Fig. 3 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 3. Specimens of mytilid bivalve Arcomytilus from the Middle and Upper Jurassic of Portugal and France. A–F. Arcomytilus morrisii (Sharpe, 1850). A. Large articulated specimen with pointed umbones and slightly imprinted anterior part. Arranhó II member, earliest Tithonian, Serra de Alrota. GML 25900. B. Small adult specimen, left valve with fine ribbing pattern and relatively straight anterior margin. Alcobaça formation, Late Kimmeridgian, Consolação. GML 25901. C. Young adult specimen, left valve with coarse ribbing pattern and large, elevated disc. Arranhó II member, Early Tithonian, Santa Cruz. GML 25902. D. Small adult, articulated specimen. Alcobaça formation, Early Kimmeridgian, Salir do Porto. GML 25903. E. Large articulated specimen with extremely triangular outline and wide−spaced, strong ribs. Arranhó II member, Early Tithonian, Lameiro das Antas. GML 25904. F. Adult specimen, left valve with bi− and trifurcation and simultaneous insertion of ribs. Arranhó II member, Early Tithonian, Santa Cruz. GML 25905. G. Arcomytilus asper. Right valve. Late Bathonian, Luc−sur−Mer, Calvados, France. MNHN J 08224. H. Arcomytilus bathonicus. Right valve. Late Bathonian, Luc−sur−Mer, Calvados, France. MNHN, coll. Deshayes 1876−8. I. Arcomytilus pectinatus. Right valve. "Corallien", La Rochelle, Charente−Maritime, France. MNHN, coll. d'Orbigny 4247.