Shark Tooth From Andalusia, Alabama

[MarcoSr]

Yes another paper on post-Cretaceous Cretalamna will follow.

Hopefully you will be able to look at the Cretolamna from the Paleocene and Eocene of the MD/VA area of the US which are currently labelled C. appendiculata. There have been a lot of individual teeth collected in this area but unfortunately no associated specimens that I am aware of.

Marco Sr.

[siteseer]

The tooth was said to be collected by someone hunting creeks in and around Andalusia, AL. I looked at an old generalized geologic map of Alabama and didn't see any Cretaceous outcrops close enough though "generalized" leaves room. Maybe one of the Point A Dam collectors can confirm that they haven't seen any Cretaceous-Paleocene in the area.

We don't really know exactly what deposit it came from, do we? What if there is a slightly older deposit, with slightly different depositional environment and characteristics of preservation, in the general vicinity but much less well known?

[MarcoSr]

If you are a shark tooth enthusiast and haven't looked at M. Siverson's pending paper on Cretaceous sharks of Cretalamna appendiculata type for which he provided a link in a reply to this post, I recommend that you do so. In the paper Cretalamna is moved from the family Cretoxyrhinidae to Otodontidae, 8 species of C. appendiculata type are described, C. gunsoni is reassigned to a new genus Kenolamna, LACM 128126 which was the subject of Shimada's 2007 paper is reassigned to a new species C. hattini, there are observations on the ancestors of Otodus obliquus and Palaeocarcharodon orientalis, there is justification for using Cretalamna versus Cretolamna, etc. Identifying a Cretaceous Cretalamna to the species level will now require a lot more attention to the features of the tooth especially the root. Teeth with even moderate abrasion/corrosion of the root may be indeterminable below the genus level.

Marco Sr.

[Al Dente]

The tooth was said to be collected by someone hunting creeks in and around Andalusia, AL. I looked at an old generalized geologic map of Alabama and didn't see any Cretaceous outcrops close enough though "generalized" leaves room. Maybe one of the Point A Dam collectors can confirm that they haven't seen any Cretaceous-Paleocene in the area.

I wouldn't underestimate lateral transport as a mechanism of moving a Cretaceous tooth into an area of non-Cretaceous deposits. I believe it occurred a lot here in North Carolina where I collect. I have found Cretaceous teeth in all Eocene and Oligocene quarries that I have collected. Reworking from Cretaceous units below the quarry can explain some of the teeth but in at least two quarries (Belgrade and Onslow) there are more Cretaceous teeth sitting on top of the quarry than within the sediment below. The Cretaceous teeth at top are usually in better shape than the ones found within the quarried sediment. At Belgrade there is a layer of large gravel near the surface (picture below) that contains crystalline rock derived from the Piedmont- over a hundred miles away- that was root rafted (caught in tree roots, the tree falls and floats down river) eastward and dropped on the Coastal Plain. I can imagine Cretaceous sediment that is exposed much closer (about 40 miles) can also be root rafted to this region and would include teeth. In years past our fossil club used to screen this gravel layer at the top of the quarry and would find a variety of fossils from Cretaceous through Pleistocene sitting on top of the Oligocene aged sediment.

Here is the gravel layer near the top of the quarry:

Here is a tree root showing how the roots will cling to rocks:

[MarcoSr]

I wouldn't underestimate lateral transport as a mechanism of moving a Cretaceous tooth into an area of non-Cretaceous deposits. I believe it occurred a lot here in North Carolina where I collect. I have found Cretaceous teeth in all Eocene and Oligocene quarries that I have collected. Reworking from Cretaceous units below the quarry can explain some of the teeth but in at least two quarries (Belgrade and Onslow) there are more Cretaceous teeth sitting on top of the quarry than within the sediment below. The Cretaceous teeth at top are usually in better shape than the ones found within the quarried sediment. At Belgrade there is a layer of large gravel near the surface (picture below) that contains crystalline rock derived from the Piedmont- over a hundred miles away- that was root rafted (caught in tree roots, the tree falls and floats down river) eastward and dropped on the Coastal Plain. I can imagine Cretaceous sediment that is exposed much closer (about 40 miles) can also be root rafted to this region and would include teeth. In years past our fossil club used to screen this gravel layer at the top of the quarry and would find a variety of fossils from Cretaceous through Pleistocene sitting on top of the Oligocene aged sediment.

