The Zoological Society of London was founded in 1826 by Stamford Raffles and established the London Zoo in Regent’s Park two years later in 1828. for scientific study. By the early 1860s, the zoo grounds covered 40 hectares with many fine flowers and ornamental trees, The predecessor of the zoological garden is the menagerie, which has a long history from the ancient world to modern times. The oldest known zoological collection.
Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes, arthropods, and molluscs—and the deuterostomes, containing both the echinoderms as well as the chordates, the latter containing the vertebrates. Life forms interpreted as early animals were present in the Ediacaran biota of the late Precambrian. Many modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago.