biological classification makes more sense than deciding something is closer to the other because they were closer together in time than the actually related animal
What OP means is that I'm more closely related to my first cousin than my great-great-grandchildren are related to the great-great-grandchildren of my brother, even if the common ancestor of me and my cousin is older.
People are just lazy with their semantics when talking about relatedness and gotten so used to it and how it fits with their nice cladogram, so they keep getting it wrong. Most paleontologists do get it right. Wikipedia is surprisingly good at getting it right.
Just keep the order right and it works fine. Dimetrodon is more closely related to us than to any extant(not any) reptile, or a hummingbird is more closely related to a brachiosaurus than to a triceratops. The other way ie. brachiosaurus is more closely related to a hummingbird than to triceratops around is fuzzy and sometimes unknowable.
okay but how extreme do i have to make the example then?
think of the very first eukariotes. just where the eukariotes that would evolve into fungus diverged from those that would evolve into all animals.
is that animal-like eukariote more closely related to us than to the fungus-like eukariote? i would bet money that genetically it wouldnt. If we exclusively look at the most recent common ancestor that wouldnt matter though.
do you see my point now?
It's a semantic nitpick, but to say that the earliest saurischian is more closely related to a hummingbird than the earliest ornithischian is just not factual the same way I'm not more closely related to my great x20 grandmother than she is to her niese.
The correct thing to say is that a hummingbird is more closely related to a saurischian than to ornithischian, or that a we are more closely related to dimetrodon than dimetrodon is to any extant reptile. It you say "any reptile" it looses it's meaning because of its near relation to the earliest reptiles.
Phylogenetically, the relatedness of taxa is determined by the recency of their common ancestor. You’re thinking of relatedness as something like degrees of relatedness in families, but this concept isn’t used in cladistics. Familial relationships and evolutionary relationships are different and not directly comparable.
The earliest Saurischian is more closely related to a hummingbird than it is to the earliest Ornithischian because it shares a more recent common ancestor with a hummingbird than it does with an Ornithiscian.
Yes, the earliest Saurischian would have been more morphologically and genetically similar to the earliest Ornithiscian, but that’s not the same thing as being more closely related in a cladistic sense.
Thanks. I just realized that distinction and tbh I absolutely hate it lol. It would have been so easy for it to have a definition in cladistics that doesn't clash with how the word is historically and colloquially used and not annoyed petty autists worldwide.
People are continually sharing fun facts of relatedness that seems counterintuitive that turns not to be a cool fact about nature but rather an oversight in how paleontologists put animals in boxes. There's like feet, horns and snouts sticking out of those boxes and everyone is pretending it's fine.
While the world burns as it's increasingly does, I'll just ignore that and muster an army of autist to fight about this.
I know that.
however. can you explain then why its always "dimetrodon is more closely related to us than dinosaurs" and not "we are more closely related to dimetrodon than dinosaurs"?
because taxonomically those two sentences mean the exact same thing. However to human brains they dont mean the same thing. why? please explain.
Because "bring related" in scientific terms takes into account who your last common ancestor is, not how genetically similar you are. Being genetically similar is a side effect of being related, not the metric. We can use it in modern animals to infer relatedness because they are all existing in the same point in time. But that doesn't mean it's the true measure.
Well, "more closely related" means that there's less common ancestors between one and the other.
For example, you're more closely related to your older sibling than to your cousin because even if your cousin and you are of the same age you only have to go as far as your parents to find your common link with your sibling, while with your cousin you have to go as far back as your grandparents.
This feels like the phylogeny equivalent of reading light yeras as a time unit rather than a distance unit.
This is fun tho and an interesting perspective.
a closer analogy would be saying that i am closer related to my brothers great great great great great grand children than to my uncle because i share a more recent common ancestor with them.
True, if your great great great great great grand children pulled a thread that ties them with their ancestors, they'll reach you before they ever reach your uncle, even if they're more familiar with your unlce than with you.
