Biology 112 Lab Report: Evolution, Mammals Comparison, and Marine Life

This Biology 112 lab report is a comprehensive analysis of human evolution and comparative studies of mammals, divided into three parts. Part 1 explores human evolution, focusing on skull trends, teeth, palate, forehead, eye sockets, snout, and foramen magnum, comparing ancestral primates to modern humans. Part 2 compares terrestrial mammals, including herbivorous, omnivorous, and carnivorous species, examining traits such as canine and molar structures, masseter muscles, eye sockets, and dental formulae. Part 3 extends the comparison to marine mammals, analyzing organisms like dolphins, river otters, sea otters, harp seals, and gray seals, focusing on nose, teeth, eye sockets, and muscle structures. The report concludes with a comparative analysis between terrestrial mammals and the harp seal. References are provided to support the findings.

Running head: BIOLOGY 112 LAB 1
Biology 112 Lab
(Author’s name)
(Institutional Affiliation)

BIOLOGY 112 LAB 2
Biology 112 Lab
Part 1Human Evolution- Skulls Trend
Features Trends as you go from the ancestral primates to modern Human
Braincase The braincase becomes larger as the brow ridges become smaller and smaller.
Additionally, the cranial ridge continues to fade as the time goes. This is due to
the fact that, early humans pass through new environmental challenges which
made them evolve into bigger bodies with more complex brains(Craze, 2013).
This is evidenced by the Australopithecus brain case was small which measured
4.5 to transitional homoerectus and homosapiens who had a brain case of 11
inches. However other modern primates have extremely evolved showing larger
forms of intelligence(Martínez-Abadías et al., 2012). For instance, a
chimpanzee male has a brain case of 6.5 inches and a male gorilla has a larger
braincase of 8.5 inches.
Teeth The trends of the teeth in human has been changing from large to smaller as
canines get smaller and less sharp over the time. This is because human
developed larger brain capacities which made them invent advanced tools thus
chewing was made easier(Martínez-Abadías et al., 2011). This is evidenced by
the modern apes like a male gorilla has very large and sharp canines followed
by a chimpanzee. The Australopithecus had no defined incisors but big molars,
homoeructus, and homo sapiens teeth are similar with equal size of incisors and
small canines.
Palate The palate has changed from a U shape to V shape. This is because the
ancestral primates had no leveled teeth as compared to homo sapiens. The
property leveled teeth of homelectus and homosapiens from the back of the
mouth assist each other in lower and upper jaws which have developed multiple
purposes(Craze, 2013).
Forehead in
relation to the
Face
The forehead of modern human have progressed to being parallel to the eyes as
compared to Australopithecus which had a pushback forehead
Eyes Socket Comparing with the Australopithecus which had very deep eye socket, the eyes
socket of homosapiens have grown close together.Additionally, the

BIOLOGY 112 LAB 3
homoerectus, and transitional homosapiens had also deep eyes sockets. The
ancestral primates had a field visual that was not equally from both eyes as
compared to the modern human where both right and left eyes have an equal
field visual.
Snout The ancestral primates had a snout that was pushed forward as compared to
Homosapien whose snout is pushed inward(Martínez-Abadías et al., 2012). The
Australopithecus had a long and wider nose as compared to a modern human
whose nose is proportional to the size of the face(Craze, 2013).
Foramen
Magnum
The ancestral primate had a foramen magnum that was in the back of the skull
which has progressed to the center of the skull(Martínez-Abadías et al., 2012).
The homo erectus and homosapiens have a foramen magnum that in the middle
of the skull.
Homo erectus was the first stage in human evolution where the hominids were able to walk
upright. This is because, by observing all the species of hominids, the only homoerectus have a
high similar characteristic with the modern man and homosapiens. In additional, Homoerectus
have distinguished features that could have made them be the first hominids to walk upright.
These include short zygomatic bones and foramen magnum located at the center.
Part 2 Comparative Study of Terrestrial Mammals (Herbivorous, Omnivores and
Carnivorous)
Traits Trends – Carnivorous, Omnivorous
and herbivorous
Explanations
Canine The carnivorous have sharp-
pointed canine teeth. Omnivorous
teeth are at the same level as other
teeth while herbivorous lack canine
teeth(Kim et al., 2016)
Carnivorous mammals need canine teeth for
tearing of fresh meat and hunting other
animals. On the other hand, herbivorous lack
canine teeth since they are just plant
eaters(Prevosti, Turazzini, Ercoli, & Hingst-
Zaher, 2012)
Molars Carnivorous have intence molars as
compared to herbivorous which
Since the herbivorous need to glide their
food, their molars are flat. Carnivorous

