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Spinosaurus News ~
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Too bad we can't time travel to observe prehistoric life. IMHO, from my point of view, Spinosaurus was a big fish-eater and shoreline scavenger. On land, he was very likely always on the lookout for Carcharodontosaurus.
 (05-18-2020, 09:48 PM)bruin Wrote: Too bad we can't time travel to observe prehistoric life. IMHO, from my point of view, Spinosaurus was a big fish-eater and shoreline scavenger. On land, he was very likely always on the lookout for Carcharodontosaurus. Yes, I'm agree... When we consider the spinosaurus's skeleton, we can see that the bones are slend, the general constitution is rather slight. The most robust bones are the backbone ones. Let us compare with the t-rex's skeleton:  *This image is copyright of its original author When we are considering these skeletons it's hard to believe that the spinosaurus can weigh 2 or 3 tons more than T-rex. Even longer I don't believe that the spinosaurus's weight could exceed 10 tons. And beside this fact, spinosaurus could absolutely not be an apex predator on land, an encounter and a confrontation with the carcharodontosaurus, as you told, should have been very problematic. 
@Spalea
I think there are a few things worth noting about Tyrannosaurus in comparison to Spinosaurus: 1: When you compare a Tyrannosaurus and a Spinosaurus of equivalent mass, and the Tyrannosaurus looks bigger, what you're seeing is volume, not mass. Roughly 9.3 to 9.5 percent of Tyrannosaurus' volume is air, while Spinosaurus is at least as dense as water if not more so. So if a Tyrannosaurus and a Spinosaurus were the same mass, the Tyrannosaurus would look bigger due to possessing more volume. 2: That is a comparison of Sue and MSNM V 4047, which, while large, is still about 400 -900 kg smaller than Sue, at 7.5-8 tonnes compared to 8.4. The largest specimen, NMC 41852, would outmass any Tyrannosaurus we have by at least 2 tonnes (see my post about it on the previous page, very bottom). 3: I'm pretty sure the ribcage on that Tyrannosaurus is overinflated; AFAIK it is based on the mount scan from Hutchinson et al. 2011, which they themselves cite as overinflated. Citing directly from them: ''the torso of the mount is inflated in width due to a dorsal displacement of the transverse processes on the trunk vertebrae, which forced a dorsal displacement of the tubercular articulations and a lateral expansion of the rib cage as a whole.'' As for encounters with Carcharodontosaurus on land, the largest Spinosaurus specimens certainly would not have been helpless - they would have been roughly 11-14 tonnes compared to roughly 9-ish tonnes for the largest Carcharodontosaurus, so I think they could have defended themselves by using intimidation.
@DinoFan83 :
About #77 and #78: I just need to see the photo of their skeletons compared. The T-rex's bones are noticeably thicker, especially the thighbone. Why ? The body to sustain is heavier, denser. Don't speak about volume, just judge what you see. The t-rex's bones are more massive (except the forelimbs, lol) and by far. No need to speak about an overinflated ribcage. Next to the t-rex, spinosaurus is a slender animal. You wanted to say that the spinosaurus being an aquatic animal didn't need to have massive bones ? OK ! But, in this case, he spended mostly his life into the water and was definitely not an apex predator on land.
My mistake, I must have misread your initial post. Now I see your point, that Tyrannosaurus is a more heavily built animal.
I definitely agree with you on that.
Paulo Leite: " Spinosaurus, digital painting "
Still an entirely aquatic spinosaurus's depiction, but no more on a "dynamic mode". In front of the numerous ways of seeing this animal as being a dynamic piscivore predator in a aquatic biotop, I'm wondering if there isn't a new view of this animal among the scientific community. All these depictions aren't fortuitous.
" Bizarre Spinosaurus makes history as first known swimming dinosaur
Photo: Reconstructed Sequential cross-sections through the tail show proximal-to-distal changes in the arrangement of major muscles and skeletal reconstruction. in Ibrahim, Maganuco, Dal Sasso, Fabbri, Auditore, et al., 2020. Art by Davide Bonadonna. In recent decades, intensive research on non-avian dinosaurs has strongly suggested that these animals were restricted to terrestrial environments. Historical proposals that some groups, such as sauropods and hadrosaurs, lived in aquatic environments were abandoned decades ago. It has recently been argued that at least some of the spinosaurids—an unusual group of large-bodied theropods of the Cretaceous era—were semi-aquatic, but this idea has been challenged on anatomical, biomechanical and taphonomic grounds, and remains controversial. Here we present unambiguous evidence for an aquatic propulsive structure in a dinosaur, the giant theropod Spinosaurus aegyptiacus. This dinosaur has a tail with an unexpected and unique shape that consists of extremely tall neural spines and elongate chevrons, which forms a large, flexible fin-like organ capable of extensive lateral excursion. Using a robotic flapping apparatus to measure undulatory forces in physical models of different tail shapes, we show that the tail shape of Spinosaurus produces greater thrust and efficiency in water than the tail shapes of terrestrial dinosaurs and that these measures of performance are more comparable to those of extant aquatic vertebrates that use vertically expanded tails to generate forward propulsion while swimming. " OK ! There wasn't smoke without fire ! When I saw so numerous depictions of spinosaurus swimming almost like a mosasaurus...
