"Exploring the Development History of Animals" PPT courseware

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"Exploring the Development History of Animals" PPT courseware

Have these creatures on earth been what they are today since ancient times? What were human ancestors like?

giant panda

The ancestors of giant pandas appeared 2 to 3 million years ago. Hundreds of thousands of years ago was the heyday of the giant panda. Later, animals in the same period became extinct one after another. However, the giant panda has survived to this day and maintained its original ancient characteristics. Therefore, it has a lot of scientific value.

The crocodile is the earliest and most primitive reptile found to be alive so far. It evolved from amphibians about 200 million years ago. It is a contemporary animal with the dinosaurs.

Horse fossil explanation: Modern horses evolved from Eohorse.

Fossils from 50 million years ago prove that Archeopteryx was only as big as a modern fox, had 4 toes on its front feet and 3 on its hind feet, and lived in the woods.

Fossils from 40 million years ago prove that horses are as big as modern sheep, with three toes on their front feet and three toes on their hind feet. They still live in the woods.

Fossils from 20 million years ago prove that horses entered the grassland life. The horse's limbs lengthened, and the middle toe grew into the only toe that touched the ground, enhancing its ability to run fast.

Fossils from 10 to 3 million years ago prove that the body shape of horses is basically similar to that of today's horses. Only the middle toes of the front and rear limbs touch the ground, and the side toes on both sides have degenerated, allowing them to run very fast.

3. The Evolutionary History of Horses

1. The evolution and reasons of horse body structure

(1) Evolutionary facts of horse body structure

individual toe

small——→large polytoed——→single toe

Crown

Low crown - → high crown

(2) Reason

①Internal factors: variation, selection, heredity, adaptation

②External factors:

forest life grassland life

Eat juicy young leaves Eat hay

Haunting in the forest and active in the grassland

Expand your knowledge: Living fossils refer to a species that has not evolved for a long time and is still an extant species. These creatures have changed little over millions of years. Correspondingly, some ancient creatures were formed that lasted for tens of millions of years. Other creatures of the same era had long since become extinct, and only they remained.

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Update Time: 2024-10-05

This template belongs to science courseware E-education edition sixth grade science volume 2 industry PPT template

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