Lesson 12 (Life in Mesozoic Oceans)

Question 1

what types of organisms were prominent in the cambrian

Answer 1

Trilobites and Burgess Shale type organisms

Question 2

what types of organisms were prominent in the paleozoic

Answer 2

trilobites and other forms of marine life (brachiopods, echinoderms on fixed stalk (crinoids) and corals)

Question 3

how did the look of the mesozoic oceans change following the permian extinction

Answer 3

• bivalves (clams) and gastropods (snails) become the more important shelly fossils as opposed to brachiopods
• cephalopods became even more common
• rugose and tabulate corals are extinct
• echinoderms move away from stalked crinoids to mobile starfish and echnoids (sea urchins)
• large marine reptiles become top predators

Question 4

what is the most common fish in the mesozoic

Answer 4

Bony fish, cephalopods also common

Question 5

what are cephalopods

Answer 5

“head foot”: group of mollusks that are relatives of squid and octopus

Question 6

what is a unique trait about Orthoconic Nautiloids, one of the early cephalopods

Answer 6

Straight shells

Question 7

what is a unique trait about Belemnites, one of the early cephalopods

Answer 7

10 arms, double row of hooks but no suckers
- belemnite comes from the greek word for dart/arrow

Question 8

What is the cousin of Belemnites? How did they get their name?

Answer 8

• Ammonites
• Egyptian god Ammon who is shown to have ram horns

Question 9

How do ammonites help with biostratigraphy?

Answer 9

Since they were so common, ammonite fossils are used to split geological time into separate ammonite zones

Question 10

how did ammonites move

Answer 10

backwards, through the water by jet propulsion created by squirting water through a tube called the hyponome

Question 11

How are Nautilus and Ammonites similar

Answer 11

• spiral shell with different chambers
• internal chambers divided from next chamber with chamber wall called ‘septum’
• grow by moving forward in their body chamber and adding a new chamber to the back of their existing body chamber when they become too large
• tube called siphuncle runs the full length of all chambers and attaches on to the living creature
• animals use siphuncle to vary fluid in each chamber, allowing them to control bouyancy in the water

Question 12

what is the first ammonoid to evolve? When did they go extinct?

Answer 12

Goniatities, Mesozoic

Question 13

how do ammonoids counterbalance an offset siphuncle?

Answer 13

• higher volume of septal face on the other side
• septal face centroid offset to the other side

Question 14

what characteristics did ammonites start to get prior to their extinction?

Answer 14

shells started to uncoil and take on unusual shapes, likely due to the changing climate

Question 15

How long was the coral gap and when was it

Answer 15

10 million years after the permian extinction

Question 16

what was the creature that new corals evolved from called

Answer 16

scleractinian corals

Question 17

what are corals composed of

Answer 17

soft, living coral polyps sitting within hard calcium carbonate cups

Question 18

what are infaunal bivalves

Answer 18

• dig down into the hard rock of reed
• bioeroders of reef environment

Question 19

what are rudist bivalves

Answer 19

• some stood vertically with one of their shells buried in sediment and the other acting like a lid
• others encrusted on surfaces
• others just lay on the sediment surface
• good collector of oil (many hooks, crannies that are well connected)

Question 20

Which type of fish went extinct during the permian extinction

Answer 20

Acanthodian fish - preevolution of bony fish

Question 21

Which evolution of bony fish could grow up to 6m long

Answer 21

Xiphactinus

Question 22

Which shark was prevalent in the late cretaceous

Answer 22

Cretoxyrhina or Ginsu Sharks
- similar size to great white

Question 23

what kinds of tetrapods shared the mesozoic environment with the invertebrates and fish?

Answer 23

• turtles (archelon): 10ft long turtle
• giant alligators (mainly fed on sea turtles)

Question 24

who collected the fossils displayed at the national history museum

Answer 24

Mary Anning

Question 25

What dinosaurs did Mary Anning discover?

Answer 25

Discovered and extracted Ichthyosaur, Several marine reptiles and the first pterosaurs outside of Germany. Also plesiosaur

Question 26

How did Anning’s idea help support the idea of extinction?

Answer 26

Supported George Cuvier’s ideas of extinction

Question 27

How does ichthyosaurs differ from modern day dolphins? Which feature would be the most significant?

Answer 27

• Position of the eye
• colour
• size of the dorsal fin
• orientation of the tail fluke. (most significant)

Question 28

what is convergent evolution

Answer 28

unrelated organisms develop similar features when living in similar environments (ichthyosaurs is a reptile while dolphin is a mammal, yet they look similar)

Question 29

what are dolphins and whales ancestor? How are they similiar?

Answer 29

Indohyus, a small herbivorous deer, the size of a raccoon
- bones that surround inner ears are similar adapted for hearing under water

Question 30

What features of ichthyosaurs indicate a terrestrial origin for the group?

Answer 30

• Two pairs of limbs with bones that resembled digits in their flippers.
• The roof of the skull had a pair of openings called fenestra which are very typical of reptiles.
• They lacked gills, so they had to draw oxygen from the atmosphere.

Question 31

What is the biggest Ichthyosaurs

Answer 31

Shonisaurus, grew up to 50 feet long

Question 32

What happened to shonisaurus?

Answer 32

37 triassic specimens were found side by side in Nevada, suggesting a mass stranding event

Question 33

What are some traits about Ichthyosaurs?

Answer 33

• Good Eyesight
• Viviparous (gave birth to living creature as opposed to egg)

Question 34

What are the two kinds of plesiosaurs

Answer 34

Short neck (PLIOSAUR)
Long neck (PLESIOSAUR)

Question 35

Largest pliosaur?

Answer 35

Kronosaurus, 12m long

Question 36

Largest plesiosaur?

Answer 36

Elasmosaurus, 14m long
- neck had 76 vertebrae

Question 37

What is the only mesozoic aquatic reptile that people claim still exist

Answer 37

Plesiosaur (Lochness moster)

Question 38

What is the history of the Lochness monster

Answer 38

1) Saint Columba, local had been mauled, lured monster out, stopped monster with the sign of the cross
2) George Spicer saw monster pass in front of car

Question 39

What are lazarus taxa

Answer 39

Organisms that were thought to have been extinct but were subsequently found

Question 40

Example of lazarus taxa

Answer 40

Coelecanths

Question 41

Example of living fossil

Answer 41

Horse shoe crab, has not changed whatsoever since it first evolved 450 million years ago

Question 42

Why is the loch ness thoery false

Answer 42

1) lack of fossils suggest none of the creatures survived the end of the cretaceous
2) it is unlikely plesiosaurs moved around on land like described by the Spicers
3) in order for there to be a viable population of plesiosaurs in the Loch there would have to be many of them and there is probably not enough fish to support that

Question 43

What explains the humps that people see in the water and claim is the Loch Ness monster?

Answer 43

Logs, Seals, Otters
Potentially the Sturgeon fish (responsible for creating caviar)

Question 44

Mosasaur Evolution Path?

Answer 44

Aigialosaurus - Cretaceous (small semi-aquatic lizard)
Dallasaurus - more aquatically adapted lizard
Tylosaurus - Largest Mosasaur

Question 45

Qualities of Mosasaurs

Answer 45

• backward pointing teeth
• additional set of teeth on their palate
• didnt chew, instead gulped
• ambush predators