History of fish Flashcards
Similar due to common ancestry (eg. the humus, radius, and ulna bones in whales, humans, birds, etc.)
Homology
When the similarity is NOT due to a common answer (eg. human eyes and cephalopod eyes)
Homoplasy
When did the first recognizable fish arise and what were they called?
470 million years ago. Craniates.
What were the features of Craniates and what part of water did they occupy?
They were jawless and finless. Occupying shallow seas or estuarine habitats.
Give three examples of developments that fish passed onto higher vertebrates.
Any of the following:
Bony endoskeletons
Brain cases
Teeth
Jaws
Brains
Appendages
Internal organ systems
Pre-fishes were called what and lived around what time?
Conodonts. Lived between 600-200 millions of years ago.
The earliest protoconodonts may have been…
Invertebrates
What were the first fishes and what were their features?
Agnathans. Ostracoderms (shell-skinned)-jawless craniate fishes with a bony shield covering the head and thorax
What were the innovations of Pteraspidomorphi?
Reduction of armor through fusion of plates
Narrowing of the head shield
Development of lateral projections
What were the innovations of Anaspida?
A body covering overlapping scales
Flexible muscularized lateral finlike projections
Internal skeleton
What were the innovations of Theolodonti?
Covered with denticles rather than bony plates
Had dorsal and anal fins
What were the innovations of osteostracomorphi?
Formed their armor from true bone cells
Another innovation is ossification of the endoskeleton
Paired lateral appendages are through to be homologus to pectoral fins in future fishes
What were some innovations in the earliest gnathostomes?
Jaws are present
Paired limbs usually present with skeletal support
Dentine-based teeth
What did the evolution of jaws allow for the first gnathostomes?
Diversification of the food types that early fishes could eat
Active defenses against predators eventually leading to de-emphasis on armor.
A supportive skeletal system
What period did the Placodermi occupy, and what were their features?
Devonian. Plated jaws with no teeth. Thought to have color vision. Heavily armored.
What were the features of Acanthodii?
Small fish occurring in fresh and salt water with spines and cartilaginous skeletons.
Large head, lare eyes, and streamlined bodies indicate that they were water column feeders.
What’s a feature we see in more advanced gnathostomes than the primitive ones?
Innovations of serially replaced teeth and of jaws that could create suction
What lineages are derived from gnathostomes?
Chondrichtyans (cartiliganous fish, sharks and rays).
Living Osteichthyans (bony fishes, coecalanths).
Dipnoi (lungfish).
Tetrapodomorphs (tetrapod ancestors).
What are some homologous features between tetrapodomorphs and humasn?
Bone arrangement. Skull bones. Rib-like structure. Eye placement.
When did the chondrocytes arise, and what were their evolutionary trends?
About 450 million years ago. Tooth replacement
Calcification of cartilaginous skeleton. Hardening skeletons with cartilage embedded with calcium deposits to make them more capable.
When did Actinopterygii, and what were their features?
Likely around 400 million years ago. Ray-finned fishes. Made up the majority of fish diversity at the time.
When did the Teleostei arise?
200 million years ago.
What were some evolutionary trends of Teleostei?
Reduction of bony elements
Change in position and function of dorsal fin
Change in gas bladder morphology and function
Change in jaw morphology and feeding specialization
