Caminalcules and Phylogenies: Fossil Evidence
Objectives



How a phylogeny can be tested & revised given new information
Increase awareness of homologies and analogies
Construct a new phylogeny for caminalcules using fossils
Constructing a Phylogeny based on Fossil Evidence
New information can alter our analysis of the relationships among living species. Genetic
information, developmental observations, and other data can aid biologists seeking to understand
how closely organisms are related and how evolution works.
The analysis of fossils can greatly assist in the construction of phylogenies also. A fossil can be
dated relatively and absolutely, and assessed for characteristics shared with other fossils and
living species. An attribute can then be classified as ancestral if it is found in common ancestors
or derived if it evolved more recently in a certain lineage (branch) or species.
For today’s lab, you will use fossil Caminalcules to test your hypothesized phylogeny from last
week’s lab. The fossil Caminalcules should provide you with additional information that you can
use to assess the relationship of the living Caminalcules. You will still have to make some
decisions about from which branch and when species have split off from an ancestral one, but the
fossils should provide a better picture of the phylogeny among the living Caminalcules than could
be achieved using only the living ones’ characteristics.
Fossil Caminalcules have an additional number in parentheses indicating the geological age of
each specimen in millions of years. Most of the fossil Caminalcules are extinct, but you will
notice that a few are still living (e.g. species #24 is found among the living forms but there is also
a 2 million year old fossil of #24 in our collection).
The Phylogeny of Caminalcules
Using a sheet of paper, construct a phylogenetic tree for the Caminalcules. Use a straight edge to
draw 20 equally spaced horizontal lines on the paper to turn in for the lab assignment. Each line
will be used to indicate an interval of one million years. Label each line so that the one at the
bottom of the paper represents an age of 19 million years and the top line represents the present (0
years). You will be provided with laminated sets of Caminalcules. Categorize them according to
their age (the number in parentheses). Beginning with the oldest fossils, arrange the
Caminalcules according to their evolutionary relationships.
For your assignment today, you are to construct a phylogeny for both the living and fossil
caminalcules. Again, keep track of what characteristics you used when linking fossils with
other fossils and/or living species.
Bi102
Caminalcules II
1
Hints, Suggestions and Warnings
a.
b.
Draw lines faintly in pencil to indicate the path of evolution. Only after your instructor has
checked your tree should you place the figures on the page and darken the lines.
Branching should involve only two lines at a time:
Like this
c.
d.
e.
Not this
Some living forms are also found in the fossil record.
There are gaps in the fossil record for some lineages. Also, some species went extinct
without leaving any descendants (remember the dinosaurs).
The Caminalcules were numbered at random; the numbers provide no clues to evolutionary
relationships.
FOSSIL CAMINALCULES:
(number in parentheses indicate age in millions of years)
Bi102
Caminalcules II
2
Fossil Caminalcules continued (number in parentheses is millions of years ago)
To test your hypothesis about the relationships of the living Caminalcules, you will use additional
data. In this case, you will use the fossil Caminalcules to construct a new phylogenetic tree and
compare it to your original tree. To construct your tree, begin by sorting fossils from oldest to
newest. Now, looking at the fossils, you will decide how the caminalcule Phylogenetic tree leads
Bi102
Caminalcules II
3
to the 14 living fossils. Note that if a fossil has the same number as a living species, then that
species has not changed since the fossil, though other species (fossil or living) may have branched
off of that line. Also, there may be large gaps in the fossil record.
After you have generated a phylogeny using the fossil data, redraw this new phylogeny
using only the living species, but retaining the branching patterns (skip the lines that do NOT
lead to a living species). As you did last week, place characteristics on the tree that you use to
determine branches. You can now compare your new phylogeny with your hypothesis phylogeny
from last week.
Bi102
Caminalcules II
4
Lab Report: Caminalcule Phylogeny with Fossils
Names: _________________
__________________
__________________
__________________
Lab Date/Time ______________
1. On a separate page (or the back of this one) draw your phylogeny of the 14 living species with
all the fossils included.
2. Draw your test tree of living Caminalcule species below. For this tree, use the tree that
includes the living species and the appropriate branching patterns from the fossil data, but
DO NOT include the fossils. This tree will look similar to the one you constructed last week.
PLACE CHARACTERISTICS on the tree that allowed you to separate groups or species.
Bi102
Caminalcules II
5
3. Now draw the hypothesis tree and the test tree next to each other below without any
characteristics added to the trees. These two trees should include the branches and the 14 living
species at the top. Draw the two trees in such a way that you will be able to analyze the
relationships between the two trees effectively.
Examination of the two trees
4a) Do you have the same set of species coming off the main two branches of each tree? If not,
list the species coming off of each branch for the two trees. After listing the species, explain why
your new branching pattern is different (in other words, analyze why you have different main
branches).
Bi102
Caminalcules II
6
4b) Did the arrangement of your groups of species change? Describe these changes.
4c) Finally, within groups of species, were relationships among species consistent or were there
rearrangements based on your new tree? Describe these.
5. Were there characteristics you used for your hypothesis tree to link species together that turned
out to give you a false tree based on your test (fossil-based) tree? What kind of characteristics
would these be: homologous or analogous? List these characteristics and why you think it is
analogous or homologous.
6. The ‘test’ tree is certainly incomplete and could now be used as a hypothesis tree. What other
types of data or information, besides fossils, could be useful in testing this new tree?
Bi102
Caminalcules II
7
Evolution: Great Transformations
What is the period of time which is thought to include the transformation of vertebrates from
water to land? How many years ago are they talking about for these fossils?
Originally, how did scientists think that fish evolved to live on land?
Which parts of the fish are hypothesized to be transformed allowing land dwelling vertebrates to
evolve?
What is thought to be the original function of the first limbs possessed by fish/amphibian-like
creatures?
How many fingers do the first limbed fossils possess?
Is evolution thought to be goal oriented? That is, was the evolution of limbs and living on land
the goal of evolution?
Bi102
Caminalcules II
8