bizarre beasts
This Furry Potato Is An Evolutionary Mystery
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Duration: | 09:45 |
Uploaded: | 2024-06-07 |
Last sync: | 2024-12-16 13:00 |
Hyraxes are furry potatoes that look a lot like rodents, but at the mammal family reunion, you won’t find them sitting by the groundhogs and chinchillas. Instead, their actual cousins are elephants and sea cows…and we’re not sure which is closer.
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This month's pin is designed by Kay Powell. You can find out more about them and their work here: https://www.simkaye.com/
You can cancel any time by emailing hello@dftba.com
Follow us on socials:
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#BizarreBeasts #hyrax
-----
Sources:
https://www.researchgate.net/profile/Robert-Eley/publication/235622778_The_hyrax_-_a_most_mysterious_mammal/links/542fa4f20cf277d58e91fa1f/The-hyrax-a-most-mysterious-mammal.pdf
https://www.sciencedirect.com/science/article/pii/B9780123847195000897
https://www.britannica.com/animal/marmot
https://www.departments.bucknell.edu/biology/resources/msw3/browse.asp?id=11400002
https://researchspace.ukzn.ac.za/server/api/core/bitstreams/75432124-1a2c-4541-a782-396e6c4a0b81/content
https://animaldiversity.org/accounts/Hyracoidea/
https://epub.ub.uni-muenchen.de/17000/1/10_1159_000063714.pdf
https://www.tandfonline.com/doi/epdf/10.1080/00212210.1992.10688671?needAccess=true
https://www.sciencedirect.com/science/article/pii/0300962994902054?via%3Dihub
https://archive.org/details/cbarchive_101826_dailyfoodconsumptionandmodeofi1966/page/n4/mode/1up?view=theater
https://www.sciencedirect.com/science/article/pii/S0277379112003319
https://www.sciencedirect.com/science/article/pii/0300962994902054?via%3Dihub
https://academic.oup.com/mspecies/article-pdf/doi/10.1644/0.645.1/8071557/645-1.pdf
https://www.scientificamerican.com/article/stone-age-animal-urine-could-solve-a-mystery-about-technological-development/
http://www.scielo.org.za/pdf/sajs/v103n11-12/a0410312.pdf
https://pubmed.ncbi.nlm.nih.gov/8529006/
https://doi.org/10.1159/000341387
https://digitallibrary.amnh.org/items/74123930-b874-44d0-8880-3884ae8c0def
https://academic.oup.com/mbe/article/3/5/427/988013
https://www.pnas.org/doi/full/10.1073/pnas.0334222100
https://scholar.sun.ac.za/server/api/core/bitstreams/246b907e-a830-4b8d-9356-8dd5b477868a/content
https://www.biorxiv.org/content/10.1101/2023.12.07.570590v1
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5867853/
https://www.mayoclinic.org/tests-procedures/hemoglobin-test/about/pac-20385075
https://www.nationalgeographic.com/science/article/one-protein-shows-elephants-and-moles-had-aquatic-ancestors
https://www.science.org/doi/10.1126/science.1234192
https://www.science.org/doi/full/10.1126/science.1234192?casa_token=fGrUU96ha78AAAAA:dTIILXBY5Tp3FDQFLD0WmB-kV9SDiDSMxOc_LAxdP4c3OYNawsIK1J5IN08Kd7Y9F7xl8Lj5mecTesg
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/convergent-evolution#:~:text=Convergent%20evolution%20occurs%20when%20species,which%20have%20a%20common%20origin.
