Phatfossils - Eocene Chadron Formation\Oligocene Brule Formation White River Group Sioux County Nebraska

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Eocene Chadron Formation\Oligocene Brule Formation White River Group Sioux County Nebraska

Here are some more micro mammal teeth, jaw fragments and claws and reptile micros including lizard jaw fragments, vertebrae and osteoderms and a snake vertebra from the M&M Ranch in Nebraska. These specimens are from ant hill matrix, from my May 2016 trip and from ant hill matrix that my son Mel collected a few years earlier, from an area of the ranch where the top foot or so is Oligocene Brule Formation covering Eocene Chadron Formation. The first jaw fragment and Osteoderm (skull fragment) with two views shown are definitely different from those that I found in ant hill matrix from areas of the ranch that were strictly Oligocene. However most of the other specimens really didn't look different. That could be because most of the specimens in the ant hill matrix came from the overlying Oligocene Brule Formation layer, or there really wasn't a massive small species change over the Eocene/Oligocene boundary or I'm just unable to recognize the differences.

If you mouse over the pictures you will see the file name which has the specimen size and my best effort at identification. I'm currently reviewing a number of papers so I can eventually id more of these specimens (thank you Eric).

Here are the group pictures of the nicer specimens from my May 2016 trip and from Mel's earlier trip from the Eocene/Oligocene area of the ranch. I could have taken many more individual pictures but just ran out of time and energy. Clique the photo to see an enlarged version.

The two most interesting specimens found in this matrix are directly below.

rhineurid amphisbaenian jaw:

Helodermoides osteoderm:


Here are some Mammal teeth:

Rodent incisors:

Rabbit teeth:

Additional mammal teeth:

Here are some mammal jaw fragments. A lot of these jaw fragments are rodent.:

Here are a number of claws which are probably all from mammals:


Most of these lizard specimens are probably from Peltosaurus granulosus.

Here are some lizard jaw fragments:

Here are two lizard, Peltosaurus granulosus, osteoderms:

Here are front and back pictures of another lizard osteoderm with a different shape and surface texture from the ones above:

I found a good number of Lizard vertebrae. Here are a few:


I found a number of snake vertebrae. The one below is an example. Snake vertebrae are diagnostic and are used to describe and id different species of snakes. However, I don't have the expertise to id these any further. I'm pretty sure that this is an Eocene specimen because it is filled with typical Eocene matrix residue:

Here are a few vertebrae that I'm not 100% sure about:

Marco Sr.