Pakicetus being presented with webbed feet.

yes. the sitatunga (tragelaphus spekeii), which lives in central african swamps, is an artiodactyl (even-toed hooved ungulate) with webbing between its toes.unfortunately, i can't find you a nice clear picture of its feet, but you'll have to trust all the biologists out in the field.This message has been edited by arachnophilia, 12-02-2005 05:28 PM

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well, that wouldn't be suprising. sitatunga's don't eat fish, they just live in marshes and swim a whole lot -- they are not as aquatic as pakicetus was. it's also important to note that sitatungas don't walk very well on land, and that they commonly swim up their eyeballs, which are not on the top of their head. we're looking at an animal less adapted to water than pakicetus.but looking at the original pakicetus picture, i don't understand your complaint. it's really hard to make out the specifics of the foot in that depiction, and in your favored depiction it's toes look a lot like a hippos, only skinnier.in other words, it seems to have webbed feet in the depiction you like. the first two paintings/drawings do have incorrect feet, displaying the wrong kind of webbing; a membrane instead of fat-filled leathery tissue. both are still aquatic adaptations.so, i think i've figured out the confusion here. maybe. you don't like the otter-like webbing in the national geographic interpretation -- you would technically be right. that's the wrong kind of webbing. but it still very likely had the other kind of webbing, like hippos and sitatungas.

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you haven't answered any counter-points about why it actually is related to whales.and it's evidently not solely a land mammal. sitatunga is considered "semi-aquatic" and it has a lot of similar to pakicetus (only slightly less aquatic -- it doesn't hunt fish). i think it's a problem of definitions here. no one is arguing that pakicetus isn't a walking animal. it's just a walking animal that also swims, like the sitatunga. it lives near river-beds and marshes, like the sitatunga. it has hooves that splay, like the sitatunga (only they splay more). the sitatunga is a land mammal, no question about it. it's just a semi-aquatic land mammal.but about the question of definitions, creationists like to have distinct lines of what's what. so such and such a species is "just a whale" and another species is "just a goat." (sic) this is not what the evidence shows -- it shows a clear pattern, relations, and progression. the "goat" and the "whale" have a long line of species at various points in between them, that are all clearly (if loosely) related. any lines are arbitrary, even the ones evolutionary biologists assign.so the question now is where you draw the line between "just a whale" and "just a goat." earlier, i posted:

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let's start from another angle: would agree that basilosaurus here is a whale?

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is basilosaurus a whale?

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here is a bear skull:here are human teeth:here is a pakicetus skull:bears and humans are omnivores. we have teeth specifically adapted for different purposes. pakicetus's teeth are all very much the same, and clearly indicate that it eats things that live in water, and ONLY things that live in water. those teeth in front are good for catching slippery things in water, like fish. the ones in the middle or basically steak knives. it's molars are pointed -- no plant grinding here.eating fish doesn't make something semi-aquatic, no. but being specially adapted to eat ONLY fish does. not insisting that. ok, looking at some info on sitatunga, i want to point something out again. look at it's foot. can you name me any artiodactyl that walks on SPLAYED hooves? they're actually not good for land at all -- ask sitatunga, who kind of wobbles and braces.

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not suprising, actually. things don't exist for just an instant. if you found the very first ambulocetus, it would be well before the very last pakicetus. one did not descend from the other, they are merely related and share a common ancestor.it's basically the "if humans evolved from monkeys, why do we still have monkeys?" question in disguise. suppose an alien race finds a modern monkey skeleton 40 million years from now, and then finds lucy who's several million years older. it's the same "problem." which might actually be right. but it indicates a trend nonetheless. since the line is not direct (as i described above) technically no "ancestral" whale is the ancestor of a modern whale. they just indicate the trend. any argument from incredulity if i ever heard one. the problem is that whales are cetaceans, but not all cetaceans are whales. it's a category that INCLUDES whales, but also dolphins and porpoises.what we're faced with is an order called "cetacea" that includes some aquatic forms, and some not-so-aquatic forms. in this case, artiodactyls include cetaceans, which include mesonychids and archeocetids, which include pakicetus. are also included, though under which bubble i'm not sure.calling pakicetus a whale may or may not be correct. i argue that it is, because it is clearly an archaeocetid, which are generally considered whale-like. but whether or not he's a whale, he's definitally a cetacean.

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no no, go back and look at the bit that you posted about why mesonychids were thought to be related to modern whales at first, and then the scientific community change its mind. that decision was based on differences in the teethhere's two skulls. the top is from a mesonychid (andrewsarchus) and the bottom is a whale (prozeuglodon).see the difference? mesonychid teeth look much more like bear teeth than they do whale teeth.

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i didn't say they did. just that they were more like whale-teeth than mesonychid teeth. they're actually a lot like shark teeth, which indicates a similar diet. that was the only point i was trying to make.pakicetus's teeth are noticeably less conical than a modern whale's. see if you can find something about what it ate.

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Pakiceid teeth look a lot like those of fossil whales, but are unlike those of modern whales. Pakicetids did not live in the sea. The rocks in which their fossils are preserved indicate that the bones were buried in a shallow stream, and that the climate was hot and dry. It is likely that pakicetids waded in these streams.

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yes, sort of like sitatunga does. wades, lives in marshes, and swims. it's still primarily a land animal, and no one is arguing that randman. really. it's just slightly adapted to life in and around water, it doesn't live there full time.

