advanced teleost fish:
    <ul>
    <li>
    Leptolepidomorphs, esp. <i>Leptolepis</i>, an excellent holostean-teleost
    intermediate
    <li>
    Elopomorphs, both fossil and living (tarpons, eels)
    <li>
    Clupeomorphs (e.g. <i>Diplomystus</i>)
    <li>
    Osteoglossomorphs (e.g. <i>Portheus</i>)
    <li>
    Protacanthopterygians
    </ul>
    Transition from primitive bony fish to amphibians:
    <ul>
    <li>
    Paleoniscoids again (e.g. <i>Cheirolepis</i>)
    <li>
    <i>Osteolepis</i> -- one of the earliest crossopterygian lobe-finned fishes,
    still sharing some characters with the lungfish (the other group of
    lobe-finned fish). Had paired fins with a leg-like arrangement of bones,
    and had an early-amphibian-like skull and teeth.
    <li>
    <i>Eusthenopteron</i> (and other rhipidistian crossopterygian fish) --
    intermediate between early crossopterygian fish and the earliest
    amphibians. Skull very amphibian-like. Strong amphibian-like backbone.
    Fins very like early amphibian feet.
    <li>
    Icthyostegids (such as <i>Icthyostega</i> and
    <i>Icthyostegopsis</i>) --
    Terrestrial amphibians with many of <i>Eusthenopteron</i>'s fish features
    (e.g., the fin rays of the tail were retained). Some debate about
    whether <i>Icthyostega</i> should be considered a fish or an amphibian;
    it is an excellent transitional fossil.
    <li>
    Labyrinthodonts (e.g., <i>Pholidogaster</i>, <i>Pteroplax</i>) -- still have some
    icthyostegid features, but have lost many of the fish features (e.g.,
    the fin rays are gone, vertebrae are stronger and interlocking, the
    nasal passage for air intake is well defined.)
    </ul>
    Transition from amphibians to reptiles:
    <ul>
    <li>
    Seymouriamorph labyrinthodonts (e.g. <i>Seymouria</i>) -- classic labyrinthodont
    skull and teeth, with reptilian vertebrae, pelvis, humerus, and digits;
    amphibian ankle.
    <li>
    Cotylosaurs (e.g. <i>Hylonomus</i>, <i>Limnoscelis</i>) -- slightly amphibian
    skull (e.g. with amphibian-type pineal opening), with rest of skeleton
    classically reptilian.
    <li>
    The cotylosaurs gave rise to many reptile groups of tremendous variety. I
    won't go into the transitions from cotylosaurs to the advanced anapsid
    reptiles (turtles and possibly mesosaurs), to the euryapsid reptiles
    (icthyosaurs, plesiosaurs, and others), or to the lepidosaurs (eosuchians,
    lizards, snakes, and the tuatara), or to most of the dinosaurs, since I don't
    have infinite time. Instead I'll concentrate on the synapsid reptiles (which
    gave rise to mammals) and the archosaur reptiles (which gave rise to birds).
    </ul>
    Transition from reptiles to mammals:
    <ul>
    <li>
    Pelycosaur synapsids -- classic reptilian skeleton, intermediate between
    the cotylosaurs (the earliest reptiles) and the therapsids (see next)
    <li>
    Therapsids (e.g. <i>Dimetrodon</i>) -- the numerous therapsid
    fossils show gradual transitions from reptilian features to
    mammalian features. For example: the hard palate forms, the teeth
    differentiate, the occipital condyle on the base of the skull doubles,
    the ribs become restricted to the chest instead of extending down the
    whole body, the legs become "pulled in" instead of sprawled out, the ilium
    (major bone of the hip) expands forward.
    <li>
    Cynodont theriodonts (e.g. <i>Cynognathus</i>) -- very mammal-like reptiles.
    Or is that reptile-like mammals? Highly differentiated teeth (a classic
    mammalian feature), with accessory cusps on cheek teeth; strongly
    differentiated vertebral column (with distinct types of vertebrae for
    the neck, chest, abdomen, pelvis, and tail -- very mammalian), mammalian
    scapula, mammalian limbs, mammalian digits (e.g. reduction of number of
    bones in the first digit). But, still has unmistakably <b>reptilian</b>
    jaw joint.
    <li>
    Tritilodont theriodonts (e.g. <i>Tritylodon</i>,
