BIOL 4141 : EXAM 2
Questions
107. (Fill in the blank) The distinguishing dental feature shared by most (but not all) carnivorans is
the carnassial teeth
108. (Fill in the blanks) Identify the continent(s) on which the major evolutionary radiations of the
following groups occurred:
a) horses: Europe/ Eurasia
b) omomyid-adapid primates: Africa and South America
c) marsupials: First radiation: Europe , Second radiation: North America , Third radiation: South
America
109. The order Carnivora is traditionally divided into two major suborders. Name these suborders.
Caniformia and Feliformia
110. (two-part question) What are carnassial teeth? Do all members of the order Carnivora have
carnassial teeth? Carnassial teeth are the upper 4th premolar and lower 1st molar= teeth in most
carnivores that are used for shearing. Not all members of Carnivora have carnassial teeth—seals and
sea lions have homodont dentition; bears and raccoons don’t have “carnassials”
111. The evolution of teeth in the xenarthrans (also known as "edentates “without teeth" name is a
misnomer) followed two, very different pathways. Refers to shape of lumbar vertebrate Describe
these evolutionary trends, naming the families involved. Myrmecophagidae are the only xenarthrans
that are edentates (without teeth). Bradypodidae and Dasypodidae have teeth with a soft dentine
core, hard dentine coat and cementum on the outside.
112. The evolutionary radiation of the order Xenarthra took place on which continent? South
America during Miocene before landbridge between North and South America broke apart. Most of
the larger and more impressive members of this order went extinct during what major extinction
event? 12-20,000 yrs ago Great Pleistocene Extinction
113. When referring to mammals of the order Insectivora, why do I prefer that we use the term
"insectivorans" rather than "insectivores"? Insectivore is a mammal that eats insects and small
animals which is inconsistent with insectivorans. Insectivore=animal eating habit, not all
insectivorans are insectivorous.
114. Provide two possible explanations for why the fossil record of early bats is so poor. (1) their
bones are small; small post cranial skeleton(2) bones are very delicate and don’t fossilize well.
115. Name the two suborders of the order Chiroptera, and describe the key morphological feature
that distinguishes between these two suborders. Yinpterochiroptera and Yangochiroptera.
Yangochiroptera use echolocation and are all other bats worldwide. Yinpterochiroptera are Old
World bats; extra nipples in pubic region in females, 2 lower incisors on dentary—other bats have
more than 2 pairs of hind limbs.
116. Do all bats echolocate? (to "echolocate" means to navigate using sound). Explain your answer.
Some bats have lost their ability probably because they are frugivorous and lack the need to hunt
and be active during the day, and are not in caves.
117. What is the term we use to describe the specialized (comb-like) lower incisors of dermopterans?
pectinate pattern
118. (fill in the blanks) The genus Purgatorius (from the Paleocene of Montana) is thought to be
among the earliest members of the mammalian order Primates. Later in the Paleocene, there was a
radiation of early primates into several recognizable families that are collectively placed in the
suborder Plesiadapiformes . Some authorities suggest that the living family Omomyid-Adapid may,
in fact, be a direct descendent of this early suborder. Others argue that this suborder is now extinct.
119. What is the major division within the anthropoid primates? Describe one dental feature that
distinguishes between most members of these two groups. Old World and New World; Old World
has 5 cheek teeth while New World has 6 cheek teeth
120. Discuss briefly the two theories for the origin of South American primates.
(1) they had holartic ancestors and when the N. Atlantic land bridge closed, it isolated them in South
America
(2) they rafted across from Africa on natural rafts—tree dwelling primates in Africa were washed
out possibly by a flood to South America
121. Which order of mammals is considered to be the most diverse order of living mammals (in terms
of number of living species)? Rodentia
122. What morphological feature is diagnostic for the order Rodentia? Single set of upper and single
set of lower incisors and diastema They all hae an infraorbital canal.
123. Superficially, the incisors of Rodentia and Lagomorpha look very similar. How are they
different? Lagomorpha have recombinant upper incisors.
124. Why is it significant to note that the earliest rodents in the fossil record were not found in the
same fossil deposits as were members of the prototherian order Multituberculata? It’s important
because it lets you know they didn’t evolve from prototherians. It might demonstrate competition
between multituberculates and rodents because one might have outcompeted the other.
