Shoot a firework rocket ~ Winners!Make a forum zoo! |
| Welcome to The Round Table. We hope you enjoy your visit. You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free. Join our community! If you're already a member please log in to your account to access all of our features: |
| Extinct Animal Questions | |
|---|---|
| Topic Started: Nov 26 2013, 10:24 PM (193,227 Views) | |
| 54godamora | Feb 19 2018, 08:45 PM Post #4006 |
![]() ![]()
|
i already turned it in to the teacher. |
![]() |
|
| BossMan, Jake | Feb 20 2018, 06:52 PM Post #4007 |
|
Son of God
![]()
|
Been doing some research and self examinations for Diabloceratops and Macharioceratops Well taking a look at the skulls side by side you'll notice how similar they are. In fact all the bones in the skull line up near perfectly ![]() I'm convinced Diabloceratops is the female to Machario's male if not at the very least a different species Now yes Machario is somewhat smaller but this could be a younger specimen or perhaps females were larger like some birds like Moas and modern day raptors Given how they were found in the same formation/state and are relatively close to each other geologically to me it seems very possible. Was wondering what some of you guys think about this |
![]() |
|
| BossAggron | Feb 20 2018, 07:30 PM Post #4008 |
|
Formerly Dilophoraptor
![]()
|
I'd say they're probably different species either way, but are probably within the same genus. Though the sexual dimorphism would be interesting, it would be the only easily visible evidence seen in ceratopsids, and would require a much larger sample of specimens before making a definite decision. |
![]() |
|
| babehunter1324 | Feb 21 2018, 05:31 AM Post #4009 |
![]()
|
If I recall correctly Machairoceratops comes from slighly younger deposits from the Wahweap formation than Diabloceratops*. If that's the case my guess is that the former evolved into the latter through anagenesis, mirroring the T. horridus -> T. Prorsus and D. torosus - > D. horneri progression. *Edit: Found the source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4871575/ Edited by babehunter1324, Feb 21 2018, 05:33 AM.
|
![]() |
|
|
|
Feb 21 2018, 11:18 PM Post #4010 |
![]() ![]()
|
Sexual Dimorphism would be unlikely, dimorphism typically only occurs if one sex needs to sacrifice sexual selection for survivability- be in rearing young, carrying them, or intraspecific competition. This is probably why we don't see significant sexual dimorphism despite so many Ceratopsians having such elaborate head ornamentation. That all said, plus considering the frill is a completely different shape, I don't think it's very likely they were the same species. Maybe close relatives as Babehunter said, but more than likely not the same. Also I will always find it hilarious and ironic that Horner had a second species of Daspletosaurus named after him after his attempts to clump the rest of Dinosauria into one species |
![]() |
|
| Incinerox | Feb 23 2018, 08:23 AM Post #4011 |
![]()
Āeksiot Zaldrīzoti
![]()
|
Or the more obvious cases where you'd have one sex sacrificing survivability for the sake of getting laid. Usually it's that way around. Survivability tends to come first, then sexually selected features happen. You don't usually get a species which starts off with bright colours or disproportionately large display features or whatever, THEN evolves to not get eaten. Either way, we have no clue how any of this affects ceratopsians since we don't know enough about their social structure, nesting behaviour or anything to draw conclusions on how it'd affect their morphology relative to their sex. |
![]() |
|
| magpiealamode | Feb 23 2018, 02:47 PM Post #4012 |
![]()
No good hero is a one-trick phony.
![]()
|
Sexual selection and dimorphism often actually riffs off of fitness and contributes directly to it. Think of peacocks, for example--they have these huge trains which should slow them down and make them easy targets. Seeing a strong, healthy peacock with a big train signals to a peahen that he's able to overcome such a setback, meaning he's probably going to father strong, healthy chicks. Also remember that fitness is not necessarily about survival--it's about who contributes most to the next generation. A flashy male who's mated many times and had scores of children, then dies young is much more fit than the drab loner who lives to a ripe old age without fathering offspring. All that said, it's really just an argument for the possibility of sexual dimorphism in ceratopsians, not actually for or against it. I don't know enough about them to address it further than those basic evolutionary principles. Edited by magpiealamode, Feb 23 2018, 02:50 PM.
