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Natural Science Forum / Biology / Paleontology / December 2005Question re. diurnal dinosaurs
Hi, I'm just peaking in to see if you can help me with some information. Can you please tell me if allasaurs and/or giganatosaurs were diurnal? Thanks! > Hi, > > I'm just peaking in to see if you can help me with some information. > > Can you please tell me if allasaurs and/or giganatosaurs were diurnal? How would anyone know? We try to recognize nocturnal animals by their possession of very large eyes. Allosaurs and giganatosaurs do not have unusually large eyes. Make of that what you will. Troodonts do have unusually large eyes; perhaps they were nocturnal. Perhaps they weren't. Thanks John! > Thanks John! That was helping? >> Thanks John! >> > That was helping? Learning that something isn't known can be a huge help. You might have added that most or even all modern predators of any size seem to be diurnal. >>>Thanks John! >> >>That was helping? > > Learning that something isn't known can be a huge help. You might have added > that most or even all modern predators of any size seem to be diurnal. I don't think that's true. >>>>Thanks John! >>> [quoted text clipped - 5 lines] >> > I don't think that's true. Name something. >>>>>Thanks John! >>>> [quoted text clipped - 7 lines] > > Name something. It seems to me that most cats are active at night. Even lions. Am I mistaken? >>>>>>Thanks John! >>>>> [quoted text clipped - 10 lines] > It seems to me that most cats are active at night. Even lions. Am I > mistaken? Leopards, jaguars, and I think tigers too. Large owls are nocturnal, of course.  SignatureJohn S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project University of Queensland - Blog: evolvethought.blogspot.com Nihil tam absurdum quod non quidam Philosophi dixerit - adapted from Cicero >>>>>>>Thanks John! >>>>>> [quoted text clipped - 13 lines] > Leopards, jaguars, and I think tigers too. Large owls are nocturnal, of > course. As well as a few prosimians. George >>>>>>>>Thanks John! >>>>>>> [quoted text clipped - 17 lines] > > George Are they large preditors. >>>>>>>Thanks John! >>>>>> [quoted text clipped - 13 lines] > Leopards, jaguars, and I think tigers too. Large owls are nocturnal, of > course. The last one avoids being active in the day time. They also don't weigh very much. >>>>>>Thanks John! >>>>> [quoted text clipped - 10 lines] >It seems to me that most cats are active at night. Even lions. Am I >mistaken? I seem to remember reading that the main reason that hyenas were originally considered to be primarily scavengers was most of their active hunting was done at night. It seems to me that all current large land preditors can be classified as either cat family (including hyenas) or dog family (including bears). The cats are generally active at night; the dogs aren't. Have I missed anything? SignatureJohn Brock jbrock@panix.com >>>>>>>Thanks John! >>>>>> [quoted text clipped - 17 lines] > hyenas) or dog family (including bears). The cats are generally > active at night; the dogs aren't. Have I missed anything? Large modern reptiles. I don't know whether Komodo dragons hunt at night, but some large snakes definitely do. I'd class big pythons as large predators - some can swallow a pig. Is this limited this to terrestrial and aerial predators? A lot of marine predators hunt at night. Those relying on vision might be confined to diurnal hunting (e.g. octopuses) but those which primarily use other senses (e.g. sharks, dolphins, angler fish) may not particularly care whether it's day or night. BTW, an activity requiring adequate lighting, such as sight-based hunting, is not completely confined to daylight hours. A full moon or near full moon with relatively clear skies also facilitates sight-based hunting. Recall the term "hunter's moon" used by large primate hunters which are otherwise mostly diurnal. So, primates on the list also? Best Regards, John. >>>>>>>>Thanks John! >>>>>>> [quoted text clipped - 21 lines] > but some large snakes definitely do. I'd class big pythons as large > predators - some can swallow a pig. But are they truly nocturnal as opposed to active day or night? I've seen film of big cats hunting during the day and I've seen small cats hunting during the day. I doubt if either the Komodo dragons or pythons care. > Is this limited this to terrestrial and aerial predators? A lot of marine > predators hunt at night. Those relying on vision might be confined to > diurnal hunting (e.g. octopuses) but those which primarily use other > senses (e.g. sharks, dolphins, angler fish) may not particularly care > whether it's day or night. My point was limited to large land preditors but have fun. > BTW, an activity requiring adequate lighting, such as sight-based hunting, > is not completely confined to daylight hours. A full moon or near full [quoted text clipped - 4 lines] > Best Regards, > John. >>>>>>>Thanks John! >>>>>> [quoted text clipped - 17 lines] > hyenas) or dog family (including bears). The cats are generally > active at night; the dogs aren't. Have I missed anything? That all of these animals hunt both day and night. >>>It seems to me that most cats are active at night. Even lions. Am I >>>mistaken? >> I seem to remember reading that the main reason that hyenas were >> originally considered to be primarily scavengers was most of their >> active hunting was done at night. It seems to me that all current >> large land preditors can be classified as either cat family (including >> hyenas) or dog family (including bears). The cats are generally >> active at night; the dogs aren't. Have I missed anything? >That all of these animals hunt both day and night. Are you saying it is typical of wolves or bears to hunt at night? I'm not saying it never happens, but my impression was that it was far less typical than for cats or hyenas. Do you have any links for this? SignatureJohn Brock jbrock@panix.com >>>>It seems to me that most cats are active at night. Even lions. Am I >>>>mistaken? [quoted text clipped - 12 lines] > far less typical than for cats or hyenas. Do you have any links > for this? I've seen some film and read some books but never had to look this up on line. Canines have fairly poor color vision and excellent night vision. My guess is that bears might be the least active at night but then they eat a lot of plant food and I don't think you'll have any trouble finding accounts of bears raiding trash cans, camp sites, and such after dark. Let me make a wild guess. You've never been out with a pack of coon hounds (any dog in a pinch) after dark. You need the flash light. They don't. >>>>>>Thanks John! >>>>> [quoted text clipped - 10 lines] > It seems to me that most cats are active at night. Even lions. Am I > mistaken? Very true. They are also active in the day time. That matches up with diurnal which is what I said. >>>>>>>Thanks John! >>>>>> [quoted text clipped - 13 lines] > Very true. They are also active in the day time. That matches up with > diurnal which is what I said. I think that if you check you will find that most big cats do most of their hunting at night. As do hyenas. Are you claiming that any day-hunting makes an animal diurnal, not nocturnal? >>>>>>>>Thanks John! >>>>>>> [quoted text clipped - 17 lines] > their hunting at night. As do hyenas. Are you claiming that any > day-hunting makes an animal diurnal, not nocturnal? Isn't that what the dictionary says? The two behaviors are on a continuum. Most animals might be more active before or after dark but only a few large terrestrial meat eaters are anything like cleanly one or the other. Are you saying that you consider animals you know hunt during daylight hours nocturnal? Many owl species and bats are nearly or even completely nocturnal. Unless disturbed they aren't going to do jack in light. I'd call them nocturnal. Some squids and many kinds of fish are as well. >>>>>>>>>Thanks John! >>>>>>>> [quoted text clipped - 19 lines] > > Isn't that what the dictionary says? I haven't looked, but I doubt it. > The two behaviors are on a continuum. Most animals might be more active > before or after dark but only a few large terrestrial meat eaters are > anything like cleanly one or the other. > > Are you saying that you consider animals you know hunt during daylight hours > nocturnal? I think that would depend on percentages. I would consider an animal that hunts mostly at night to be nocturnal, and one that hunts mostly during the day to be diurnal, and if the proportions were about even I wouldn't know what to call it. > Many owl species and bats are nearly or even completely nocturnal. Unless > disturbed they aren't going to do jack in light. I'd call them nocturnal. > Some squids and many kinds of fish are as well. This has become a very silly argument. >>Hi, >> [quoted text clipped - 6 lines] > unusually large eyes. Make of that what you will. Troodonts do have > unusually large eyes; perhaps they were nocturnal. Perhaps they weren't. Well, no one's ever seen one about at night. That counts for something, doesn't it? SignatureJohn S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project University of