------
Images:
https://docs.google.com/document/d/1IJ4Bxw9ElN6XsVN6sPp3kgka7G0Wt5SPwAmI0EUma6U/edit?usp=sharing
Subscribe to the pin club here: https://complexly.store/products/bizarre-beasts-pin-subscription
This month's pin is designed by Kay Powell. You can find out more about them and their work here: https://www.simkaye.com/
You can cancel any time by emailing hello@dftba.com
Follow us on socials:
Twitter: https://twitter.com/bizarrebeasts
Instagram: https://www.instagram.com/bizarrebeastsshow/
Facebook: https://www.facebook.com/BizarreBeastsShow/
#BizarreBeasts #hyrax
-----
Sources:
https://www.researchgate.net/profile/Robert-Eley/publication/235622778_The_hyrax_-_a_most_mysterious_mammal/links/542fa4f20cf277d58e91fa1f/The-hyrax-a-most-mysterious-mammal.pdf
https://www.sciencedirect.com/science/article/pii/B9780123847195000897
https://www.britannica.com/animal/marmot
https://www.departments.bucknell.edu/biology/resources/msw3/browse.asp?id=11400002
https://researchspace.ukzn.ac.za/server/api/core/bitstreams/75432124-1a2c-4541-a782-396e6c4a0b81/content
https://animaldiversity.org/accounts/Hyracoidea/
https://epub.ub.uni-muenchen.de/17000/1/10_1159_000063714.pdf
https://www.tandfonline.com/doi/epdf/10.1080/00212210.1992.10688671?needAccess=true
https://www.sciencedirect.com/science/article/pii/0300962994902054?via%3Dihub
https://archive.org/details/cbarchive_101826_dailyfoodconsumptionandmodeofi1966/page/n4/mode/1up?view=theater
https://www.sciencedirect.com/science/article/pii/S0277379112003319
https://www.sciencedirect.com/science/article/pii/0300962994902054?via%3Dihub
https://academic.oup.com/mspecies/article-pdf/doi/10.1644/0.645.1/8071557/645-1.pdf
https://www.scientificamerican.com/article/stone-age-animal-urine-could-solve-a-mystery-about-technological-development/
http://www.scielo.org.za/pdf/sajs/v103n11-12/a0410312.pdf
https://pubmed.ncbi.nlm.nih.gov/8529006/
https://doi.org/10.1159/000341387
https://digitallibrary.amnh.org/items/74123930-b874-44d0-8880-3884ae8c0def
https://academic.oup.com/mbe/article/3/5/427/988013
https://www.pnas.org/doi/full/10.1073/pnas.0334222100
https://scholar.sun.ac.za/server/api/core/bitstreams/246b907e-a830-4b8d-9356-8dd5b477868a/content
https://www.biorxiv.org/content/10.1101/2023.12.07.570590v1
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5867853/
https://www.mayoclinic.org/tests-procedures/hemoglobin-test/about/pac-20385075
https://www.nationalgeographic.com/science/article/one-protein-shows-elephants-and-moles-had-aquatic-ancestors
https://www.science.org/doi/10.1126/science.1234192
https://www.science.org/doi/full/10.1126/science.1234192?casa_token=fGrUU96ha78AAAAA:dTIILXBY5Tp3FDQFLD0WmB-kV9SDiDSMxOc_LAxdP4c3OYNawsIK1J5IN08Kd7Y9F7xl8Lj5mecTesg
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/convergent-evolution#:~:text=Convergent%20evolution%20occurs%20when%20species,which%20have%20a%20common%20origin.
------
Images:
https://docs.google.com/document/d/1IJ4Bxw9ElN6XsVN6sPp3kgka7G0Wt5SPwAmI0EUma6U/edit?usp=sharing
This furry potato looks an awful lot like a rodent.
It’s got the general size and shape of your typical marmot. It has incisors that keep growing for its entire life, like a rodent.
And heck, could those whiskers lie? But at the mammal family reunion, you won’t find the hyrax sitting by the groundhogs and chinchillas of the world. Instead, its closest relatives hint at something much weirder going on in its evolutionary history.
Because, its actual cousins are elephants and sea cows… and we’re not sure which is closer. [ ♪♪ INTRO ♪♪ ] If you want to support the channel, the Bizarre Beasts pin club is open for subscriptions for the whole month! Sign up by June 20th and the first pin you will get will be one of these incredible fuzzy potatoes. And stick around for the end of the video for some bonus hyrax facts.
There are six or seven extant species of hyraxes, depending on who you ask, and they can be found in the Middle East and throughout much of Africa. They may look cute, but they can sound truly horrible. [Hyrax Noises] Some hyrax species are solitary and live in trees, while others live socially in groups on rock outcrops. And like a lot of animals their size, they eat plants and bugs.
So far, nothing really out of the ordinary here. But before we get into their bizarre family tree, we gotta say that hyraxes have some noteworthy weirdness all their own. As a diurnal species, they can often be found basking in the sun… But this isn’t just a comfort thing: they’re actually not great at regulating their internal body temperature, so they need that extra solar boost to stay warm.
Luckily, they have an easy time climbing and clinging to nice sunny spots thanks to their suction cup feet! The muscular structure of their foot pads combined with some fancy gland secretions help them grip onto surprisingly steep and smooth surfaces. Hyraxes also don’t eat like most other animals.
Their front teeth may at first glance look like the gnawing incisors used by rodents, but they’re actually simple tusks used for displays and for grooming. So they have to turn their heads sideways to bite with their molars – teeth that scientists at one point thought more closely resembled those of rhinos and horses – and then chew normally. From there, things go right back to strange again when the food makes its way into their unique multi-chambered digestive system that ferments with the help of microbes, a lot like in cows and other ruminants.