BIOLOGY 112 LAB 4
have flat molars(Kim et al., 2016) molars are spikey as they are used to break
bones
Masseter
Muscles
The masseter muscles become
enlarged from carnivorous to
herbivorous
Carnivorous shred up food that they do not
need larger masseter muscles. On the other
hand, Herbivorous larger masseter muscles
are used to assist in gridding food(Kim et al.,
2016).
Eye
sockets
Carnivorous and herbivorous
mammals have had eye sockets
located on the sides but those of
carnivorous are more intersecting.
Omnivorous mammals’ eyes
sockets are just below the forehead.
Carnivorous eye sockets are used to assist in
hunting and locating the prey. Herbivorous
eyes sockets are used to provide a good
visual of the surrounding as a defense
mechanism from the carnivorous(Prevosti et
al., 2012).
Temporalis
Muscles
The temporalis muscles decrease
from carnivorous to herbivorous
The large temporalis muscles obtained from
carnivorous are used for prey gripping. Due
to the fact that herbivorous are plant eater,
they do not require temporal muscles for
hunting the prey.
Dental
formulae
The number of teeth decreases
from carnivorous to herbivorous as
the number of molars increases.
Incisors and molars are present to
all groups but the herbivorous lack
canines(Nelson, Rogers, & Brown,
2013).
Herbivorous lack canine teeth thus they have
less number of teeth as compared to
carnivorous and omnivorous(Clauss,
Kleffner, & Kienzle, 2010). In addition, the
number of molars increases due to the fact
that herbivorous need more molars for
grinding of food. The difference in dental
formula is because all the three groups have
different nutrition thus their teeth evolve
differently.
The blowhole of a dolphin corresponds to nasal passages the terrestrial mammal's skull have.
The terrestrial mammals are able to breathe through the use of snout and thus the dolphin

BIOLOGY 112 LAB 5
blowhole operates in the same way. The dolphin's zygomatic bones are different as compared to
carnivores since dolphins swallow fish as a whole but do not grip them but carnivorous always
chew their food.
Considering that dolphins have many canines and incisors with pegged teeth, they are likely to
swallow their prey as a whole. in addition, dolphins lack molars thus they are not likely to grid
their food.
Part 3 Marine Mammals
Organism Nose Teeth Eye sockets Masseter and temporalis
muscles
Dolphin Snout
present
Dolphin have
Pegged teeth
The dolphin
have eye sockets
located on the
sides of the skull
making them
have an
overlapping
visual(Perrin,
Wursig, &
Thewissen,
2009)
Dolphins have very small
masseter muscles nearer to
based but their temporalis
muscle are basically
large(Perrin et al., 2009)
River otter Snout
Present
River otters have
very large canine
teeth and sharp
molars
The eyes of
river otters are
located toward
the sides of the
skull
The River Otters have large
masseter muscles but
temporalis muscles are
diminutive(Berta, Sumich, &
Kovacs, 2005)
Sea otter Snout
present
Sea otters have
levelled molars and
spikey and larger
canine teeth
The eye sockets
of a Sea Otter
are located
toward the sides
Sea Otters have large
Tempolais and Masseter
Muscles