    <i>Bienotherium</i>) -- skull
    even more mammalian (e.g. advanced zygomatic arches). Still has
    reptilian jaw joint.
    <li>
    Ictidosaur theriodonts (e.g. <i>Diarthrognathus</i>) -- has all the mammalian
    features of the tritilodonts, and has a <b>double</b> jaw joint; both the
    reptilian jaw joint and the mammalian jaw joint were present, side-by-side,
    in <i>Diarthrognathus</i>'s skull. A really stunning transitional fossil.
    <li>
    Morganucodonts (e.g. <i>Morganucodon</i>) -- early mammals. Double jaw joint,
    but now the mammalian joint is dominant (the reptilian joint bones are
    beginning to move inward; in modern mammals these are the bones of
    the middle ear).
    <li>
    Eupantotheres (e.g. <i>Amphitherium</i>) -- these mammals begin to show the
    complex molar cusp patterns characteristic of modern marsupials and
    eutherians (placental mammals). Mammalian jaw joint.
    <li>
    Proteutherians (e.g. <i>Zalambdalestes</i>) -- small, early insectivores with
    molars intermediate between eupantothere molars and modern eutherian
    molars.
    <li>
    Those wondering how egg-laying reptiles could make the transition to
    placental mammals may wish to study the reproductive biology of the
    monotremes (egg-laying mammals) and the marsupials. The monotremes
    in particular could almost be considered "living transitional fossils".
    [see Peter Lamb's suggested marsupial references at end]
    </ul>
    Transition from reptiles to birds:
    <ul>
    <li>
    <i>Lisboasaurus estesi</i> and other "troodontid dinosaur-birds" -- a bird-like
    reptile with very bird-like teeth (that is, teeth very like those of
    early toothed birds [modern birds have no teeth]). May not have been
    a direct ancestor; may have been a "cousin" of the birds instead.
    <li>
    <i>Protoavis</i> -- this is a <b>highly controversial</b> fossil that may or may not be
    an extremely early bird. Not enough of the fossil was recovered to
    determine if it is definitely related to the birds, or not. I mention it
    in case people have heard about it recently.
    <li>
    <i>Archeopteryx</i> -- reptilian vertebrae, pelvis, tail, skull, teeth, digits,
    claws, sternum. Avian furcula (wishbone, for attachment of flight
    muscles), forelimbs, and lift-producing flight feathers. <i>Archeopteryx</i>
    could probably fly from tree to tree, but couldn't take off from
    the ground, since it lacked a keeled breastbone (for attachment of large
    flight muscles) and had a weak shoulder (relative to modern birds).
    <li>
    "Chinese bird" [I don't know what name was given to this fossil] --
    A fossil dating from 10-15 million years after <i>Archeopteryx</i>.
    Bird-like claws on the toes, flight-specialized shoulders, fair-sized
    sternal keel (modern birds usually have large sternal keel); also
    has reptilian stomach ribs, reptilian unfused hand bones, & reptilian
    pelvis. This bird has a fused tail ("pygostyle"), but I don't know how
    long it was, or if it was all fused or just part of it was fused.
    <li>
    "Las Hoyas bird" [I don't know what name was given to this fossil] --
    This fossil dates from 20-30 m.y. after <i>Archeopteryx</i>. It still
    has reptilian pelvis & legs, with bird-like shoulder. Tail is
    medium-length with a fused tip (<i>Archeopteryx</i> had long, unfused tail;
    modern birds have short, fused tail). Fossil down feather was found with
    the Las Hoyas bird.
    <li>
    Toothed Cretaceous birds, e.g. <i>Hesperornis</i> and <i>Ichthyornis</i>. Skeleton
    further modified for flight (fusion of pelvis bones, fusion of hand
    bones, short & fused tail). Still had true socketed teeth, which are
    missing in modern birds.
    <li>
    [note: a classic study of chicken embryos showed that chicken bills can
    be induced to develop teeth, indicating that chickens (and perhaps other
    modern birds) still retain the genes for making teeth.]
    </ul>
    </ul>
