Sorry it's not in color, but I just finally got it scanned! A Suchomimus catching a young plesiosaur.A few years ago I was asked what I thought of the swimming Spinosaurus idea (I was told this was put forth by Robert Bakker but I've only heard it mentioned a few times so I have no idea.) At the time I said I found it unlikely, at least for Spinosaurus, the sail would be a hinderence in the water, waves would topple it, the local crocs would eat it for lunch as they were far more adapted to the water, yadda, yadda, yadda. I didn't really look into it, I knew spinosaurs seemed to found close to water, and that they would eat fish (fish scales found in the stomach area of Baryonyx) but that's all I had read about swimming spinosaurs... until a few months ago.
Other than the scene in JP3 most of the spinosaur pictures show them wadding out into ankle deep water looking for fish, like some giant egret or stork. Since spinosaurs are so poorly known and fragmentary it's very difficult to get an idea about what they might have been doing, why did they get to big? Spinosaurs has been said to be 65 feet long dwarfing every other theropod, that's at least 17 feet longer than the next largest theropod (this is highly unlikely but is found all over the web. They were more likely similarly sized to the other large theropods, perhapse a bit longer but more gracile.) Did they eat fish exclusively? A spinosaur tooth has been found embeded in a pterosaur bone, along with the fish scales in Baryonyx's stomach were the remains of an Iguanadon (so the answer to that would be no.) How did they behave? Questions upon questions that we'll most likely never be able to fully answer.
I stumbled upon this site looking for skeletal reference: spinosauridae.fr.gd
(This is the English translated version, its really easy to read so don't let the translation stop you!)
On the site are papers, drawings and pretty much the best place to go for info on spinosurs on the web. As I read the papers cited, and looked at the images, the site was trying to tell me something. The papers mentioned isotopes from spinosaur bones are more in line with crocodiles and animals that live in an aquatic habitat, foot print traces of swimming theropods... this site was arguing FOR semi aquatic spinosaurs. I spent a few hours looking everything over (I'd go over specifics some, but I can't get it to load properly, my computer has bogged down, but go read it for yourselves!) And while I think more finds need to be located, it's very compelling stuff. Semi aquatic spinosurs... cool!
Best,
Brett
Posts
"Spinosaurs has been said to be 65 feet long".
ReplyDeleteThat's science fiction: all the known largest specimens of spinosaurids are as large as the largest tyrannosaurids and carcharodontosaurids.
Someone has estimated very large size for them, but actually these are only weak extrapolation. My estimate for Spinosaurus's length, based on the measurement of the known vertebrae and skull bones, is 14 meters (42 feet long).
The skeletons of the baryonychinae is not particularly different from those of other theropods, so there are not very evidence of a more aquatic behaviour. Spinosaurinae are too poorly known, so I think it's better not to say more.
In my opinion, most theropods were more aquatic than we usually imagine, and some forms, for example Majungasaurus, may be better swimmers than others (this is based on their leg and tail anatomy, that differ from those of most theropods).
Spinosaurid skull and dental anatomy recall those of some crocodyles: don't forget that crocodyles are not only fish-eaters, but well adapted and generalized predators. The same would apply to spinosaurs.
Good post, Brett!
''Spinosaurs has been said to be 65 feet long".
ReplyDelete'That's science fiction: all the known largest specimens of spinosaurids are as large as the largest tyrannosaurids and carcharodontosaurids.'
I agree that it's most likely science fiction, but I have read that in several articles and websites. I don't agree with it myself, that's why I said 'has said to have been.' Perhaps that's a bit too vague, it does seem like I'm saying they are 65 feet long... I'll change that. I only get the computer in the mornings so I'm always a bit foggy;)
This was more of a question like post than facts, just to get people to go read the Spinosaur website, I really found it fascinating:) I actually agree with everything you've said:)
Best,
Brett
Hi Brett,
ReplyDeleteMany thanks for the very kind comments about my website. I appreciate a lot.
I just want to emphasis that all the information on this website comes from scientific publications. Contrary to other websites and blogs, I don't give my opinion. I just give the facts that have been found in serious sources such as books and scientific articles.
Although I studied palaeontology in England, I'm not able to translate my website in your language yet (perhaps will I deal with that one day, I don't know). But all the abstracts in the "news section" are in English.
Now I come with Andrea's comments on Spinosaurus.
Based on a very well preserved snout, Dal Sasso et al. 2005 (including Andrea's friend Maganuco) have estimated Spinosaurus to reach a lenght of 16 to 18 meters. Later, Therrien & Henderson (2007) have revised body size to 12.57 meters. They are all estimations based on this small piece of the skeleton. Andrea's opinion is that Spinosaurus could not exceed 14 meters (based on vertebrae and several skull bones) while Mickey Mortimer's opinion, which I think is also very well founded, is that Spinosaurus could reach the size proposed by Dal Sasso et al. (2005) and certainly not the one given by Therrien & Henderson (2007). What is the truth? The truth is that Spinosaurus was a very big theropod dinosaurs, and everyone shound not care whether it was bigger than Trex, Carcharodontosaurus or Giganotosaurus or exceed 14 meters...
