Were Spinosaurus Teeth Really That Common?

[-Andy-]

We see thousands and thousands of Spinosaurus teeth come out of Morocco each year in all shapes and sizes.

Question is, do they truly all belong to Spinosaurus as they are so often named after?

I would not doubt that those high quality 4" and above teeth do belong to the giant sailed predator, but what about the numerous teeth that are 2" or below?

Have there been any other Spinosaurids found from the Kem Kem Beds of Morocco?

[Paleoworld-101]

I guess they just lost a lot of teeth in a similar way to sharks.

As far as I am aware Spinosaurus was the only genus of Spinosaurid in Morocco at the time. There was Suchomimus in Niger though a bit older than the Kem Kem Spinosaurus fossils.

The smaller teeth have sometimes been confused with the teeth of crocodiles but I'd say yes the majority are Spinosaurus. The fact that there are so much more small teeth than large teeth could be a preservational bias? In general I find that the teeth are better preserved the smaller they are. Perhaps fewer of the large teeth survive the fossilisation process.

Edited April 25, 2014 by Paleoworld-101

[painshill]

It’s an interesting question, particularly against the backdrop that (apart from the fragmentary stuff) we’ve had only six main partial fossils to study, of which only five remain. The original holotype was destroyed during a British bombing raid on Munich in 1944 (sorry!) No complete skeletons, of course.

There are perhaps some clues in what we have learned from the study material available. Spinosaurus had a long narrow snout with straight conical teeth that have no serrations. There were six or seven teeth on each side of the premaxillae of the upper jaw and another twelve in both maxillae behind them. The anterior teeth at the very tip occupied the expanded area of the snout, creating a cage-like “fish-trap”. Those few teeth in the snout were much larger than the rest of the premaxillary teeth, creating a gap between them and the large anterior first few teeth of the upper maxillae. That gap was opposed by a cluster of large teeth in the lower jaw which filled the gap when the jaw closed.

As a dental arrangement, it would have been pretty useless for slicing through flesh but great for grabbing large slippery prey and holding on to it. It has been suggested that Spinosaurus may have shaken its head while holding live prey in its jaws until it was incapacitated by spinal snapping. Cuff & Rayfield (Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians, 2013) determined that Spinosaurus had relatively poor torsion resistance in the skull compared to other predators with similar dentition and would likely have struggled when dealing with prey other than fish.

So, perhaps its teeth habitually suffered loss or breakage during rough encounters with prey that put up a good fight and continual tooth replacement was the norm. If you add in the fact that teeth survive rather better than bones in general and particularly so in phosphatic sediments – which is where most of these teeth originate – maybe that’s some semblance of an explanation.

[-Andy-]

So far, I have came across 3 different names when it comes to dealing with Kem Kem Spinosaurus teeth.

Spinosaurus aegyptiacus

Spinosaurus maroccanus

Spinosaurus sp.

As I am aware, S. aegyptiacus is perhaps the only truly confirmed and named species of Spinosaurus. But it comes from Egypt, not Kem Kem.

S. maroccanus is not a confirmed species unfortunately, but I am assuming that this species was made to account for the numerous Spinosaurus teeth that comes from Morocco.

S. sp. is probably the sellers' thoughts echoing mine: That the Spinosaurus teeth they have simply cannot be linked or confirmed to be a particular species, so it stays as a simple sp. for now.

[Opisthotriton]

In any animal population, the youngest ages are the most abundant, because plenty of juveniles die before reaching adulthood. So there are a lot of juveniles running around shedding small teeth.

Preservation biases generally work against smaller fossils, so if anything, there were even MORE small teeth lying around back in the Cretaceous.

[Paleoc]

Also the teeth varied in size along the jaw. As for number of teeth, Spinosaurus lived in a wet environment which greatly favored preservation over dry land sites.

[Stocksdale]

I do find it interesting that there are so many Spinosaurus teeth around. But as far as skeletal fossils, there are just a few very fragmentary parts.

