How did life emerge on Earth? How have life and Earth co-evolved through geological time? Is life elsewhere in the universe? Take a look through the 4-billion-year history of life on Earth through the lens of the modern Tree of Life! This course will evaluate the entire history of life on Earth within the context of our cutting-edge understanding of the Tree of Life. This includes the pioneering work of Professor Carl Woese on the University of Illinois Urbana-Champaign campus which revolutionized our understanding with a new "Tree of Life." Other themes include: -Reconnaissance of ancient primordial life before the first cell evolved -The entire ~4-billion-year development of single- and multi-celled life through the lens of the Tree of Life -The influence of Earth system processes (meteor impacts, volcanoes, ice sheets) on shaping and structuring the Tree of Life This synthesis emphasizes the universality of the emergence of life as a prelude for the search for extraterrestrial life.
7.8. The Primates
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Do curso por University of Illinois at Urbana-Champaign
Emergence of Life
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Week 7 - Cenozoic Mammals and Global Environmental Change
With the demise of the dinosaurs, mammals rapidly radiated and diversified during the Cenozoic. The combination of abundant food sources and significant fluctuations in global climate fostered extreme variations in morphology, body size, and interaction with the environment. You'll learn why mammals had a distinct advantage over previous groups, and you'll also have the opportunity to explore multiple theories on primate and hominoid evolution in the context of global conditions during this period.
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Bruce W. Fouke, Ph.D.Director of the Roy J. Carver Biotechnology Center
Department of Geology, Department of Microbiology, and Institute for Genomic Biology
[SOUND]
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Today we're talking about primates.
All right, so we're going to get into great detail
about this group of mammals and so, hold onto your hats.
[LAUGH] All right, this is going to be a good one.
I wish we had some live specimens here but
we'll make due with our little casts here of their skulls, that'll be just fine.
All right, so this is an order, taxonomically, the order Primates, and
this order is characterized by their agility in trees, something I wish I had.
Their agility in trees in general and they have a large brain and acute vision.
Additionally, they have a kind of more of a flattened face that allows for
stereoscopic vision.
So stereoscopic vision means that the eyes are positioned such that they can focus on
one object and perceive depth, basically.
So stereoscopic vision is specific to primates.
Additionally, their parental care is unique in that
it's attentive [LAUGH] if you will.
You probably know this.
So their parental care is attentive, and they actually have relatively long lives
with respect to other mammals and other organisms.
So primates range in weight from 30 grams, tiny, a pygmy mouse lemur,
to a 175 kilograms with your gorilla, that's a huge range.
So the earliest probable primates was around the Late Cretaceous, and
radiation of true primates occurred in the Eocene, so much later actually.
And that radiation kind of started with the emergence of lemur-like tree climbers.
The closest non-primate relative is Scandentia,
and those are your tree shrews.
So tree shrews have padded fingers, and
have an unusually large brain for a mammal.
So we're kind of getting towards that large brain case, that large brain,
that primates exhibit.
So primate evolution has been mapped out with some degree of certainty.
There's definitely some missing puzzle pieces.
But I'd kind of like to walk you through, from the order level taxonomically all
the way up to the super family group that will be referring today.
So I kind of want give you a chart here, that you can
follow as we throw out some of these names out of the taxonomical groups.
So it starts at the bottom with Primates as the order.
It branches into two suborders, Strepsirrhini and Haplorrhini.
We're going to follow Haplorrhini even more in-depth and
Haplorrhini branches into two infraorders, the Tarsiers and Anthropoidea.
The Anthropoidea infraorder branches into Platyrrhini,
a parvorder and Catarrhini another parvorder.
Following Catarrhini a little bit more closely,
that parvorder divides into Hominoidea and Cercopithecoidea, and
these are two super families that we'll be discussing today.
So we can dive in here with our first group the Strepsirrhini,
these are your lemurs, lorises and galigos.
And they're identified by their wet noses actually, so that's a distinguishing
morphological feature or function, is the presence of a wet nose, interesting.
They have a smaller brain to body ratio than other primates and
they're mostly nocturnal and tree-dwelling.
The group Haplorrhini includes your tarsiers and your anthropoidea.
And your tarsiers are generally unlike primates.
And it's kind of been a source of contention,
as far as where the tarsiers actually belong in this evolutionary process so,
in their phylogenetic relationship with the other primates.
So it's just something to keep in mind.
So they're generally unlike other primates.
And the other group is the anthropoidea.
Anthropoidea is then divided into several groups that we've mentioned before and
we'll start with the Platyrrhini.
Platyrrhini arose in the Oligocene and persist in the recent, and
they're called New World monkeys.
So if you hear that term, the New World monkeys,
are referring to this group Platyrrhini.
And they live in Central and South America.
So our New World monkeys here, we have a skull of a New World monkey.
And the New World monkeys actually have prehensile tails that can be used as
a fifth limb.
So that's what prehensile means, it actually can be used as another limb.
So probably very advantageous when you're climbing through the trees, I'm sure.
And the name Platyrrhini refers to, it actually means flattened nose.
So we're kind of referring to their facial structure here, so Platyrrhini.
And some of the New World monkeys actually lack an opposable thumb,
something to note.
