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: |
| What annoys you about paleontology?; Rant on about moronic theories, complaints, or just animals that annoy you. | |
|---|---|
| Topic Started: Sep 28 2013, 05:04 PM (256,225 Views) | |
| Luca9108 | Jul 2 2015, 01:55 PM Post #4126 |
![]()
Master of Dinosaurs
![]()
|
You forgot this one :}
|
![]() |
|
| Rex T | Jul 2 2015, 02:00 PM Post #4127 |
![]() ![]()
|
I guess I can't say what I want to say so I guess I'll stop. I just hope that however dinosaurs are depicted now and in the future it has as much science backing it and correctly shows how they lived.
Edited by Rex T, Jul 2 2015, 02:01 PM.
|
![]() |
|
| Luca9108 | Jul 2 2015, 02:06 PM Post #4128 |
![]()
Master of Dinosaurs
![]()
|
Also I am annoyed by people, who think the "new" Spinosaurus is inaccurate. Especially if they say it is inaccurate, because bones of other Spinosaurs were used for the new reconstruction and it was a juvenile one. For the old reconstruction were more other Spinosaur bones used and all new bones were from a juvenile so the proportions are correct. |
![]() |
|
| Rex T | Jul 2 2015, 02:11 PM Post #4129 |
![]() ![]()
|
The new spino makes complete sense to me given how it lived and how it hunted. Why would a fish eater need to be larger then a t.rex when that would have just made it harder for it to catch its prey. P.S Once again thank you for the video Luca very informative. |
![]() |
|
| Luca9108 | Jul 2 2015, 02:14 PM Post #4130 |
![]()
Master of Dinosaurs
![]()
|
You're welcome .
|
![]() |
|
| Paleop | Jul 2 2015, 02:28 PM Post #4131 |
|
Paleopterix
![]()
|
no T rex left behind :
|
![]() |
|
| CyborgIguana | Jul 2 2015, 02:30 PM Post #4132 |
![]() ![]()
|
That's what we all want, since it's pretty much the entire goal of paleo-art.
|
![]() |
|
| Yi Qi | Jul 2 2015, 03:29 PM Post #4133 |
![]() ![]()
|
About the "too big fur fedd0rz" argument...JESUS F**** HADN'T WE HAD THIS DISCUSSION LIKE, A ZILLION TIMES? Do i really have to cite everything again, link to the posts by Albertonykus and Martyniuk, talk about how integument loss in large mammals has NOTHING to do with their size and that they are all poor examples to compare to dinosaurs and all that crap all over again? I'm freaking tired of that, i'd rather enjoy my last days on Finland with my GF than engage on this discussion for the 9000th time so can someone please link the guys that are spewing this argument to my old posts and the links contained in them? Im sorry if i sound worked up, but things aren't funny anymore after they've been exhaustively done over and over again. Edited by Yi Qi, Jul 2 2015, 07:26 PM.
|
![]() |
|
| Tyranachu | Jul 5 2015, 01:30 AM Post #4134 |
|
Nerdasaurus
![]()
|
![]() ... |
![]() |
|
| Luca9108 | Jul 5 2015, 01:41 AM Post #4135 |
![]()
Master of Dinosaurs
![]()
|
Oh no David Peters' alien pterosaurs! Reminds me to Primeval.
Edited by Luca9108, Jul 5 2015, 01:46 AM.
