Euteleostomi Characteristics Sarcopterygii • Truly ossified skeletons (some secondary losses) • skull with sutures • teeth usually fused to the jaw bones • soft segmented fin rays • swim bladder or functional lung • spiral valve usually absent • low blood concentrations of urea (except in lungfish and the living coelacanth) Actinopterygii Euteleostomi Grade Teleostomi, Class Sarcopterygii, Subclass Coelocanthomorpha Grade Teleostomi, Class Sarcopterygii, Subclass Coelocanthomorpha • ~120 species • Thought to gave gone extinct • Unossified notocord, ossified rays, vertebral spines • first live specimen collected 1938 • Spiral valve • annual catch 2-4/year • Lobed finnes • Up to 1.8 m long • long lived (>60 yrs?) • High electrosensitivity 1 Grade Teleostomi, Class Sarcopterygii, Subclass Dipnoi, lungfishes Grade Teleostomi, Class Sarcopterygii, Subclass Dipnoi, lungfishes • Fossil records • Evolutionary trends in Dipnoi • Three surviving genera • Mix of derived and primative traits • Piltdown fish Grade Teleostomi, Class Sarcopterygii, Subclass Dipnoi, lungfishes Class Actinopterygii – ray finned fishes • Ganoid scales • Vast majority of fishes (38 orders, 426 families, 4064 genera) • Tooth plates • Monophyletic group • Some parental care • Group arose 200 mya • Three subclasses • Australian • Common characteristics – Cycloid, ctenoid or ganoid scales • S. American and African – Spiracle usually absent – Gular plate usually absent – branchiostegal rays usually present • Larvae typically more reliant on gills – Uroneural, hypeural bones – flattened neural and haemal (external) arches, hypural plate – Mobile, detached premaxilla (jaw suspension, protrusability) – Interopercle bone usually present 2 Polypteriformes: Class Actinopterygii, Subclass Cladista, Order Polypteriformes bichirs Lobe-like fins Larvae with gills, adults with lungs • Fossils restricted to Africa, Gular plate Taxonomy unresolved • 2 genera, 10 species • Most obligate air breathers • Ganoid scales • Horizontal dorsal finlet rays Actinopterygii Euteleostomi Class Actinopterygii, Subclass Cladista, Order Polypteriformes bichirs lungfish • Traits that complicate classification – Larva with external gills, adults with 2 lungs (lungfish) – Exhaled air exist via spiracles (sturgeon) – 2 gular plates (Coelocanth) – Reduced heterocercal tail (gar) Polypteridae Sarcopterygian Ichthyostega 3.