Ammonites - Hood Co., TX

Kingdom: Animalia, Phylum: Mollusca, Class: Cephalopoda, Subclass: Ammonoidea, Order: Ammonitida

Ammonites, are common in North Texas. They vary in size from very small (one inch) to several feet in diameter. Some are coiled, while others are straight. They are cephalopods, and come in several shapes and sizes, and are early cousins to our current Nautilus shell. As the animal grew, it created more shell, living only in the very largest part of the shell. As newer parts of the shell were created the older sections were sealed off with septum, or walls, that connected to the inside of the shell. This connection creates sutures or patterns on the fossil that are distinct, and can be used to identify the various fossils. 
Our property in Hood Co., TX has two main type of ammonites. In one area, in the Walnut Clay formation, we find Metengonoceras dumbli. It is a relatively flat ammonite with very ornate sutures, as shown to the left. In another area, in the Comanche Peak formation, we find the Oxytropidoceras. These are usually fragments and are much larger ammonites (see below). In addition, they are not as flat as the Metengonoceras. This is the Goodland and Comanche Peak Formations -Cretaceous - Albian stage (c. 105 mya).

Click on images to enlarge.

Hood County, TX  

Kingdom: Animalia, Phylum: Mollusca, Class: Cephalopoda, Order: Ammonitida

Oxytropidoceras #146

Walnut Clay Formation

Hood Co., TX

Oxytropidoceras

Walnut Clay Formation

Hood Co., TX

Oxytropidoceras Suture

Walnut Clay Formation

Hood Co., TX

Oxytropidoceras #125

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras (worn) #99

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #398

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #398a

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras (very worn)

Walnut Clay Formation 

Hood Co., TX

 

Oxytropidoceras #149

Comanache Peak Formation

Hood Co, TX

Oxytropidoceras #156

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #164

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras#165 Comanche Peak Formation Hood Co., TX

Oxytropidoceras#165

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras  #146

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras  #123

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #395

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #354

Comanche Peak Formation

Hood Co., TX

Metengonoceras #406a

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #360

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #360b

Comanche Peak Formation

Hood Co., TX

Oxytropidoceras #407

Walnut Clay Formation

Hood Co., TX

Metengonoceras dumbli

Walnut Clay Formation

Hood Co., TX

Metengonoceras Reverse

Walnut Clay Formation

Hood Co., TX

Metengonoceras

Walnut Clay Formation

Hood Co., TX

Metengonoceras #390b

Comanche Peak Formation

Hood Co., TX

Metengonoceras dumbli

Walnut Clay Formation

Hood Co., TX

Cephalopod #292

Comanche Peak Formation

Hood Co., TX

Metengonoceras #406

Comanche Peak Formation

Hood Co., TX

Metengonoceras 

Walnut Clay Formation

Hood Co., TX

Metengonoceras #238

Comanche Peak Formation

Hood Co., TX