Module 12 Flashcards
what creature characterize the Cambrian?
Cambrian is often characterized by trilobites and Burgess Shale type organisms.
what joined Cambrian creature in the Ordovician that would characterize the Paleozoic oceans
brachiopods, echinoderms on fixed stalks (crinoids) and corals (in particular forms called rugose and tabulate corals)
How did the oceans change after the Permian extinction
- look
- important shelly fauna
- cephalopods
- coral
- echinoderms
- top predator
- look more modern
- instead brachiopods, bivalves (clams) and gastropods (snails) become the important shelly fossils
- cephalopods become even more common
- rugose and tabulate corals have become extinct, other creature produce reefs
- echinoderms there is a move away from the stalked crinoids to more mobile star fish and echinoids (sea urchins).
- Large marine reptiles take on the role of top predators
how may species echinoids (sea urchins survived Permian extinctions
6 species
When did boney fish evolve? where the abundant in the Mesozoic
Devonian, yes abundant in the Mesozoic
what group was in Mesozoic oceans in vast numbers
- group mollusk called cephalopods “head foot”
related to squid/octopuses
- When where Cephalopods present?
- example in Ordovician
- By the Mesozoic, cephalopods ______ even further and had evolved into ___of different forms.
- example
- Paleozoic
- in the Ordovician, Orthoconic Nautiloids, one of the top predators in the ocean, had straight shells
-By the Mesozoic, cephalopods diversified even further and had evolved into lots of different forms.
- Belemnites were like modern squid, except they had 10 arms with a double row of hooks but no suckers
Ammonites often have _______ shells meaning they coil in single _________ planes
Ammonites often have planispiral shells meaning they coil in single horizontal planes
why are ammonites biostratigraphic tool of choice during the Mesozoic
- what does that mean
very very common
- are used to split geological time in to various ‘ammonite zones’, characterized by particular definitive and widespread species that can be used in correlation.
how did ammonites move
- what is a hyponome
- did they move together?
- moved backwards through the water by jet propulsion, created when they squirted water through a tube called the hyponome.
- They may have moved through the ocean in large groups
ammonites (and similarly Nautilus)
- what is there shell like?
- what is a septum
- how do they grow?
- what is a siphuncle/ what’s it used for
- shell with a spiral form that included many different chambers, with a much longer body chamber at the end
- internal chamber is divided from the next chamber by a chamber wall called a ‘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 a siphuncle runs the full length of all the chambers and attaches on to the living creature in the body chamber. The animals use the siphuncle to vary the amount of fluid in each chamber, allowing them to control their buoyancy in the water column.
- first ammonites?
- suture pattern?
- when did the become extinct/what took over?
- first ammonoids to evolve were the goniatites
- possess the simple suture lines you see here in this zig zag pattern
- Mesozoic, the goniatites had become extinct and the ammonites with the more complex suture line style were one of the main cephalopod groups present in the oceans
where ammoniates fast swimmers?
yes, had hydrodynamic shells used to slice through water
1.What type of asymmetry is found in planispiral ammonite shells in the earliest Jurassic?
2.What is the name and function of the tube that is offset from the centre line of the venter in this research project?
3.How widespread is the asymmetry within the genera shown in the phylogeny of the earliest Jurassic ammonites?
- siphuncle to the left?
- siphuncle and used to help with buoyancy
- very widespread
*check
- what environment where ammonites found in?
- how big can they grow?
-found in a number of environments, probably including the open ocean, as many of their shells are found in sediments where few other types of fossils are present with virtually no shallow marine species.
- Some ammonites got very big with shells over 2m in diameter
1.What should you look for in an ammonite fossil to see if it is complete?
2.What should you look for in an ammonite fossil to see if it is mature?
3.The size discrepancy is very large between the males and females of the same species. How do we know they belong to the same species?
4.Is the smaller or larger fossil the male?
5.Biologically speaking, how does ammonite reproduction work? (e.g. Do they give birth to live young?)
