croc lineage Flashcards
what is the order of a croc?
archosaur
what are some archosaur characters?
antorbital fenestra and mandibular fenestra
thecodont teeth in sockets
fourth trochanter - for powerful femur-to-tail muscle
what causes the croc lineage of archosaurs? what makes them different?
crurotarsal ankle joint at astragalus and calcaneum
astragalus is sutured to the tibia
calcaneum - functionally part of the foot
how do crocs walk?
with a high walk - due to an erect gait for overland travel
unlike predecessors who were bipedal
sprawling - more dragging across the floor
reasons for erect or sprawling posture?
due to the pelvis and femur
erect - femur has a steeper angle
sprawling - femur is at a shallower angle
what are a crocs pelvic aspirations?
inspiration causes the diaphragmatic muscle to pull the liver back
during expiration, - the rectus abdominis muscle will return the pubis to release the diaphragmatic muscle
what are the characteristics of the croc scales?
keratinised scales known as scutes cover the skin
has dorsal scutes
also reinforced with bony plates known as osteoderms - known as ridge or keel
what causes croc skin colour?
chromatophores:
epidermal melanocytes - stripes and patches and spots on dorsal scales
dermal melanophores - dark and grey background
dermal xanthophores - brown/ yellow or orange
what are the integumentary sensory organs?
minute skin elevations on jaws
also body of crocodiles but not alligators
arrays of tactile receptors on epidermis and dermis of integumentary sense organs
detect water movement and movement of prey in jaws