First reptiles {stem reptile} were anapsids. Cut-lizard cotylosaur was low, stocky, and 20 centimeters to two meters long. Reptilia {reptile} include gecko, snake, iguana, turtle, crocodile, alligator, and lizard.
classes
The six reptile subclasses have different skulls: anapsid, diapsid, euryapsid, parapsid, synapsid, and therapsid.
evolution
Evolution was anapsid to diapsid to synapsid to therapsid. Euryapsids and parapsids evolved from diapsids.
land
Reptiles can live whole life cycle on land.
development
Reptiles have no larval stage in water. They develop continuously from egg to adult, requiring mechanisms for replacement and renewal.
skin
Thick dry leathery skin, with horny scales, allows continuous dry land existence, because it conserves water.
respiration
Reptiles have lungs.
skeleton: bone
Bones have growth rings in seasonal climates, with few blood vessels and haversian canals.
skeleton: pelvis
Reptiles have a strong pelvis, allowing running and/or standing on hind legs.
skeleton: jaw
Reptiles have muscles and jaws for chewing, not just grasping and tearing.
reproduction
Reptiles reproduce by intercourse and have internal fertilization. They lay eggs with leathery shells on land. An egg sac {amnion} holds water, so egg does not need to get water from sea, lake, or stream. Reptiles have egg-laying rituals, courtship rituals, territoriality, and sexual intercourse behaviors.
cloaca
The same body opening is for anus and reproductive tract.
muscle
Reptiles have only involuntary muscles controlled by automatic neuron circuits in ganglia and paleocortex.
nervous system
Cerebellum outer-layer basket cells process sensorimotor information and allow walking, running, and chewing. Brains have two-layered cortex and several ganglia. Paleocortex controls involuntary muscles and glands. Cortical neurons send axons to other cell layers and regions and receive signals from other paleocortex layers and regions. Paleocortex areas analyze information.
senses
Sense organs with more than one cell layer preprocess signals before sending them to brain. Median eye detects infrared light and later became pineal gland.
Biological Sciences>Zoology>Kinds>Reptile
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Date Modified: 2022.0224