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Tifoid t1_j1z9zri wrote

Reply to comment by PA55W0RD in The hand of a Chinese giant salamander by Trulystagnate23

What about snakes (no limbs), insects like centipedes and ants (more than 4 limbs), animals with hooves (no fingers)?

Guess you are right for land based mammals … but not “every land living or amphibious animal”.

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volpiousraccoon t1_j20fy0b wrote

It should be more like every tetrapod (four-limbed vertebrate that share ancestry with fish) has 4 limbs and 5-ish fingers configuration.

You are correct when you said that there are exceptions to this with some changes in fingers number and some animals with missing/vestigial limbs but the configuration it is generally true for most tetrapods. Some hooved mammals have one or two big fingers for their hooves because they evolved to loose their other digits over time. Marine mammals like whales are still considered therapods even though they do not really have back legs anymore but they still have the five finger configuration. Snakes are still considered tetrapod because their ancestors were reptiles that had all 4 limbs. It's kind of confusing and complicated, but generally the limb configuration is true for land-living vertebrates.

Insects and centipedes are not even vertebrates, so they do not have anatomy similar to tetrapods. It's kind of complicated but really cool to learn about once you get into it.

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TinTamarro t1_j1zjt5s wrote

Insects didn't descend fron fish?????

And snakes lost their limbs but their ancestors still had 4? And horses too?

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