Here is the gravel layer near the top of the quarry:

Belgrade gravel circled.jpg

Here is a tree root showing how the roots will cling to rocks:

rocksintreeroots.jpg

Eric

I see a lot of downed trees, with the roots clinging to formation matrix, along the rivers that I collect in the MD/VA area. I can easily see how these trees could be transported down river and then drop the matrix from the roots.

Marco Sr.

[siteseer]

Al Dente,

In the case of the Andalusia teeth, there is no history of finding Cretaceous or even Paleocene teeth in the area. People have been collecting teeth there for decades. I have been getting teeth from there for years off and on from at least four different people and none of the teeth received looked like they could be Cretaceous. Furthermore, a few members of the FF have posted photos of teeth from there and all those teeth look like what you would expect from the Middle Eocene. I think Mike R. collected there in the 90's.

I also read the linked thesis and there was no mention of reworked material in the geology section. It reveals that the teeth from there actually come out of the Lisbon Formation - not the Tallahatta. The author points out that the geology of the area is not well-documented and is ripe for future research but it appears that no one has reported any reworked Cretaceous material neither formally nor informally.

I have seen cases where fossils logjammed with debris among the roots of trees. Given enough trees getting knocked down in storms over time, you would find quite a few fossils that seemed to come out of nowhere like boulders carried and dropped off by melting glaciers.

Jess

I wouldn't underestimate lateral transport as a mechanism of moving a Cretaceous tooth into an area of non-Cretaceous deposits. I believe it occurred a lot here in North Carolina where I collect. I have found Cretaceous teeth in all Eocene and Oligocene quarries that I have collected. Reworking from Cretaceous units below the quarry can explain some of the teeth but in at least two quarries (Belgrade and Onslow) there are more Cretaceous teeth sitting on top of the quarry than within the sediment below. The Cretaceous teeth at top are usually in better shape than the ones found within the quarried sediment. At Belgrade there is a layer of large gravel near the surface (picture below) that contains crystalline rock derived from the Piedmont- over a hundred miles away- that was root rafted (caught in tree roots, the tree falls and floats down river) eastward and dropped on the Coastal Plain. I can imagine Cretaceous sediment that is exposed much closer (about 40 miles) can also be root rafted to this region and would include teeth. In years past our fossil club used to screen this gravel layer at the top of the quarry and would find a variety of fossils from Cretaceous through Pleistocene sitting on top of the Oligocene aged sediment.

[MikaelS]

No it is the other way around, C. pachyrhiza is the junior synonym. The nominal C. borealis takes priority as it was named first. In plain English please use the name C. borealis for teeth of 'pachyrhiza' type.

That's what i thought about my tooth, thank you for your information, Michael, I didn't knew that C. borealis was a junior synonym for C. pachyrhiza, that's useful. I'm learning every day, but I've never painted in blue a vertebra of pliosaurid yet to make it a door stop, nothing is lost for me

[Sélacien34]

No it is the other way around, C. pachyrhiza is the junior synonym. The nominal C. borealis takes priority as it was named first. In plain English please use the name C. borealis for teeth of 'pachyrhiza' type.

Thank you again for this precision, clearly important.

[Sélacien34]

No it is the other way around, C. pachyrhiza is the junior synonym. The nominal C. borealis takes priority as it was named first. In plain English please use the name C. borealis for teeth of 'pachyrhiza' type.

Could i ask you your opinion about those teeth :

http://www.thefossilforum.com/index.php?/topic/47333-question-about-a-moroccan-tooth/