Group Members: Selina Chin, Marvin Aguire, Octavia Baxley
Teacher: Ms. Lemus
Period: 1
Date: May 6th, 2013
D
Bottlenose
Dolphin
J
F
Humpback
Orca
A
C
E
Hippo
Basilsaurus
Dorudon
B
G
H
Mesonychid
Pakicetus
Ambulocetus
I
Rodhocetus
s
Team Past
Orca whales can have ancestors from the past. For example, Ambulocetus, Dorudon, and many
other animals from the past. The orca’s and the animals from the past have some physical traits that are
similar; plus, they have similar habitats. However, they might not be real ancestors, because some of the
animals from the past do not have all the physical traits. Plus, another thing is that the orca’s cannot
move as swiftly as the past animals.
From our phylogenetic tree, we think that the Orca whales and the Rodhocetus could be related
by their physical traits. The physical trait that they have in common is their strong powerful tail. “The
sizes of these extensions on the top of the vertebrae where muscles are attached indicate that
Rodhocetus had developed a powerful tail for swimming” (Gingrich, 1994). They both use these tails to
swim in the waters. Plus, an interesting thing that both animals ungulate their spine up and down to
swim. Another reason why the Bailosaurus and Dorudon might be related is that they live in similar
habitats. “Basilosaurs and Dorudon were fully aquatic whales” (Gingrich and Uhen, 1996).
Some evidence that contradict our explanation is that the animals back then had
legs/arms/limbs. For example the basilosaurus had limbs, in the article, Basilosaurs, it said,“The limbs
were too small for effective swimming; the legs were at least 60 cm long on this 15 meter animal . . .”
(Sutera, 2001). The basilosaurs had legs, but if they were ancestors of the orca whales what happened
to those legs. Plus, the animals from the past, Ambulocetus and Rodhocetus also had legs. Another thing
is that the animals back then could walk on land. “The ambulasorus could walk on land but not very
efficiently” ( Sutera, 2001). Our orca whales now a day cannot walk on land. In the water, orca whales
ungulate their spins up and down, just like a mammal ungulate their spins when they run.
In conclusion, the orca whales in our present day might or might not have ancestor. They could
have ancestors because they have similar physical traits, like their powerful tail. Plus, they both mostly
lived in the water. However, they might not be related/ be ancestor because the animals back then have
legs/limbs, and the orca whales now do not have legs and limbs, they have fins. Plus, most of them
walked on land, and our orcas do not walk on land. So, they might not be relatives, or they developed
new traits along the years.