ZOO 2090 Lecture Notes - Lecture 3: Fish Anatomy, Premaxilla, Osteolepiformes

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Jinzhong Fu

Document Summary

Agnathans: jawless fishes/jawless fishlike vertebrates: hagfish, lampreys, conodonts, ostracoderms are the main groups, mouth present, but no biting apparatus derived from pharyngeal arches, groups were already highly specialized by 330mya and display features likely representative of. Two extant groups, hagfishes and lampreys, together often referred to as cyclostomes ancestral agnathans. Conodonts (cid:894)e(cid:454)ti(cid:374)(cid:272)t (cid:858)ja(cid:449)less(cid:859) fish like ve(cid:396)te(cid:271)(cid:396)ates(cid:895: only known from hard tooth-like elements, had highlighted (cid:448)e(cid:396)te(cid:271)(cid:396)ae (cid:272)ha(cid:396)a(cid:272)te(cid:396)s su(cid:272)h as . So abundant they are used for stratigraphic dating. Fossils fou(cid:374)d i(cid:374) ea(cid:396)l(cid:455) (cid:1005)(cid:1013)(cid:1012)(cid:1004)(cid:859)s: dentin and enamel, notochord, myomeres, postanal tail (cid:862)feedi(cid:374)g appa(cid:396)atus(cid:863, complex feeding basket in the pharynx and large eyes suggest that they were active feeders, the monophyly of conodonts is uncertain. Four major groups (relationships between the relationships are disputed: pteraspidomorpha, most had a head shield made of fused bone plates, caudal exoskeleton was made up of small plates and scales(cid:198)this allowed movement of their single caudal fin.