ERTH305 Midterm 2 Misc

Cephalocordata

• A subphyla of phylum Chordata

• They have a brain / cranium, but do not have hard bony skulls like vertebrates

• They were amphibious

Vertebrata

• a subphyla of phylum Chordata

• They have a cranium & a skull

• Most have vertebrae instead of notochord (notochord does not become vertebrae)

• Have an axial skeletal system (early limbs)

Axial Skeleton

• Cranium + Vertebrae

Notochord

• flexible rod-shaped chord made of cartilage cells serving as a skeletal axis in chordate embryos - an early spine (evolved into spine)

Osteichthyes

• Phylum Chordata, (Gnathostomata)

• Fish with Jaws

• Boney bones, (ossified, not cartiledge)

  • Three Orders:

  • Dipnoi aka Lungfish (gigantism, early version of lungs to breathe air)

  • Actinistia (primitive, mostly extinct)

  • Rhipidistia (invasion of land, ancestor of amphibians)

• Late silurian

Cladoselache

• cartilaginous fish

• Like a shark

• Late Devonian, North America

Chondrichthyes

• Cartilaginous fish with jaws

• Late silurian

Analogous Feature

• Looks similar, evolved independently

Homologous Feature

• Evolved from same thing, branched out but looks similar

Acanthodii

• Subclass of the Chondrichthyes

• Type of Jawed fish, cartilage not bone

• “Spiny sharks"

• Early gnathostomata

• Middle Silurian - Lower Permian

• Evolved into Placodermi

Placodermi

• the most numerous and diverse fishes of the Devonian

• Evolved a strong cephalic shield

• Includes the genus Dunkleosteus (looks like a shark, strong cephalic shield, top predator)