Details on the characteristics of Pectinator spekei, the only species in the genus Pectinator, were given in a paper by W. Peters in 1870. His article is on line.
Distinctive features include its bushy tail, the ears are rounded and covered with soft hair on the outside that become stiff and form a fringe at the margins of the ears. It differs from many of its relatives in having four, not three, molars above and below.