|
![]() |
|
| BossMan, Jake | Feb 24 2018, 12:54 AM Post #4013 |
|
Son of God
![]()
|
Interesting, I'l keep all this in mind Now do we have any strong points for the theory that Ornitholestes was arboreal or atleast partially? Or is that still up in the air? Edited by BossMan, Jake, Feb 24 2018, 12:54 AM.
|
![]() |
|
|
|
Feb 26 2018, 10:55 AM Post #4014 |
![]() ![]()
|
Well yes, I was looking at it the opposite way around. Obviously survivability and sexual selection evolve at the same time, saying otherwise would be silly. All animals will typically sacrifice survivability to an extent, it's a case of how far they can go before it becomes detrimental to the species rather than just the individual. This is why turtles, who are usually pretty gaudy in appearance, show little sexual dimorphism besides size because the babies are kinda just left to live on their own and hiding is pretty pointless for most turtle species since nothing can really mess with them, anyways. Meanwhile, a female bird is usually pretty drab compared to a male because she has to watch out for the babies and herself while she is sitting on the nest- so in this way it's the female who's making the sacrifice, technically, just in her ability to be colorful like males. Also I would disagree in saying we don't know enough about Ceratopsians to draw conclusions in this case. Maybe not definitive ones, but from their sheer size the chances of a female having to hide to protect young is probably pretty low so chances of sexual dimorphism because of sexual selection is probably not very high. That said, there are species (particularly in fish) where the two sexes are both super gaudy but in different ways, so it is possible they could go that route, though I'd say it's again unlikely since most marine fish are sight-based animals that barely use scent and almost never use hearing, while tetrapods tend to use both sight and sound, and a lot also use scent as well. |
![]() |
|
| magpiealamode | Feb 26 2018, 11:17 PM Post #4015 |
![]()
No good hero is a one-trick phony.
![]()
|
I'm not sure you're understanding the meaning of sexual selection, and if you are it's not coming through to me. Sexual selection specifically operates via sexual attraction; it's not just normal selection that happens to apply to one sex or the other. Sex selection is not what makes female ducks drab, it's what makes male ducks colorful. In no way is a female duck sacrificing anything to be inconspicuous, she is only making herself harder to detect and increasing her fitness, and if you haven't noticed, drakes are kind of sex machines so I don't think attraction is an issue. I think sex selection in ceratopsians would work the same way. It wouldn't be operating on the females, if I understand ceratopsian behavior and parental care properly; females would mostly be subject to normal natural selection. However, being showy make may make a male more attractive, and being bigger/stronger could also increase his chances of mating if harems are a thing. I don't think having to hide and protect young would play into it; as you said, size would most likely preclude that. Again, this is not an argument in favor of sexual dimorphism in ceratopsians. It's just an argument that it could be possible. |
![]() |
|
| stargatedalek | Feb 27 2018, 01:12 AM Post #4016 |
|
I'm not slow! That's just my moe!
![]()
|
If as you claim it was the male duck making the sacrifice to be colourful, than the females should be choosing the male. Male ducks will just take whatever females they want, they don't have the ability to choose their mates, so why would male ducks be more colourful if that wasn't the default? Colour serves a great many functions besides sexual selection, and pretty much every non-mammalian animal that doesn't spend extended periods of time guarding or hiding young has some degree of display colouration. You are misinterpreting the entire concept. |
![]() |
|
|
|
Feb 27 2018, 01:22 AM Post #4017 |
![]() ![]()
|
As the animal kingdom shows us, sexual selection dictates that both sexes will be as colorful as possible. This is why in animals where the female does not have to watch out for young- such as turtles, fish, reptiles, and even mammals that have few predators or no need to hide are almost without fail always very colorful unless they need to be a different color for some reason or are color blind- the latter is why even the most "showy" mammals are usually just super contrasting in coloration rather than being very colorful, except in primates, because they have decent color vision, and it is no surprise both male and female primates are very showy in most cases. Another great example is cassowaries, which have, as far as I know, no natural predators, and it should come as no surprise that all cassowary species are very colorful in both sexes because of this very reason. It's nonsensical to say that an animal that can't physically hide (At least in most cases) would be drab in the females and colorful in the males just "because". Using color-blind mammals as an example for Dinosaur coloration will always be a bad idea. Edited by Flish, Feb 27 2018, 01:23 AM.
|
![]() |
|
| stargatedalek | Feb 27 2018, 01:26 AM Post #4018 |
|
I'm not slow! That's just my moe!
