Cretaceous

Mammalian Evolution in the Cretaceous: Inner Ear

Advantages to Mammals:

Read through the description and summarize the advantages that lead to the rise of mammals after the mesozoic era.

Precise Hearing

The mammal ear works like a tiny hammer vibrating to the sounds coming in and hitting the ear membrane to send signals to the brain. The internal ear is much more sensitive than the simple reptile ear and as a result mammals are able to use hearing to sense the world around them.

Advanced Balance & Locomotion

The sensitive inner ear also allowed mammals to develop a sense of equilibrium, which allowed them to find their balance easily. This eventually lead mammals to develop unique locomotion styles like balancing easily on tree limbs, swinging in trees, and standing upright.

Modern Reptile Ears

Some Modern Mammal Ears- the external structure directs sound to the inner ear bones

Advanced mammal hearing has evolved to echolocation- locating objects with sound!

The Jurassic Earth

For the ocean currents, draw blue arrows for cold currents and red arrows for warm currents. Observe how more warm water is moved to the poles since there are shallow seas next to continents that move heat more evenly around the globe.

To find the physical stats, go to Earthviewer and click on the tabs at the bottom to find the correct period.

CO2: Give the highest and lowest levels in ppm (parts per million)

Average Temp: Give the highest and lowest in °F or °C

Sea Level: -100 m to -350 m compared to now

O2: give as a % in atmosphere

Climate: Subtropical, Warmer than now, no ice sheets, more humid, active volcanism throughout.

Representative Species

Pick an animal that was present in the cretaceous time and include :

Labeled Scientific Diagram (be sure to write the name!)
Size
Diet (what did it typically eat?)
Habitat (where did it live?)

Links to help you research:

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