4.7. Vertebrates: Successes of Life With a Backbone

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來自 University of Illinois at Urbana-Champaign 的課程

Emergence of Life

60 個評分

University of Illinois at Urbana-Champaign

Emergence of Life

60 個評分

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.

從本節課中

Week 4 - Paleozoic Life After the Advent of Skeletons

This week, you'll learn more about the Cambrian Explosion, which led to the development of external hard skeleton components at 542 million years before present. The initial successes of the invertebrates were shortly followed by the appearance of vertebrates with internal skeletons. Life then utilized these newfound evolutionary capabilities, beginning distinct cycles of radiation, diversification, and extinction, which define the three great Eukarya faunas of the Phanerozoic.

4.1. Cycles of Radiation and Extinction7:33

4.2. Cambrian Explosion3:43

4.3. Cambrian Fauna: Origin of Vertebrates14:40

4.4. Burgess Shale Experiment5:38

4.5. Invertebrates: Successes of Life Without a Backbone18:26

4.6. Paleozoic Fauna12:06

4.7. Vertebrates: Successes of Life With a Backbone3:28

4.8. Evolution of Jaws and Perfecting Predation13:15

4.9. Heavily Armored Fish Without Jaws6:44

4.10. Fish Evolution: Hook, Line, and Sinker10:16

與講師見面

Bruce W. Fouke, Ph.D.
Director of the Roy J. Carver Biotechnology Center
Department of Geology, Department of Microbiology, and Institute for Genomic Biology

[MUSIC]

I'm Carli Miller at the University of Illinois, and

the topic of discussion today is the Phylum Chordata and

the Subphylum Vertebrata of which you are a member.

So you are a vertebrae, and we will be discussing the specific characteristics

that define this phylum and the subphylum.

And the reason why we would like to go into depth with this

is because we are kind of marching through geologic time and

we're observing that organisms are getting more and

more complex, more organized, and generally more sophisticated.

So there are three common characteristics that the phylum chordata exhibits during

their ontogeny, which is development from the embryological stage to adulthood.

And the first of those common characteristics is the presence of

a hollow dorsal neural tube.

And what that is, is it basically comprises your spinal cord and your brain,

so your central nervous system.

Secondly, there is the presence of a notochord, which again

is some kind of axial support, usually going up the dorsal side of the organism.

So it's providing support for that organisms body.

Lastly, it will exhibit gill slits which

is a way of drawing in oxygen from your environment and

even you have exhibited gill slits some point in your embryological stages.

So that is the third common characteristic that an organism in the final chordata

will exhibit.

So, if we're going down in taxonomical hierarchy,

we're now in the sub filing vertebrata which is a member of the phylum chordata.

And these organisms also exhibit certain characteristics.

And kind of the primary one that distinguished a vertebrate,

from an invertebrate, for example, is that the notochord

which again provides that axyl support is surrounded or replaced by vertebrae.

So those vertebrae can be actually composed of a softer cartilage material or

hard bone.

And so that's actually important to consider because if we think back to

how an organism is preserved in the rock record, those soft versus hard parts,

could introduce a bias in the fossil record.

So, an organism with a cartilaginous vertebra or

vertebral column may not be as well or as accurately represented in the rock record

as a really robust hard skeleton would be represented.

So what we need to consider moving forward when thinking about

the organisms as they emerge and radiate through geologic time is that any

organism in the subphylum vertebrata will exhibit these features.

And so that's just something that we want to keep in mind if we're thinking

about fish, to tetrapods, to amphibians, to mammals, dinosaurs, and

all the way up through modern day humans.

[MUSIC]

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