And they have an extra premolar with reference to the Old World monkeys,
the next group we'll talk about, and the apes.
So if we can take a look a little bit closer here,
we're identifying this group of primates based on the dental formula.
So we have our incisors in the front, our canines are next.
And then starting to get towards the back of the mouth, we have one,
two, three premolars, and one, two, three molars.
So that dental formula it's two, one, three, three on the top and two,
one, three, three on the bottom.
That actually distinguishes your New World monkeys from your Old World monkeys.
The next group within anthropoidea are the Catarrhini primates.
They arose in the legosyne and persist in the recent and within Catarrhini we're
going to zero in on the cercopithecoidea, and these are your Old World monkeys.
Let's get our big example here of Old World monkeys.
All right, we have a big gorilla here and so I'll put him down to continue.
All right, so we're zeroing in on these large primates, our Old World monkeys.
That refers to, Old World refers to Africa and Asia, actually here.
And Old World monkeys lack a prehensile tail.
And they have narrow,
kind of downward pointing nostrils, which is different from the Platyrrhini,
which kind of had up, remember, that was named for their flat face.
Their nostrils kind of facing forward actually, or pointing forward.
These have narrow, downward pointing nostrils.
Their dental formula, lets see who is it going to be?
All right, how about this one?
So their dental formula distinguishes them from the New World monkeys.
And so we can go through here again really quickly,
starting in the mesial part of the jaw, the midline.
We have two incisors, one canine, two premolars actually.
And that's the distinction between Old and New World monkeys,
these two premolars, and the three molars.
Examples of Old World monkeys are your baboons and other African monkeys.
So our next super family within our group Catarrhini are your Hominoidea.
And so here's where we start marching through the trek in human evolution
towards our modern day Homo sapiens.
So within the superfamily Hominoidea, we have two families,
the Hylobatidae and the Hominidae.
So I know we've got a lot of similar terms here, so
let's just try to keep those straight, and I'll try to be clear and concise.
So our Hylobatidae are your gibbons and siamangs, and
these are termed your lesser apes.
Your lesser apes and they're the fastest of all animals in the trees.
So this Hylobatidae group, or gibbons and siamangs,
these are your fastest animals in the trees.
Pretty interesting there, good group.
The Hominidae, these are your orangutans, African apes, and humans.
All right, so we're Hominidae here.
And these are termed greater apes, great apes.
So the Hominidae, this group, they evolved in East Africa and
some moved into Asia and now represented by orangutans.
Kind of an interesting note here, just, I want to bring this up.
There's a group within your Hominidae called Gigantopithecus.
And Gigantopithecus was thought to arise around 5 million years ago and
maybe persisted until about 100,000 years ago.
But that end date is under contention so
we'll see how that works out in the future here.
But Gigantopithecus lived in southeast China, and is the largest known ape.
And here's where you're going to knock your socks off.
So Gigantopithecus was six to nine feet tall.
Whoa, that is a huge primate.
Six to nine feet tall, and over 600 pounds.
Holy smokes, that is a really huge, huge primate.
And something kind of interesting, if we could add a little mythical element here,
Gigantopithecus was thought to maybe inspire these stories of Yetis or
Big Foot or Sasquatch, who knows.
So Gigantopithecus is kind of an interesting primate there.
So the split between apes and
humans is thought to be approximately around 7 million years ago.
And if we could kind of define a human, the features that we would
identify are that we have a larger brain, and we're bipedal.
So that's actually distinct with humans in contrast to some of the other apes,
or the other primates, is we're bipedal, meaning walking and
running on two legs or two limbs.
So it's thought that the walking came first and
then the development of the larger brain actually followed that process.
So the larger brain is only found in the genus Homo, which again,
these dates could be altered a little bit with further research,
but the genus Homo in around 2 million years ago.
So something to keep in mind there, that walking is thought to have come first, and
then the development of that larger brain.
So adaptations for walking included a non-opposable toe, you may have noticed
that on your own body, a non-opposable toe, and a straight hinged knee actually.
So it kind of bends forward and
backward as opposed to kind of projecting out to the side more.
So a straight hinged knee.
And then the foramen magnum, if I could pick up one of our specimens here.
The foramen magnum is this huge window basically,
this large hole at the base of the skull that allows the passage
of the spinal cord to go into the brain basically, to connect with the brain.
And so here we have our Old World ape.
And on a human skull we also have that foramen magnum.
And what we want to look at is the position of that opening,
where it is on the skull with relation to the rest of his body.
So if can refer back to our interesting gorilla here,
you'll see that the foramen magnum is kind of towards the back of the skull,
towards of the back of the skull here.
And I'll, again, contrast to our human,
Where the foramen magnum, is actually almost in the center,
almost in the center of the skull, so pointing downward.
And what we're referring to here is how was the head to body kind of angle, or
position, how did that differ between those two groups?
So you can imagine, if you're standing upright, your support system,
your axial support,
your spinal cord is almost going to be going into the middle of your head.
Whereas if you're kind of crouched over, if you're quadrupedal,
that foramen magnum would be in the back of your skull projecting kind of almost at
an angle back towards the ground.
So this is something that distinguishes humans from other apes,
is that position of the foramen magnum.
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