Fossils B/C

[amerikestrel]

The mammoth is much taller than the mastodon.

[Deeisenberg]

The teeth are very different, also, while somewhate more subtle, the curvature of the tusks are different.

[googlyfrog]

Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.

[Deeisenberg]

Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.

Mucrospirifer is more or less a 180 degree angle in the back on the axis of the hinge, platystrophia is not.

[gneissisnice]

Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.

Mucrospirifer is more or less a 180 degree angle in the back on the axis of the hinge, platystrophia is not.

They're actually pretty distinct.
Mucrospirifer is more elongated, and platystrophia is more zig-zaggy (if that makes any sense). Go compare pictures of them to see what I mean,

[googlyfrog]

Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.

Mucrospirifer is more or less a 180 degree angle in the back on the axis of the hinge, platystrophia is not.

They're actually pretty distinct.
Mucrospirifer is more elongated, and platystrophia is more zig-zaggy (if that makes any sense). Go compare pictures of them to see what I mean,

Yeah, I see what you mean, thanks!

Does anyone know if there's a difference (besides color) between gryphaea and exogyra? The only difference I can get is that gryphaea is more twisted and slightly flatter. Sorry for all the questions about differences, I'm sure this will be the last.

[blufoster6]

Exogyra is usually larger than Gryphea and Exogyra has a more layered pattern on it.

[amerikestrel]

I agree, the exogyra seems to have more distinct layers than the gryphea. If you don't understand what I mean, look at two pictures of them side by side.

[Deeisenberg]

Gryphaea is symmetric about the plane it rotates on, exogrya is not.

[E Edgar]

Gryphaea is symmetric about the plane it rotates on, exogrya is not.

I have seen a gryphaea that are slightly asymmetric about their plane of rotation but, yes, this tends to be pretty reliable.

Also, look at the point where the shell begins coiling (the coils are at their smallest). Exogyra often coils outwards as in the image below.