    <p>
    Now, on to some of the classes of mammals.
    <ul>
    Transitional fossils from early eutherian mammals to primates:
    <ul>
    <li>
    Early primates -- paromomyids, carpolestids, plesiadapids. Lemur-like
    clawed primates with generalized nails.
    <li>
    <i>Notharctus</i>, an early Eocene lemur
    <li>
    <i>Parapithecus</i>, a small Old World monkey (Oligocene)
    <li>
    <i>Propliopithecus</i>, a small primate intermediate between <i>Parapithecus</i>
    and the more recent O.W. monkeys. Has several ape-like characters.
    <li>
    <i>Aegyptopithecus</i>, an early ape.
    <li>
    <i>Limnopithecus</i>, a later ape showing similarities to the modern gibbons.
    <li>
    <i>Dryopithecus</i>, a later ape showing similarities to the non-gibbon apes.
    <li>
    <i>Ramapithecus</i>, a dryopithecine-like ape showing similarities to the
    hominids but now thought to be an orang ancestor.
    <li>
    <i>Australopithecus</i> spp., early hominids. Bipedal.
    <li>
    <i>Homo habilis</i>.
    <li>
    <i>Homo erectus</i>. Numerous fossils across the Old World.
    <li>
    <i>Homo sapiens sapiens</i>. This is us. (NB: "Cro-magnon man" belongs
    here too. Cro-magnons were a specific population of modern humans.)
    <li>
    <i>Homo sapiens neanderthalensis</i> (not on the direct line to <i>H. sapiens
    sapiens</i>, but worth mentioning).
    <li>
    [I haven't described these fossils in detail because they're fairly well
    covered in any intro biology text, or in any of several good general-
    interest books on human evolution.]
    </ul>
    Transitional fossils from early eutherian mammals to rodents:
    <ul>
    <li>
    Paramyids, e.g. <i>Paramys</i> -- early "primitive" rodent
    <li>
    <i>Paleocastor</i> -- transitional from paramyids to beavers
    <li>
    [yick. I was going to summarize rodent fossils but <i>Paramys</i> and its
    friends gave rise to 5 enormous and very diverse groups of rodents, with
    about ten zillion fossils. Never mind.]
    </ul>
    Transitional fossils among the cetaceans (whales & dolphins):
    <ul>
    <li>
    <i>Pakicetus</i> -- the oldest fossil whale known. Only the skull was found.
    It is a distinct whale skull, but with nostrils in the position of a
    land animal (tip of snout). The ears were <b>partially</b> modified for
    hearing under water. This fossil was found in association with fossils
    of land mammals, suggesting this early whale <b>maybe</b> could walk on land.
    <li>
    <i>Basilosaurus isis</i> -- a recently discovered "legged" whale from the
    Eocene (after <i>Pakicetus</i>). Had hind feet with 3 toes and a tiny remnant
    of the 2nd toe (the big toe is totally missing). The legs were small and
    must have been useless for locomotion, but were specialized for swinging
    forward into a locked straddle position -- probably an aid to copulation
    for this long-bodied, serpentine whale.
    <li>
    Archaeocetes (e.g. <i>Protocetus</i>, <i>Eocetus</i>) -- have lost hind legs entirely,
    but retain "primitive whale" skull and teeth, with forward nostrils.
    <li>
    Squalodonts (e.g. <i>Prosqualodon</i>) -- whale-like skull with <b>dorsal</b>
    nostrils (blowhole), still with un-whale-like teeth.
    <li>
    <i>Kentriodon</i>, an early toothed whale with whale-like teeth.
    <li>
    <i>Mesocetus</i>, an early whalebone whale
    <li>
    [note: very rarely a modern whale is found with tiny hind legs, showing
    that some whales still retain the genes for making hind legs.]
    </ul>
    Transitional fossils from early eutherian mammals to the carnivores:
    <ul>
    <li>
    Miacids (e.g. <i>Viverravus</i> and <i>Miacis</i>) -- small weasel-like animals
    with very carnivore-like teeth, esp. the carnassial teeth.
    <li>
    Arctoids (e.g. <i>Cynodictis</i>, <i>Hesperocyon</i>) -- intermediate between
    miacids and dogs. Limbs have elongated, carnassials are more
    specialized, braincase is larger.
    <li>
