Flashcards in Brief intro to vertebrates Deck (11):
What is the splanchnocranium?
The facial skeleton, formed from neural crest.
What is the chondro/neurocranium?
Supports the brain, formed from neural crest.
What is the dermatocranium?
The insides and roof of the skull, formed from ectoderm.
What are the 2 hypothesis for the relationships of the agnathostomes?
1. Molecular: the hagfish and lampreys are a clade
2. Morphological: the lampreys and gnathostomes form a clade, the hagfish are a sistergroup (as they do not have a notochord).
Describe a hagfish.
A carrion feeder. They produce slime and tie themselves in knots during prey capture and predator evasion.
One of the hypotheses for the origin of jaws states that they were formed from the anterior-most gill arches. What was this initially an adaptation for?
Improved gill ventilation, not for feeding.
In sharks, the teeth are embedded in the jaw bone. True or false?
False: they are embedded in the flesh.
What is the jaw articulation in lissamphibia and lepidosaurs?
Meta autostylic: the upper jaw is fused to the skull. The lower jaw is attached via the quadrate and articular.
What is the jaw articulation in mammals?
Craniostylic: lower jaw is fused to the braincase via the squamosal and dentary.
What are the 'adductor mandibulae'?