But unlike true ruminants, hyraxes don’t regurgitate a cud to continue chewing – their digestive system is one-way. And because they live in such dry habitats, hyraxes also have pretty efficient kidneys that help them conserve water. This means that their urine is extra concentrated when nature finally calls, and it quickly dries into something resembling molasses.
Social hyrax species often use middens, effectively common bathroom mounds, to do their business, creating mountains of pee crystals that fossilize over time. And fossilized hyrax waste is so abundant and unique that it even gets its own special mineral name: hyraceum. Fossilization of this thick, quick-drying urine can also capture environmental data, like atmospheric radioisotopes and airborne pollen – you can think of it as a less glamorous version of the “insect in amber” effect.
So while colder regions can use ice cores as time capsules for studying climate change, South Africa gets to use huge piles of fossilized hyrax pee. All of that is weird and wild enough, but let’s get back to the common ancestor of the elephant in the room: what is the deal with hyrax taxonomy? They look like rodents.
They digest sort of like ruminants. They chew with teeth like horses’. They have incisors that are kinda like tusks.
So where in the mammal family tree do they fit in? By looking at bones and later at proteins, scientists have concluded that hyraxes belong in a clade called Paenungulata, literally “almost ungulates”. This group is comprised of the orders Proboscidea (elephants), Sirenia (manatees and dugongs), and Hyracoidea (our friends, the hyraxes).
The Paenungulates likely arose roughly 65 million years ago, when mammals really started to go nuts after the dinosaurs were gone. And although grouping these three orders together has been pretty agreed upon since the mid-20th century, figuring out how exactly each order is related to the other two has been messy. Comparisons using anatomy, amino acids, and different gene sets have each given contradictory answers.
Even with the help of increasingly sophisticated DNA tools, we still don’t have a totally clear answer as to which of the three orders branched off when – in other words, between hyraxes, elephants, and sea cows, we still can’t really tell who’s more closely related to whom. Right now, there is basically equal molecular evidence supporting any of the three possible arrangements… Hyracoidea could have split off first from Proboscidea and Sirenia, Sirenia could be an outgroup to Proboscidea and Hyracoidea, or Hyracoidea and Sirenia could be more closely related to each other than to Proboscidea. And the persistence of this uncertainty makes it very possible that this specific case is an example of a polytomy.
A polytomy is when speciation occurs not as a two-way branching event on a phylogenetic tree, but as a simultaneous branching of three or more species from the same common ancestor. Usually this is simply a placeholder in an evolutionary tree until we can figure out which species branched off first, which is a scenario called a “soft polytomy.” But it is possible for a three-way species radiation to be, for all intents and purposes, truly simultaneous – or, a “hard polytomy.” And chromosomal evidence suggests that radiation among the Paenungulata orders took 4 to 7 million years, and the latest genetic analyses suggest that this radiation began from an honest-to-goodness hard polytomy. So hyraxes don’t just have surprising relatives: their speciation represents a rare evolutionary occurrence as well!
And to cap it off, according to some researchers, these screaming teddy bears may also have an aquatic background. Red blood cells contain the protein hemoglobin, which transports oxygen and iron throughout the body. Muscles contain a similar molecule called myoglobin, and animals that dive deep underwater and hold their breath for a long time tend to have high concentrations of extra-positively charged myoglobin molecules in their muscles.
The positive charge causes the molecules to repel each other, allowing myoglobins to be highly concentrated in the muscles without sticking together and becoming useless. And this extra myoglobin helps diving animals maximize their oxygen usage until they can get another breath. Hyraxes and elephants have this same telltale pattern of more myoglobin than most terrestrial animals and extra-charged myoglobin in their muscles.
It’s not as extreme as it is in, say, modern whales, but it is significantly higher than in species with strictly terrestrial mammal ancestors. Because scientists have yet to pinpoint the exact nature of the evolutionary branching of the Paenungulates, we can’t say for sure who this past aquatic common ancestor was. But all signs point to Proboscideans, Sirenians, and Hyracoideans descending from one of the earliest known placental mammals to become underwater specialists.
You might see a weird, rock-hopping, guinea pig-looking critter today, but appearances alone don’t tell a fraction of the long and storied history in play here. So the evidence is in! Hyraxes definitely are not rodents, and definitely are the way-cool descendants of a common, possibly aquatic, ancestor of elephants and sea cows.
