Cranial Skeleton Flashcards
(34 cards)
What are the two components of the skull?
The cranium and mandible
What are the three components of the cranium?
Dermatocranium, splanchocranium, chrondocranium
What does the dermtocranium form?
The flat bones of the neurocranium
How is the dermatocranium formed?
Through intramembranous ossification
What is intramembranous ossification?
Direct formation of bone in the mesenchyme of the cranium
What does the chondrocranium form?
The base of the cranium and surrounds the capsules fr special sense
How is the chondrocranium formed?
Through endochondral ossification
WHat is endochondral ossification?
Ossification where the bone forms in the cartilage template. The template is invaded by osteoblasts and ossifies it
What does the splanchocranium form?
The viscerocranium
What kind of ossification forms the splanchocranium?
Intramembranous
What developmental structure is the splanchocranium related to?
The Branchial arches
WHat are agnatha?
A subclass of vertebrate fish that are of ancient origins
What kind of feeding do agnathans display?
Scavenging at the sea floor
What are the two extet species of agnathans?
Lamprey and hagfish
What do agnathans posses in place of a vertebral column?
A notochord and pharyngeal slits
What do agnathans posses in place of jaws?
A cyclostma - a round oral opening with affixed teeth
What did the development of jaws allow for?
Scavengers to become hunters
What are Chondrichthyes?
Fish with a cartilaginous skeleton
What is the only calcifie element of Chondrichthyes?
Teeth
What kind of jaws do Chondrichthyes posses?
Mobile
What are Osteichthyes?
Bony fish
What is the function of an operculum?
It protects and shields the gills to allow onl oxygen transfer and gas exchange.
What are the 4 orders of extent reptiles?
Squamata, crocodiliana, rhynococephilia, Chelonia
What are poikilothermic species?
Species that have a varying internal temperature and so need to adapt to environmental changes
