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Showing results for tags 'pecan gap chalk'.
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Hello friends, I'm very much a novice, but have fallen in love with this hobby after having found some Ilymatogyra, Texigryphaea, Neithea, and Pycnodonte specimens in the creek beds here in South Central Texas. Thank you for having me as a member. ps - My member photo is of our family's pit bull Dahlia, who loves flowers.
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- Austin Chalk
- Bexar County
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Found several years ago in an area of Cibolo Creek that cuts through the Pecan Gap Chalk near San Antonio. After some brief research and comparison with other fossils, my best guess of what this fossil could be is a possible species of Exogyra. All other similar looking fossils in my small collection do not have any color like this specimen and I haven’t seen any other fossils this well preserved (if that is the original color of the shell). I don’t know too much about the evolution of bivalves but another guess is it a “newer” species from a time period other than Cretaceous and is younger or not as weathered. I am open to any other suggestions, questions and especially confirmation of what the little critter was!
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- exogyra?
- pecan gap chalk
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These show up fairly often in the basal pecan gap which has been the focus of my searches recently, nearly all the shark teeth here have the root dissolved so that diagnostic piece is missing but this looks unique enough I'm sure someone has seen something similar, they seem to have a sort of nacre look to the white part so maybe not sharks tooth. This is the largest I have. Microscope pictures with a phone are shaky at best. end on and the back And a smaller more typical example any help appreciated
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- pecan gap chalk
- shark teeth
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I took advantage of the nice weather on my last couple days off and went to a couple sites around town, in no particular order here's the most interesting things I found. First a worn ptychodus anonymous tooth from the eagle ford shale. next what I think is a pachidiscus travisi from the basal pecan gap chalk and a half of a graptocarcinus texanus carapace from the buda formation in a location I had never found anything particulary interesting before. Quite worn but still recognizable And while normally one finds echinoids and ammonites in the georgetown this time I only found what I think is a partial pycnodont tooth
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- ammonite
- buda formation
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Found at the contact between the pecan gap chalk and Austin chalk. I'm thinking some kind of scaphites but trachyscaphites spiniger which is known from this formation doesn't look similar to me. As always, thanks! PS @Uncle Siphuncle
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- bexar
- pecan gap chalk
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- pecan gap chalk
- south texas
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When I was preparing my previous entry on nodosariid forams from the Pecan Gap Chalk, I originally included a specimen that I had identified as a member of the genus Dentalina. This identification was incorrect, and I edited the entry to remove that specimen. Here it is again, with what I hope is the correct identification! The genus Strictocostella is a member of the family Stilostomellidae, and this species is illustrated in Frizzell's "Handbook of Cretaceous Foraminifera of Texas" as a member of the genus Stilostomella. He also listed it as occurring in the Pecan Gap Chalk. Better images can be found on the World Foraminifera Database -- they show specimens with some very small spines around the bases of each chamber, almost what one might call "hispid". The drawing in Frizzell does not show this feature, nor does my specimen. I have not yet looked at Cushman's original description, but I am reasonably confident that this difference is within the range of natural variation. (I have seen this kind of variation on images of other stilostomellids.) I like it when I "Live and Learn!" And I'm glad that I caught the error.............
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- cretaceous
- foraminifera
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Four Nodosariid Foraminifera from The Texas Cretaceous
Rumi posted a blog entry in Microfossil Mania!
I have recently been studying a sample of washed residues from the Pecan Gap Chalk Formation of the Cretaceous Gulfian Series, from an outcrop in the vicinity of Austin, Texas. Most of the Gulfian formations are richly fossiliferous, and the Pecan Gap is no exception. It has abundant, well-preserved microfossils, particularly forams and ostracodes. In this blog entry I would like to show some forams of the family Nodosariidae, which I find of particular interest. All belong to the genus Frondicularia, which has compressed, biserial tests. Frondicularia archiaciana d'Orbigny, 1840 is one of the maddeningly similar "narrow" forms within the genus, whose identification often requires close attention to the contours of the test outline. The biserial growth form of the test appears in most members of the genus as inverted chevrons when the image is oriented with the aperture uppermost. This structure is more-or-less apparent depending on the relative transparency of the individual test, and it shows quite well in this image. What one is seeing are the suture lines between the chambers. The aperture in members of the Nodosariidae is radiate; this type of aperture does not stand up very well to post-depositional forces, and is very frequently broken away -- true of all four specimens in this entry. Frondicularia frankei Cushman, 1936 is one of a group of taxa within the genus in which the base of the test is not compressed. In profile, the base appears to be bulbous, with rather wide "ripples" oriented lengthwise. The upper 3/4 of the test is compressed, and appears quite flat in profile. The basal spine is one of the distinguishing characters of this species, although many others show such a spine also. Frondicularia intermittens Reuss, 1865 is another taxon of the "narrow" group, in which the chevrons produced by the biserial structure are less apparent. A few bright, length-wise streaks show that the sutures separating the chambers are depressed. The largest of the nodosariids that I have found thus far is Frondicularia mucronata Reuss, 1845. The larger, more ovoid appearance of this taxon is due in part to the greater length of the individual chambers, which also gives the "inverted chevron effect" a somewhat different character. The specific epithet is from the small basal tooth on the initial chamber (proloculus) of the test. Hopefully, readers have enjoyed looking at these little fossils. If so, stay tuned -- I'll be writing more about microfossils from the Texas Gulfian Series, and will also upload an entry on Pleistocene Ostracoda from the San Pedro Formation of California in the near future.-
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- foraminifera
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Was looking through boxes for an ammonite and found what I thought was a starfish arm but now not sure. This is an old find from the Sulphur R. Ozan Form. Any ideas, the back side is featureless and the front not much better Tom
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- Campanian
- Pecan Gap Chalk
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