The Evolution of Mammals (Every Mammal Family Explained)

Table of Contents:
Introduction (0:00)
The First Synapsids In The Paleozoic (0:38)
Mammal Ancestors In The Mesozoic And The First True Mammals(3:47)
Monotremes (9:29)
Eutheria (10:51)
Marsupials (11:45)
Placentals (17:08)
Placentals: Atlantogenata (17:57)
Placentals: Euarchontoglires (20:38)
Placentals: Laurasiatheria (28:15)

Mammals are a fascinating group of animals that can be found everywhere on Earth, from the land to the seas to the skies. From small rodents like mice and rats to behemoths like elephants and whales, mammals are found in all kinds of shapes and sizes, occupying numerous environmental niches. This rich grouping of animals comprises a vast network of different lineages and in this video I want to explain the origins and the spread of mammals. As such this video will be broken up into two parts: in the first I will cover the evolution of mammals, and in the second I’ll be going over the major extant orders and explaining every living mammalian family.

Image Credits:
WillemSVDMerwe
Julio Lacerda

Sources:
Handbook of the Mammals of the World
Steve Brusatte

[timothymoore]

I absolutely loved the video one small complaint is I wish you would’ve brought up humans when you mentioned great apes I think it’s very important to acknowledge that we are also animals especially since a lot of people don’t actually know where we fit.

[baleighhoenshell]

when i was a kid i was obsessed with animals, i wanted to be a vet or a marine biologist or a dog trainer or a herpetologist or a conservationist, list goes on and on. as a result, i used to get tons of nonfiction books as christmas and birthday gifts, huge encyclopedias and hardcover treasure troves of information. but i was so so young that i enjoyed moreso the concept of these books than actually being able to appreciate all the information, and unfortunately i had to donate almost every single one in high school, with the thought process that my childhood animal-dreams were dead. this video is so close to those euphoric memories i had of reading through all those books, except now as an adult it actually makes way more sense and is. honestly that much more fun. thank you so much for giving that back to me and reminding me how important it is and was to me

[navrongo]

Periodically referring back to a family tree would have been very helpful for orientation. Good video.

[clemnthyme]

im taking mammalogy this semester, and it really helps to have such a nice overview of mammal phylogeny. i can only imagine how much work this took! amazing job!

[hollylogue]

I was raised in a Young Earth Creationist cult environment and I want to thank you, so genuinely, for being so thorough and easy to understand.

[whatabouttheearth]

"these animals were not reptiles". Thank you! It drives me nuts when people say mammals came from reptiles, Reptiliomorpha is not Eureptilia (reptile), Eureptilia is down from Sauropsida, the sister clade to Synapsida.

[xel_nave]

Knowing about early synapsids still baffles me. I'm used to thinking since I was a child that reptiles basically ruled the land and our ancestors only got a chance when the dinosaurs died out so it's still a pretty wild idea that our ancestors (or those our ancestors are related to) were the dominant group before even the dinosaurs.

[ThePlayfarer]

Makes me appreciate just how varied us mammals are.

[YuBeace]

I just saw so many animals I had never seen before, even those who weren’t extinct and I somehow still hadn’t known about. The world is so vast.

[Ibian]

Honestly did not expect to sit through this whole thing. Very interesting to see whales progressing from horrifying rat/gator hybrids to the noble creatures we have today.

[PantheraRex]

No way, I was trying to make a phylogeny of every mammal family coincidentally. This is amazing. Just finished Ferae, now I'm starting with the Ungulates

[ivanscottw]

I'd love to see series on
the evolution of arthropodes
- Insects
- Arachnids and consort
- Crustacean
- You name it (probably missed some)..
The evolution of mollusks
- shelled vs non shelled.. why and how...
- gasteropods, cephalopods, bivalves

Also a video about the emergence of symmetry (axial, bilateral - notion of up and down/head and tail - evolutionary advantage of each strategy) in the Animalia kingdom, and the evolution of non-symmetric animals (sponge, corals..) and how symmetry emerged ? (Jellyfish ?)

[tuckercaldwell]

This was awesome! I love how in-depth you were despite covering such an enormous group of animals I'd love to see more videos like this!

[glenngilbert]

You've done a fantastic job - now I realise how outdated my knowledge of mammal lineage actually is

[DanielDavis]

Fun Fact: Placentia is a bit of a misnomer because the Marsupials also use a placenta. The difference is in the length of time the babies remain in the womb and stage of development when they're born. Placentals keep the baby in the womb much longer than marsupials and have a much more developed placenta.

[anniecampbell]

i used your channel in my sources for a mammalian evolution essay i did for my finals and now you have a whole video on the subject lol i love ur content sm

[prototropo]

It's really illuminating to have all the clades mentioned, with selected illustrations. Because otherwise, I think it's too easy to settle into our easy memory of the big or charming mammals, like tigers, rabbits, armadillos, bears, kangaroos, beavers, antelope, platypus, lions, boars, zebras, sloths, elephants, bats, giraffes, moles, rhinos, foxes, anteaters, porcupines, monkeys and whales. In other words, all the animals that get a place of honor in childhood media programming because they lend themselves to caricature for graphic images and personality for animated cartoons.
But those media ignore the beauty and intrigue of rare, unexpected and less familiar species of the enormous mammalian evolutionary tree. Consequently, even adults with PhDs in mathematics or chemistry might not know the difference between the sugar glider, flying squirrel and fruit bat, and how distant or different their origins. The distinctions we easily absorbed about dinosaurs, thanks to great books and movies about them, haven't been extended to the general grasp of equivalent distinctions in mammalian evolution. Most people, for example, assume seals, manatees and whales are closely related, which is far from the case. The reasons they have dramatically different ancestry are utterly fascinating, and yet the evolutionary history of mammals are probably far less understood by the supposedly educated public than are dinosaurs, living reptiles or birds. How many kids or science-literate adults can confidently describe the differences between monotremes, marsupials and placentals? Probably far fewer than those who can explain the pterosaur, ichthyosaur, dinosaur divide.
And that ignorance begins with widespread unfamiliarity about the earliest branching of synapsids and sauropsids, far earlier in the history of terrestrial animals than almost anyone understands--many millions of years before dinosaurs thundered over the Earth, or into our imaginations, or across modern movie screens! The film and book industry really should see the mammals' story, in the Cenozoic especially, as the goldmine it could be for educational textbook and entertainment creativity. Oh, and perhaps museum collections, university graduate programs and research grants, as well?

[Dunkleosteusenjoyer]

This video must have been a lot of work. It turned out great. Thank you.

[allenbanks]

Good god, this is a crazy amount of information to put together! I enjoyed just sitting back and listening, every once in a while recognizing one of the names (particularly for the earlier ones). Thank you for doing all of this!

[billyr]

Humans are just another mammal, and shouldn't be ignored. Simply because we can use complex communication methods doesn't mean we aren't mammals. Why you exclude humans from the video is beyond me.