Inner Fish
What advantages does a paleontologist have as an anatomy professor?
Because other creatures offer a road map to humans
What are the characters of Tiktaalik that made it fishlike? What are the characters that underscored that it is a tetrapod ancestor?
Fish-like: scales, fins, gills
Land: lungs, neck, hand bone structure
Conditions along coasts and estuaries are much less constant so animals have to cope with abrupt changes in salinity and can tolerate wide variations so are called
euryhaline
•Helps allow animals to reach homeostasis
• Serves excretory and respiratory functions
• Contributes to temperature regulation
Integument
Teeth that humans have
Molars, premolars, Caine, incisors
Describe some of the similarities that link humans and fish
Backbones, brain wiring
One of first transitional species, already likely on land Forelimbs could push top of the body off the ground, back limbs like paddles in water or stabilizers on land
What is notable about Ichthyostega?
Freshwater fish that has more solutes than environment. Water flows into fish and they fight to keep it out
Hypertonic
4 bone functions
1. Structure
2. Protection
3. Mineral Balance
4. Blood cell production
– E.g.: Gastric mill and chitinous teeth in arthropods, gizzard in oligochaetes and archosaurs
Mechanical breakdown of food
What is the pattern of hand bones that Richard Owen identified as being homologous in turtles, humans and birds?
One bone, two bones, lots of bones, digits
Describe some of the similarities between fish and human embryos?
Look similar, both have gill arches, heads (cranium), tail
Nonavian reptiles and birds excrete _________ instead of _________ through the tubular epithelium
uric acid, urea
Produces blood cells. Spongy bone: ribs, vertebrae, flat bones
Red Marrow
E.g.: Crop in oligochaetes and archosaurs, multichambered stomachs of some herbivorous mammals
Food storage with chemical breakdown and/or fermentation
What was Darwin’s contribution to understanding this pattern of bones that are homologous in turtles, humans, and birds?
They all share a common ancestor, therefore likely to have a transitional species
Weak spot where testes have to descend, intestines can go through, reminder of fish ancestors
hernias
Less solutes than environment in a saltwater fish. Water flows out of the fish and they fight to keep it in
Hypotonic
• Contributes to animal’s ability to interact with the environment
• Contains sensory receptors
• Secretes scent molecules
• Used in signaling and display (communication)
Integument
• Force exerted on the walls of the blood vessels by the blood (caused primarily by the pumping of the heart)
• Keeps the circulatory fluid moving through the system (in addition to other forces)
Requires the maintenance of “blood pressure”
What is the age and rock type do paleontologists need to target to find transitional species?
Devonian, 360 million years ago, Penn. Road cut
is the gene that causes the start of signals to develop digits
The signal starts strong then weakens, if the signal stays strong, an organism will get extra fingers
This same function is found in very ancestral fish--skates
Sonic Hedgehog
uses blood pressure across capillary walls to produce a protein-free filtrate
Glomerular filtration
Feed on decaying organic matter
Saprophagous
3 things
vessels that carry blood from heart to capillaries
vessels that carry blood from capillaries to heart
tiny, porous vessels through which molecules diffuse in to/out of body tissues
Arteries
Veins
Capillaries