I am a little bit sadder about Andrea's opinion on the semi-aquatic lifestyle of Spinosaurus. Amiot et al. (2008) have used a very reliable tool in order to know whether some extinct animals were mostly acquatic or terrestrial. This is the measure of oxygen isotope composition of teeth which is, again, very reliable. In the case of spinosaurid theropods, the results show that the values of delta18Op are within the range of crocodiles and turtles values. After a conversation with Amiot, it is not possible to deny such results. This is not an opinion or an estimation of something but a fact that can not be debatted. Spinosauridae are therefore at least semiaquatic animals and it is not the shape of the skeleton of baryonychine spinosaurs that can be opposed to this. For instance, hippopotamus skeleton does not seem to be the one of an aquatic animals, yet this animals spend all of the day into water. There are many other exemples among living animals (otter, beaver,...). We should therefore see spinosaurids as aquatic and terrestrial dinosaurs, spending some of their time into water.
Indeed, we do know that Spinosauridae are not fish eating dinosaurs only. Direct evidence show that they ate juvenile dinosaurs such as Iguanodon and pterosaurs. However, everything about the skull tell us that there were piscivorous. A semiaquatic lifestyle seem therefore prety normal for such fascinating dinosaurs.
Christophe
Ps: Sorry for all English mistakes. I'm shattered 'cause it's 2 pm here in Belgium!
Christophe,
ReplyDeleteBabblefish and Google translate your site really well. I didn't have any problems with it. I would have gotten more in depth but for some reason my browser wouldn't load it.
The teeth say semi aquatic, but you would expect that if the animal was fishing with it's head in the water, it doesn't absolutely mean they were swimming and living in it like crocodiles, they could have been more like herons or cranes, fishing while wading.
Hippos do have special adaptions that show us they are aquatic, larger leg bones to weigh them down, telescopic eyes so they can see above waterlevel, splayed toes, things spinosaurs don't show. But that doesn't mean they weren't aquatic, turtles don't have telescoping eyes. I'm just playing devils advocate here.
The evidence is compelling but I think not a slam dunk or home run.. yet. It would help explain why so many large theropods were able to live in the same area together.
Best,
Brett
Hi Brett,
ReplyDeleteI had the same a priori about oxygen composition of teeth than you. I though that all fish eating animals would have the same delta18Op signature, which would be the one of an aquatic or semi-acquatic animal. But it is absolutely not the case. According to Amiot, the d18Op values of teeth reveal the oxygen fluxes which came in and came out of the animal body during all its life. Oxygen fluxes are different from acuatic and terrestrial animals, the latter sweating much more than the first one. The feeding habbit of an animal does have an influence on the d18O but this is minor in carnivorous animals according to Amiot. Therefore, the fishes ate by spinosaurid dinosaurs do not affect the d18Op of the teeth.
There is a big difference between a semi-acquatic animal and a paddleling animal. Hippopotamus, crocodiles, turtles and amphibians are semi-aquatic animals. They swim and spend most of their time into water. Oxygen composition of of Baryonyx, Spinosaurus and Siamosaurus teeth reveals they were semi-aquatic. So, we must visualize them as aquatic (and terrestrial) animals.
Concerning what you wrote on Hippopotamus, you're right by saying there are a few anatomical caracters that tell us there are semi-acquatic animals. But this is absolutely not obvious when you just have the squeleton of this animal. Same remark for a beaver and an otter. Futhermore, spinosaurid skull could have had special adaptation of an aquatic lifestyle as well. According to Witmer (see Dal Sasso et al., 2005), Spinosaurus may have had rostrally placed fleshy nostrils. Besides, while I see Hartman recontruction of the sclerotic bones in spinosaurids, I remark that eyes are placed quite dorsaly in the skull when compared to other theropod dinosaurs. The evidence of an aquatic spinosaurid is quite compelling to me, as much as a terrestial spinosaurid (when regarding the hindlimbs). Cool, they were both!
Christophe
Christophe,
ReplyDeleteBut would a wadding animal like a heron have the same d180 signature? I believe they ate fish, no doubt in my mind, but wouldn't wadding explain the d180 or would that not be enough time spent in the water? If herons, have a different level then the aquatic idea would be even more compelling (I'm not sure if this is covered in the papers on your site, I'll have to check it out.)
I still disagree on the hippos, the eyes are placed high on skull, they protrude a classic aqautic adaption for an animal that also is tied to the land, the added mass on the leg bones and the splayed feet. A good anatomist would recognise the signs. Now I'll give you an otter but I'm not sure about the beaver. The nasal openings of Spinosaurs, aren't really any higher than Dilophosaurus's if you take the crests off ( I personally liked Greg Paul's Dilophosaur/Spinosaur idea but I know it's not in favor anymore.) The eyes could go either way to me, either for aquatic or for wadding.
Basically it comes down to the d180, if wadding gives you a different d180 reading than aquatic than aquatic it is.
Best,
Brett
Best,
Brett
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