Mokele

Well, they're active and have a high metabolism for a reptile, but they're still a long way from actual endothermy. Actually, that data has since been withdrawn; it was a measurement error. It has mass homeothermy, but it's basal metabolism is as expected for a reptile of its size. Well, AFIAK, the consensus on the fillaments is that they're tough fibers that served to strengthen and support the wing membrane. As for metabolism, maybe. Given that they could actively fly, which requires a very high aerobic metabolism, it's very likely that they were endotherms. But, we only have two groups of large true-flyers now, so can we really assume that for the past? Maybe pterosaurs were ecotherms with some sort of biological "trick" that no longer exists to manage flight? As always with the metabolism of extinct animals, we can't be certain. Not in metabolism, but they display some interesting behaviors that could lead down an often-traveled path of croc evolution. Cubans are much more terrestrial than other crocs, with longer, stronger legs; they can actually gallop as adults, while most crocs can only do this as juveniles. That's helped by their smallish size (9 foot males and 7 foot females are average). Interestingly, they also appear to be pack hunters. (The curiously flattened teeth in the back of their mouths and some fossils lead some to suspect they evolved pack hunting to take down Pleistocene ground-sloths). Anyhow, this is significant because running crocodiles are a repeated theme in their evolution. They actually started out as small, erect runners about the size of dogs, became aquatic and large, but have returned to terrestrially active predations at least 2 times since the dinosaurs, possibly more (sketchy fossil evidence so we can't be sure). We don't know if these running crocs ever were endothermic, for the same reason we don't know about the dinosaurs, namely that the only stuff that fossilizes is correlated to metabolism, not causally linked. Given that close relatives of the crocs who retained the active, terrestrial lifestyle eventually became dinosaurs and then birds, it's possible they were warm, cold, or something in between. Yes, crocs and dinos are archosaurs. And yes, the 4 chambered heart seems likely for dinos and pterosaurs. But the problem is whether that (and the other derived traits you mention) truly indicates endothermy? Sure, it's correlated with it, but there's a painfully small sample size of modern endotherm taxa, so how can we be sure, especially since we know that the four-chambered heart can be possessed by cold-bloods (crocs). To complicate things, many amphibian hearts have varying decress of ventricular separation, and all reptile hearts (aside from crocs) are effectively 5-chambered, via temporary muscular ridges and valves that only show up during contractions. Indeed, if we go by taxa, complex hearts are more strongly correlated to aquatic/amphibious lifestyle than to endothermy. Never simple, is it? Mokele

Unfortunately, AFIAK, right now this is one of those Contentious Issues which have no clear answer. On one hand, there *are* a lot of similarities. On the other, it's possible that many of them are convergent and some recent work I've heard indicates they aren't *quite* as similar as they seem. I'll try to dig up that work, if I can (I left the book in my office). Mokele

What about loss of a loved one? Surely there's no "intent" there, since that implies it's something you have control over. Season Affective Disorder, in which individuals feel down and depressed when not exposed to enough of the proper kind of light (I strongly suspect I have this myself). In that case, a purely biological but non-pain system can cause emotional unhapiness. Well, it's easy to be sure: All thought, happy or sad, is the product of chemicals. Depression is the product of a particular balance (or imbalance) of chemicals. Now, how that situation comes about can vary: maybe it's purely environmental, like your pet died, or maybe an environmental trigger causes a natural (hereditary) tendency towards imbalance to manifest, or maybe the individual is just born that way. As such, even if a trigger is required, what's *keeping* them depressed isn't the trigger, it's the continuing chemical imbalance. Mokele

Well, we know it's happened twice (birds and mammals evolved endothermy independently), so it's not a one-time0only thing. But beyond that, it's hard to say. Maybe it's easy if the situation is right, but then what's the right situation? The difficulty of extrapolating metabolism from fossils makes it even more difficult. I wouldn't put it past reptiles to produce endothermic descendants again, though. Cuban crocs are my bet, or varanid lizards. Mokele

IIRC, there have actually been experiments done that give some pretty firm support to that theory. But it's not my area, so I'm not really "in the know". Except that many reptiles have already evolved ways of doing that, usually simply involving expanding the ribcage in order to flatten the body or by changing color to a dark skin tone when basking. It's possible that the ability to flatten the ribcage can lead to collapsible rib-wings like the flying lizard of genus Draco, but you won't see it in truly large animals, since their thermal inertia means they don't face quite as bad of a problem as small reptiles in the same habitat, since they retain heat through sheer bulk to a degree. Also, in large animals such heat collectors would need to be a lot larger (proportionally) than in small animals before they begin offering aerodynamic advantages. Mokele