And their superficial similarities to rodents can be chalked up to convergent evolution – occupy the same ecological niche long enough, and you’ll eventually end up with unrelated species who share similar adaptations. The confusion about the hyrax’s lineage is a reminder that taxonomy, for all its structure and rules, is at the end of the day a human construct. We love to understand the world around us, what things are, and where they come from, but our tools for answering these questions always have limits.
And as those tools become increasingly sophisticated, we can potentially solve more of these evolutionary mysteries, making beasts like the hyrax seem less bizarre to us. Don’t forget to sign up for the pin club at BizarreBeastsShow.com by June 20th if you want one of these little potato-guy pins. And now for some bonus facts… [ ♪♪ BONUS FACTS ♪♪ ] Okay, hyraxes are just so weird that we couldn’t fit all their weirdness into the main part of the video, so here are a couple of bonus facts: We mentioned that hyraxes aren’t great at regulating their own body temperatures, so along with basking in the sun, rock hyraxes will also do a behavior called ‘heaping’ to keep warm.
And that’s pretty much exactly what it sounds like. The hyraxes will pile themselves together in a furry little stack in their den to conserve body heat, which sounds adorable, to be honest. Hyraxes also have relatively long gestation periods for mammals of their size, something like six to eight months.
And it’s been suggested that this is just an evolutionary leftover from their ancestors, many of whom were much bigger – up to rhino-sized! [ ♪♪ OUTRO♪♪ ]
It’s got the general size and shape of your typical marmot. It has incisors that keep growing for its entire life, like a rodent.
And heck, could those whiskers lie? But at the mammal family reunion, you won’t find the hyrax sitting by the groundhogs and chinchillas of the world. Instead, its closest relatives hint at something much weirder going on in its evolutionary history.
Because, its actual cousins are elephants and sea cows… and we’re not sure which is closer. [ ♪♪ INTRO ♪♪ ] If you want to support the channel, the Bizarre Beasts pin club is open for subscriptions for the whole month! Sign up by June 20th and the first pin you will get will be one of these incredible fuzzy potatoes. And stick around for the end of the video for some bonus hyrax facts.
There are six or seven extant species of hyraxes, depending on who you ask, and they can be found in the Middle East and throughout much of Africa. They may look cute, but they can sound truly horrible. [Hyrax Noises] Some hyrax species are solitary and live in trees, while others live socially in groups on rock outcrops. And like a lot of animals their size, they eat plants and bugs.
So far, nothing really out of the ordinary here. But before we get into their bizarre family tree, we gotta say that hyraxes have some noteworthy weirdness all their own. As a diurnal species, they can often be found basking in the sun… But this isn’t just a comfort thing: they’re actually not great at regulating their internal body temperature, so they need that extra solar boost to stay warm.
Luckily, they have an easy time climbing and clinging to nice sunny spots thanks to their suction cup feet! The muscular structure of their foot pads combined with some fancy gland secretions help them grip onto surprisingly steep and smooth surfaces. Hyraxes also don’t eat like most other animals.
Their front teeth may at first glance look like the gnawing incisors used by rodents, but they’re actually simple tusks used for displays and for grooming. So they have to turn their heads sideways to bite with their molars – teeth that scientists at one point thought more closely resembled those of rhinos and horses – and then chew normally. From there, things go right back to strange again when the food makes its way into their unique multi-chambered digestive system that ferments with the help of microbes, a lot like in cows and other ruminants.
But unlike true ruminants, hyraxes don’t regurgitate a cud to continue chewing – their digestive system is one-way. And because they live in such dry habitats, hyraxes also have pretty efficient kidneys that help them conserve water. This means that their urine is extra concentrated when nature finally calls, and it quickly dries into something resembling molasses.
Social hyrax species often use middens, effectively common bathroom mounds, to do their business, creating mountains of pee crystals that fossilize over time. And fossilized hyrax waste is so abundant and unique that it even gets its own special mineral name: hyraceum. Fossilization of this thick, quick-drying urine can also capture environmental data, like atmospheric radioisotopes and airborne pollen – you can think of it as a less glamorous version of the “insect in amber” effect.
So while colder regions can use ice cores as time capsules for studying climate change, South Africa gets to use huge piles of fossilized hyrax pee. All of that is weird and wild enough, but let’s get back to the common ancestor of the elephant in the room: what is the deal with hyrax taxonomy? They look like rodents.
They digest sort of like ruminants. They chew with teeth like horses’. They have incisors that are kinda like tusks.