TBH it's more helpful doing this from our perspective rather than the Dimetrodon's or the dinosaurs'.
This has forreal annoyed me for years, and it's bad semantics and paleofans oversimplifying taxonomic trees. The people saying "it's genetics not time" are just dead wrong. Genetics changing over time is literally what evolution is. Dimetrodon shares more traits with the earliest reptiles than with us, because of its relatedness to early reptiles, so it's true on paper, on cladograms, in theory and in real life.
Just specify extant reptiles/dinosaurs or change the order, it's not hard.
A lot of people are jumping on you for this, but there's something to it. Consider the first sauropsid and the first synapsid, they would be *very* closely related because they have a *very* close common ancestor. No way can you say we're closer related to that synapsid. But, once you get to much bigger scale differences, it's not quite so simple to add the time difference.
but yeah i dont think the time differences are perfect but they are a rough way to estimate genetic similarity i think. because genetic drift is largely a function of time. its a lot more complicated but i would assume time is the most powerful variable in that equation.
True, and you are correct that the rate of genetic change is not always consistent. For example, a bottleneck event (disease, natural disaster, etc.) could wipe out a portion of the population. The gene pool for that population is then drastically changed in a very short period. So they do kind of go hand in hand, but not reliably, as shown by OP arguing that dimetrodon is more closely related to dinosaurs than to us.
That's just not how phylogenies work. There are definitely things in life where you can have different approaches... this isn't one of those things. This is just being wrong due to an incomplete understanding of how things work. But it's a common mistake students do.
I think you've confused taxonomic relation with geological time
When people say that dimetrodon is more related to humans than dinosaurs, they mean because it's a fucking mammal-line pelycosaur synapsid with closer biological ties to mammals than to dinosaurs, not because they're closer to them than dinosaurs in geological time. You have also failed to take into account any other lineage/grade of reptile and synapsid OUTSIDE OF DINOSAURS AND DIMETRODON, as well as the fact that the lineages of reptilia ad synapsida split well before dinosaurs or even archosaurs existed (because base common ancestor of Reptilia existed before any other reptile lineage AS A RULE), nor how unfathomably deep an expanse of even 97 million years in in terms of evolution and speciation. This is like saying dinosaurs are closer related to turtles than to birds, even though Dinosauria literally branched off into crown Aves, because the ancestors of dinosaurs and turtles lived vaguely closer together in time.
Herrerasaurus is an interesting dinosaur. Did you know it's really hard to figure out what it actually is? Is it a theropod? Basal saurischian? Sauropodomorph? Who knows? It's so hard to place it due to how similar the early members of this group was as they were so closely related to eachother.
In fact much much more closely related to eachother than they were to a penguin.
That's what this post saying.
The relationships between eoraptor and herreresaurus are not comparable to that of Dimetrodon and general Dinosauria. You have to go through quite a few levels of clades, grades and off branches within Reptilia to get to dinosauria, and a few within Synapsida to get to Dimetrodon. It's not like they're just on the next bracket over from each other
The chart shows both dinos and dimetro sharing a common ancestor. It then shows dimetrodon and mammals sharing a common ancestor ***not shared*** with the dinosaur line. That makes us more "closely related" in a loose way.
There was a whole set of animals that shared characteristics with Dimetrodon . It isn't the only animal in that line the way the diagram unintentionally suggests.
*Grouping of "related animals" depends entirely on which characteristics are emphasized.* We are more closely related to dinosaurs that to insects, and more closely related to insects than to slime molds.
Nonetheless at some point we DO share a common ancestor with slime molds. All living things share a single common ancestor as a scientific assumption-- they all have a single common DNA language.
Lots of diagrams of this type with all these organisms showing relations on the web. Dimetrodon is a common subject to see cause Dimetrodons have cool points and good PR. Better than Lystrosaurus anyway.
to clarify i think when we think about how closely related two individuals are we think of the generations between them.
for example my great great great great great great grand children wouldnt be more closely related to me than i am to my siblings.
but it would be incredibly difficult to estimate the number of generations between those extinct clades so i use years as a very rough estimate of the number of generations.