Queensland - Blog: evolvethought.blogspot.com Nihil tam absurdum quod non quidam Philosophi dixerit - adapted from Cicero >>>Hi, >>> [quoted text clipped - 9 lines] > Well, no one's ever seen one about at night. That counts for something, > doesn't it? I thought I saw one once under my bed when I was a child. It turned out to be an old shirt. lol George >>>Hi, >>> [quoted text clipped - 9 lines] > Well, no one's ever seen one about at night. That counts for something, > doesn't it? Dunno about you, but I've seen plenty: owls, nighthawks, and nightjars mostly. You may have seen a frogmouth or two. Alright now, I knew I was potentially inviting ridicule by going to the experts on this question. The reason I ask is because I am working on an animation for a biotech company that is producing a drug which targets the negative effects of macular degeneration. We are starting off by showing eye structure comparisons (rods vs. cones) between a dinosaur and a mammal. Didn't want to risk making a poor choice of dinosaurs to illustrate this. If for some reason one of the two types I mentioned were suspected to be nocturnal and not diurnal, then that would affect the credibility of the introduction. I really do appreciate the input, and the giggles. So once again, thanks John! > >>>Hi, > >>> [quoted text clipped - 12 lines] > Dunno about you, but I've seen plenty: owls, nighthawks, and nightjars > mostly. You may have seen a frogmouth or two. > Alright now, I knew I was potentially inviting ridicule by going to the > experts on this question. [quoted text clipped - 10 lines] > I really do appreciate the input, and the giggles. So once again, > thanks John! Sure, but however would you determine the eye structure of an extinct theropod? You would be better off using a living theropod, like a chicken or pigeon. For the extinct ones, I suppose you could pick something in between a crocodile and a bird, but that would closely resemble a random guess. [snip] >> Alright now, I knew I was potentially inviting ridicule by going to the >> experts on this question. [quoted text clipped - 16 lines] > something in between a crocodile and a bird, but that would closely > resemble a random guess. Are you sure that their eyes are that different? > [snip] >>>Alright now, I knew I was potentially inviting ridicule by going to the >>>experts on this question. [quoted text clipped - 18 lines] > > Are you sure that their eyes are that different? No. If we're talking about maculae, though, structure differs tremendously within birds. I don't know anything about crocodile eyes. > Alright now, I knew I was potentially inviting ridicule by going to the > experts on this question. [quoted text clipped - 10 lines] > I really do appreciate the input, and the giggles. So once again, > thanks John! As a group the remaining dino relatives have excellent color vision normally including animals which continue to be active at night. This suggests that the trait of being active during the day is very old. Humans have some of the best color vision going for mammals which as a group don't have first rate color vision. Dino age mammals may have been mainly nocturnal. I guess I'm saying you should be safe showing any dino as being active during the day time with good vision. >> >>>Hi, >> >>> [quoted text clipped - 13 lines] >> Dunno about you, but I've seen plenty: owls, nighthawks, and nightjars >> mostly. You may have seen a frogmouth or two. > Alright now, I knew I was potentially inviting ridicule by going to the > experts on this question. I'm no expert - I'm a professional Mocker. John H knows this. ... SignatureJohn S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project University of Queensland - Blog: evolvethought.blogspot.com Nihil tam absurdum quod non quidam Philosophi dixerit - adapted from Cicero "Arkitek" <amyesj@yahoo.com> wrote in news:1133397654.081243.182520 @g47g2000cwa.googlegroups.com: > Hi, > [quoted text clipped - 3 lines] > > Thanks! If you believe they were exothermic, then probably. -- Barney, who usually comes out at 10:30 am, check your local listings > "Arkitek" <amyesj@yahoo.com> wrote in news:1133397654.081243.182520 > @g47g2000cwa.googlegroups.com: [quoted text clipped - 8 lines] > > If you believe they were exothermic, then probably. Okay you lost me. Don't you mean the other way around? Of course these animals were so large as adults that being evenly mildly active would produce a lot of heat not rapidly lost. > -- Barney, who usually comes out at 10:30 am, check your local listings |
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