1.rostrum
- rostrum
- similar morphology
- smaller male
- live young
- when did ammonites become extinct?
- what was happening to ammonite diversity before extinction?
- what shapes did ammonites take then
- end Cre
- diversity alredy declining before
- some started to uncoil and take unusual shapes
- what happen to coral after Permian, how long
- what coral went extinct
- what new coral evolved in Tri and from what
- 10 mil yr coral gap
- tabulate and rugose corals, had both become extinct
- scleractinian corals, still fill important roles in today’s reefs
- parts of coral
- how do they grow
- soft, living coral polyp w/in hard CaCO3 cups
- put more CaCO3 down to grow up
Infaunal bivalves
- live where
- These types of bivalves dig down into the ____ _____ of the reef, after it is formed, so they are considered ______ in the reef environment
- live reefs
- These types of bivalves dig down into the hard rock of the reef, after it is formed, so they are considered bioeroders in the reef environment
What are two ways we can tell the sediment was already lithified into rock before the animal moved into it?
- outside hole not sloping in, soemmjjdkf
*check
what type bivalve start building reefs in later Jur and Cre
- what did they look like?
- Rudist bivalve
- occupy the niche that is often populated by the corals
- Some stood vertically with one of their shells (valves) buried in the sediment and the other acting like a lid on the top of a long tube.
- some encrusted on surfaces
- others just lay on the sediment surface
______ were some of the most important components of tropical reef communities during this time and were particularly important on the margins of the _______ Ocean and the early ____, fringing North America from the Gulf of Mexico to the Maritime Provinces.
Rudists were some of the most important components of tropical reef communities during this time and were particularly important on the margins of the Tethys Ocean and the early Atlantic, fringing North America from the Gulf of Mexico to the Maritime Provinces.
Reefs dominated by rudists could be hundreds of meters thick, what was there success due to?
- ocean conditions where saltier and maybe 14C warmer then today
- seas to warm/salty for coral
how are Rudist reef important today
- make lots of nooks/crannies (increase porosity) that are connected well (high permeability)
- good place for the oil we use today to accumulate
What happened to boney fish in Permian extinction
- after?
- suffered
- after Tri dead zone, would radiate into a wide and diverse number of forms
Sharks in Mezesoic
- when
In the open ocean, sharks similar in size to the large Great White sharks today, Cretoxyrhina or ‘Ginsu Sharks’ (the common name referring to the kitchen knife that ‘slices and dices’),
- patrolled the oceans of the Late Cretaceous.
when did turtles evolve?
- did they get big?
- ex
- late Tri
- giant
- Archelon, a 3 m (10 ft) long turtle, was so large that it had to have a bony framework rather than a complete shell in order to reduce weight so it could move around.
When were there giant Alligators
- Ex, how did they hunt, evidence, mainly feed on?
- late Cre
- up to 12 m (40 ft) such as Deinosuchus. This alligator probably ambushed dinosaurs that strayed a little too close to the edges of the shallow oceans where they lived.
Evidence for this includes hadrosaur bones that have been found with Deinosuchus teeth embedded in them! That said,
mainly fed on sea turtles.
Who was Mary Anning
born in Lyme Regis, England, in 1799, cliffs in the area contain some wonderful Jurassic fossils
- 1st discover /extract ichthyosaur/several other marine reptiles
- expert on Jurassic marine mammals
- got honorary membership of the geological society/small pension from the British civil list to recognize her contributions to geology
(be better if a man)
What did Mary Annings contribute to?
George Cuviers iseas about extinction
What does an ichthyosaurs look like?
dolphins
- Apart from the extra set of flippers towards the rear of the animal, what other major structural differences can you see b/w ichthyosaurs and dolphins?
- Which of the features you identified above is likely to be the most significant to the animal and why?
- Position of the eye, colour, size of the dorsal fin, orientation of the tail fluke.