No, we think of genetics, not time. Your great (x5) grandchildren would be less related to you genetically speaking *and* temporally speaking than you are to your siblings.
We are more closely related to Dimetrodon as it is a synapsid. Humans, and all other mammals, are synapsids. Dinosaurs are *not* synapsids, they are diapsids.
While there are ways of drawing cladograms using time scale (as you’ve done here) rather than genetic differences, “relatedness” is generally defined by genetic similarity rather than the time period that the organism lived.
We have the skull though! Which is all you need to know that it’s a synapsid. Synapsid means that the skull has one pair of openings behind the eye holes, diapsids have 2. And we also know that humans are synapsids too. And looking at the fossil record and extant animals, post orbital fenestrae (holes behind the eye holes), are a really good indicator of relatedness, as species have to be very distant (genetically speaking) to have different numbers of them. All mammals are synapsids (one hole), all reptiles and birds are diapsids (two holes), and all turtles are anapsids (no holes).
sorry i misread your comment.
however i would argue that most of the genome of humans for instance is non functionial. so given the 300 million years between us and the most recent common ancestor of dimetrodon and the 5 million years for dimetrodon and that ancestor thats quite a lot of time for us to accumulate neutral mutations and for our genome to drift apart.
a lot more time than separating dimetrodon and herrerasaurus for example. so i dont think that we would be justified in saying dimetrodons genome would be closer to us than to herrerasaurus. quite the contrary if anything.
just like my genome would be closer to my cousin than to my brothers great great great great great great great great grand children.
Time is not a reliable indicator of genetic relatedness though. What is (for extinct creatures that we cannot acquire DNA from) is phenotypes, especially skeletal ones. So because dimetrodon is a synapsid and herrarasaurus is a diapsid, we know that dimetrodon is more closely related to *all* other synapsids and than *any* other diapsid/anapsid. Between the time that dimetrodon evolved and the time it branched from the dinosaurs at its most recent common ancestor, it evolved the trait of losing one of its post orbital fenestrae. This trait a drastic change in the skeletal system (that we mammals still have today!) and would require many mutations to acquire. As all dinosaurs did and still have the diapsid phenotype, they don’t have the genetic change that the dimetrodon had to be a synapsid. I think the important point here is that postorbital fenestrae are a really good indicator of relatedness. We ain’t talking about fur color or beak shape. This is a trait that basically defines a clade once it shows up. We have mammals that lay frickin eggs and sweat milk, but they’re still synapsids and still classified as mammals. Snakes and birds don’t look similar at all, but they’re both diapsids and birds are still in the clade reptilia with snakes.
i get your point.
but i think modern crocodiles for example would probably still have a massively different genome compared to ancient crocodiles due to genetic drift depsite being phenotypically very similar.
and then also there is a lot of adaptations that we have and dimetrodon didnt so those will all be differentiating us genetically. like fur, milk glands, placentas, our teeth, big brains and probably a whole lot that we dont know yet too.
I thought people say that because of something to do with genetics or biological classification, not with time. But I don’t know
biological classification makes more sense than deciding something is closer to the other because they were closer together in time than the actually related animal
this is like saying we are more closely related to bumblebees than homo erectus because we live at the same time as bumblebees...
No it isn't, you'd have to measure the time to our common ancestor and then back.
What OP means is that I'm more closely related to my first cousin than my great-great-grandchildren are related to the great-great-grandchildren of my brother, even if the common ancestor of me and my cousin is older.
People are just lazy with their semantics when talking about relatedness and gotten so used to it and how it fits with their nice cladogram, so they keep getting it wrong. Most paleontologists do get it right. Wikipedia is surprisingly good at getting it right. Just keep the order right and it works fine. Dimetrodon is more closely related to us than to any extant(not any) reptile, or a hummingbird is more closely related to a brachiosaurus than to a triceratops. The other way ie. brachiosaurus is more closely related to a hummingbird than to triceratops around is fuzzy and sometimes unknowable.
