530 million years ago, chordates {vertebrate} developed cartilage or bone notochords, allowing more muscle attachment.
skeleton
Vertebrates have internal cartilage or bone skeletons, to replace or reinforce notochord. They have backbone segments {vertebra, vertebrate}. They have one cranium. Distinct trunks are between heads and tails.
circulation
Closed circulatory systems use blood vessels.
pharynx
Pharynx separates digestion pathway from respiratory pathway, making both more efficient and independent.
skin
Two-layer skin has epidermis and dermis.
communication
All vertebrates communicate using signs, such as gestures, odors, calls, cries, songs, and dances.
nervous system
Vertebrate brain has hindbrain, midbrain, and forebrain. Hindbrain has ganglia for sleep, wakefulness, and sense information analysis, and cerebellum for coordinating motor behavior. Midbrain has ganglia for sense information analysis. Forebrain has occipital lobe for visual information analysis, temporal lobe for hearing and equilibrium information analysis, parietal lobe for touch and temperature information analysis and motor output, and frontal lobe for smell information analysis.
senses
Eyes develop from brain. Ears are for balance in lower vertebrates and for sound in higher vertebrates.
evolution
Early vertebrate was Sacabambaspis [-450000000].
evolution: superclasses
Superclass is fish (Pisces), with highly vascular gills. Superclass is legged vertebrates (Tetrapoda), with four appendages, including amphibians (Amphibia), reptiles (Reptilia), birds (Aves), and mammals (Mammalia).
Biological Sciences>Zoology>Kinds>Vertebrate
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Date Modified: 2022.0224