<h2>540 million years ago
</h2>
Paleozoic.
Era immediately follows Precambrian It lasted about 4.5 billion years.
When did abundant fossil evidence first appear in the geologic record.
540 million years ago.
Answer:
There are three types of neurons are present i. e. sensory neuron, motor neurons and inter neurons.
Explanation:
Sensory neurons are the nerve cells which is responsible for sending the information from the sense organs such as tongue, nose, skin, ears, and eyes to the spinal cord and the brain while the motor neurons are responsible for the transportation of instruction from the brain and spinal cord to the muscles. The inter neuron helps in communication between motor or sensory neuron and the nervous system.
An egg is the organic vessel containing the zygote in which an animal embryo develops until it can survive on its own, at which point the animal hatches. An egg results from fertilization of an ovum. Most arthropods, vertebrates, and mollusks lay eggs, although some do not, such as scorpions and most mammals.
Reptile eggs, bird eggs, and monotreme eggs are laid out of water, and are surrounded by a protective shell, either flexible or inflexible. Eggs laid on land or in nests are usually kept within a favorable temperature range (warm) while the embryo grows. When the embryo is adequately developed it hatches, i.e. breaks out of the egg's shell. Some embryos have a temporary egg tooth with which to crack, pip, or break the eggshell or covering.