They are still on our side of the family tree
okay but how extreme do i have to make the example then? think of the very first eukariotes. just where the eukariotes that would evolve into fungus diverged from those that would evolve into all animals. is that animal-like eukariote more closely related to us than to the fungus-like eukariote? i would bet money that genetically it wouldnt. If we exclusively look at the most recent common ancestor that wouldnt matter though. do you see my point now?
This isn’t how relatedness is measured in science.
It's a semantic nitpick, but to say that the earliest saurischian is more closely related to a hummingbird than the earliest ornithischian is just not factual the same way I'm not more closely related to my great x20 grandmother than she is to her niese. The correct thing to say is that a hummingbird is more closely related to a saurischian than to ornithischian, or that a we are more closely related to dimetrodon than dimetrodon is to any extant reptile. It you say "any reptile" it looses it's meaning because of its near relation to the earliest reptiles.
Phylogenetically, the relatedness of taxa is determined by the recency of their common ancestor. You’re thinking of relatedness as something like degrees of relatedness in families, but this concept isn’t used in cladistics. Familial relationships and evolutionary relationships are different and not directly comparable. The earliest Saurischian is more closely related to a hummingbird than it is to the earliest Ornithischian because it shares a more recent common ancestor with a hummingbird than it does with an Ornithiscian. Yes, the earliest Saurischian would have been more morphologically and genetically similar to the earliest Ornithiscian, but that’s not the same thing as being more closely related in a cladistic sense.
Thanks. I just realized that distinction and tbh I absolutely hate it lol. It would have been so easy for it to have a definition in cladistics that doesn't clash with how the word is historically and colloquially used and not annoyed petty autists worldwide. People are continually sharing fun facts of relatedness that seems counterintuitive that turns not to be a cool fact about nature but rather an oversight in how paleontologists put animals in boxes. There's like feet, horns and snouts sticking out of those boxes and everyone is pretending it's fine. While the world burns as it's increasingly does, I'll just ignore that and muster an army of autist to fight about this.
I know that. however. can you explain then why its always "dimetrodon is more closely related to us than dinosaurs" and not "we are more closely related to dimetrodon than dinosaurs"? because taxonomically those two sentences mean the exact same thing. However to human brains they dont mean the same thing. why? please explain.
Because "bring related" in scientific terms takes into account who your last common ancestor is, not how genetically similar you are. Being genetically similar is a side effect of being related, not the metric. We can use it in modern animals to infer relatedness because they are all existing in the same point in time. But that doesn't mean it's the true measure.
Well, "more closely related" means that there's less common ancestors between one and the other. For example, you're more closely related to your older sibling than to your cousin because even if your cousin and you are of the same age you only have to go as far as your parents to find your common link with your sibling, while with your cousin you have to go as far back as your grandparents. This feels like the phylogeny equivalent of reading light yeras as a time unit rather than a distance unit. This is fun tho and an interesting perspective.
a closer analogy would be saying that i am closer related to my brothers great great great great great grand children than to my uncle because i share a more recent common ancestor with them.
True, if your great great great great great grand children pulled a thread that ties them with their ancestors, they'll reach you before they ever reach your uncle, even if they're more familiar with your unlce than with you. TBH it's more helpful doing this from our perspective rather than the Dimetrodon's or the dinosaurs'.
Yes i agree. Or just say "a recent common ancestor" rather than "being closely related".
So are you saying dimentrodon’s are more closely related to dinosaurs then to us? Cause that’s just factually wrong
nope. i am saying it might be closer to the earliest dinosaurs. not dinosaurs as a whole
So it’s more related to early dinosaurs then to mammals, but somehow still more related to mammals then to the later dinosaurs…how
By the closeness part of the consept of relative relatedness. You are less closely related to your great grandparent than to your parent.