    <i>Cynodesmus</i>, <i>Tomarctus</i> -- transitional fossils between arctoids
    and the modern dog genus <i>Canis</i>.
    <li>
    <i>Hemicyon</i>, <i>Ursavus</i> -- heavy doglike fossils between the arctoids
    and the bears.
    <li>
    <i>Indarctos</i> -- early bear. Carnassial teeth have no shearing action,
    molars are square, short tail, heavy limbs. Transitional to the
    modern genus <i>Ursus</i>.
    <li>
    <i>Phlaocyon</i> -- a climbing carnivore with non-shearing carnassials,
    transitional from the arctoids to the procyonids (raccoons et al.)
    </ul>
    Meanwhile back at the ranch,<br>
    <ul>
    <li>
    <i>Plesictis</i>, transitional between miacids (see above) and mustelids
    (weasels et al.)
    <li>
    <i>Stenoplesictis</i> and <i>Palaeoprionodon</i>, early civets related to the
    miacids (see above)
    <li>
    <i>Tunguricits</i>, transitional between early civets and modern civets
    <li>
    <i>Ictitherium</i>, transitional between early civets to hyenas
    <li>
    <i>Proailurus</i>, transitional from early civets to early cats
    <li>
    <i>Dinictis</i>, transitional from early cats to modern "feline" cats
    <li>
    <i>Hoplophoneus</i>, transitional from early cats to "saber-tooth" cats
    </ul>
    Transitional fossils from early eutherians to hoofed animals:
    <ul>
    <li>
    Arctocyonid condylarths -- insectivore-like small mammals with classic
    mammalian teeth and clawed feet.
    <li>
    Mesonychid condylarths -- similar to the arctocyonids, but with blunt
    crushing-type cheek teeth, and flattened nails instead of claws.
    <li>
    Late condylarths, e.g. <i>Phenocodus</i> -- a fair-sized animal with
    hoofs on each toe (all toes were present), a continuous series of
    crushing-type cheek teeth with herbivore-type cusps, and no collarbone
    (like modern hoofed animals).
    <li>
    Transitional fossils from early hoofed animals to perissodactyls:
    <li>
    [Perissodactyls are animals with an <b>odd</b> number of toes; most of the
    weight is borne by the central 3rd toe. Horses, rhinos, tapirs.]
    <li>
    <i>Tetraclaeonodon</i> -- a Paleocene condylarth showing perissodactyl-like
    teeth
    <li>
    <i>Hyracotherium</i> -- the famous "dawn horse", an early perissodactyl, with
    more elongated digits and interlocking ankle bones, and slightly
    different tooth cusps, compared to to <i>Tetraclaeonodon</i>. A small, doggish
    animal with an arched back, short neck, and short snout; had 4 toes
    in front and 3 behind. Omnivore teeth.
    <li>
    [The rest of horse evolution will be covered in an upcoming "horse
    fossils" post in a few weeks. To whet your appetite:]
    <li>
    <i>Orohippus</i> -- small, 4/3 toed, developing browser tooth crests
    <li>
    <i>Epihippus</i> -- small, 4/3 toed, good tooth crests, browser
    <li>
    <i>Epihippus (Duchesnehippus)</i> -- a subgenus with <i>Mesohippus</i>-like teeth
    <li>
    <i>Mesohippus</i> -- 3 toed on all feet, browser, slightly larger
    <li>
    <i>Miohippus</i> -- 3 toed browser, slightly larger [gave rise to lots of
    successful three-toed browsers]
    <li>
    <i>Parahippus</i> -- 3 toed browser/grazer, developing "spring foot"
    <li>
    <i>'Parahippus' leonensis</i> -- a <i>Merychippus</i>-like species of <i>Parahippus</i>
    <li>
    <i>'Merychippus' gunteri</i> -- a <i>Parahippus</i>-like species of <i>Merychippus</i>
    <li>
    <i>'Merychippus' primus</i> -- a more typical <i>Merychippus</i>, but still very
    like <i>Parahippus</i>.
    <li>
    <i>Merychippus</i> -- 3 toed grazer, spring-footed, size of small pony
    (gave rise to tons of successful three-toed grazers)
    <li>
    <i>Merychippus (Protohippus)</i> -- a subgenus of <i>Merychippus</i> developing
    <i>Pliohippus</i>-like teeth.
    <li>
    <i>Pliohippus</i> & <i>Dinohippus</i> -- <b>one</b>-toed grazers, spring-footed
    <li>
    <i>Equus (Plesippus)</i> -- like modern equines but teeth slightly simpler.