- difference in orientation of the tail fluke, because it would have changed the way the ichthyosaurs swam compared with dolphins.
what type of evolution do ichthyosaurs and dolphins show?
what is it?
example
Convergent evolution
process that accounts for why unrelated organisms (reptile vs mammal) independently evolve very similar features when they adapt to similar niches
both species the dorsal fin evolved in the same location on the body from no pre-existing structure. Dolphins and ichthyosaurs are both fast, hydrodynamic hunters of fast moving prey like fish and squid (and ammonites for ichthyosaurs).
what did cetaceans evolve from
small herbivorous deer-like creature called Indohyus, ~ size of a raccoon, 60 cm long
- live along the edge of rivers and lakes in the area which is now elevated as the Himalayas about 49 million years ago.
- line that would give rise to modern whales would evolve, about 54 million years ago.
similarities between Indohyus and cetaceans
auditory bulla (the bones that surround the inner ear) are very distinctive. They are adapted for hearing under water and only shared by this group and the cetaceans
lots of intermediate forms in between
- what did ichthyosaurs evolve from (hazy)
What features of ichthyosaurs indicate a terrestrial origin for the group
- thought they evolved from a group of land based, unidentified egg laying tetrapods in the Late Permian or Early Triassic
- 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.
how big could ichthyosaurus grow?
what happened to the fossils found in Nevada?
did they live in pods?
- Shonisaurus was up to 15 m (50 ft) long
- 37 Triassic specimens found in Nevada, fossilized together side by side in the same direction.
suggests a mass stranding event reminiscent of similar occurrences in the whales and dolphins today - also suggest might live in pods
what’s cool about ichthyosaurus eyes
where they viviparous?
- good eyesight (large eye sockets)
- plates in the eye were likely an adaptation to prevent water pressure distorting the eyes as they dived for fish
- yes (gave birth to live young)
who found 1st virtually complete plesiosaur in Jur rocks at lime Ridge
Mary Anning
what are the 2 types plesiosaurs
long/short neck
largest plesiosaur, when did it live, hunted what?
Late Cretaceous Kronosaurus was largest at 12 m long.
It probably hunted other marine reptiles in addition to fish and ammonites
Elasmosaurus
-length
- # vertebrae
- The whole body was tightened by strong ________ strung along the creature. can often be seen carved in to the fossil bones
- 14m (46ft)
- 76 vertebrae
- The whole body was tightened by strong ligaments strung along the creature.
what is Lazarus taxa?
ex
organisms thought to have become extinct, that are subsequently found living in relict populations.
- Coelacanths are fish thought to have become extinct at the end of the Cretaceous; however, in 1938 a coelacanth was found among the catch of a South African fisherman
what is a living fossil
ex
regarded as having gone through no significant evolution, right from the time they first evolved
horse shoe crab has remained virtually unchanged since it first evolved, about 450 million years ago
why is it not possible for loch ness monster to exist?
- what could be
- lack fossils in Cenozoic, plesiosaurus can’t move on land like described in stories, not enough fish to support a breeding population
- sonar scan showed no big objects in lake
- seal, sturgeon (a living fossil)
Mosasaurs
______ from the _______. A small, semi-aquatic lizard, who probably spent much of its time diving in to the water to avoid the dinosaurs. evolve and you end up with _______, a more aquatically adapted lizard.
both ~ __m long
Aigialosaurus from the Cretaceous. A small, semi-aquatic lizard, who probably spent much of its time diving in to the water to avoid the dinosaurs. Give Aigialosaurus a few million years to evolve though, and you end up with Dallasaurus, a more aquatically adapted lizard.
1m long
Aigialosaurus -> Dallasaurus -> ?
size?
diet?
Tylosaurus
17.5m (57ft)
ate anything, including fish, plesiosaurs and probably other mosasaurs
what type teeth did mosasaurs have?
how did they hunt
- rows of backward pointing teeth that allowed them to hold their prey secure in their mouth when they bit
- had an additional set of teeth on their palate, which would hook into the severed flesh and push it down their gullet
- didn’t chew
- probably ambush predators
- used their long tails and powerful flippers to rapidly swim upwards and grab the unsuspecting prey in their enormous jaws
