Two Fossils ??

[usa2stay]

I found both of these in a flood control area in San Antonio. I went through a number of images online and I think the one on the left (white circular object) is a fossilized lizard egg. The one on the right appears to be a fossilized fish vertebrae. First do you agree that I am correct and second how old do you think they are? Thanks a bunch!

 

[DanKnug]

I would say neither. Look like weathered limestone rocks. The one on the left looks like it could have be a brachiopod fossil or a nodule of some sort.

 

[usa2stay]

Well DanKnug you have certainly taken me in a different direction. I appreciate your comment. I guess I need to go to a University and ask what if anything they are. Hopefully, something a little more sexy than weathered limestone. LOL

 

[creskol]

When I saw the title, "TWO FOSSILS" .. my first thought was that this was a post about me and my wife!

 

[DanKnug]

Well DanKnug you have certainly taken me in a different direction. I appreciate your comment. I guess I need to go to a University and ask what if anything they are. Hopefully, something a little more sexy than weathered limestone. LOL

It is hard to tell for sure what a rock or mineral is from only a picture unless it has some very unique distinguishing characteristic. I live in an area full of weathered limestone, and that's what it appears to me. They thing about limestone is it dissolves easily over time and will form some interesting looking shapes that appear to be things that they really aren't. From your picture, the white smooth object appears to be a brachiopod, an ancient marine bivalve, which would fit with the limestone since limestone was formed in an ancient marine environment. So if it is limestone, you would not find a lizard egg in it, but marine fossils would be likely. If you look at a geologic map of your area, you could possibly identify the rock type (formation) that your rocks came from. By knowing the formation name, you will then know the age of the formation. If that is limestone, I am surmising that it is from the Mississippian Era which predates the age of the dinosaurs. You need to find some Jurassic/Triassic/Cretaceous age rocks to find the lizard and dinosaur fossils. I know that there are some great fossils in Texas as I have found some around Dallas. There are some really great Cretaceous-age ammonite fossils to be found in some areas of Texas. If you want to find good fossils, find a geologic map of your area and look for the Jurassic/Triassic/Cretaceous age rocks for dinosaurs and ammonites. You can find some marine fossils in Mississippian rocks, but they will be horn corals, brachiopods, bryozoa, crinoids, etc. Trilobites are always nice to find, too. Good luck in your hunting!

 

[DanKnug]

Hey USA2stay, I looked up a geologic map of San Antonio and it looks like the limestone in your area is Cretaceous age.
http://http://www.twdb.state.tx.us/groundwater/aquifer/GAT/san-antonio.htm
This is the age of the dinosaurs and also the golden age of the ammonites, some really cool marine animals that look like a Chambered Nautilus. You will not likely find dinosaur eggs in a limestone deposit. Any dinosaur fossils will have been from marine dinosaurs such as a mosasaur. It really depends on the rock formation as to what fossils you will likely find. My advice to you is to look on the map, locate where you found your rocks, and identify the rock formation that they came from. Then do an internet search for the name of the rock formation to see what fossils you would likely find. If I were you, I would try to find rock formations in your area that yield ammonite fossils. You will not be disappointed to find ammonites. Some people mount them on wood blocks to make bookends. Shark teeth are another possibility, but it all depends on the particular rock formation as to what fossils you will find. Good luck, and let us know how many ammonites you find!