You made an incorrect logical leap. Yes, correlation can tell us what is the *most likely* causation, and we can be 99.999% certain of that, but it can *never* give us 100% proof without experiment. And I can also be *wrong*, even with strong correlations. Let's give a better example: Say I'm a farmer, and I plant species X. On the years I have a dry spell, the plants do poorly, and they do better when wet. I could repeat this 1000 times and still get the same results. Does this mean plant species X requires lots of water to do well? According to you, yes, this establishes a causal connection. But then I do *experiments*. I grow plant species X in sterile, controlled conditions and find out that it doesn't need much water at all. Closer observation reveals that there are two types of bugs in my fields, one that eats the plant, and one that parasitizes the plant-eating bugs. But the herbivore bugs can deal with drought, while the parasite species that controls them needs moisture. In dry seasons, the parasite species cannot control the herbivores, and the bugs cause the damage to the plants, not the weather itself. The point is that a correlational study between crop yield and rainfall will give a strong, consistent, predictable relationship, but assuming that relationship is directly causal is *wrong*. Only once I experimented did I find that out. You cannot assume causality from correlation, no matter how convincing it looks. Mokele

Well, it's only half the story. The other half is that they breed like guppies in captivity, and we've got over 20,000 total in various reserves. The main obstacle is habitat, but the Chinese government has recently decided to make them a big priority (like panda-level priority), and they've begun reclaiming habitat. Yes and no. The Acanthodian fish possessed several "extra fins" compared to other fish lineages, and could have produced 8-legged land vertebrates. However, you probably noticed the use of the paste tense in that sentence; that lineage of fish has been extinct for over 270 million years. To the best of my knowledge, nothing in the Chordate line before or since has had more than 4 limbs. Mokele

Yes, many parasites *do* survive in humans, sometimes as part of their natural life cycles (many species go through 2 or even 3 hosts in their lives). Additionally, some can "accidentally" wind up in humans (meaning they can parasitize us, but will not be able to reproduce; like being stranded on a desert island). A few parasites can also go from cold-blooded to warm-blooded hosts. But it's easier, in terms of adaptations needed by the parasite, to go from warm to warm. Mokele

No idea if it's true or not, but if it was near Chernobyl, that was almost definitely not the only thing wrong with it. Probably a similar mutation to what I described about, though. Well, with the frogs, it's not a mutation, but a developmental disruption caused by external chemicals (pollution). Such things only rarely do produce benefits, but in certain circumstances, they can. Remember, unless it's outright sterilizing or lethal, a mutation's value is primarily a function of ecology. But this *is* old-school; it's where fish got their fins and we got our legs. Alterations in developmental genes are a major catalyst for evolution. Mokele

It could happen as described, but would take a *LONG* time, and all intermediates would have to offer advantage over the prior situation (hardly a given). Alternatively, it could happen the same way we got our legs in the first place: duplications of the HOX cluster of genes, which control limb development (among other things). This sort of duplication could conceivably happen in one mutation, and from there, the extra limbs could become wings. Assuming that no horrible developmental disorders resulted, as they often do when HOX is tinkered with. Mokele

AFAIK, there's no difference at the cellular level. Because of the nature of the air-sacs and avian lung, compared to the complex alveolar structure of mammals, I'd guess the bird lung is lighter per unit volume. The main difference in efficiency is the flow of air through the system. In mammals (and other creatures with tidal airflow in the lungs), there's a lot of "dead air" in the lungs, and the blood can only have the same O2 concentration as the air. In birds, because there is no "dead air" in the gas-exchange surfaces, and the flow is unidirectional (with the blood flowing the opposite way), the system is a counter-current exchanger. As a result. The concentration of O2 in the blood can actually be *higher* than in the air, and the exhaled CO2 per breath is higher too. Mokele