For Tyrannosaurus, there are over 50 specimens that have been found. And several are nearly complete. For Spinosaurus, the most complete one was only a lower jaw, a few dorsal vertebrae and neural spines. And it got destroyed in WWII. Here's an image of it.

Since then, it sounds like only very fragmentary parts have been found. http://en.wikipedia.org/wiki/Spinosaurus#Specimens. One thing that strikes me is that there are no leg bones found with the holotype and just a few separate fragmentary leg bone parts found since then.

Anyway, are people just not searching for Spinosaurus skeletons like they have for T-Rex and so these remains are yet to be discovered?

A related question, is how do they know what they look like. Is the typical leg arrangement that is shown simply conjecture? Could the legs be entirely different and be more like a crododilian?

So, could Spinosaurus be a crocodile?

Edited September 2, 2014 by Stocksdale

[Troodon]

I'm not an expert in the Kem Kem beds but my sense is that the preservation process was vastly different than other areas which makes finding articulated specimens very difficult. There have been expeditions to Morocco and they just have not found one. The desert and mountains make for a very harsh collecting environment.

My guess is that the leg arrangement is based on looking at the skeletal remains of other Spinosauridae found in other parts of the world like Baryonyx in the UK. However its only an educated guess until one is finally excavated in the Kem Kem.

[fossilized6s]

Interesting theory Paul. It is a good point.

Whom ever has described this creature had a far superior understanding then mine. But wouldn't the Spinosaurus' teeth have to be hollow rooted for constant replacement teeth pushing through?

[caldigger]

Oooooo, and the mystery goes on! Could it be that Spinosaurs are actually aliens from another planet and they are the true builders of the pyramids?...stay tuned...same spinosaur time...same spinosaur channel

[Stocksdale]

I'm not an expert in the Kem Kem beds but my sense is that the preservation process was vastly different than other areas which makes finding articulated specimens very difficult. There have been expeditions to Morocco and they just have not found one. The desert and mountains make for a very harsh collecting environment.

My guess is that the leg arrangement is based on looking at the skeletal remains of other Spinosauridae found in other parts of the world like Baryonyx in the UK. However its only an educated guess until one is finally excavated in the Kem Kem.

Yes, that makes sense. I see that they have much more complete skeletons of Baryonyx and Suchomimus to work with and it makes sense for Spinosaurus to have basically the same arrangement just bigger and badder.

Edited September 2, 2014 by Stocksdale

[Troodon]

Interesting theory Paul. It is a good point.

Whom ever has described this creature had a far superior understanding then mine. But wouldn't the Spinosaurus' teeth have to be hollow rooted for constant replacement teeth pushing through?

Let me try to de-mystify Spino roots from an amateur collector point of view. The first image is just an example of how replacement teeth come into play on theropod teeth. In this image its a Tarbo tooth with its original replacement tooth, in place, that went up for auction a couple of years ago, unfortunately its not in my collection One can see how the replacement tooth comes in on the side and pushes up. So the main root is hollow so that it can compress and will eventually give way and dissolve. Now if we look at a Spino rooted tooth (6") you can see the same root structure to allow the replacement tooth to come alongside of it and eventually replace the original tooth. You can see its also hollow. To take it one step further if you look down at a Spino jaw with two original replacement teeth you can see they are coming in from the side ready to do their thing.

[fossilized6s]

Thank you for clarifying that. I own five Spino teeth and none are hollow, so i just assumed all Spino teeth were like this.

I should learn by now not to assume anything.....but it happens from time to time. Haha

[Troodon]

Thank you for clarifying that. I own five Spino teeth and none are hollow, so i just assumed all Spino teeth were like this.

I should learn by now not to assume anything.....but it happens from time to time. Haha

I have a few like that not sure if its positional, age or ??

[Opisthotriton]

The hollow part of the root is very fragile and breaks off easily, back in the Cretaceous and with modern weathering. Plus, when the old teeth are ready to be shed, the root resorbs, making it thinner and even more fragile. Most found teeth are just the crowns, sometimes with the beginnings of the root. In the photos Troodon posted, you can see that the root is much larger than the crown itself.