![]()
|
Even the smaller ceratopsians weren't going to be able to hide unless they had wobbegong tier camouflage. Some tiny differences in frill shape, let alone in colour, wouldn't mean squat for such a giant animal. It is not speculative but actively unrealistic to depict ceratopsians with sexual dimorphism. |
![]() |
|
| Danny | Feb 27 2018, 04:17 AM Post #4019 |
![]() ![]()
|
I wouldn't say it is actively unrealistic to expect differences in size, ornamentation or weaponry? If we look at the (admittedly very limited) range of large terrestrial animals alive today, sexual dimorphism is certainly not uncommon. Male elephants and rhinoceroses have larger tusks and horns, respectively. Males of most large terrestrial mammals are larger. In crocodiles, males are larger than females and in the largest species, this is even more pronounced. Same in Komodo dragons... As Flishpointed out in cassowaries, males actually do the incubation and rearing of young. Hence, females are not a "limiting resource", which would explain why males aren't significantly more colourful... In fact, female southern cassowaries are usually considered more colourful, if only slightly, and are larger too (can be up to almost twice the weight). So, if anything, it is a good example of just how strongly sexual selection pulls the competitive sex to be larger and more ornamental. In emus, males also do the incubation and rearing, and you do see sexual dimorphism during the breeding season, when female plumage darkens (males and females both also exhibit blue skin colouration). In ostriches, males court females and mate with several females in a harem and so, as expected, the male is more distinctly coloured than the female. I have also read a paper on moas which suggested in some species, females could have been almost 50% taller and easily more than double the weight of males. Surely it isn't wrong to speculate that there may be some slight differences between the sexes due to intraspecific competition. Specifically, the sex which participates least in parental care (usually but not always males) will be competing for the other sex (usually but not always females) which are limited in availability due to the fact that the increase in parental care means they have less time to mate. Ornaments and differences in colouration can have disadvantages for the sex that possesses them aside from a loss of camouflage. Ornaments and weapons can make an animal slower or make it harder for that animal to move around in a forested environment (this would be expected to be more of an issue in LARGE animals). Being large and growing large structures also takes extra energy and nutrient resources. So there are always trade-offs even if the animal is big. |
![]() |
|
| magpiealamode | Feb 27 2018, 09:12 AM Post #4020 |
![]()
No good hero is a one-trick phony.
![]()
|
I don't think I mentioned ceratopsian color once and afaik there is no evidence of it so I am gonna call that a moot point for now. This isn't about hiding, anyway; I did say that they were too big for that, so let's stop talking about camouflage because I think we all agree. I also never said I thought female ceratopsians would be drab. Regardless, I think ducks are kind of a bad example. Peafowl works much better, as both sexes are colorful but males are much more so. Right now I'm talking about structural characteristics such as size, ornamentation, and weaponry. Danny already made some important points: increasing these things has a cost and animals won't do it unless there is some benefit. Obviously, protection is one reason for size, as are a few other things. Beyond that however, sexual selection plays into it. Sexual selection may have gone with color, and it's possible then that we will find no obvious evidence of sexual dimorphism. However, perhaps it went with things like horns, muscular strength, or frill size--a species that keeps harems and/or competes with for mates would select for these things, as the biggest, strongest individual would be the one with the most chances for mating and the highest fitness. However, the non-competitive sex wouldn't maximize this stuff as it could be too costly to be useful. |
![]() |
|
| 2 users reading this topic (2 Guests and 0 Anonymous) | |
![]() Our users say it best: "Zetaboards is the best forum service I have ever used." |
|
| Go to Next Page | |
| « Previous Topic · Extinct Animals & Evolution · Next Topic » |

FAQ
Search
Members
Rules
Staff PM Box
Downloads
Pointies
Groups















