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NORTH TEXAS FOSSILS

 

 

In Texas, my adopted state, I havenít had to travel far to find fossils.In fact, most of my fossils have been collected in a radius of less than one city block from my house and a few were found in my backyard.Most of my specimens belong to the Fort Worth Formation of Tarrant County, Texas, which, according to online sources, has been placed in the Lower Cretaceous Period.Important exceptions to this ongoing collection were found in North Richland Hills, Haltom City, Southlake, near Grapevine Lake, also in Tarrant County, and the nearby Dallas areaóthe latter two locations belonging to the Woodbine Formation.Unlike my other collections, my efforts in my adopted state have really just begun.My Texas collection is an ongoing project, which will be upgraded with each new discovery.Included in this brief introduction, are three excellent links to the geological history of north Texas: North Texas Fossils, Surface Geology of Dallas and Tarrant Counties, and Geology of North Central Texas.Before presenting my Texas Collection, I pause to generate a stratigraphy (geological column) of the North Texas area.The important exception to this stratigraphy is my Upper Pennsylvanian brachiopod shown below.

 

 

Lower Cretaceous Pelecypods††

 

 

Across the street from my house in Fort Worth Texas, I discovered a mother lode of gryphaea (ďTexas OystersĒ).As the photo below illustrates, the matrix of the slab filled with gryphaea is solidly packed with these marine invertebrates.I estimate that the strata are nearly ten feet thick and are so dense that there is scarcely any non-fossiliferous matrix.I found a similar phenomena in Haltom City where the creek had worn the conglomeration down, but in North Richland Hills, the gryphaea were loosely scattered on a hill.All three locations, including the excellent specimen I found near my home, are filled with other marine invertebrates shown below, but the gryphaea constitute at least ninety percent of the Lower Cretaceous deposits in this quadrangle.The few samples of clams were found in my wifeís garden.

Note ĖTo enlarge photo, click Zoom to reach magnifier then click to enlarge photo.To return, click back arrow on top of page.

 

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Lower Cretaceous Exogyra

 

††††††††††† Compared to the much larger gryphaea oyster, exogyra arietina is not impressive.For me itís its bizarre shape that makes it unique.Unlike its larger cousins, I found in North Texas, which look like fossils, the arietina shells almost seem as if they were picked up off the shoreline of a beach.

Note ĖTo enlarge photo, click Zoom to reach magnifier then click to enlarge photo.To return, click back arrow on top of page.

 

 

Ammonite Fragment

 

There are many excellent ammonite specimens showcased online and at the above-mentioned paleontological links.Until very recently, however, I failed to find in my fossil hunting in Texas any evidence of this sought after marine invertebrate.There have been several locations cited, which I havenít visited, but all I could find so far is one fragment, discovered almost by accident on my daily walk.Looking down at the local park trail in my neighborhood, I spotted the unmistakable ridges and spine of an ammonite shell.Because of its location and the surrounding surface geology (Kpd), I estimate that itís the same age as my gryphaea, shown above.Geologists have given this formation an ambiguous label: Denton/Weno/Pawpaw undivided.So far, after investigating Rufe Snow vacant lots in Richland Hills, the Haltom City and Park Glenn areas, and my own backyard, I had been convinced there were no ammonites in this quadrangle, but I was wrong.Because my neighborhood is private property and the nearby park is a restricted location for collection, Iím not sure if Iíll risk a fine.Hopefully, there might be accessible road cuts in the future and, on my daily walk, Iíll stumble across another specimen, this time a whole ammonite.Shown below next to a similar specimen identified in Lance Hallís site (North Texas Fossils) is my ammonite fragment.

 

 

 

Upper Cretaceous Marine Slab

 

While exploring my daughterís large backyard in Southlake, Texas, I discovered an interesting slab (possibly uncovered during the building of the house).I havenít attempted to extract fossils from it.In fact, I decided to leave it in its present state.†† So far I have identified species of turritella, gastropods, and pelecypods.Because my daughterís house is very close to Lake Grapevine, I was able to date it and place it in the correct time period.According to a geological map I discovered online, Iíve determined that this specimen is within the Woodbine Formation (Upper Cretaceous).

Note ĖTo enlarge photos, click Zoom to reach magnifier then click to enlarge photo.To return, click back arrow on top of page.

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Upper Pennsylvanian Brachiopod

 

††††††††††† When I literally stumbled across these tiny fossils, I was unfamiliar with the geology of Texas, especially when I saw the small brachiopods up close, but my brachiopods from Graham County, Texas, look very similar to brachiopods I found in New Mexico that are also of Upper Pennsylvanian age (Neospirifer dubari and Neospirafer alatus).Later I discovered on Lance Hallís North Texas Fossil site, a family of brachiopods (neochonetes) that look very similar to my own samples, as well as the neospirafer alatus from New Mexico.A modest selection of these small brachiopods is shown below to compare with the neospirafer alatus from my New Mexico Collections given in the preceding link.

Note ĖTo enlarge photo, click Zoom to reach magnifier then click to enlarge photo.To return, click back arrow on top of page.

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