[painshill]

Yes, it’s correct that we don’t have any limb bones to study but here’s Painshill’s “tip of the day”: have a look on Ebay, because at any given time there is usually a “Spinosaurus” leg bone from Morocco for sale. I’ve seen at least three this year alone.

Although the holotype was destroyed during WWII, we have the detailed drawings made by Ernst Stromer:

[image from Wikipedia]

Until June 2000, that’s all we thought we had of Stromer’s finds, since it was believed that the all of the original photographs were destroyed along with the fossils and only the drawings survived. Remarkably, Josh Smith of Washington University in St. Louis discovered two original photographs in the archives of the Palaontologische Staatssammlung in Munich. They had been donated to the museum by Ernst Stromer’s son Wolfgang, but their significance was not realised at the time.

Smith published the find in 2006, commenting: “These are, to our knowledge, the only surviving photographs of this, the one irrefutable specimen of S. aegyptiacus, which, prior to the initial print releases, has only been represented by Stromer's drawings… This is a significant find from the perspective of the history of paleontology.” Here’s one of the pictures:

[spinosaurus aegyptiacus, mount of the holotype IPHG (BSP) 1912 VIII 19. After Smith et al., 2006.]

[Stocksdale]

Yes, it’s correct that we don’t have any limb bones to study but here’s Painshill’s “tip of the day”: have a look on Ebay, because at any given time there is usually a “Spinosaurus” leg bone from Morocco for sale. I’ve seen at least three this year alone.

Should probably buy one of those eBay finds to donate to the Smithsonian or better yet to give to the museum in Munich.

There's a Spinosaurus limb bone and a foot bone on eBay at this very moment

Edited September 3, 2014 by Stocksdale

[Stocksdale]

Looks like there is a new exhibit at the National Geographic Museum that opens September 12. It will feature some new information and an updated reconstruction by Paul Sereno.

https://events.nationalgeographic.com/events/exhibits/2014/09/12/spinosaurus-lost-giant-cretaceous/

[Troodon]

Maybe its new information from the material they picked up from eBay

thanks for the information

[Carcharodontosaurus]

Looks like there is a new exhibit at the National Geographic Museum that opens September 12. It will feature some new information and an updated reconstruction by Paul Sereno.

https://events.nationalgeographic.com/events/exhibits/2014/09/12/spinosaurus-lost-giant-cretaceous/

I wanted to post this. Apparently he found more remains.

[Stocksdale]

Looks like Spinosaurus is getting two humps and a bit more horizontal stance.

Edited September 4, 2014 by Stocksdale

[Troodon]

Wow very cool and they have to rename it to Spinobactriansaurus a two hump Spino

This is very different that the other Spinosauridae they have found if the photo is real

Edited September 4, 2014 by Troodon

[Nicola1986]

I bought a specimen from a Spinosaurus sp. from this formation in Whitby for £5. I had a really hard time believing that it was, because of the price but the store owner has a sign that says everything instore has been checked by local paleontologists...£5 though? It's around two inches long - not too bad - but there are some no bigger than my Shar Pei's front canines. :/

Edited September 7, 2014 by Nicola1986

[ReeseF]

I bought a specimen from a Spinosaurus sp. from this formation in Whitby for £5. I had a really hard time believing that it was, because of the price but the store owner has a sign that says everything instore has been checked by local paleontologists...£5 though? It's around two inches long - not too bad - but there are some no bigger than my Shar Pei's front canines. :/

It's probably legitimate, but it could be composited or restored--could you post a picture of it ?

Reese

Edited September 7, 2014 by ReeseF

[Regg Cato]

Looks like Spinosaurus is getting two humps and a bit more horizontal stance.

If legit this is pretty big...honestly with those proportions I have a very hard time believing it wasn't quadrupedal/aquatic. So different from the 80s/90s restorations of it with a semicircular sail and an allosauroid skull.