Review Questions for Biology 404

HOL Ch. 16: Marine Reptiles

From my lecture notes:


Related to terrestrial Permian anapsids

First turtles about Late Triassic

Diverse in Jurassic and Cretaceous

Up to 3 m long, 4 m flipper span


Also derived from terrestrial ancestors

Separate invasion of aquatic habitats to parasuchids (phytosaurs)

Got huge (15+ m, 18 tons)


Like dolphins with vertical tail

Known as fossils for over 200 years

Up to 15 m (Nevada, including mass stranding of 37 animals)

Mostly Jurassic, One survivor in Cretaceous

Live Birth


"Nothosaurs" -> Later ->

Plesiosaurs (to 12 m., most smaller)

(Early Jurassic -> Late Cretaceous)

Pliosaurs (to 12 m., like an ichthyosaur)


Big monitor lizards (to 10 m.)

Review Questions

1. What are the five main groups of aquatic reptiles that lived in the Mesozoic Era? What evidence is there that each of these groups reinvented the aquatic environment separately?

2. How are these reptiles similar to each other? How do they differ? (Be sure to also consider the last section on air breathing at sea.) How can one come to the conclusion that many of the similarities are due to convergent evolution, not due to common ancestry.

3. How does an ichthyosaur compare to a dolphin?

4. How does a plesiosaur compare with a pliosaur? Which of these (if any) is more closely related to a mososaur?

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