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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This is one of those cases where people have a very skewed view of what happens in a science field.
It is almost never immediately obvious what the relationship between fossils is.
Multiple times “new species” turned out to be juveniles, or sexual dimorphism, or some other type of variation (like different “castes” of insects). But it’s often after decades of debates and vitriolic rivalries, thanks to new groundbreaking analysis techniques.
Just as often “related” species turn out to be convergent evolution.
And this is just as often the case with living species, much less extinct ones. So aside from the occasional “obvious” relationship, it takes years upon years of nitpicking through finer and finer anatomical details, again often with brand new techniques, to eventually arrive at a relationship that the community can agree on. And even then, it often takes more discoveries to chain together an evolutionary line that wasn’t obvious.
TL;DR It’s really messy and can take decades, with new discoveries inbetween, to come to any sort of consensus.
>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?
It’s one of those dirty secrets, but making discoveries is how you get more funding, so of something isn’t previously described or just obviously malformed (like a tumor or fracture), bam new species. Leave it to others to disprove, you have your published paper with a brand new discovery.
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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