Character Details
amniotic egg
amniotic egg with a unique set of membranes: amnion, chorion, and allantois
thicker skin
a relatively impervious skin that reduces water loss
horny nails
horny fingernails and toenails for digging and grasping
more renal tubules in kidney
greater density of renal tubules in the metanephric kidney to reduce water loss
larger large intestines
larger size of large intestines for better water resorption
better Harderian and lacrimal glands
full differentiation of the Harderian and lacrimal glands in the eye socket whose moistening secretions include an antibacterial component
third eyelid
a third eyelid, the nictitans, for eye protection
better muscle stretch receptors
an extensive system of muscle stretch receptors enabling finer coordination and greater agility during locomotion
enlarged lungs
enlarged lungs
loss of lateral sensory system
complete loss of the lateral sensory system
two or more sacral ribs
two or more pairs of sacral ribs
astagalus in ankle
an astragalus bone in the ankle, fusing the separate tibiale, intermedium, and proximal centrale bones
two more cranial nerves
paired spinal accessory (11th) and hypoglossal (12th) cranial nerves incorporated into the skull
+-Deuterostomata
+-Echinodermata
+-Hemichordata
+-Chordata
+-Urochordata
+-Cephalochordata
+-Craniata
+-Mixinoidea
+-Vertebrata
| +-Hyperoartia
| +-Jawless Fishes
+-Gnathostomata
+-Placodermi
+-Chondrichthyes
+-Teleostomi
+-Acanthodii
+-Osteichthyes
+-Actinopterygii
+-Sarcopterygii
| +-Coelacanthimorpha
| +-Dipnoi
+-Tetrapoda
+-Amphibia
+-AMNIOTA <<<<< Taxon for this page
+-Synapsida
| +-Primitive Synapsids
| +-Mammalia
| +-Monotremata
| +-Marsupialia
| +-Eutheria
| +-Edentata
| +-Glires
| +-Archonta
| +-Insectivora
| +-Carnivora
| +-Ungulata
+-Reptilia
| +-Testudines
+-Diapsida
+-Primitive Diapsids
+-Sauria
+-Ichthyosauria
+-Sauropterygia
+-Lepidosauromorpha
+-Archosauromorpha
+-Crocodylomorpha
+-Pterosauria
+-Dinosauria
