Dragonfly

Dragonflies did not have folded wings.

Musée du Séminaire de Sherbrooke

© Musée du Séminaire de Sherbrooke. All Rights Reserved.


Insects, spiders and scorpions are arthropods. They were the first animals to emerge from the water and they did so 400 million years ago. When the law of the jungle took hold, some insects developed an ingenious way to evade predators: they began to fly. This was just the beginning of their incredible diversification and proliferation.

The first insects were tiny. Yet 100 million years later, some had grown wingspans of 70 centimetres. Many were unable to close their wings. These insects couldn’t hide from predators as easily, and so they died out (except for a few species like the dragonfly).
Insects, spiders and scorpions are arthropods. They were the first animals to emerge from the water and they did so 400 million years ago. When the law of the jungle took hold, some insects developed an ingenious way to evade predators: they began to fly. This was just the beginning of their incredible diversification and proliferation.

The first insects were tiny. Yet 100 million years later, some had grown wingspans of 70 centimetres. Many were unable to close their wings. These insects couldn’t hide from predators as easily, and so they died out (except for a few species like the dragonfly).

© 2001, CHIN. All Rights Reserved.

Within 225 million years, insects had developed a complex system of joints. As a result, they could fold their wings over their bodies. Wingless insects, however, evolved little. Surprisingly enough, cockroaches, mayflies, grasshoppers, bedbugs, spiders, centipedes and several other arthropod have survived 300 million years without any major evolutionary change. In fact, no other creatures have evolved so little.

In the early Cretaceous period, a few families of insects hadn’t yet emerged. Not until flowering plants began sprouting did pollinating insects appear.
Within 225 million years, insects had developed a complex system of joints. As a result, they could fold their wings over their bodies. Wingless insects, however, evolved little. Surprisingly enough, cockroaches, mayflies, grasshoppers, bedbugs, spiders, centipedes and several other arthropod have survived 300 million years without any major evolutionary change. In fact, no other creatures have evolved so little.

In the early Cretaceous period, a few families of insects hadn’t yet emerged. Not until flowering plants began sprouting did pollinating insects appear.

© 2001, CHIN. All Rights Reserved.

Cockroaches

Cockroaches were already very widely distributed during the Cretaceous.

Musée du Séminaire de Sherbrooke

© Musée du Séminaire de Sherbrooke. All Rights Reserved.


The first land vegetation can be traced back about 425 million years. These small, simple plants spread and diversified. Some 100 million years later, they’d given way to lush forests of ferns and gymnosperms (trees with naked seeds).

In the early Cretaceous period, gymnosperms continued to dominate the flora on the continents. Yet several species were in serious decline, with only conifers flourishing. In the middle Cretaceous period, angiosperms appeared. These flowering plants enclosed their seeds in an ovary. By the late Cretaceous period, angiosperms dominated the landscape. Angiosperms encompassed some 50 tree families, including birch, fig, holly, magnolia, oak, palm and sycamore. Apart from man-made structures, few changes have altered the landscape as much as angiosperms.

Angiosperms were also helpful to the planet’s ecology. Nectar from flowers was a new food source. It gave rise to new groups of insects, including butterflies, wasps, bees, termites and ants. These were the first known social insects. They lived in highly structured colonies where each member had a task to perform. This way of life guaranteed enormous evolutionary succes Read More
The first land vegetation can be traced back about 425 million years. These small, simple plants spread and diversified. Some 100 million years later, they’d given way to lush forests of ferns and gymnosperms (trees with naked seeds).

In the early Cretaceous period, gymnosperms continued to dominate the flora on the continents. Yet several species were in serious decline, with only conifers flourishing. In the middle Cretaceous period, angiosperms appeared. These flowering plants enclosed their seeds in an ovary. By the late Cretaceous period, angiosperms dominated the landscape. Angiosperms encompassed some 50 tree families, including birch, fig, holly, magnolia, oak, palm and sycamore. Apart from man-made structures, few changes have altered the landscape as much as angiosperms.

Angiosperms were also helpful to the planet’s ecology. Nectar from flowers was a new food source. It gave rise to new groups of insects, including butterflies, wasps, bees, termites and ants. These were the first known social insects. They lived in highly structured colonies where each member had a task to perform. This way of life guaranteed enormous evolutionary success. To the landscape’s great benefit, these insects helped plants reproduce and evolved in tandem with vegetation. By the end of the Cretaceous period, insects had become specialized in particular flower species.

© 2001, CHIN. All Rights Reserved.

Wasps

Wasps contributed to the diversity of landscapes.

Musée du Séminaire de Sherbrooke

© Musée du Séminaire de Sherbrooke. All Rights Reserved.


Learning Objectives

The learner will:
  •  Develop enthusiasm and continuing interest in the study of science
  • Describe some of the invertebrate animals of the Cretaceous and their ecology
  • Describe how evolution shaped the invertebrate communities of the Cretaceous, with examples
  • Define angiosperm and gymnosperm and describe the evolution of flowering plants on Earth

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