|
![]() |
|
| babehunter1324 | Jul 5 2015, 05:57 AM Post #4136 |
![]()
|
One thing that I wonder however is whether the presence of Crocodilians in Campanian and Maastritchian is really a proof of a Tropical non seasonal climate or not. Most crocodilain species of the era with the exception of Deinosuchus (which only occured in the southern areas of Appalachia and Laramidia), were actually pretty small. Champsaurus (I know they ain't crocodiles, but they were likely echtotherms), Brachychampsa and others were barely ever over 2 meters long in the Maastritchian period. While most modern crocodilians live in areas which hold at least some water throughout most of the year Northern Nile Crocodiles manage to make a living in the areas around the margins of the Sahara desert by entering in a temporal slumber during the dry season. Not only that but at least one species of Crocodilian, the Chinese Alligator lives in temperate habitats and enters a period of slumber in underground dens during winter, I really want to stress this because Alligator sinensis is remarkably similar in several traits to the Maastritchian era Brachychampsa: They both had a similar size, they both lived in areas with variable seasonal amounts of water but which never really dry up, they both appeared to have a more extensive osteoderm cover than most Crocodilians and they both had somewhat similar skulls... What if those characteristics were the result of having a similar lifestyle and living in areas with a similar climate? Maybe the climate of Norther Laramidia was similar to a subtropical area in summer but due to the fact that it was so far North it became actually quite cold in Winter, forcing most ectotherm into a seasonal hibernation period. To further reinforce my point, it is usually assumed that the reason by Champsaurus, Brachychampsa and other reptilians that survived the K/T event became bigger in the Paleocene due to the decrease of competition with Theropods, however we know some crocodilians attained huge size even when a lot of competition with large Theropods was present (like the previously mentioned Deinosuchus), what if the reason they managed to attain larger size was actually related with the general increase in global temperature during the Paleocene allowing cold blooded animals to attain larger sizes even in very high latitude regions? Edited by babehunter1324, Jul 5 2015, 05:09 PM.
|
![]() |
|
| CyborgIguana | Jul 5 2015, 07:09 AM Post #4137 |
![]() ![]()
|
Pfft...even Primeval's pterosaurs are better than Peters' monstrosities! |
![]() |
|
| Luca9108 | Jul 5 2015, 07:33 AM Post #4138 |
![]()
Master of Dinosaurs
![]()
|
I meant a vampire pterosaur reminds me to piranha pterosaurs from Primeval. |
![]() |
|
| Incinerox | Jul 5 2015, 12:26 PM Post #4139 |
![]()
Āeksiot Zaldrīzoti
![]()
|
Actually, this raises an interesting point. See, if we look at it from a broad perspective, using extinct crocodilians in general and comparing them with modern crocodilians in general, we can say that generally speaking, crocodilians can be a reasonable indicator of a generally warm climate, one that's generally warm enough for crocodilians to exist and breed successfully (because remember, crocodilians need to incubate their eggs, and the temperature of incubation is what determines the sex of the offspring that hatch). So in general terms, warm climates are a given, and that's what people most often refer to when talking about crocodilians as climate indicators. Because the NORMAL crocodilian range are well watered areas in the tropics, therefore their ancestors must be the same too. But if we look specifically like you've done and take exceptions and species level behaviour into consideration, things get more interesting. And tricky. So I'm just going to focus on Brachychampsa given it's the most similar morphologically to modern alligators (especially since it itself was an alligator). Brachychampsa's a globidont, a stem-alligator, meaning it's ancestral to both alligators AND caimans. So if we're going for modern comparisons, that broadens our scope to include ALL modern alligatorids, not just the American and Chinese alligators. But given the size and distribution of Brachychampsa, we can say for sure one of two things: 1) Its ecosystem was extensive. or 2) It was a highly adaptable animal. Given the nature of the Hell Creek -> Lance -> Ojo Alamo ecosystems, we're looking at a similar, if gradual change in ecology. At this point I should mention that Brachychampsa is known from as far south as Ojo Alamo Formation right up into Saskatchewan. The end of the Cretaceous was warmer than today, there's no doubt about that, so it's fairly obvious that Brachychampsa's environment in New Mexico was hot. Definitely hot enough for crocodilians. But back then, North America was further east AND further north than it is today (Hell Creek back then would've been where Winnipeg is now), and we know Saskatchewan is already further