Serratolamna? Texas Shark Tooth

[Ramon]

Hello, I found this small shark tooth near Austin. The geology of the area corresponds to the Ozan formation (early Campanian) ~78 million years.

It looks like a Serratolamna serrata tooth, but I haven’t heard of Serratolamna from the Ozan formation. 
Or could this be a Cretalamna appendiculata instead?

Edited October 14, 2021 by Ramon

[Al Dente]

It does look very much like S. serrata but they don’t occur in the early Campanian. Are there any Maastrichtian deposits in the area?

[Ramon]

2 hours ago, Al Dente said:

It does look very much like S. serrata but they don’t occur in the early Campanian. Are there any Maastrichtian deposits in the area?

It looks like the creek has some tributaries further upstream, that do intercept the Upper Taylor and Navarrro groups, which are late Campanian and Maastrichtian.

This little tooth probably came from there.

[erose]

5 hours ago, Ramon said:

It looks like the creek has some tributaries further upstream, that do intercept the Upper Taylor and Navarrro groups, which are late Campanian and Maastrichtian.

This little tooth probably came from there.

I have a variety of fossils from Austin creeks that are all just labeled as being from stream gravel and then I list what occurs up stream.  Not as satisfying as stuff right out of the matrix but still worth collecting.

 

[Ramon]

15 hours ago, Al Dente said:

It does look very much like S. serrata but they don’t occur in the early Campanian. Are there any Maastrichtian deposits in the area?

After doing more research on S. serrata, it appears that it has been found in the early Campanian. So I guess it’s possible that this came from the Ozan formation (locally called the “Sprinkle Formation” in Austin), which is the formation that most of the creek where I found these shark teeth passes through.
 

[Jared C]

2 hours ago, Ramon said:

from the Ozan formation (locally called the “Sprinkle Formation” in Austin)

So in Austin, do the names "Ozan formation", "sprinkle formation", and "Lower Taylor marl" all refer to the same formation? I've been confused about trying to find a definitive answer to that question

[DPS Ammonite]

We need a competent Texas stratigrapher. I note that Geolex claims that the Sprinkle and Ozan Formations have been called the Lower Taylor Marl.

 

@Uncle Siphuncle @erose

 

https://ngmdb.usgs.gov/Geolex/UnitRefs/OzanRefs_9728.html

 

https://ngmdb.usgs.gov/Geolex/UnitRefs/SprinkleRefs_10537.html

 

 

This is a reference that mentions the Sprinkle and Ozan Formations and may give insight if both formations are the same. Anyone have access?

 

Publication:

Liddicoat, J.C., Hazel, J.E., Brouwers, E.M., Bryant, W.A., and Bottjer, D.J., 1981, Magnetostratigraphy of Upper Cretaceous deposits in southwestern Arkansas and northeastern Texas [abs.]: American Association of Petroleum Geologists Bulletin, v. 65, no. 4, p. 764-765. [Available online, with subscription, from AAPG archives: http://www.aapg.org/datasystems or http://search.datapages.com]

 

 

 

Edited October 15, 2021 by DPS Ammonite

[Ramon]

52 minutes ago, Jared C said:

So in Austin, do the names "Ozan formation", "sprinkle formation", and "Lower Taylor marl" all refer to the same formation? I've been confused about trying to find a definitive answer to that question

Yes, it appears that they are all interchangeable names for the same stratigraphic unit from what I’ve read so far.

[JohnJ]

1 hour ago, Jared C said:

So in Austin, do the names "Ozan formation", "sprinkle formation", and "Lower Taylor marl" all refer to the same formation? I've been confused about trying to find a definitive answer to that question

 

My understanding is the names refer to similarly aged strata in different geographic areas.

 

 

[doushantuo]

 

Young noted numerous "sea level incursions" that didn't seem to correspond well with the conventional Vail((sequence stratigraphic) units.

It could be that all of these formation names have little or no chronostratigraphic meaning

edit:spelling

 

Edited October 15, 2021 by doushantuo

[doushantuo]

e.g.:

[Uncle Siphuncle]

I’m only used to seeing Serratolamna in the Escondido and Kemp fms.

[Mikrogeophagus]

Ressurecting this topic because I have a couple of teeth directly out of the Ozan of Austin I had initially thought to be Serratolamna but later disregarded as Cretalamna... until yesterday when I came across an article that prompted me to do a bit more research. 

 

Teeth in question. Both pulled out of the same creek bed in Austin. The area is solidly within the Ozan according to usgs map.

 

Here's the paper: https://doi.org/10.1016/j.cretres.2016.08.008

 

It's on Middle Campanian teeth from the Aguja out in West Texas. I believe our Ozan is also Middle Campanian in age, so the fauna represented out there should have a lot of similarity. In the paper, they list Serratolamna cf. S. caraibaea and Cretalamna sarcoportheta as two species present. They labeled some teeth as Serratolamna cf. S. caraibaea on the basis of having multiple paired cusplets, saying such a feature isn't present in other genera. Additionally, those teeth bear a nutrient groove that the article later states C. sarcoportheta lacks. In Figure 4., the teeth for both species are shown. I think my teeth compare well with the "lateral tooth" labeled 3/4 in the figure.

 

My teeth have a nutrient groove and the presence of doubled cusplets. I do have one example of C. sarcoportheta from the Austin Ozan, albeit a different creek, and it is much bigger with a proportionally wide central cusp. But there could be other variables to explain that discrepancy. I had a look through Siverson's Cretalamna paper and I didn't see anything that stood out as being extremely similar, but it's also a big paper with many details so maybe I missed something.

 

I will also mention that Ramon's teeth are a color I haven't seen so far out of the Ozan of Austin. They look suuuper black. My Ozan teeth all tend to look like the couple I just posted. Greyish brown crowns with pale tan roots. I haven't been around the Maastrichtian enough to have an opinion on what those look like.

 

So I'm curious what you all have to think about the idea of Serratolamna in the Ozan?

 

 

 

 

 

[Ramon]

1 hour ago, EPIKLULSXDDDDD said:

I will also mention that Ramon's teeth are a color I haven't seen so far out of the Ozan of Austin. They look suuuper black. My Ozan teeth all tend to look like the couple I just posted. Greyish brown crowns with pale tan roots. I haven't been around the Maastrichtian enough to have an opinion on what those look like.

I have several teeth from the same locality, showing a wide range of coloration. None of these teeth were found directly on the sediment, but the type of species and the geology of the area leads me to believe that atleast most of them come from the Ozan formation. 

 

Here’s some of the teeth I’ve found in that locality, for reference. 

Edited March 2, 2023 by Ramon

[Mikrogeophagus]

Nice collection you've got going! Those look more like the typical Ozan preservation. Gravel finds can be a huge headache to confidently identify, even if they are in relatively good shape. For example, one of my favorite gravel finds from my Ozan localities is a Ptychodus occidentalis tooth that is in very nice condition. However, this species of ptychodus is known from the Bouldin Flags member (Cenomanian) of the Eagle Ford which is present 10 miles up stream. It had to cross the Cenomanian, Turonian, and Coniacian before reaching the Campanian spot I picked it up. You can imagine the out of place things that may appear in gravel beds