So where in the mammal family tree do they fit in? By looking at bones and later at proteins, scientists have concluded that hyraxes belong in a clade called Paenungulata, literally “almost ungulates”. This group is comprised of the orders Proboscidea (elephants), Sirenia (manatees and dugongs), and Hyracoidea (our friends, the hyraxes).
The Paenungulates likely arose roughly 65 million years ago, when mammals really started to go nuts after the dinosaurs were gone. And although grouping these three orders together has been pretty agreed upon since the mid-20th century, figuring out how exactly each order is related to the other two has been messy. Comparisons using anatomy, amino acids, and different gene sets have each given contradictory answers.
Even with the help of increasingly sophisticated DNA tools, we still don’t have a totally clear answer as to which of the three orders branched off when – in other words, between hyraxes, elephants, and sea cows, we still can’t really tell who’s more closely related to whom. Right now, there is basically equal molecular evidence supporting any of the three possible arrangements… Hyracoidea could have split off first from Proboscidea and Sirenia, Sirenia could be an outgroup to Proboscidea and Hyracoidea, or Hyracoidea and Sirenia could be more closely related to each other than to Proboscidea. And the persistence of this uncertainty makes it very possible that this specific case is an example of a polytomy.
A polytomy is when speciation occurs not as a two-way branching event on a phylogenetic tree, but as a simultaneous branching of three or more species from the same common ancestor. Usually this is simply a placeholder in an evolutionary tree until we can figure out which species branched off first, which is a scenario called a “soft polytomy.” But it is possible for a three-way species radiation to be, for all intents and purposes, truly simultaneous – or, a “hard polytomy.” And chromosomal evidence suggests that radiation among the Paenungulata orders took 4 to 7 million years, and the latest genetic analyses suggest that this radiation began from an honest-to-goodness hard polytomy. So hyraxes don’t just have surprising relatives: their speciation represents a rare evolutionary occurrence as well!
And to cap it off, according to some researchers, these screaming teddy bears may also have an aquatic background. Red blood cells contain the protein hemoglobin, which transports oxygen and iron throughout the body. Muscles contain a similar molecule called myoglobin, and animals that dive deep underwater and hold their breath for a long time tend to have high concentrations of extra-positively charged myoglobin molecules in their muscles.
The positive charge causes the molecules to repel each other, allowing myoglobins to be highly concentrated in the muscles without sticking together and becoming useless. And this extra myoglobin helps diving animals maximize their oxygen usage until they can get another breath. Hyraxes and elephants have this same telltale pattern of more myoglobin than most terrestrial animals and extra-charged myoglobin in their muscles.
It’s not as extreme as it is in, say, modern whales, but it is significantly higher than in species with strictly terrestrial mammal ancestors. Because scientists have yet to pinpoint the exact nature of the evolutionary branching of the Paenungulates, we can’t say for sure who this past aquatic common ancestor was. But all signs point to Proboscideans, Sirenians, and Hyracoideans descending from one of the earliest known placental mammals to become underwater specialists.
You might see a weird, rock-hopping, guinea pig-looking critter today, but appearances alone don’t tell a fraction of the long and storied history in play here. So the evidence is in! Hyraxes definitely are not rodents, and definitely are the way-cool descendants of a common, possibly aquatic, ancestor of elephants and sea cows.
And their superficial similarities to rodents can be chalked up to convergent evolution – occupy the same ecological niche long enough, and you’ll eventually end up with unrelated species who share similar adaptations. The confusion about the hyrax’s lineage is a reminder that taxonomy, for all its structure and rules, is at the end of the day a human construct. We love to understand the world around us, what things are, and where they come from, but our tools for answering these questions always have limits.
And as those tools become increasingly sophisticated, we can potentially solve more of these evolutionary mysteries, making beasts like the hyrax seem less bizarre to us. Don’t forget to sign up for the pin club at BizarreBeastsShow.com by June 20th if you want one of these little potato-guy pins. And now for some bonus facts… [ ♪♪ BONUS FACTS ♪♪ ] Okay, hyraxes are just so weird that we couldn’t fit all their weirdness into the main part of the video, so here are a couple of bonus facts: We mentioned that hyraxes aren’t great at regulating their own body temperatures, so along with basking in the sun, rock hyraxes will also do a behavior called ‘heaping’ to keep warm.
And that’s pretty much exactly what it sounds like. The hyraxes will pile themselves together in a furry little stack in their den to conserve body heat, which sounds adorable, to be honest. Hyraxes also have relatively long gestation periods for mammals of their size, something like six to eight months.
And it’s been suggested that this is just an evolutionary leftover from their ancestors, many of whom were much bigger – up to rhino-sized! [ ♪♪ OUTRO♪♪ ]