125. The order Cetartiodactyla used to be divided into two orders. Name them. Artiodactyla and
Cetacea
126. (fill in the blank) The closest living relatives of the proboscideans are placed in the order
Sirenia.
127. (fill in the blanks) All living elephants belong to the family Elephantidae . Living elephants are
the direct descendants of what group of Plio-Pleistocene proboscideans (common name okay)
mammoths
128. Discuss the early history of the order Proboscidea. Your answer should mention the following
groups, including their times of origin, relationships to each other, and brief descriptions of these
groups. Groups to mention: mastodons, Elephantidae, Deinotherium, Moeritherium, gomphotheres,
and mammoths. Elephantidae have a common ancestor with Sirenia & Hyracoidea, lived during the
earliest Eocene in Africa. Moeritherium lived during the Eocene, lacked a trunk and had minor tusks- split
into 2 groups during the Myocene/Pliocene: Deinotherium and Gomphotheres. Deinotherium had
enlarged lower 2nd incisor or tusk, had a trunk and went extinct by the Pleistocene. Gomphoteres had a
trunk and enlarged upper incisor, it evolved hypsodont teeth for beginning grazing and rolling eruption
teeth. They split into 2 more groups: Mastodons and Mammoths. Mastodon’s cusp patterns were little
mounds that wear off and were browsers went extinct by Pleistocene. Mammoths were grass eaters and
gave rise to the modern day elephant Elephantidae.
129. How can we tell from the fossil record whether or not an extinct proboscidean had a trunk? By
the length of the snout.
130. The early fossil record of the proboscideans is especially rich in what region of the world? Africa
131. Describe the structure of the teeth of mammals of the order Tubulidentata. They have no
enamel and no incisors or canines. Little hexagons on the teeth have pulp in the middle with a
dentine outer covering and cementum over that. Coat of cementum on the outside, dentine prisms
that are filled with pulp.
132. How do we explain the relatively rapid evolution of large body size in early cetaceans? When
they became obligate aquatics they grew a large body to deal with the coldness of the water. Low
surface to volume ratio is better and easier for thermoregulation.
133. Discuss the early history of the suborder Cetacea. Your answer should mention the major
groups in this order (both extant and extinct), including their times of origin, relationships to each
other, and brief descriptions of these groups. The earliest fossils from early Eocene. Early whales
lived in coastal environments and were amphibious. Grew large body when the became obligate
aquatics: elongation of skull, reduction of hind limbs and pelvis. In early Eocene, whales were placed
in the Superfamily Archaeoceti are were located in Asia and Africa and had the primitive number of
teeth. In Oligocene we see superfamily Odontoceti found off coast of North America. Other
superfamily Mysticeti were found off the coast of New Zealand.
134. The informal term "ungulate" refers to which order(s) of living mammals? Perissodactyla and
Cetartiodactyla, Sirenia, proboscidea
135. The "odd-toed ungulates" are placed in the order Perissodactyla. The three living families of
odd-toed ungulates are: Equidae, Tapiridae, and Rhinocerotidae.
136. Why do we refer to horses as "odd-toed ungulates"? they have an odd number of toes
137. List three factors that may explain why the horse family, Equidae, has the best fossil record of
any group of living vertebrates. (1)They had large bodies that were heavily boned so large fossils (2)
lived in open Savannah fields which had soils that preserved pretty well; grasslands are better for
Document Summary
America: the order carnivora is traditionally divided into two major suborders. Carnassial teeth are the upper 4th premolar and lower 1st molar= teeth in most carnivores that are used for shearing. Refers to shape of lumbar vertebrate describe these evolutionary trends, naming the families involved. Myrmecophagidae are the only xenarthrans that are edentates (without teeth). America during miocene before landbridge between north and south america broke apart. 12-20,000 yrs ago great pleistocene extinction: when referring to mammals of the order insectivora, why do i prefer that we use the term. Insectivore is a mammal that eats insects and small animals which is inconsistent with insectivorans. Yangochiroptera use echolocation and are all other bats worldwide. World bats; extra nipples in pubic region in females, 2 lower incisors on dentary other bats have more than 2 pairs of hind limbs: do all bats echolocate? (to "echolocate" means to navigate using sound).