    <li>
    <i>Equus (Hippotigris)</i>, the modern 1-toed spring-footed grazing zebras.
    <li>
    <i>Equus (Equus)</i>, the modern 1-toed spring-footed grazing horses & donkeys.
    [note: very rarely a horse is born with small visible side toes, indicating
    that some horses retain the genes for side toes.]
    <li>
    Hyrachyids -- transitional from perissodactyl-like condylarths to tapirs
    <li>
    Heptodonts, e.g. <i>Lophiodont</i> -- a small horse-like tapir, transitional
    to modern tapirs
    <li>
    <i>Protapirus</i> -- a probable descendent of <i>Lophiodont</i>, much like modern
    tapirs but without the flexible snout.
    <li>
    <i>Miotapirus</i> -- an almost-modern tapir with a flexible snout, transitional
    between <i>Protapirus</i> and the modern <i>Tapirus</i>.
    <li>
    Hyracodonts -- early "running rhinoceroses", transitional to modern rhinos
    <li>
    <i>Caenopus</i>, a large, hornless, generalized rhino transitional between the
    hyracodonts and the various later groups of modern & extinct rhinos.
    <li>
    Transitional fossils from early hoofed animals to some of the artiodactyls
    (cloven-hoofed animals):
    <li>
    Dichobunoids, e.g. <i>Diacodexis</i>, transitional between condylarths
    and all the artiodactyls (cloven-hoofed animals). Very condylarth-like
    but with a notably artiodactyl-like ankle.
    <li>
    <i>Propalaeochoerus</i>, an early pig, transitional between <i>Diacodexis</i> and
    modern pigs.
    <li>
    <i>Protylopus</i>, a small, short-necked, four-toed animal, transitional between
    dichobunoids and early camels. From here the camel lineage goes through
    <i>Protomeryx</i>, <i>Procamelus</i>, <i>Pleauchenia</i>, <i>Lama</i> (which are still alive;
    these are the llamas) and finally <i>Camelus</i>, the modern camels.
    <li>
    <i>Archeomeryx</i>, a rabbit-sized, four-toed animal, transitional between the
    dichobunoids and the early deer. From here the deer lineage goes through
    <i>Eumeryx</i>, <i>Paleomeryx</i> and <i>Blastomeryx</i>, <i>Dicrocerus</i> (with antlers) and
    then a shmoo of successful groups that survive today as modern deer --
    muntjacs, cervines, white-tail relatives, moose, reindeer, etc., etc.
    <li>
    <i>Palaeotragus</i>, transitional between early artiodactyls and the okapi &
    giraffe. Actually the okapi hasn't changed much since <i>Palaeotragus</i> and
    is essentially a living Miocene giraffe. After <i>Palaeotragus</i> came
    <i>Giraffa</i>, with elongated legs & neck, and <i>Sivatherium</i>, large ox-like
    giraffes that <b>almost</b> survived to the present.
    </ul>
    </ul>
    So, there's a <b>partial</b> list of transitional fossils.
    <p>
    This really only scratches the surface since I left out all groups
    that have no surviving relatives, didn't discuss modern amphibians or
    reptiles, left out most of the birds, ignored the diversity in modern
    fish, didn't discuss the bovids or elephants or rodents or many other
    mammal groups.... I hope this gives a taste of the richness of the
    fossil record and the abundance of transitional fossils between major
    vertebrate taxa.
    <p>
    By the way, notice that this list mostly includes transitional fossils
    that happened to lead to modern, familiar animals. This may
    unintentionally give the impression that fossil lineages proceed in a
    "straight line" from one fossil to the next. That's not so; generally
    at any one time there are a whole raft of successful species, only a
    few of which happened to leave modern descendents. The horse family is
    a good example; <i>Merychippus</i> gave rise to something like 19 new
    three-toed grazing horse species, which traveled all over the Old and
    New Worlds and were very successful at the time. Only one of these
    lines happened to lead to <i>Equus</i>, though, so that's the only line I
    talked about. Evolution is not a ladder, it's a branching bush.<p>


