Search the Community
Showing results for tags 'poc'.
-
From the album: Post Oak Creek
I'm pretty sure these are S. raphiodon teeth. They are much smaller than S. texanus with a narrow main cusp and finer striations than S. texanus. Compare: http://oceansofkansas.com/sharks/Kansas/shscap3.jpg -
From the album: Post Oak Creek
Symphyseal teeth are found in the midline of the shark's jaw. They are usually small and squashed-looking. Since only a few rows produce these teeth, they are much rarer than other positions. -
From the album: Post Oak Creek
-
From the album: Post Oak Creek
The fossils in the creek can have varying levels of preservation: from the pristine glassy enamel seen at the top, to more river-worn seen below. -
From the album: Post Oak Creek
These oysters are common in the creek, and support the Turonian age of the fossils. -
From the album: Post Oak Creek
These oysters are common in the creek, and support the Turonian age of the fossils. -
I haven't seen much discussion on the geology of the well-known Post Oak Creek here in North Texas. I'd usually seen it referred to the Eagle Ford Group/Formation, but without much substantiation. I really hadn't given it much care, but as is a healthy practice in science, one should often reevaluate one's beliefs especially in light of new information. I believe there is some evidence to support the Eagle Ford assignment, granted I'm not a professional nor very knowledgable about geology and I welcome discussion and contrarian input. The Eagle Ford (Kef) is exposed near Sherman, so it's a possibility. The Austin Group/Austin Chalk is also here (Kau): ^https://ngmdb.usgs.gov/Prodesc/proddesc_19387.htm Here is the evidence that I believe favors that most of the Cretaceous fossils from POC are from the Eagle Ford: 1. Lithology USGS describes the lithology of the Eagle Ford formation: "In Sherman Sheet (1967) (NE Texas) shale, selenitic, bituminous, [calcareous] concretions and septaria, thin platy beds of [sandstone] and sandy [limestone]. in middle and upper part, [medium] to [dark] gray; marine megafossils; thickness 300-400 ft." (https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=TXKef%3B0) (http://northtexasfossils.com/pdfs/shermansheet.pdf) I've found several matrix pieces with shark teeth in it that match the preservation of the vast majority of sharks in POC, which are sandstones. There are also septarian nodules like this one: 2. Presence of Cameleolopha bellaplicata Anyone who has been to POC has seen these oysters everywhere. They are often embedded in the same sandstone. Note that this illustrated one from Hook & Cobban (2011) was collected near Sherman (probably POC since they refer to it). Here is a specimen I collected: Hook & Cobban (2011) say that "Cameleolopha bellaplicata (Shumard 1860) is an easily recognized fossil oyster that occurs abundantly in sandy strata in Arizona, Colorado, New Mexico, Utah, and Texas, where it is restricted to the middle Turonian ammonite zones of Prionocyclus hyatti and P. macombi." These together are consistent with the description and age of the Eagle Ford formation. One possible strata for POC is also the lowest part of the Austin Group, the Atco. However, I've yet to find a description of the lithology which matches better than that above for EF. In addition, there is disparity in the fauna between the Atco and POC. There are many genera found in the Atco which I've yet to find after a few years of hunting Post Oak (e.g. Heterodontus, Protolamna, Dallasiella, Pariasurus, Pseudocorax, Microcorax, etc.; see Hamm & Cicimurri (2011)). This may be because I haven't looked long enough or there could be some other bias. If you have any of the sharks mentioned above from POC, I'd love to see them. That's all I've got from a one-sitting internet exploration last night, so please do double check my rambling.
- 2 replies
-
- 5
-
-
- eagle ford
- eagle ford formation
- (and 7 more)
-
From the album: Post Oak Creek
Reconstructed tooth set from a "Crow" shark - Squalicorax (could be S. falcatus) - illustrating the variety of tooth positions. Anterior teeth have erect, triangular cusps. Lateral teeth and posteriors are more common and have an increasingly posteriorly slanted crown, resembling the teeth of modern tiger sharks. -
From the album: Post Oak Creek
The "big guy" to find at POC. Though, this one is smaller, the preservation is as good as it gets for this location. In fact, it makes me believe that POC could draw from layers adjacent to the Eagle Ford Group. I've found matrix pieces that are consistent with the geology of EFG, but need to find matrix pieces with this kind of preservation to confirm Atco or something else. I'm also not sure that this is C. crassidens anymore since this smaller, narrower form differs so much from the holotype. I currently believe it's an undescribed species since I haven't found something that matches. Please let me know if you find a paper that fits this tooth (and the others at POC). -
.jpg.0013b7fa288439bcd72849c8f777d5cb.jpg)
From the album: Texas Cretaceous Fossils: Crustaceans
-
.jpg.f1acd78f5ef61b02bc5d3e240370fc1d.jpg)
From the album: Texas Cretaceous Fossils: Crustaceans
-
.jpg.92f76574c7efd51a34938841dd695603.jpg)
From the album: Texas Cretaceous Fossils: Crustaceans
-
From the album: Post Oak Creek
To find denticles, you need to go to the finest grain size. This beautiful one could be shark, but I'm not certain.-
- 1
-
-
- denticle
- dermal denticle
- (and 9 more)
-
From the album: Post Oak Creek
-
- 1
-
-
- cantioscyllium
- cantioscyllium decipiens
- (and 11 more)
-
From the album: Post Oak Creek
-
From the album: Post Oak Creek
-
- 1
-
-
- microfossil
- microfossils
- (and 9 more)
-
From the album: Post Oak Creek
Rhinobatos teeth are probably the smallest teeth you can hope to find here - they are about as small as grains of sand.-
- 1
-
-
- guitarfish
- microfossil
- (and 7 more)
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
-
From the album: Post Oak Creek - February 20th, 2022
.thumb.jpg.51c371f10936bbc883322324e44cc518.jpg)
.jpg.0013b7fa288439bcd72849c8f777d5cb.jpg)
.jpg.f1acd78f5ef61b02bc5d3e240370fc1d.jpg)
.jpg.92f76574c7efd51a34938841dd695603.jpg)
