From a cladistic perspective, in the phylogenetic tree shown above, the cartilaginous skeleton is a(an):A) apomorphyB) pleisiomorphyC) sympleisiomorphyD) synapomorphy8. From a cladistic perspective, in the phylogenetic tree shown above, the bony skeleton is a(an):A) apomorphyB) pleisiomorphyC) sympleisiomorphyD) synapomorphy VertebrataCyclostomataGnathostomataOsteichthyesChondrichthyesosteichthyancrown nodechondrichthyancrown nodegnathostomecrown nodevertebratecrown node7. From a cladistic perspective, in the phylogenetic tree shown above, the cartilaginous skeleton isa(an):A) apomorphyB) pleisiomorphyC) sympleisiomorphyD) synapomorphy8. From a cladistic perspective, in the phylogenetic tree shown above, the bony skeleton is a(an):A) apomorphyB) pleisiomorphyC) sympleisiomorphyD) synapomorphy

Introduction :- Apomorphy is a derived trait that is unique to a particular species and all its descendants , which can be used as a defining character for a species . For example :possesion of feathers is unique to birds and defines all members of class Aves . It is of two types :- Autoapomorphy , which is restricted to a single species ,it alone cannot provide any information about phylogenetic relations of this species 2) synapomorphy : The derived trait which is shared by two or more species or groups ,such traits define the monophyletic groups or clades . Pleisiomorphy: is an Ancestral trait which is retained further within a particular group of organisms . Sympleisiomorphy : it is also an Ancestral trait that is shared by two or more modern groups .Answer :- 7)- pleisiomorphy 8)- apomorphy Explanation :- Vertebrate (crown node means present at the base) node is the point from where branches arises and new characters are derived from ancestral species to form a new taxa . Vertebrate are the oldest common ancestor means all species having vertebral column .Now a new character derived in two groups :1) vertebrates that possess jaws are *Gnathostomes* 2) vertebrates that doesn't possess jaws are *Agnathostomes* Gnathostomes have cartilagenous endoskeleton , that is being retained in the chondrichthyes (means ancestral trait is retained but differs with other species )which represents *pleisiomorphy* while osteichthyes having bony skeleton which is only present in one species so this is the *apomorphy*