    They merely rearrange the traits that already exist in a species, sometimes repeating, sometimes deleting what is already there.

    There is once again no basis to this argument. Mutations can add a genetic sequence which doesn't already exist.

    As expected…most mutations are either lethal or harmful to the organism experiencing them.

    No they aren't. Chances are that you have mutated genes in your body. They just won't get passed on unless they are in your reproductive organs.

    an eye or wing coming into being) has ever been found in either living or fossil specimens.

    I'll repeat the fossil names from the info above:
    Lisboasaurus estesi and other "troodontid dinosaur-birds"
    Protoavis
    Archeopteryx
    "Chinese bird"
    "Las Hoyas bird"
    Toothed Cretaceous birds, e.g. Hesperornis and Ichthyornis.

    Natural selection is a conservation mechanism, not one of innovation as required by evolution. Evolution requires new traits. Natural selection does not provide any; it merely selects what is already present.

    True, natural selection only limits the choice, but mutations can increase the choice.
     
  17. Deist27 Registered Senior Member

    Messages:
    61
    [You are too dangerous to give that
     
  18. Deist27 Registered Senior Member

    Messages:
    61
    "ape->human skulls and shows that even creationists can not tell decide if the transitional fossils are more ape or more human."
    The 3 ape skulls you showed are not human. They all appear about the same time and there is not transitional forms leading one to the other. You practice deception. Same applies to all your other alleged examples. They are separte and distinct species all with no transitional forms none.

    So, there's NO list of transitional fossils not partial not complete and mutations are destructive even destroying earlier mutation that occured mutations can increase the choice but a later mutations decrease the choice far more often. Thus no gain thru change.

    Taking one more of your false examples - Archeopteryx existed BEFORE the reptiles they allegedly evolved from.
     
  19. Persol I am the great and mighty Zo. Registered Senior Member

    Messages:
    5,946
    As soon as a transitionary fossil is found, creasionists then say it's really a new species. You're not going to find every single fossil in a sequence, but they have found many.
     
  20. Deist27 Registered Senior Member

    Messages:
    61
    "As soon as a is "new species" is found, evolutionist then say it's really a transitionary fossil because it is a new species that has been found. You're not going to find fossils in a sequence, because they coexisted with each other therefore they can't be transitional species but separate and distinct from each other. Evolutionists line them up in a purely subjective preconceived way.
     
  21. ElectricFetus Sanity going, going, gone Valued Senior Member

    Messages:
    18,523
    Don't forget genetic linage Persol which more then verifies that view.
     
  22. Dudeyhed Conformer Registered Senior Member

    Messages:
    246
    There's been a lot of interesting stuff said but I'm still not really sure about how the actual changes occur.