First off, yes, reptile RBCs are nucleated. In fact, IIRC, mammals are the only vertebrates without nucleated RBCs. Probably not. The DNA will be too degraded to use, nucleated RBCs tell us nothing since both birds and reptiles have them (and mammals don't), and most of the rest seems to be structural fibers and the like. The O2 loading curve of the hemoglobin might give us an indication of metabolic rate, but a) we don't know if the curve would be the same for mass homeotherms and endotherms and b) it's probably too degraded to tell. For Tyrannosaurus, it'd be interesting, but not too surprising if we did find out it was endotherming. They weren't actually very closely related to prior large theropods like Allosaurus, and were instead more close to birds, small theropods like raptors and troodonts, forming a group of fast-moving, possibly-endothermic-but-maybe-just-high-metabolism-ectotherm dinosaurs called the coelurosaurs. Ooh, i'd be much obliged, if you could. The article is: Padian, de Ricqles & Horner, "Dinosaurian growth rates and bird origins", Nature 412, 405 - 408 (26 July 2001) Mokele

I'd say, in general, yes. For parasites, each organism is an ecosystem, and you have the problem of competition. Many parasites are not only specialized to deal with a single host species and organ system, but even specific regions of that host's organ system. If you cut open fish, you find different parasites of the digestive system in different portions of the system for the same reason animals become specialists: to reduce competition. Ergo, the more "niches" an animal has to parasitize, the more species of parasite will find a way in. However, this is a *very* broad generalization, with numerous counter-examples; for instance, reptiles are about as complex as mammals, but have less parasites becuase the continually warm mammal body is a much more inviting home than the body of a reptile, which varies it's temperature. Also, for plants, what do you define as "parasite"? A wood-boring beetle or a termite colony could be considered a plant parasite. In terms of health, the important thing is how many of those parasites can or will affect you if you eat them. Heavily parasitized species might be fine to eat if none of the parasites can survive in a human host. Mokele

It can be easily disproven. Here, give me your hand and a hammer. The trouble is the "all" in your statement. Lots of other things can cause unhappiness. That doesn't mean your cause isn't also one of them, or a singificant one (since it seems to generalize well to many situations), just that you should be careful of using the word "all" in such a way. After all, clinical depression is unhapiness cause by chemicals, nothing more. Mokele

Nowhere, hence why dragons (at least as they're envisioned in european myth) cannot exist. Of course, that leaves aside the problems of an animal that large flying; most of the pterosaurs that had wingspans over 20 feet has bones so thin you could easily crush their entire ribcage with a punch. Ironicly, one chinese dragon *is* flesh and blood, the Tung Long ("muddy dragon"), who lives in ponds and streams, and whose roars bring storms. You can even ask natives on Anhui province to show you them; they'll point straight to one of the few remaining wild Chinese Alligators. But to them, it's a dragon. Of course, one cannot escape the irony that China's population boom and the argiculture needed to feed all those people has almost killed off the flesh-and-blood chinese dragon in the wild. Less and 50 left, and only 1 wild nest in the past decade. Mokele

It's about ecology, and strategy. Think of it like gambling. Each offspring is an energy gamble. If you/they win, they reproduce and further your genes. Otherwise something eats them. On one hand, you could spread your energy out, making a large number of high risk bets. This is analagous to having lots of offspring: you produce huge numbers of babies, each with a minimal investment/bet, and hope that by sheer probability, one of them will survive and reproduce (because if even one does, then they'll have *lots* of babies like you did). On the other hand, you could place a lot of your energy in a few, low-risk bets. This is analagous to having only a few kids, but putting as much energy into them as possible to ensure they suceed and get to reproduce. Ecology, evolution, and physiology play a large role in determining what strategy is best. If offspring mortality is high, no matter *how* well invested, and spending extra energy on kids doesn't significantly increase their liklyhood of survival, then it's smarter to use that extra energy to have an extra kids (in analagy, bet on more roulette numbers rather than betting more on one number). This is often seen at the low end of the food chain, with the reverse (few, well-invested kids) seen at the top of the food chain (usually). Sometimes, biology limits one's choices. There are no *true* mass-reproducers among mammals, because of our biology; even rabbit reproducion pales in comparison to that of frogs or fish. Conversely, the external fertilization and aquatic eggs of frogs constrains them to the 'lots of kids' strategy; they simply *cannot* invest more (usually; dart frogs occupy a unique niche that has allowed them to circumvent this, emphasizing the role of ecology as well as biology in selection of reproductive strategies.) Like in most of evolution, there's no *universal* strategy; which is best depends on the phylogenetic and ecological situation. Mokele

If you're referring to broadcast channels (the stuff you pick up without cable, satelite, or internet), then that's all I watch, those few times I watch TV. Ditto for many of my friends. There's a single, unifying factor: poor college students. We simply cannot afford to waste $30+/month on cable or other such luxuries. (Also, we're talking about people who don't piss away $100 per week in booze money, but actually try to be somewhat financially responsible.) Mokele, off to go yank around the coax cable that serves as his antenna