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randman, remember what you said about education and thinking critically instead of indoctrination? i'm posting pictures because i'm asking you to look at them.mesonychids have somewhat triangular teeth. archaeocetids have teeth that are more triangular. modern whale teeh are conical (if they have teeth). the argument for relation is based on the teeth -- pakicetus is more related to whales that mesonychids are. not everything is cut and dry and arbitrary.just look at the picture -- do they look the same? do they have similarites, even if they're not identical? and? as are cetaceans, btw. but i'm not sure whether or not there were seals in eocene. my vague reference to "things that live in the water" hypothetically includes seal ancestors.This message has been edited by arachnophilia, 12-02-2005 06:50 PM

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*sigh*ok, randman, nevermind. don't think. you need to know something about biology first, so it's schooling time.crocodilian teeth do not interlock and alternate. they also protrude above and below the gumline, and often below the jaw. reptilian teeth are all analagous forms, just varying in size (exlucing dimetrodons and ancestral mammals). whales have similar, but not analagous teeth. note the differences in curvature.crocodile teeth are more similar to these guys:flattened at the edges, round in the center. whale teeth are round all the way around. reptilian teeth tend to be serated on the front and back egde, i don't imagine that whale teeth are because they don't have edges. whale teeth are slightly bulbous towards the end, reptile teeth are larger towards the base. whale teeth have slight second curve in teh root structure, reptilian teeth don't. reptile teeth point backwards, whale teeth point down.the jaw structure works differently, too. whales have a post-orbital ridge, that the musclature attaches through, like most other mammals. reptiles have a flat hinge. the cranial structure in that area is also different, mammals have a recession for the muscle to attach to, reptiles have a hole.This message has been edited by arachnophilia, 12-02-2005 07:04 PM

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... i can tell the difference.the false killer whale and the german shepherd look more similar to me than the whale and the crocodile. for instance, all of the dentiary differences i described above.bot mostly the jaw/ear structure, the temple reagion, the orbital structures, and the generally more intricate structure, opting for thin solid structures instead of heavy ones with holes.this is seriously elementary biology, randman. i'm sorry i ever gave you the idea to compare things, because clearly you don't even know how to look at some animal's skull, and conclude that therefor no else must know either.

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2 seconds on google to confirm what honestly was my own analysis of its teeth:

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C. Anatomical Transitions in Archaeocetes
  * Dentition
    o initially - complex heterodont teeth with big canines
    o reduction in heterodonty - associated with fish eating diet
    o finally - simpler cheek teeth; some conical; some triangular & serrated

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Not Found (class notes)

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FROM HOOVES TO FLIPPERS: NEW INSIGHTS INTO THE ECOLOGY OF EOCENE MARINE MAMMALS FROM STABLE ISOTOPES

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CLEMENTZ, Mark T.¹, GOSWAMI, Anjali², KOCH, Paul L.¹, and GINGERICH, Philip D.³, (1) Earth Science, Univ of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, clementz@es.ucsc.edu, (2) Committee on Evolutionary Biology, Univ of Chicago, Chicago, IL 60637, (3) Museum of Paleontology, Univ of Michigan, Ann Arbor, MI 48109

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The evolution of cetaceans and sirenians is marked by similar morphological changes, such as loss of hindlimbs and development of tail flukes, which are associated with adaptation to a fully aquatic existence. Yet, how these changes correlate with ecological transitions within these lineages remains unclear. Coupled carbon and oxygen isotope analysis is one source of ecological information for early taxa within these groups. Enamel d¹³C values are controlled by diet and are labeled by the d¹³C composition of primary producers at the base of the food web. Enamel d¹³C values are low for freshwater foragers, intermediary for C3 terrestrial consumers, and high for marine foragers, particularly consumers of marine macrophytes. Mean enamel d¹⁸O values can reflect the d¹⁸O composition of environmental waters, and thereby distinguish marine and terrestrial taxa. However, physiological and dietary differences also influence enamel d¹⁸O values, which complicates interpretation of mean values. An alternative is to look at differences in d¹⁸O variance among populations, since terrestrial taxa typically exhibit higher variance than aquatic taxa.

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Using a coupled isotope approach, we assessed the habitat and dietary preferences of early cetaceans (Pakicetus, Basilosaurus, and Dorudon) and sirenians (Protosiren, Eosiren, and Eotherium) through comparison with co-occurring terrestrial mammals. Pakicetus and Protosiren represent basal members of these two lineages that morphologically were still capable of terrestrial locomotion, while the other taxa were most likely fully aquatic. Among cetaceans, the mean d¹³C value for Pakicetus was significantly lower than terrestrial taxa, as was the d¹⁸O variance, suggesting that Pakicetus was principally aquatic and foraging within freshwater ecosystems. More derived cetaceans, Basilosaurus and Dorudon, also showed low d¹⁸O variance, but mean d¹³C values were higher than terrestrial taxa, indicating these cetaceans were marine foragers. Likewise, sirenians exhibited low d¹⁸O variance indicative of aquatic habitat use, but d¹³C values for all sirenians, including Protosiren, were significantly higher than values for all other taxa, and represent the earliest clear evidence of feeding on seagrass by any lineage of mammals.

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http://gsa.confex.com/...1AM/finalprogram/abstract_28631.htm (emphasis mine)

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This message has been edited by arachnophilia, 12-02-2005 07:16 PM

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