Spinosaurus - More Than One Species In Kem Kem?

[Troodon]

Answer: who knows and we will have to wait for new discoveries.

I came across a research paper that examined a number of mormorphological differences of Spinosaurus teeth and raised the question did more than one species exist in the Kem Kem. The study focused on the ornamentation differences of a group of teeth and came up with three morph types.

1)Ones with strong high apicobasal ridges on both the lingual and labial side (22%).

2)Ones with strong ridges on the lingual side and weak ones on the labial side (60%).

3)One group was smooth and did not have any ridges (18%).

The ornamentation types were not the result of different preservational states of the tooth crowns and were about the same size.

Explanation for the differences:

1) More than one Spinosaurus species especially with the smooth teeth

2) Strong variation in dentition of Spinosaurus. This has never been observed in Spinosaurus

3) Data not relevant because of small sampling size

So what do you think?

How do your teeth fit the morph types?

Collectors usually have the the largest sampling pool so we can add to this research. I'll do mine and post the results

Photos show different types

[Auspex]

IMO: (3), but not necessarily because of the number of teeth examined, but because teeth alone are not best evidence.

[sseth]

Troodon

There is a paper currently being reviewed that looks at teeth, a couple of large jaw sections and a sacrum from a deeper deposit and one from a shallower deposit. I am not sure when it will be published but I believe it will be in the next year. I can't discuss much but it will have some interesting information related to your question of two different species of spinosaurs.

I will let you know more when it is available.

[Troodon]

Troodon

There is a paper currently being reviewed that looks at teeth, a couple of large jaw sections and a sacrum from a deeper deposit and one from a shallower deposit. I am not sure when it will be published but I believe it will be in the next year. I can't discuss much but it will have some interesting information related to your question of two different species of spinosaurs.

I will let you know more when it is available.

That's what necessary, skeletal remains and someone able to study and publish. Super looking forward to seeing it. Edited August 19, 2015 by Troodon

[Troodon]

The idea of multiple Spinosaurus species in the Kem Kem was proposed by a paleontologist in 2006. Not sure what the basis was for that proposal. Hopefully we will have an answer.

[-Andy-]

 

On 8/19/2015 at 10:32 PM, Troodon said:

Answer: who knows and we will have to wait for new discoveries.

I came across a research paper that examined a number of mormorphological differences of Spinosaurus teeth and raised the question did more than one species exist in the Kem Kem. The study focused on the ornamentation differences of a group of teeth and came up with three morph types.

1)Ones with strong high apicobasal ridges on both the lingual and labial side (22%).

2)Ones with strong ridges on the lingual side and weak ones on the labial side (60%).

3)One group was smooth and did not have any ridges (18%).

The ornamentation types were not the result of different preservational states of the tooth crowns and were about the same size.

Hi Frank, when you mentioned "ridges", did you mean striations; the lines that run down the teeth akin to pliosaur teeth?

[LordTrilobite]

I literature I've seen use of both the words striations and fluting. I find that the description of teeth surfaces is often confusing. It's hard to describe scale. Ridges seems like a more catch all term but isn't descriptive enough I think.

[Troodon]

The Kem Kem paper that described these features called them ridges.

 

If you look at a Screen-Shot from a paper that wants to standardize teeth terminology they use two terms "flutes" (Fig H & I) and "longitude ridges" (Fig G).  However if you look at the papers definition of "flutes" it's a groove separated by two ridges.  So ridges seems to be the more standard term.  I did not see the use of words striations or ribs in their new terminology although they note some papers refer to it.

 

Paper is not open and large

 

http://www.bioone.org/doi/abs/10.1080/02724634.2015.982797

 

 

 

[LordTrilobite]

That's certainly informative. I've seen striations used in describing Mosasaur teeth I think.

[Troodon]

I made an edit above  to add that although the proposed terminology does not use the term "striations" they note that it's been used in a paper has well as the term ribs  

[-Andy-]

An expert I asked mentioned that smooth teeth could be indicative of young Spinosaurus, and ridges/striations indicative of adults.

[Troodon]

I'm not sure I buy that since I have tiny Spino teeth with ridges.  I believe you're looking at jaws with teeth that vary in ornamentation. It can also be like the paper said indicative of different species.  I'm inclined to think its jaw to jaw or positional variation.

[LordTrilobite]

Taking Mosasaurs as an example again... In Mosasaurus hoffmanni the teeth generally have fluting on the teeth. But within this species there is quite a lot of variation. From strong fluting to those with barely anything. Though I've not seen them I've read about Mosasaurus hoffmanni teeth that have no fluting at all.

 

So until there is more evidence I don't think we can rule out individual variation, ontogenetic change or variation in the tooth position.