Re: Fossils B/C
Posted: December 10th, 2009, 3:26 pm
The mammoth is much taller than the mastodon.
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Re: Fossils B/C
Posted: December 10th, 2009, 3:55 pm
The teeth are very different, also, while somewhate more subtle, the curvature of the tusks are different.
Re: Fossils B/C
Posted: December 11th, 2009, 1:35 pm
Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.
Re: Fossils B/C
Posted: December 11th, 2009, 5:29 pm
Mucrospirifer is more or less a 180 degree angle in the back on the axis of the hinge, platystrophia is not.googlyfrog wrote:Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.
Re: Fossils B/C
Posted: December 11th, 2009, 6:17 pm
They're actually pretty distinct.Deeisenberg wrote:Mucrospirifer is more or less a 180 degree angle in the back on the axis of the hinge, platystrophia is not.googlyfrog wrote:Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.
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,
Re: Fossils B/C
Posted: December 12th, 2009, 10:32 am
Yeah, I see what you mean, thanks!gneissisnice wrote:They're actually pretty distinct.Deeisenberg wrote:Mucrospirifer is more or less a 180 degree angle in the back on the axis of the hinge, platystrophia is not.googlyfrog wrote:Mucrospirifer and Platystrophia look somewhat alike and I keep messing them up.
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,
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.
Re: Fossils B/C
Posted: December 12th, 2009, 11:27 am
Exogyra is usually larger than Gryphea and Exogyra has a more layered pattern on it.
Re: Fossils B/C
Posted: December 12th, 2009, 12:23 pm
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.
Re: Fossils B/C
Posted: December 12th, 2009, 1:37 pm
Gryphaea is symmetric about the plane it rotates on, exogrya is not.
Re: Fossils B/C
Posted: December 12th, 2009, 3:21 pm
I have seen a gryphaea that are slightly asymmetric about their plane of rotation but, yes, this tends to be pretty reliable.Deeisenberg wrote:Gryphaea is symmetric about the plane it rotates on, exogrya is not.
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.