Here's a quote from SpinoInWonderland regarding the most recent information on Spinosaurus' size. It should also be noted that due to the tail change, Spinosaurus is a bit shorter than otherwise thought. Scaled 132% from the neotype in Ibrahim et al. 2020, MSNM v4047 is 14.4 meters instead of 15+ for instance. This also affects the other specimens:
"Ibrahim et al. (2020) has a volumetric estimate for the neotype, at 3864 litres. Using a mean density of 0.95 for Spinosaurus gives a mass estimate of ~3.67 tonnes. Scaling up to MSNM v4047 (32% greater dimensions as per Ibrahim et al. 2014) yields about ~8.44 tonnes. It has been argued that the chest of the new reconstruction is too deep, but then the scapulacoracoid is also placed too far back at the chest - these might cancel each other out. Henderson (2018) got a mass estimate too low as the chest they modellled for Spinosaurus was way too narrow than was indicated by the known material." Now I think a density of 1 is probably more likely as the majority of aquatic animals tend to be neutrally buoyant (EG crocodiles, which converge a lot on Spinosaurus). Assuming that density, we get: ~3.86 tonnes for the neotype (~10.93 meters) ~8.89 tonnes for MSNM v4047 (scaled up 32%, 14.43 meters). Note that going by the corrected model from Henderson (2018), that I have outlined on page 7, MSNM v4047 could be up to 12.26 tonnes. ~10.31 tonnes for NHMUK R-16421 (~15.16 meters), following the discrepancy between it and the neotype that SpinoInWonderland got (link) ~13.66 tonnes for NMC 41852 (~16.62 meters), following what SpinoInWonderland restored for the neotype (51 cm humerus) scaled to the restored size of NMC 41852 fit into the humerus of the Baryonyx holotype (77.7 cm in this image given a length of 48.3 cm for the humerus of the Baryonyx holotype). Note that although NMC was probably 96.6 cm instead of 77.7 cm and that the estimation is tentative until we have more Spinosaurus humeri, it would most likely be around this size. Going by this, the average size of the 3 Spinosaurus adults we have seems to be ~15.46 meters and ~10.95 tonnes (note that this goes up to 16 meters and 12.1 tonnes if we use the corrected MSNM v4047 from Henderson (2018). That's definitely in pre-2014 Spinosaurus territory, so it looks to me as though Spinosaurus was never really downsized but just got a new look.
The new spino's version sketched...
Rob Soto: " Quick warm up from this morning. Another Spinosaurus, doing that heron thing. " Second depiction: 
Tbh I don't think spinosaurus was an aquatic dinosaur, itsi too speculative to think that, palaeontologists like Donald M. Henderson and Mark P. Witton and 2 more have disagreed and some have even criticized Nizar Ibrahim's interpretation of S. Aegyptiacus. Proff. Witton has argued that the tail of the spinosaurus could not have been flexible enough to allow it to swim underwater, it was more like the tail of a basilisk and he speculates it was used as rather a display feature than a propulsive body part, and then Donald Henderson has argued that the tail alone could not make such a heavy creature swim, all these palaeontologists think that it hunted more like a grizzly bear than a swimming predator, kinda like how the BBC video on spinosaurus portrayed itsi hunting style. So while it is entirely possible it could have swam, there's great arguments saying otherwise too so I think it's too speculative for now to safely say it did swim and I don't like sites like Nat Geo stating it as a fact.
Science is not about what you "like" or what you "think". Science is about facts based in evidence. In this case, evidence suggest that Spinosaurus was an aquatic dinosaur that had adaptations that allowed it to live most of the time in the water. Dr Ibrahim and all the team behind him had presented evidence, but when I read the post of Witton he do not present any evidence, just speculations from his part. Also, he forget the fact that the Spinosaurus had sacs of air in its body, so the weight of the tails is no problem, the Sauropods already showed that. It is funny that first the people complained that the animals was too long in the front part to be a biped and now that we had a big tail to contrarest, they complain that the tail is too long! Seriously, the fans of "Jurassic Park 3" must forget that false monster and accept the real animal.
There are very few videos in English from REAL experts that actually take the time to explain all the information about Spinosaurus, but I can show two videos (in Spanish) from a true Paleontologist where he explain that the information about Spinosaurus is accurate, although he also critizise that the previous idea that Spinosaurus was cuadruped had no real base. I can translate it is you want: You can search him in Youtube and Facebook as "Palaeos". What we actualy know is that Spinosaurus was a bidepal animal, that lived most of the time in water and that his head had more affinities with Conger Eels than with crocodiles:  *This image is copyright of its original author Check these two studies about the acuatic life and affinities of Spinosaurus: 1 - Taphonomic evidence supports an aquatic lifestyle for Spinosaurus https://www.sciencedirect.com/science/ar...712030313X 2 - Convergent Evolution of Jaws between Spinosaurid Dinosaurs and Pike Conger Eels https://bioone.org/journals/acta-palaeon....2016.full
To anyone that love the Spinosaurus, this article from NatGeo is mandatory: https://www.nationalgeographic.com/scien...-swimming/
 *This image is copyright of its original author Artwork by Joschua Knüppe. A scale chart comparing Spinosaurus aegyptiacus with various contemporaneous taxa. S. aegyptiacus formed one of the main connections allowing nutrient flow between the terrestrial & aquatic biomes.