east and further north than Hell Creek, and DEFINITELY further north than New Mexico (it's also the furthest north we get any of the Hell Creek-Lance biota, so something happened further north that we don't quite understand yet). And as you've pointed out we know both Alligator species, particularly Chinese Alligators are fairly cold tolerant, seeking shelter to go into some kind of stasis or hibernation to wait out the cold. This perhaps ignores caimans, but no caiman has anywhere near the environmental range as Alligator mississippiensis (that I'm currently aware of, so correct me later if need be), so our best comparison really is the American alligator for this exercise. So this is where your point comes in. Because we have to make one of two assumptions: 1) The ability to wait out cold climates is ancestral to all alligatorids, meaning Maastrichtian Saskatchewan could have been cold. 2) Brachychampsa did NOT share the same behaviour as modern alligators, meaning Saskatchewan could NOT have been cold at all. Personally, I agree with 1). But at the same time, if anyone intends to use Brachychampsa as a climate indicator, 2) is simply less parsimonious, and therefore the more logical to work with for any scientific argument until other factors say otherwise. So at the end of the day, as a result of your point about crocodilians being more resilient than people give them credit for, I must add on to your point that "it annoys me that people assume a climate must be tropical based on the presence of crocodiles" and say that "it annoys me when people even bother to use crocodiles as their primary climate indicator, because all a crocodilian can tell you is that an ecosystem is bloody warm enough during the breeding season to incubate eggs, and not cold enough to permanently shut their bodies down". And that prettymuch covers everywhere in Maastrichtian Earth except for Alaska, Siberia/North China and Australia-Antarctica. And what we have of the fossil record of plant matter tells us that Hell Creek and Lance were well watered evergreen beech forests anyway. So in conclusion: If you are in need of a good crocodilian to use as a climate indicator for a Cretaceous ecosystem, use pollen. |
![]() |
|
| babehunter1324 | Jul 5 2015, 05:35 PM Post #4140 |
![]()
|
It also seems that sexual determination in Crocodilians isn't exactly in the same temperature ranges depending in the genus... The difference seems rather narrow however... With that said as it would be expected Chinese Allgators nest during the more humid and warmer periods of the year (and apparently the warmer season was almost the most humid in Hell Creek too). It's also worth pointing out that if a study on Alligator sinensis sexual determination temperature range has ever been done I have failed to find it anywhere (which is understable considering the critical conservation status of the species). http://www.pulseplanet.com/dailyprogram/dailies.php?POP=2075 http://www.nature.com/nature/journal/v296/n5860/abs/296850a0.html Another thing, that makes me think that it is very likely that Brachychampsa did hibernate is the fact that even IF the climate was warm during Winter the days would had still be rather short, probably lasting about 8 hours throught the day which might not had been optimal for a Ectothermic animal, then again this could also be one of the reason why the genus was so small during the Maastritchian it may had aided the animal to stay active even in winter since their smaller mass may had make it easier for them to warm up, tough it may also had resulted in a lower surface to volume... So I still think that hubernation was the more likely alternative (and it is also quite likely for several of the Chelonids genera's known from Hell Creek and adjacent formations). As for what vegetation can tell us about Hell Creek's climate: http://specialpapers.gsapubs.org/content/503/173.abstract I wouldn't describe the given calculated interval for avarage temperature exactly subtropical... If it really was like that it was probably about as cold as Yixian in which Crodilians likely didn't occure but they were a lot of diversity of Choristodera, which again, are present in Hell Creek (even if Champsaurus was very different to the Yixian taxa). I'm not 100% sure, tough I'm going to guess that they based the avarage temperature based in the ecological preference of clossely related taxa, but for all we know there's still a possibilty that Maastritchian era Metasequoia and Fagus were better suited for somewhat warmer climates than modern taxa... Edited by babehunter1324, Jul 5 2015, 05:50 PM.
|
![]() |
|
| 3 users reading this topic (3 Guests and 0 Anonymous) | |
![]() ZetaBoards gives you all the tools to create a successful discussion community. Learn More · Sign-up Now |
|
| Go to Next Page | |
| « Previous Topic · Extinct Animals & Evolution · Next Topic » |

FAQ
Search
Members
Rules
Staff PM Box
Downloads
Pointies
Groups







.

:







