Edestus "shark"

[Fossildude19]

5 hours ago, Still_human said:

 

i just noticed--look at the jaw on the bottom right. It has alternating teeth too! None of the others do. Maybe it's my imagination, but it looks like the jaw shape of that one is different than the rest. Much shorter and thicker. 8 teeth present, and missing at least 3. That's the same amount of teeth as the largest jaw right next to it. Thats got to be a different species. It actually appears to have a much heavier alternation than the other alternating one in the picture above, even taking the angle into consideration.

Have you taken age of the animal and sexual dimorphism into account here? 

It doesn't have to be a different species, necessarily due to differences in morphology.

In hand, up close study would be needed to make such a claim. 

[Troodon]

I agree with Tim and you really need to look at these jaws first hand and not draw any conclusions from photos.  A friend of mine provided me this paper a few years ago.  It gives a little background into the number of species that exist and the makeup of the jaw.

 

 "The type species is Edestus vorax Leidy 1856b, which is based on a very incomplete specimen having little stratigraphic data.  Other species of Edestus from the Pennsylvanian of North America have been described, including E. minor Newberry 1866, E. heinrichi Newberry and Worthen 1870, Edestus giganteus Newberry 1889, E. crenulatus Hay 1910, E. serratus Hay 1910 and E. mirus Hay 1912. According to Branson (1964), E. giganteus is a junior synonym of E. vorax. Edestus protopirata Trautschold 1879, E. karpinskyi Missuna 1908, Edestus minusculus Hay 1910 and E. kolomnensis (Lebedev 2001b) have been described from the Pennsylvanian of Russia, near Moscow. Edestus triserratus Newton 1904 and Edestus pringlei Watson 1930 have been described from the Pennsylvanian of Britain."

 

 

itano2012.pdf

[Miocene_Mason]

This whole thing is difficult for me to follow, I always thought it was strange that Edestus jaws always came in a single arc rather than two connecting, like one would expect. I winder if the other side disappeared or merged.

The only thing I can add that is helpful is that the great white specific epithet is carcharias.

 

[Still_human]

Whodaman, you just blew my mind! 

 

I definitely need to keep working on making sure I express myself more clearly and better thought out! I wasn't trying to sound quite so definitive about that, like its the final word, or something. That was meant as more of a jumping off point--like if I added  ", right?" or something, leaving it open like a lot of times.  Wow, that's an awesome find Troodon! I can always count on you to really come through with very useful info! I'm surprised though, that unless I missed it somehow, they didn't mention the alternating teeth. That's a pretty big thing, especially if the alternations can be as significant, and different from the standard looking ones as the bottom right jaw looks like they might be. At least in the case of the specific bottom right jaw in that picture, I doubt age would be a realistic factor there, cause the overall jaw size/mass and number of teeth on both definitely give an adult appearance, but yeah, I sexual differences could easily account for that. With some fish that's not even noticeable, but then some animals have sexual differences big enough to seem like totally difference species. I feel silly to say that it didn't even cross mind.

[Still_human]

Oh yeah, the article shot down my ponderings of edestus being an early helicoprion. I don't know why, but that really disappoints me. Also that I believe it said they believe edestus was the end of their genetic line:(