There’s plenty of fossils and I get they can be dated pretty accurately but how do we know certain animals are actually related? Most ancestors shown in media about evolution of particular animals look completely different than what they turned into. So how do scientist look at different fossils and determine how they were related?
Also a follow up question: how do paleontologists know they found a new species? Plenty of animals are only known from, like, two teeth or something. How can you definitively call this a separate animal and not just a bit strange or slightly disabled version of a known one?
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Some changes in species happen easily because there is pressure for the change and gradual changes are improvements. For example if some dogs live by the sea and discovers it can eat fish, the dogs might start going in the water a lot. The dogs that can swim better will get more food and escape sharks better than dogs that don’t swim well. A little extra skin on the paws helps. A little extra fat to stay warm in the water helps. The ability to hold breath a bit longer help. Over time the dogs evolve into something like seals. Wait even longer and and they evolve in to animals like dolphins and whales.
But what doesn’t happen? They don’t evolve gills. A change from lungs to gills is huge and there aren’t simple gradual steps.
Hair doesn’t easily transform into scales.
By looking at what changes and what doesn’t, scientists figure out the family trees. But it does involve a lot of guesswork. It’s like solving a puzzle except there are a lot of missing pieces and you’re not sure what the end result should look like.
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