As more and more plants starting living on land, this prompted aquatic animals to also move on land due to the availability of food. Similar to plants, animals also had several problems to solve on moving from water to land.

Different challenges Animals faced when they moved onto land:

Solutions!

Animals show a greater variety as they move around and encounter different habitats. As a result, animals have developed specialized adaptations that allow them to take advantage of these diverse eating opportunities. For example:

some predators have developed specialized hunting techniques to capture prey in different habitats
some parasites have evolved complex life cycles that enable them to survive in different hosts.

Additionally, many animals have evolved specialized digestive systems that allow them to extract nutrients from a wide range of food sources. This ability to adapt to different habitats and food sources has allowed animals to thrive in a wide variety of environments and has contributed to the remarkable diversity of life on Earth.

The Animal Kingdom

Arthropods

Arthropods are a group of invertebrate animals that include insects, spiders, crustaceans, and others. Arthropods were the first animals to successfully colonize land.

Characteristics that made arthropods successful on land include:

Body segments and jointed legs that facilitate mobility on dry land.
A waterproof exoskeleton that prevents water loss and protects against predators.
An advanced sensory system that allows them to detect and respond to environmental cues

Primitive arthropods and their co-evolution with seed plants:

Primitive arthropods, particularly insects, co-evolved with seed plants, giving rise to a diversified terrestrial vegetation.
Insects facilitated pollination and consequently the evolution of angiosperms (flowering plants).
This co-evolutionary relationship between insects and plants led to the development of complex ecosystems on land

Amphibians

Amphibians evolved from fish and were the first vertebrates to colonize land.

They have primitive lungs supplemented by gaseous exchange through a moist, scaleless skin.
They have limbs and a strong endoskeleton to support their body on land.
Amphibians need a watery medium for external fertilization and egg laying.

Reptiles

Reptiles are the first truly successful land vertebrates.

They have dry, scaly, waterproof skin that prevents water loss.
They have strong limbs that support their body on land.
Reptiles reproduce through internal fertilization and lay shelled eggs on land.

Mammals

Mammals are a class of animals found in a wide range of habitats around the world and have diversified into a vast array of forms and sizes, from tiny shrews to massive whales. They have evolved from reptiles and their main characteristics include:

they are endothermic (able to regulate their body temperature internally)
body covered with hair
mammary glands that produce milk
external ears
diaphragm separating the thorax from the abdomen
give birth to live young.

There are three different reproductive methods in mammals:

Monotremes are the most primitive mammals and have retained the reptilian egg-laying method.
Marsupials give birth to live underdeveloped young whose development is completed in the marsupial.
Placentals give birth to live young that have been nourished before birth in the mother's uterus through a placenta

Humans

Humans and primates are not directly related, but both descend from a common ancestral animal.

Human evolution culminated in the appearance of Homo sapiens and was characterized by changes in:

Posture (becoming fully erect on two legs)
Cranial capacity (with brain size increasing)
Facial angle (becoming flatter and reaching a vertical face).

Human evolution was not a linear process, but was characterized by a whole series of interlinked (branching) lines of different ancestors and descendants. These various ancestors and descendants appeared because of various available niches and disappeared because of competition and/or interbreeding with ancestors of modern humans.