What is an ammonite? Ammonites are fossils found in sedimentary rocks around the world. Ammonites are an extinct group of cephalopods – they’re basically squids in coiled shells (the living chambered nautilus also has a squid-in-a-coiled-shell body plan, but ammonites are a different group). Ammonites get their name from their coiled shell shape being reminiscent of a ram’s horn. These creatures lived in the seas between 240 – 65 million years ago, when they became extinct along with the dinosaurs.
In Northern and North East Texas they are found along the shores of lakes and rivers. They can be found along the banks of the North sulphur river, Lake Texoma, and Denison Dam near Eisenhower Park. I found one on the red river below the Denison Dam, weighing about 40 lbs., complete and now in my garden. I did not have to pry it out. I did have to wade into the water a little ways. It is especially good to go out after we have had a dry spell. Actually you could stop by most water spots and find all kinds of fossils.
Be sure and dress in comfortable clothes with good hiking shoes. You may have to wade a little bit. I don’t believe in hacking things up. I like to leave those for others to see, and just look for the ones that the water and movement of the land have loosened. You can also find fossils along side cuts of roads. By closely looking at the area, usually you can tell if there are any fossils.