The common ancestor of all these chordate groups except the probably had paired appendages. chondrichthyes aves echinodermata mammalia agnatha

Lampreys resemble eels with regards to their scaleless, elongated bodies. They lack paired fins, and adult lampreys are characterized by a toothed, funnel-like sucking mouth. Of the 38 known extant species, parasitic lamprey species are most well-known. They feed by boring into the flesh of other flesh in order to suck out blood. Adult non-parasitic species do not feed but instead live off on reserves that they have acquired as larvae through filter feeding. 

make   gliitsh plesea   !

geologic time scale (for gradpoint) =)