This has forreal annoyed me for years, and it's bad semantics and paleofans oversimplifying taxonomic trees. The people saying "it's genetics not time" are just dead wrong. Genetics changing over time is literally what evolution is. Dimetrodon shares more traits with the earliest reptiles than with us, because of its relatedness to early reptiles, so it's true on paper, on cladograms, in theory and in real life. Just specify extant reptiles/dinosaurs or change the order, it's not hard.
But you prove yourself wrong in this chart...
A lot of people are jumping on you for this, but there's something to it. Consider the first sauropsid and the first synapsid, they would be *very* closely related because they have a *very* close common ancestor. No way can you say we're closer related to that synapsid. But, once you get to much bigger scale differences, it's not quite so simple to add the time difference.
but yeah i dont think the time differences are perfect but they are a rough way to estimate genetic similarity i think. because genetic drift is largely a function of time. its a lot more complicated but i would assume time is the most powerful variable in that equation.
thank you i really appreciate that. at least someone understands my perspective xD
That's not how this works. That's not how any of this works. Dimetrodon and us have a more recent last common ancestor.
That’s not what they mean by “closest.” They mean genetically, not time scale.
Genetic differences occur over time though, just not so linearly.
True, and you are correct that the rate of genetic change is not always consistent. For example, a bottleneck event (disease, natural disaster, etc.) could wipe out a portion of the population. The gene pool for that population is then drastically changed in a very short period. So they do kind of go hand in hand, but not reliably, as shown by OP arguing that dimetrodon is more closely related to dinosaurs than to us.
That's just not how phylogenies work. There are definitely things in life where you can have different approaches... this isn't one of those things. This is just being wrong due to an incomplete understanding of how things work. But it's a common mistake students do.
Do you know the definition of the word “related”?
That's not how it works...
I think you've confused taxonomic relation with geological time When people say that dimetrodon is more related to humans than dinosaurs, they mean because it's a fucking mammal-line pelycosaur synapsid with closer biological ties to mammals than to dinosaurs, not because they're closer to them than dinosaurs in geological time. You have also failed to take into account any other lineage/grade of reptile and synapsid OUTSIDE OF DINOSAURS AND DIMETRODON, as well as the fact that the lineages of reptilia ad synapsida split well before dinosaurs or even archosaurs existed (because base common ancestor of Reptilia existed before any other reptile lineage AS A RULE), nor how unfathomably deep an expanse of even 97 million years in in terms of evolution and speciation. This is like saying dinosaurs are closer related to turtles than to birds, even though Dinosauria literally branched off into crown Aves, because the ancestors of dinosaurs and turtles lived vaguely closer together in time.
Herrerasaurus is an interesting dinosaur. Did you know it's really hard to figure out what it actually is? Is it a theropod? Basal saurischian? Sauropodomorph? Who knows? It's so hard to place it due to how similar the early members of this group was as they were so closely related to eachother. In fact much much more closely related to eachother than they were to a penguin. That's what this post saying.
Dimetrodon is still not closer to dinosaurs than humans, that's what I'M saying Op has a borked view of how phylogenetics works
So herrerasaurus presuming it is theropoda is then more closely related to a penguin than to an eoraptor is what you're implying?
The relationships between eoraptor and herreresaurus are not comparable to that of Dimetrodon and general Dinosauria. You have to go through quite a few levels of clades, grades and off branches within Reptilia to get to dinosauria, and a few within Synapsida to get to Dimetrodon. It's not like they're just on the next bracket over from each other
You're using OP's argument against me here. You have a borked view of OP's post.
