Why do Archen and Archeops belong in the Water 3 egg group?

Question

They are listed here.

Answer 1

Alright, I'll have a go at answering this.

Fossils are most commonly found in Sedimentary Rock.

Sedimentary Rock itself is most commonly formed by sediments being moved by WATER. This water then squeezed out by a massive amount of pressure, leaving you with sedimentary rock.

Is it a tenuous connection? Yes, it is. But it is the only reason I could think of. As for why Water 3, in particular, it is really on the only Water egg group that fits. Water 1 contains all the Water-types that work well on both water and land (e.g. Squirtle, Politoed, etc.). Water 2 contains all the fish-type Water Pokemon (e.g. Carvanha, Lanturn, etc). Water 3 contains pretty much any of those Pokemon either based on a crustaceans, or have a vague connection to the water (e.g. Krabby, Skorupi, etc).

Sources: Fossils in Water, Sedimentary Rock

Answer 2

To add more variety to the game
every fossil pokemon but aerodactyl is there.

And I quote:
"The last of three water egg groups, Water 3 is a mix of different pokemon types, including fossil pokemon, crabs and invertebrates"

Comments

Wait, is that why Skorupi and Drapion are also in it?

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Cranidos, Rampardos, Shieldon, and Bastiodon are not included in this egg group either. This is because they represented terrestrial extinct animals, as Archen and Archeops does. (and now a days with the inclusion of Tyrunt and Amaura, it reduces this pattern even further).

Cranidos, Armaldo, Kabutops, Omanyte, etc were fossils, yes, but they all represented extinct, aquatic invertebrates. So, it was appropriate for them to be in water 3. It doesn't make sense for Archen and Archeops to be in there. So it is still a mystery as to why this was done.

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Can I ask WHY "Water 3 is a mix of different pokemon types, including fossil pokemon, crabs and invertebrates"?

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Think about it, crabs are invertabrates and wouldn't it make sense to put other invertabrates in there like Drapion as they come from the same classification as invertabrates?

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Technically, insects are more similar to crustaceans, such as crabs, than they are to arachnids. So since the bug egg group includes almost all insects and arachnids, shouldn't it include Pokemon like Krabby and Binacle? Also, I didn't understand Jawa's post very well.