Um, yes, it can be. If I claim Lamarckian inheritance is real, that can be falsified. If I claim that natural and sexual selection can operate as countervailing pressures in certain circumstances, I can prove that. Some sources are more reputable than others, and can back up their claims with facts and experiments and observational studies. Others cannot. Ergo, not all sources are equal. Evidently, you do not understand what "theory" is, in scientific terms. Mokele

I'm with ecoli on this; the clones would be almost useless in terms of genetic diversity, which is a huge problem for many endangered species. For instance, I know that recently a zoo had to destroy an entire clutch of healthy, viable eggs of an endangered crocodile species. Why? Because the pair that produced the eggs is *already* overrepresented in the remaining gene pool, and further representation will be detrimental to the species as a whole. It's not just numbers, it's genetic diversity. Cloning, by definition, cannot add to this diversity in a cost-effective way (especially compared to simple selective breeding to ensure maximum diversity). Habitat is also a large piece of the problem, and more pressing than cloning. For instance, the Chinese alligator is nearly extinct in the wild, less than 2 dozen individuals. Captive population: over 20,000, and they breed like reptilian guppies. But we've got nowhere to *put* them; all their habitat has been turned into rice paddies and the farmers hate them because they eat the ducks (also the rats, but people are rarely sensible about such things). IMHO, cloning endangered species is a waste of time and money, a misplaced effort. Mokele

Well, reptiles and birds do tend to live unusually long for animals of their size. Parrots and crocodiles can both live over a century. It's reasonable to suspect that dinosaurs had similar lifespans. However, growth isn't so easy. Yes, most reptiles technically never stop growing, but they slow down dramaticly at adulthood. For small and short-lived species (relatively speaking), the post-maturity growth doesn't really add much. However, bird and mammals stop growing at adulthood. A recent article in Nature shows that dinosaurs had a similar tendency, but I am unable to access the full-text, so I don't know if this is just theropods. The diversity of Dinosauria, as well as the very early split between Saurischians and Ornithischians, makes me a bit skeptical of anything that supposedly applies to dinosaurs as a whole. -------- As for this topic as a whole, first, Newtonian is wrong: scraps of protien can and have been recovered from many fossils, just nothing more than a few amino-acids long before. Fossilization *can*, in theory, lead to what has just been found, just not very commonly. Personally, the biggest use I see of this is in phylogeny. Previously, if we wanted to make a phylogenetic tree, we had to rely on morphological comparisons (which can be difficult on account of having to "eyeball" for convergences but have the advantage of using both fossil and living taxa) or genetic comparisons (which are strongly quantifiable with nice discrete data, but could not use extinct taxa). Now, we can incorporate molecular data from extinct taxa, which hopefully will yield interesting results and, just maybe, will clear up some long-standing conflicts. I strongly doubt we're gonna be seeing Jurassic Park in reality from this, but it *will* be interesting. Mokele

Shouldn't this be in the Psuedoscience forum?

Empathy is a normal human experience, an adaptation by a highly-intelligent primate for the social interactions that govern its (our) existence. Everyone has it, though to greater or lesser degrees. Nothing special or supernatural. Mokele

Yes, hence why I said no significant use. They've been adapted for sexual purposes, but are by no means essential; all "advanced" snakes reproduce just fine, and a defining characteristic of them is that they lack any pelvic vestiges at all. Mokele

You know what would help clear up a lot of useless clutter? A "Creationist Bull****" forum. Of course, you could probably name it something a bit less direct (though I feel my proposed title is quite accurate). But there's a large amount of this crap that clogs up boards and distracts from genuine scientific threads. By putting in it's own forum, those who want to debate it can just go to that forum, while preventing it from wasting space in other forums. Mokele

Incorrect, and you seem to have a bad case of adaptionism going on. Just because something exists does not mean it's an adaptation. For instance, my snakes have legs, or at least leg-bones. Remnants of the pelvis and leg bones are embedded in the body wall, with two small "spurs" (claws) on each side of the cloaca. They serve no significant function that we know of. By your own claim, snakes could not have evolved, since they have lost their legs. Or what about cave-fish which have lost their eyes, yet still retain vestiges in early development? In order for evolution to take place, either producing a part or removing it, there must be variation. If there are no mutations that remove a useless body part without causing massive problems elsewhere in the body or during development, then it will stay around, even if useless. Vestigial organs have already been dealt with in great detail in this thread. Mokele