CUMINS CO. NEBRASKA - Fossil ID's please

[Dpaul7]

Hello!  I've just swapped for some fossils, from eastern Nebraska, Cuming County.  I suspect the shells are inoceramus - What do you think?

There is also Petrified Wood - Any idea on age?  It is agatized, it seems.  These were from a dragline-type operation - Mammal fossils are also found....

I attach a photo of my Mammoth tooth, from the same area.   I have searched for data to no avail!

 

So, firstly, what are the shell fossils?  I think perhaps inoceramus.  But what era?

 

Secondly - The petrified wood - a time period would be helpful if possible. 

 

Thirdly - The Mammoth Tooth - Is my ID correct?

 

Mammoth Tooth - Mammuthus columbi
0.00    12/18/2017    Chris Stalp  (trade)
West Point, Cumings County, Nebraska
 Late Pleistocene - (About 25 thousand years old)
The Columbian mammoth (Mammuthus columbi) is an extinct species of mammoth that inhabited North America as far north as the northern United States and as far south as Costa Rica during the Pleistocene epoch. It was one of the last in a line of mammoth species, beginning with M. subplanifrons in the early Pliocene. The Columbian mammoth evolved from the steppe mammoth, which entered North America from Asia about 1.5 million years ago. The pygmy mammoths of the Channel Islands of California evolved from Columbian mammoths. The closest extant relative of the Columbian and other mammoths is the Asian elephant. Columbian mammoths had four functional molar teeth at a time, two in the upper jaw and two in the lower. About 23 cm (9.1 in) of the crown was within the jaw, and 2.5 cm (1 in) was above. The crown was pushed forward and up as it wore down, comparable to a conveyor belt. The teeth had separated ridges of enamel, which were covered in "prisms" directed towards the chewing surface. Wear-resistant, they were held together with cementum and dentin. A mammoth's molars were replaced five times over the animal's lifetime. The first molars were about the size of those of a human, 1.3 cm (0.51 in); the third were 15 cm (5.9 in) long, and the sixth were about 30 cm (1 ft) long and weighed 1.8 kg (4 lb). With each replacement, the molars grew larger and gained more ridges; the number of plates varied between individuals.
Kingdom: Animalia
Phylum: Chordata
Class:     Mammalia
Order:     Proboscidea
Family: Elephantidae
Tribe:     Elephantini
Genus:     †Mammuthus
Species: †columbi

[Tidgy's Dad]

Looks like Cretaceous Inoceramus to me. 

[Dpaul7]

Thank you, Tiggy's Dad!  Good to have a confirmation! I've read a bit about these....  I'm pretty happy with them!

[Miocene_Mason]

I agree with mammoth and inoceramus, as for the wood (also from Nebraska?) I have no idea but Cretaceous is a gut feel for some reason. Assuming it is in a roughly close area then it would be close in age to the inoceramids.

edit: forgot to add, for the mammoth, pretty much has to be Colombian as wooly didn’t  make it that far south (as far as we know, I do seem to remember some taxonomic difficultly distinguishing the two) 

[Dpaul7]

Hi!  I also think cretaceous for the wood!  The formation these came from is not named; the fellow from the mine said "  Have UNL and the Smithsonians mammoth project doing research to figure out if it’s a continuation of the ash falls formation or its own separate We have about another 15-20 years of pumping and mining to do after which the 2000 acres will be turned into a fossil park and nature preserve"

He said the site dates 75-100 mya - but THAT part is too early for the mammoth.  He says he has mammoth skulls, smilodon skulls, etc.

I am REAL happy with my mammoth tooth.