We’re here because of this little beast that survived Astraspida
Their structure, although poorly known, has often been used in evolutionary scenarios to illustrate the primitive state of the vertebrate dermal skeleton. Because of the acellular structure of their dermal skeleton, they were initially considered heterostracans
Astraspida - Wikipedia
Their structure, although poorly known, has often been used in evolutionary scenarios to illustrate the primitive state of the vertebrate dermal skeleton. Because of the acellular structure of their dermal skeleton, they were initially considered heterostracans
Astraspida - Wikipedia