Turtle / Croc - Armour Plate?

[sward]

I was on my favorite hillside again on 11Jun checking it out after a nice rain. In discussions with vertman (Richard), this hillside has been narrowed down to either Grayson/Mainstreet or possibly Pawpaw formation. As helpful as Richard is, he has offered to visit to take a look at it and help me understand the geology better.

While searching, I came across this on the surface:

I started to scrape away the top surface to see what else might be in the area and came across this. In the top left is a "plate" with three "ribs" on it. Scatterted throughout is bony material, these are the reddish tinted areas. On the right, is a large "shell". In this pic, it is only partially uncovered, so far.

Here is a close-up of the "shell" material:

This vert is one of the items found on the surface (previously posted):

To be continued...

[sward]

I returned the next day and continued uncovering the area. I ended up having to recover some of the pieces (the "plate", misc pieces, etc) that were on the surface because a thunderstorm was moving in and I was afraid some of them may become damaged if there was hail in it. We did end up getting some hail so I'm glad I recovered what I did.

The last pic is a close-up of the "shell" material. It seems to have two layers to it as can be seen in the pic.

To be continued...

Edited June 19, 2012 by sward

[sward]

On 16Jun, I pedestalled and plastered the entire area to recover it. I learned a big lesson this time. When I plastered the fish I found on this hillside (http://www.thefossil...__hl__plastered), I had dug a "decent" pedestal. The fish was much smaller than this area.

This time, I dug a similar pedestal before I plastered it. I went back on 17Jun to recover it. However, when I started trying to flip the plaster jacket, everything crumbled from inside the plaster jacket. My lesson from this was that when trying to pedestal and plaster a large area, the pedestal probably needs to be much deeper. I believe if I had made my pedestal deeper, I would have had a better chance of recovering it without it crumbling out of the plaster jacket. Oh well...live and learn. It was a good experience in my learning curve.

Since it crumbled from the plaster jacket when I tried to flip it, I've since been having to put the puzzle back together. Some of the pieces I was able to retrieve basically in the same orientation, so that helps in the "reassembly".

All of this material is intertwined with quartz, so I've been having to remove a layer of quartz from most of the pieces. It's a slow and tedious process.

Here are some pics of the puzzle that I've gotten put back together and removed the quartz from so far.

This pic is part of the "shell" with a "rib" running through it.

This is the "plate" from the original posting. It has three "ribs" running through it.

This is one of the "bony" pieces:

To be continued...

Edited June 19, 2012 by sward

[sward]

The vert on the right was previously posted as a surface find. The bone on the left was below surface level and found while uncovering the area.

A piece of bone that has been reassembled.

So, my question is...

What is it?

[Opisthotriton]

It is the turtle Naomichelys or something closely related. Nice!

[Foshunter]

That will be an interesting puzzle to put together, great find---Tom

[LanceH]

Great find!

[Fossils4U]

Nice find! Love the texture in the shell. Looks to be turtle or maybe some kind of armor plate!

[sward]

It is the turtle Naomichelys or something closely related. Nice!

Thanks Opisthortriton for the id. Thanks everyone for the comments.

I've since been trying to research Naomichelys on the web. There sure doesn't seem to be alot of info about them, particularly pics, so I'm having trouble trying to identify parts of the anatomy. My best resource so far has been "The Fossil Turtles of North America" by Oliver Perry Hay. Even this book has only a few pics of shell fragments.

So far, I've been able to re-assemble some pieces. Thank goodness I had taken pics of the surface finds as well as while uncovering it. These pics have helped with some of the reassembly.

Some of the shell. You can see the shell seems to have two "layers" to it.

Humpty Dumpty continues...

Edited June 22, 2012 by sward

[sward]

Interesting read from "The Skull of the Solemydid Turtle Helochelydra Nopcsai from the Early Cretaceous of the Isle of Wight (UK) and a Review of Solemydidae" by Walter G. Joyce, Sandra D. Chapman, Richard T.J. Moody and Cyril A. Walker.

"The holotype of the North American Naomichelys speciosa is shown to originate

from the Lower Cretaceous (Aptian) Kootenai Formation

and the fossil record of this taxon is summarized for the

first time. Solemydids are known from the Berriasian–

Maastrichtian of Europe and from the Aptian–Campanian of

North America. The palaeoecology of solemydid turtles

remains ambiguous as the presence of limb osteoderms

suggests terrestrial habitat preferences whereas the flattened

palate is more typical of an aquatic molluscivore."

Additionally,

"Palaeoecology of solemydid turtles

Most solemydid material is derived from terrestrial sediments,

and it is apparent that they were not marine turtles.

As the North American taxon Naomichelys speciosa and the English taxon

Helochelydra aff. nopcsai are known to have had limbs covered with osteoderms (FMNH

PR273; Barrett et al. 2002), we speculate that these structures

were present among solemydids in general. Among

extant turtles, osteoderms are only known among terrestrial

testudinids, and the presence of osteoderms has consequently

been used to infer terrestrial habitats in the Triassic turtle

Proganochelys quenstedti (Joyce and Gauthier

2004) or Cretaceous nanhsiungchelyids (Hutchison

2000). Using the same rationale provides supporting evidence

for the terrestrial habits of solemydids."

Also, it appears that they have been found in this area before:

"Solemydid material from the Cretaceous of North

America has been recorded as Naomichelys speciosa (Hay

1908; Ostrom 1970; Kranz 1998; Brinkman 2003), but

this taxon was only recently linked phylogenetically with

European representatives of the Solemydidae to the

exclusion of all other turtles (Lapparent de Broin and

Murelaga 1996, 1999; Hirayama et al. 2000; Lipka et al.

2006). The type of this taxon was originally reported to

have been recovered from the Upper Jurassic Morrison

Formation (Hay 1908), but herein we demonstrate that

this stratigraphic assessment is incorrect and that the

type material originates from the Albian Kootenai Formation

(see Systematic Palaeontology, below). A nearly

complete skeleton, including a partial skull and nearcomplete

shell, of this taxon was discovered in the

Aptian–Albian Trinity Formation of Texas more than

50 years ago. Although Hirayama et al. (2000) provided

a reconstruction of the shell, this specimen still awaits

formal description."

If I read this correctly (I by no means claim to understand scientific papers), the Naomichelys might have been a terrestial turtle, rather than aquatic. If that is the case, could this have been an example of "bloat-and-float"? I really don't think about turtles "floating" though.

Also, I understand that another example was found in the Trinity formation more than 50 years ago.

This is one of the things I love about this hobby so much. You find a new fossil and you never know where the research is going to lead you.

Edited June 22, 2012 by sward

[Ramo]

Awesome find.

Some times things just crumble.

Ramo

Edited July 5, 2012 by Ramo