    Here's my understanding of the evolutionary process so far. I should note that I'm just a high school student so i'm not going to say that what I'm about to say is the truth, in fact, I could be completely incorrect. (like my spelling often is.)

    ok...

    A certain species exists. Something in their habitat changes, eg, new preadatorial (is that a word?) species (or old species becomes more efficient), competition for food increases, climate change, etc...

    A community of a certain species has a gene pool. Those organisms which have genes better suited for the change in habitat will be more likely to survive and are often the ones that will produce the new generations as they are the ones that will survive the change. (my understanding of natural selection)

    over many years of habitat change, the community will continue to be 'naturally selected'. But that's were I don't really understand evolution. According to the way i understand it all, its still the same genotypes (maybe by genotype I'm meaning chromesome, a chromesome is one set of genes right? or am i wrong? please correct me.. I do hope to get into biology in uni...) that exist, there is no gene for new structures and the like.

    How/why did monkeys loose their tails as they evolved into humans? Did the 'tail' gene just disappear over the years? maybe i can answer this for myself:

    I saw a documentary once on the congo i think it was, and a point was raised about the possibility that the first stage of human evolution happened there. They showed footage of monkeys which were at the barrier of a forrest, just beside a open land, clear, without any obstacles. These monkeys would sometimes venture out of the forests and onto these open lands. And then they showed some remarkable footage of the monkeys stading up onto their hind legs, much like a human, straight backs. they were getting up to see further down the land. Perhaps it was from this community, millenia ago that the first step towards homo sapiens were made.

    Perhaps in that community, as more monkies moved onto the plain, height became a more important trait than having a tail... and so those with more height and less tail were chosen as mates.. I dunno.

    I could be completely wrong..

    please don't comment on the story, It might be totally incorrect and innaccurate, that was something i saw years ago and I'm not saying thats just how it was.

    But my explaination doesn't add up for me... how could the tail come out of existance? the gene is still there...

    That's what's puzzling me.

    If all orgainisms, or a great deal of then anyway, did evolve from one eons ago, how did new genes add on or drop off or how did they change?

    I've seen mutation mentioned more than a few times. What exactly is mean by mutation? Do you mean the deformation of DNA? if that is so, can all evolution be soley the result of this? How common is deformed DNA? (If mutaion's got nothing to do with deformation please don't answer that question)

    I hope someones got the aswer for me, let alone understands my question... there have been more than a few tangents so far...

    This thread should have nothing to do with creation, just the theory of evolution.
     
  23. paulsamuel Registered Senior Member

    Messages:
    882
    reply

    all good questions dude

    speciation: the first thing that has to happen is geographic isolation, that is, no gene transfer between isolated populations. once gene pools are isolated, changes can occur in each population independently. these changes can be random and neutral (that is, they don't have to be adaptive changes in response to some environmental condition). if one of the isolated populations is small, the differences between populations can arise very quickly. over time, differences accumulate resulting in reproductive isolation (that is, even if the separate populations come together again, they are unable to interbreed). the source of these differences (changes) between populations is genetic mutation.

    genetic mutation: the genetic material of organisms is made up of DNA. DNA is comprised of long strings of 4 kinds of nucleotides (adenine (A), guanine (G), thymine (T) and cytosine (C)). Portions of these strings act as templates (blueprints) for the production of proteins (the structural and metabolic building blocks of an organism). These portions of the DNA are called genes. The different genes in an organism are different because they have different templates and these different templates are based on the different sequences of the A's, G's, T's and C's. Sometimes, during cell replication, there's a copying error in the DNA that's being copied for the new cell. When this happens in the production of gametes (the sex cells) the error is heritable and is passed on in the next generation. Sometimes the error results in a slightly different protein product than the original. Over the millions of years, these errors in replication accumulate and result in the major differences we see between species.

    This is necessarily an abbreviated outline of the processes. If you want more detail or have questions, please ask.

    BTW, I think that tailess monkeys are old world monkeys (chimps, baboons, etc.) and new world monkeys (americas) are tailed. A primatologist could answer that question.
     

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