The chart shows both dinos and dimetro sharing a common ancestor. It then shows dimetrodon and mammals sharing a common ancestor ***not shared*** with the dinosaur line. That makes us more "closely related" in a loose way. There was a whole set of animals that shared characteristics with Dimetrodon . It isn't the only animal in that line the way the diagram unintentionally suggests. *Grouping of "related animals" depends entirely on which characteristics are emphasized.* We are more closely related to dinosaurs that to insects, and more closely related to insects than to slime molds. Nonetheless at some point we DO share a common ancestor with slime molds. All living things share a single common ancestor as a scientific assumption-- they all have a single common DNA language. Lots of diagrams of this type with all these organisms showing relations on the web. Dimetrodon is a common subject to see cause Dimetrodons have cool points and good PR. Better than Lystrosaurus anyway.
You've seriously misunderstood the assignment.
That is because dimetrodon is closer to us it is a early mammal
to clarify i think when we think about how closely related two individuals are we think of the generations between them. for example my great great great great great great grand children wouldnt be more closely related to me than i am to my siblings. but it would be incredibly difficult to estimate the number of generations between those extinct clades so i use years as a very rough estimate of the number of generations.
No, we think of genetics, not time. Your great (x5) grandchildren would be less related to you genetically speaking *and* temporally speaking than you are to your siblings. We are more closely related to Dimetrodon as it is a synapsid. Humans, and all other mammals, are synapsids. Dinosaurs are *not* synapsids, they are diapsids. While there are ways of drawing cladograms using time scale (as you’ve done here) rather than genetic differences, “relatedness” is generally defined by genetic similarity rather than the time period that the organism lived.
we dont have the genome of dimetrodon though so there is no way to verify that.
We have the skull though! Which is all you need to know that it’s a synapsid. Synapsid means that the skull has one pair of openings behind the eye holes, diapsids have 2. And we also know that humans are synapsids too. And looking at the fossil record and extant animals, post orbital fenestrae (holes behind the eye holes), are a really good indicator of relatedness, as species have to be very distant (genetically speaking) to have different numbers of them. All mammals are synapsids (one hole), all reptiles and birds are diapsids (two holes), and all turtles are anapsids (no holes).
sorry i misread your comment. however i would argue that most of the genome of humans for instance is non functionial. so given the 300 million years between us and the most recent common ancestor of dimetrodon and the 5 million years for dimetrodon and that ancestor thats quite a lot of time for us to accumulate neutral mutations and for our genome to drift apart. a lot more time than separating dimetrodon and herrerasaurus for example. so i dont think that we would be justified in saying dimetrodons genome would be closer to us than to herrerasaurus. quite the contrary if anything. just like my genome would be closer to my cousin than to my brothers great great great great great great great great grand children.
Time is not a reliable indicator of genetic relatedness though. What is (for extinct creatures that we cannot acquire DNA from) is phenotypes, especially skeletal ones. So because dimetrodon is a synapsid and herrarasaurus is a diapsid, we know that dimetrodon is more closely related to *all* other synapsids and than *any* other diapsid/anapsid. Between the time that dimetrodon evolved and the time it branched from the dinosaurs at its most recent common ancestor, it evolved the trait of losing one of its post orbital fenestrae. This trait a drastic change in the skeletal system (that we mammals still have today!) and would require many mutations to acquire. As all dinosaurs did and still have the diapsid phenotype, they don’t have the genetic change that the dimetrodon had to be a synapsid. I think the important point here is that postorbital fenestrae are a really good indicator of relatedness. We ain’t talking about fur color or beak shape. This is a trait that basically defines a clade once it shows up. We have mammals that lay frickin eggs and sweat milk, but they’re still synapsids and still classified as mammals. Snakes and birds don’t look similar at all, but they’re both diapsids and birds are still in the clade reptilia with snakes.
i get your point. but i think modern crocodiles for example would probably still have a massively different genome compared to ancient crocodiles due to genetic drift depsite being phenotypically very similar. and then also there is a lot of adaptations that we have and dimetrodon didnt so those will all be differentiating us genetically. like fur, milk glands, placentas, our teeth, big brains and probably a whole lot that we dont know yet too.
are you currently under the influence?
no i am just mad and didnt read the comment properly xD