The vertebrate story…
Agnatha Extinct: Ostracoderms *Covered by bony armor *Mostly small fish 2cm (some up to 2m) *Small mouth openings *4 openings on dorsal surface of head *Extinct after abundance of jawed fishes on the scene
Agnatha Extant: “Cyclostomes” Hagfish and Lamprey *Are not as closely related as might appear *Hagfish are scavengers that lack the rasping denticles of lamprey *Most Lamprey are parasitic ds_trawl/images/HagfishLR.jpg
Extant Jawless fishes…
Extant Jawless fishes…
Extant Jawless fishes…
Extant Jawless fishes…
Extant Jawless fishes… Broad-gilled Hagfish Broad-gilled Hagfish
Extant Jawless fishes…
qa
Extant Jawless fishes…
Extant Jawless fishes…
_Aquarium_Finisterrae.JPG
Extant Jawless fishes…
Extant Jawless fishes…
Extant Jawless fishes…
Gnathostomes 3 groups appeared in the Paleozoic: 1) Placoderms (ex. Arthrodires) had large boney plates and paired fins /Zimg/dicksonosteus.jpg
Gnathostomes 3 groups appeared in the Paleozoic: 2) Chondrichthyans (cartilagenous fishes) *Includes sharks, rays, skates, and ratfish *Cartilaginous skeletons *Many with placoids *No bony operculum s/sharks04_r2_c2.jpg /fish/large/ratfish.jpg
Gnathostomes 3 groups appeared in the Paleozoic: 3) Teleostomes (spiny and bony fishes) *Acanthodians are (spiny fishes) are extinct *Had skeleton of bone and cartilage *Had an operculum es/R-acanthodians.gif
Osteichthyans Shared ancestors with tetrapods Have an air sac Dermal bone Paired fins… either ray finned (actinopterygii) or fleshy finned (sarcopterygii)
Actinopterygii Basal groups include Sturgeon and Paddlefish %20&%20Sturgeon%202.jpg
Actinopterygii Advanced groups include Gars, Bowfins and Teleosts (most other bony fish) 0Alligator%20Gar% JPG
Sarcopterygii Have fleshy lobed fins, internal nares and a bony operculum 2 major clades: Actinistians, extinct except “coelocanths” Rhipidistians (and dipnoi) “lungfish” 5/1116/34-14-Coelocanth.jpg gfish.jpg
Amphibia *Paraphyletic group… omitting amniote descendants *Extinct groups include Labrynthodonts (Ichthyostega) *Extant group (Lissamphibia) includes: Apoda (caecilians) Urodela (salamanders) Anura (frogs) r.jpg s_theme/frogs_K/frog_species/barred/images/barred_leaf_frog _jpg.jpg tanus-PC1b.jpg
Amniotes Group includes Reptiles and Synapsids Reptilia (paraphyletic) Chelonia (testudinea) “turtles” Rhynchocephalians “tuatara” Squamates “lizards, snakes etc.” Crocodylians “crocodiles” etc. Aves “birds”
Synapsids Amniotes with synapsid skull, hair, mammary glands & nipples (most)
Mammalia Monotremata
Mammalia Marsupialia
Mammalia Insectivora
Mammalia Xenarthra
Mammalia Tubulidentata
Mammalia Pholidota
Mammalia Chiroptera
Mammalia Primates
Mammalia Lagomorpha
Mammalia Rodentia
Mammalia Carnivora
Mammalia Pinnipedia
Mammalia Perissodactyla
Mammalia Atriodactyla
Mammalia Hyracoidea
Mammalia Proboscidea
Mammalia Sirenia
Mammalia Cetacea
Cloaca/Eggs No front teeth (or no teeth at all) Opposable thumbs Peg-like teeth (African) Pouch Scaly Smooth cerebral cortex/sharp teeth Two pairs of incisors (only central growing) Wings Aquatic ungulates without hind- limbs Aquatic with nostrils on top of head Canine with fins/terrestrial birth Growing incisors/hoof-like nails Incisors form tusks Single pair of growing incisors Ungulates with even # toes/paraxonic foot Ungulates with odd # toes (usually)/mesaxonic foot Well developed canines