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of the skull
Harp seal Snout
Present
The harp seal have
small canine teeth
and the molars are
absent(Perrin et al.,
2009)
The harp Seal
eyes Sockets are
located
anonymously
and nearby
Both the masseter and
Temporalis muscles are very
small near to absent(Perrin et
al., 2009)
Gray Seal Snout
Present
Gray seals have
large canine but
molars are absent
Gray Seals Eyes
are located
distantly toward
the sides of the
skull
Gray seals have regular sized
masseter and temporalis
muscles
.
The above marine animals can be grouped into three major categories. This includes the
dolphins in one group, the Gray Seal and Harp Seal in another group and the final group could
consist of River Otters and Sea Otters. The Dolphin, Harp Seal, and Gray seals have no molars
but temporaries muscles. This means they can be able to tear food but cannot grid. However, the
dolphins have pegged teeth as compared tp Harp Seal and Gray seal which has Canines thus
differentiating them into two groups. In addition, the River Otters and sea otters have both
masseter muscles and all type of teeth thus differentiating them to a very different group(Berta et
al., 2005).
Comparative of Terrestrial and Harp Seal
Organism Eyes Teeth Masseter and temporaries muscles
Sheep Eyes are
located
sideways to
provide an
extensive
view
Have incisors and molars
only but lack canines
Have large masseter muscles but
lack temporalis muscles
Dog Have sharp and spikey
canine teeth. Molars are
Have both masseter and temporalis

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present muscles
Raccoon Raccoon have both canines
and flat molars
Have masseter but lack temporalis
muscles
Leopard Leopards canine are sharp
and spiky.
Have tempralis muscles but lack
masseter muscles
Human Human have both flat
canine and molars
Have both masseter and temporalis
muscles
Harp Seal Harp seal have canines but
lack molars
Lack both masseter and temporalis
muscles
(Perrin et al., 2009)
Comparing all the above mammals with Harp Seal, the leopard has many mutual characteristics
although the two mammals have differences when it comes to large temporalis muscles and
molars.

BIOLOGY 112 LAB 8
References
Berta, A., Sumich, J. L., & Kovacs, K. M. (2005). Marine mammals: Evolutionary biology.
Second Edition. Academic Press San Diego CA 494pp 1999 (Vol. 406). Retrieved from
http://books.google.com/books?id=4sWbuL0hM1kC&pgis=1
Clauss, M., Kleffner, H., & Kienzle, E. (2010). Carnivorous mammals: Nutrient digestibility and
energy evaluation. Zoo Biology, 29(6), 687–704.
Craze, P. (2013). Early human evolution and the skulls of Dmanisi. Significance, 10(6), 6–11.
Kim, S., Cho, Y. S., Kim, H. M., Chung, O., Kim, H., Jho, S., … Yeo, J. H. (2016). Comparison
of carnivore, omnivore, and herbivore mammalian genomes with a new leopard assembly.
Genome Biology, 17(1).
Martínez-Abadías, N., Esparza, M., Sjøvold, T., González-José, R., Santos, M., Hernández, M.,
& Klingenberg, C. P. (2012). Pervasive genetic integration directs the evolution of human
skull shape. Evolution, 66(4), 1010–1023.
Martínez-Abadías, N., Mireia, E., Sjøvold, T., González-José, R., Santos, M., Hernández, M., &
Klingenberg, C. P. (2011). Pervarsive genetic integration directs the evolution of human
skull shape. Evolution, 1–14.
Nelson, T. M., Rogers, T. L., & Brown, M. V. (2013). The gut bacterial community of mammals
from marine and terrestrial habitats. PLoS ONE, 8(12).
Perrin, W. F., Wursig, B., & Thewissen, J. G. M. (2009). Encyclopedia of Marine Mammals.
Encyclopedia of Marine Mammals.
Prevosti, F. J., Turazzini, G. F., Ercoli, M. D., & Hingst-Zaher, E. (2012). Mandible shape in
marsupial and placental carnivorous mammals: A morphological comparative study using
geometric morphometrics. Zoological Journal of the Linnean Society, 164(4), 836–855.