week 8

Question 1

what are the 4 new mammalian super orders?

Answer 1

laurasiatheria - boreoeutheria
afrotheria
xenarthra
euarchotoglires - boreoeutheria

Question 2

ungulates can be divided in to 2 groups what are they?

Answer 2

odd toed - perissodactyla

even toed - artiodactyla

Question 3

examples of perissodactyla?

Answer 3

rhinos horses tapirs

Question 4

examples of artiodactyla

Answer 4

10 families anntelopes, hippo, pigs, camels etc

Question 5

recent research indicates that the ungulates have their origin in which super order?

Answer 5

laurasiatheria - northern hemisphere

Question 6

3 points about ungulates (hoofed animals)

Answer 6

adapted to a terrestrial lifestyle
rapid locomotion
herbivorous diet

Question 7

in the ungulates which bones is it in the limb that are extended?

Answer 7

metapodials

Question 8

ungulates show adaptations for digestion because of their herbivorous diet, which 2 areas?

Answer 8

teeth morphology

gut

Question 9

perissodactyls - odd toed ungulates are ___ fermentation

Answer 9

hind gut

large caecum

Question 10

artiodactyls - even toed ungulates are ____ fermentation

Answer 10

foregut

ruminants

Question 11

What are the early ungulates called?

Answer 11

protoungulata

within this there is the group condylarthra

Question 12

what were the condylarths like?

Answer 12

non specialist in diet

artificial grouping of several distinct lineages at the base of the radiation of later ungulates

Question 13

how many families are there within the condylarths? what is the important one?

Answer 13

4

mesonychids

Question 14

What is the well known mesonychid fossil?

Answer 14

Mesonyx
carnivorous ungulate
wolf sized
pointed molars

Question 15

what are the 2 super ordinal groupings?

Answer 15

protoungulata - early ungulates

paenungulata - near ungulates

Question 16

Early perissodactyls, horse evolution explain

Answer 16

went in the eocene from smaller size, when it was a browzer with small leaf crushing molars, to larger grazers with large grass grinding molars

Question 17

what was the evolution of the horse likely driven by?

Answer 17

evolution of teeth and limb morphology thought to be driven environmental change (spread of grassland)

Question 18

what is the characteristic feature of an early artiodactyls?

Answer 18

double pulley astragalus

Question 19

modern artiodactyls fall in to 2 groups, what are they? and what are they distinguished by?

Answer 19

Selenodontia - cheek teeth with selenodont pattern
Bunodontia / suriformes - pigs and hippos - bulbous cusps on molars

teeth

Question 20

Explain how the abundance of ungulates has changed?

Answer 20

in the eocene the land was dominated by perissodactyls and there were few artiodactyls, however climate change drove many perissodactyls to extinction due to their hind gut fermentation being less efficient than foregut fermentation, especially in grasslands

Question 21

What are cetacea?

Answer 21

whales and dolphins

Question 22

where are cetacea thought to have evolved?

Answer 22

tethys sea - between gondwana and laurasia

Question 23

early cetaceans are lumped together in the ____

Answer 23

archaeocetes

Question 24

what are 3 characteristic features of the archaeocetes?

Answer 24

differentiated teeth
nostril placement
limbs reduced or still present

Question 25

The early cetaceans were in 3 genera?

Answer 25

pakicetus
ambulocetus
basilosaurus

Question 26

After the eocene the whales radiated into two main groups:

Answer 26

odontoceti

mysticeti

Question 27

describe features and examples of the 2 broad groups of whales

Answer 27

odntoceti - evolved sonar, toothed whales - orca, dolphin, porpoise

Mysticeti - baleen whales - evolved song - blue whales, humpbacks

Question 28

There are 2 major diversification radiations of whales. Caused from what?

Answer 28

Steeman et al.
Created a bayesian tree calibrated to give chronogram

toothed whales monophyletic
support for increased diversification during physical restructuring of oceans

Question 29

Where did cetaceans evolve from? what is the traditional palaeontological view

Answer 29

Primitive whales and Mesonychia are sister groups based on similarities in teeth and skulls
Gingerich and russel 1981
oleary and geisler 1999

Question 30

What is the evidence from the teeth that mesonychids are “sister taxon” to the whales? (3)

Answer 30

O leary and Uhen 1999
Similarities in teeth - both mesonychids and early cetaceans possess pre molariform molars with simple, tall and sharply pointed protoconids and laterally compressed distal ends.

Importantly this is not seen in other ungulates.

Luo and GIngerisch 199 - Similarities in the ear - both mesonychids and early cetaceans show elongation of external auditory meatus and mastoid process of the petrosal

Paraxonic foot posture - oleary 2002 - mesonychids and early cetaceans also share this foot posture in which the weight bearing axis passes between digits 3 and 4, as opposed to digit 3 in perissodactyls

Question 31

Genetic evidence suggested an alternative sister group, what did Shimamura et al 1997 show?

Answer 31

Using SINES and assessment of transposons showed that cetaceans cluster within artiodactyla and so artiodactyla is a paraphyletic group.

Question 32

The position of cetaceans within artiodactyla led to a re examination of ____

Answer 32

the ankle bone
previously thought to support monophyletic origins of artiodactyls.
Artiodactyls have a double pulley astragalus
no modern whales have kept hind limbs so cannot look at this feature but can look at early whales and mesonychids

Question 33

What did Muizon 2001 show about the ankle bones of ungulates and primitive whales?

Answer 33

early whales (Pakicetus and ambulocetus), early artiodactyls have double pulley astragalus where as mesonychids do not.

Question 34

So how does the ankle bone relate to the emergence of the hypothesised clade cetartiodactyla?

Answer 34

Because early morphological data suggested that the ankle bone pulley had developed on the artiodactyla branch however with the new evidence it shows that this feature actually shared with cetacea and so there is an order cetacea and artiodactyla

Question 35

So what exactly is the sister group of whales if its not mesonychids?

Answer 35

hippos or cows shimamura et al 1999

Question 36

What is the extant sister group shown by nikaido et al

Answer 36

1999
isolated and characterised 10 additional SINE loci

showed clustering of whales and hippos - monophyletic group

further supported by boisserie et al 2005 measured 80 ostological characters constructed trees using parsimony analysis - placed hippos as monophyletic group with cetaceans

Question 37

what are some characters that extant whales and hippos share? (4)

Answer 37

hairlessness
lack of sebaceous glands
ability to nurse offspring underwater
absence of paraconules on upper molars

previously thought these traits were due to convergent evolution, however might be ancestral traits that occurred before cetaceans became fully aquatic

Question 38

why do problems persist in naming hippos as the sister taxon to cetacaeans?

Answer 38

because cetaceans are 50mya in south asia whereas the family hippopotamidae arose 15mya so there must be something even closer to cetazceans

Question 39

What does thewissen et al 2007 state?

Answer 39

whales originated from aquatic artiodactyls in the eocene epoch of india

• INDOHYUS

Question 40

What are the 3 pieces of evidence thewissen 2007 states that indohyus are closely related to cetaceans?

Answer 40

they have a similar ration for the medial tympanic wall and lateral tympanic wall in the ear

osteosclerotic bones

ate aquatic plants - isotope analysis