(06-13-2020, 04:37 PM)DinoFan83 Wrote: Here's a quote from SpinoInWonderland regarding the most recent information on Spinosaurus' size. It should also be noted that due to the tail change, Spinosaurus is a bit shorter than otherwise thought. Scaled 132% from the neotype in Ibrahim et al. 2020, MSNM v4047 is 14.4 meters instead of 15+ for instance. This also affects the other specimens: Interesting calculations, but the official values at this moment are up to 15-16 meters long and up to 7 tons in the biggest specimen, check these articles: https://peerj.com/articles/5409/ https://www.nationalgeographic.com/scien...-swimming/ I am going with the official data for the moment.   *This image is copyright of its original author
(09-09-2020, 12:43 AM)GuateGojira Wrote:I think a few things should be noted regarding Donald Henderson's model:(06-13-2020, 04:37 PM)DinoFan83 Wrote: Here's a quote from SpinoInWonderland regarding the most recent information on Spinosaurus' size. It should also be noted that due to the tail change, Spinosaurus is a bit shorter than otherwise thought. Scaled 132% from the neotype in Ibrahim et al. 2020, MSNM v4047 is 14.4 meters instead of 15+ for instance. This also affects the other specimens: -It had assumed that Spinosaurus was pneumatic when it was in fact not; Ibrahim et al. 2014 even stated the bones to be of very high density and with no pneumaticity whatsoever. So not only is the theory about Spinosaurus being highly terrestrial most likely bunk, the wrongly assumed pneumaticity underscores the mass of the animal quite unnecessarily. -The ribcage on Henderson's model is apparently way too narrow given the known material. This is what SpinoInWonderland has told me, and given what the dorsal view from Ibrahim et al. 2020 looks like compared to Henderson's model I am inclined to agree with him. I apologize if the resolution on this is too low but here are the dorsal views compared from Ibrahim (2020) and Henderson (2018):  *This image is copyright of its original author It should be beyond clear that judging from Ibrahim's model, Henderson's model is SUBSTANTIALLY too narrow - it's literally about 1/2 the width at the torso and this underscores the mass of the animal quite a bit. -I would not consider Henderson's model to be as accurate as Ibrahim et al. 2020 in terms of its overall anatomy. In addition too the very narrow torso and the unnecessary pneumaticity, the torso on the model from Henderson is much shallower than the new model from Ibrahim, nor does it have the new tail added onto it. All of this is underscoring the model's mass. By the way, even if we take Henderson's estimation of 7 tonnes for MSNM v4047 at face value (which is a poor choice when Ibrahim's model is available considering what I went over above), it still does not factor in NHMUK R-16421 nor NMC 41852, both of which are most likely larger. Using the discrepancies in my above post on Spinosaurus' size, NHMUK would be about 8.12 tonnes, and NMC (although tentative until we find more Spinosaurus humeri) would be 10.55 tonnes. As for that National Geographic article you linked, I am afraid that when I clicked on it the page said it no longer existed. However I suspect they are referring to the outdated model from Ibrahim (2014) that suggested 6 to 7 tonnes instead of the new model from the 2020 study in their article. By the way, if you didn't already see this, there is something to consider:  *This image is copyright of its original author Nizar Ibrahim himself supports masses of 10-12 tonnes for Spinosaurus in light of the new and more accurate model, and these sizes are easily replicated using the corrected model I outlined on the next page, NHMUK R-16421 and (possibly) NMC 41852. The old 6 to 7 tonne estimations are outdated. So if you want to stick with the old 7 tonne estimations I suppose I can't stop you, but considering everything above the double digit tonnage is almost certainly more accurate.  (09-09-2020, 12:43 AM)GuateGojira Wrote:(06-13-2020, 04:37 PM)DinoFan83 Wrote: Here's a quote from SpinoInWonderland regarding the most recent information on Spinosaurus' size. It should also be noted that due to the tail change, Spinosaurus is a bit shorter than otherwise thought. Scaled 132% from the neotype in Ibrahim et al. 2020, MSNM v4047 is 14.4 meters instead of 15+ for instance. This also affects the other specimens: The Henderson study was not very evidence-based relative to Ibrahim et al. The author assigned an arbitrary density then "proved" Spinosaurus was too buoyant to dive. Just noting his as most people don't seem to understand the methods in dinosaur paleontology are much more subjective and inconsistent than mammalian paleontology. Official values aren't the end all be all, remember M. kabir is still 490 kg in the literature and the methods to produce that mass are much more objective than GDI. |
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