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Post by creature386 on Nov 28, 2014 0:00:01 GMT 5
I somehow feel sorry for you Godzillasaurus, it will take a lot of time to reply to two novels (OK, actually one and a half, mine is not that long)…
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Post by Godzillasaurus on Nov 28, 2014 6:24:41 GMT 5
I will add more responses later...
You are talking about pre-mammalian synapsids... Pre-mammalian synapsids are vey different from actual mammals, yet they are still synapsids cladistically. Birds evolving from non-avian dinosaurs, which in-turn evolving from basal archosaur-arising groups does not make birds any different when it comes to the fact that they were all diapsids (which is a relatively old trait, evolving in both lepidosaur and archosaur lineages).
Unless a synapsid skull morphology is completely unrelated to evolutionary relationships between different groups of animals, this argument does not make sense. Of course I may not know everything when it comes to cladistics (of or relating to clades, WHICH DEFINE EVOLUTIONARY RELATIONSHIPS, NOT CHARACTERISTICS), but let's try and hold back on this one-sentenced "Incorrect" riffraff
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Post by theropod on Nov 28, 2014 11:14:48 GMT 5
I was consistently talking about ALL synapsids, so was creature, and no, pre-mammalian synapsids were not all that different from mammals.
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Post by creature386 on Nov 28, 2014 20:26:14 GMT 5
I will add more responses later... You are talking about pre-mammalian synapsids... Pre-mammalian synapsids are vey different from actual mammals, yet they are still synapsids cladistically. Birds evolving from non-avian dinosaurs, which in-turn evolving from basal archosaur-arising groups does not make birds any different when it comes to the fact that they were all diapsids (which is a relatively old trait, evolving in both lepidosaur and archosaur lineages). Unless a synapsid skull morphology is completely unrelated to evolutionary relationships between different groups of animals, this argument does not make sense. Of course I may not know everything when it comes to cladistics (of or relating to clades, WHICH DEFINE EVOLUTIONARY RELATIONSHIPS, NOT CHARACTERISTICS), but let's try and hold back on this one-sentenced "Incorrect" riffraff So, what point are you trying to make? That it is not an own class which is ? I don't like these obscure and old terms so much anyway. The whole debate is a phylogenetic one, so was my whole post, so I don't see the point of bringing characteristic-based own classifications in the debate. Besides, evolutionary relationships are also based on characteristics, just not on so obvious ones. |
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Post by Deleted on Dec 11, 2014 19:49:08 GMT 5
If you use the traditional definition for reptiles/reptilia, then no, dinosaurs are not reptiles.
I pretty much prefer using sauropsida because it avoids having to deal with people used to the traditional definitions.
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Post by creature386 on Dec 11, 2014 20:32:16 GMT 5
Note: This is no response to brolyeuphyfusion. I wrote this post because him mentioning Sauropsida made me think. I am not sure if Sauropsida and Reptilia are synonyms. www.iucn-tftsg.org/wp-content/uploads/file/Articles/Modesto_and%20Anderson_2004.pdf^This paper claimed Sauropsida to be Reptilia+all amniotes closer than them than to mammals (this would destroy my claim "Reptilia is a sister taxon to Synapsida") and Wikipedia claimed Sauropsida to be part of Reptilia. Gosh, this is more complicated than I thought and depends heavily on the position of Mesosauridae. Personally, I'd prefer to treat them as synonyms. |
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Post by theropod on Dec 11, 2014 21:01:06 GMT 5
There are different definitions for many taxa, but the ambiguity for birds is far worse than that for reptiles. But I think usually when people without a psychological issue about the inclusion of birds talk about reptiles, what they mean is a monophyletic clade, usually a stem-based clade synonymous with Sauropsida. That’s imo the most sensible definition, although there is the alternative of making it node-based (but that brings up the problematic of unresolved internal relationships within sauropsids).
Wikipedia still seems a little stuck in the past with its labeling of reptilia as a paraphyletic grade, but there’s a section on the modern definition in the article that shouldn’t be overlooked.
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Post by creature386 on Dec 11, 2014 23:07:56 GMT 5
The problem concerning Sauropsida was not so much about birds, both contain birds. It was about some more obscure clades (like Mesosauridae).
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Post by theropod on Dec 13, 2014 3:10:02 GMT 5
You’re right. Birds were just an example of a taxon for which there is debate on how it should be defined.
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Post by creature386 on Jun 21, 2018 22:46:32 GMT 5
[Researchers estimate their body temperature may have been anywhere between 32 and 37 degrees Celsius, around the same temperature as a human. Is there any citation for this? Not that I don't believe you, but it sounds interesting. |
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Post by theropod on Jun 23, 2018 1:35:36 GMT 5
Well, Not totally sure what exact source you are referring to, but this is nothing new: The histologic growth record suggests that, at least from about 20% maximum linear size (Sander, 2000; Klein & Sander, 2008), juvenile sauropods grew at rates comparable to those of large mammals because they laid down the same type of laminar fibrolamellar bone. However, at a body size of 102 kg, juvenile sauropods would not have enjoyed the benefits of gigantothermy and must have had the BMR of modern mammals. How can the evidence for tachymetabolism provided by bone histology be reconciled with the overheating problem indicated by heat exchange modeling of adult sauropods? As reviewed above, internal cooling surfaces must have existed that allowed sauropod dinosaurs to shed their excess body heat, and these presumably were located in the extensive air sac system and trachea of sauropods. The unique ontogenetic body size range of sauropods presumably was accompanied by an equally unique ontogenetic variation in BMR (Farlow, 1990; Sander & Clauss, 2008). Growing sauropod dinosaurs must have been tachymetabolic endotherms, but BMR may have decreased rapidly as maximum size was approached, when the heat loss problem became most severe, and a high BMR was no longer needed to sustain growth. Sander, P. M., A. Christian, M. Clauss, R. Fechner, C. T. Gee, E.-M. Griebeler, H.-C. Gunga, J. Hummel, H. Mallison, and S. F. Perry. 2011: Biology of the sauropod dinosaurs: the evolution of gigantism. Biological Reviews 86:117–155. Of course the full discussion in review of this subject far longer than this, and taken out of context different parts could be used to argue completely opposite situations, but the evidence for tachymetabolic sauropods, at least during phases of active growth, seems to be by far the strongest. Metabolic rates simply must have been high in order for these animals to attain the sizes we are talking about within their lifespans. No doubt similar inferences are possible for other non-avian dinosaurs as well. In theropods and small ornitischians at least, we have the additional evidence of feathers. |
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Post by Infinity Blade on Jun 23, 2018 1:55:48 GMT 5
He mentioned Stony Brook University, so he's probably mentioning this. www.stonybrook.edu/newsroom/general/150528warmbloodeddinosaurs.phpWith further regards to dinosaur metabolism, in response to taliragreycrest, there is also work (Pontzer et al. 2009) finding that bipedal non-avian dinosaurs (at least larger ones) would have been endothermic. Though, I'm not opposed to there being variation in just how high metabolic rates were among taxa; i.e. specific dinosaurs may have had higher or lower metabolic rates than others. This doesn't mean they weren't still what we might consider "endothermic", though (I checked Legendre et al. 2016, and apparently a chicken would have a higher basal metabolic rate than a house mouse, though I don't think anyone would say the latter isn't endothermic). |
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