Vertebrata Flashcards
Notocord
semi flexible rod running along the length of the animal
myomeres
v-shaped muscle blocks
Chordates
Craniates, Myxini, Conodont,Lampreys, “Ostracoderms”, “Placoderms”,chondrichthye, osteichthyes,
Vertebrates
sequentially arranged cartilaginous endoskeletal elements flanking the spinal cord.
Extrinsic eye muscles, two semicircular canals
Vertebrates 2
Earliest vertebrates lacked mineralized tissue
Cartilaginous skeleton
-Bone contains hydroxyapatite
-Conodonts earliest bones
Early Vertebrates
Earliest bone appears in latest cambrian
First bone is external
Why bone?
right attachment surface for muscles
source of metabolic minerals
Ostracoderms
- Paraphyletic group of jawless fish
- Bony armor
- Cartilaginous skeleton
- extinct at the end of the devonian
Osteostracans
- Ossified braincase
- Paired pectoral fins
Gnathostomata
Possess jaws (first appeared in Silurian)
Paired pelvic thins
-Jaw evolved from gill supports in ancestral forms
Placoderms
Silurian-Devonian
- Heavily armored jawed fishes
- Paraphyletic
- Dominant in devonian
Chondrichhyes
Silurian to recent
Sharks, rays
Cartilaginous skeleton
Osteichthyes
Actinopterygians: Ray finned
-articulate with rows of basal and radial elements
Sarcopterygians: Lobe-finned fishes
-attaches to body by single bone
Tiktaalik
Late devonian origin of tetrapods
forelimbs had movable joints
Acanthostega
one of the earliest tetrapods
Temnospondyl
earliest amphibians originated
Amniotes
egg contains specialized membranes allowing for gas exchange and wast containment outside of water
Amniote Skulls
Anapsid: no opening behind the eye
Synapsid: 1 opens
Diapsid: 2 openings
Pelycosaurs
early paraphyletic group of synapsids
Therapsids
foot becomes symmetrical
trunk vertebrate become differentiated
secondary palate (internal opening of nostrils)
Fur comes about
Mammals
-Characteristics that don’t fossilize
-warm-blooded, covered w/ fur, sweat glands, mammary glands, parental care of young
Fossilize: specialized teeth, jaw composed of a single bone
Mammilian Jaw Evolution
- Bones previously part of jaw and jow joint become incus, malleus, and tympanic bone
- Middle ear bones initially develop as part of your jaw
Reptilia
-Includes anapsid and diapsid
Diapsids 2 major groups
- Lepidosauria: lizards, snakes, tuataras, etc
- sprawling posture
- Archosauria- crocs, dinos/birds
- addisional skull openings
- upright
Archosauria
- Dominant terrestrial in Mesozoi
- 2 lineages: 1) Crocs 2) Birds
Pterosaurs
- Triassic
- first verts with powered flight
- wing support by elongate 4th digit
Dino Hips (2 groups)
Saurischian: pubis projects forward
Ornithischian: Pubis projects backward
