A symmoriiform from the Late Devonian of Morocco demonstrates a derived jaw function in ancient chondrichthyans

摘要

PIMUZ A/I 4806, early/ middle Famennian, Madene el Mrakib. a Photo and b line drawing of the specimen. c Head region including parts of the rostrum, sclerotic ring, mandibular arch, hyoid arch, branchial skeleton and shoulder girdle in ventral view. d Soft tissue remains, including liver and spiral valves. e Pelvic and caudal region. Scale bars, 100 mm (a, b), and 30 mm (c–e). chy, ceratohyal; cop, copula; cbr, ceratobranchials; fs, fin spine; liv, liver; mc, Meckel’s cartilage; p.pl, pelvic plate; pq, palatoquadrate; ros, rostrum; scl.r, sclerotic ring; scor, scapulocoracoid; stc?, stomach content; spv, spiral valves.