guide in PDF format
Guide to morphotyping (or binning) a fossil flora (Step-by-step)
1. Prepare and number specimens: Label each specimen with a locality
number and prepare it in the lab so that the features of the leaf are as visible
as possible. Create a specimen label that contains the locality and accession data
for the specimen. Create a second "morphotype tag" to keep track of the fossil’s
morphotype number, your initials and the date. It is useful to place each specimen
in a specimen tray so that the labels remain with the specimen.
2. Bin the flora: Sort the fossils into groups based on shared
leaf-architectural characteristics following the binning flowchart below. (For a
more detailed description, see
guide to binning to binning under the identification tab.) Begin by separating
the specimens into three groups: non-leaves, non-dicots and dicots. Below is an
example using a very small locality that contains 6 fossils. Of this group, fossils
1-4 are dicots and fossils 5 and 6 are ferns. First, separate the ferns – they belong
in bin 7.
Next we divide the dicots with the bin flow chart in hand. The initial sorting of
dicots is done on the basis of the presence and type of lobes, toothed versus entire
margins, and primary and secondary vein patterns. These characters are usually stable
within morphotypes. Less reliable characters are leaf size and shape.
Flowchart depicting structure of the identification menus of this website
(Category "bins" are numbered for easy reference.)
In our six leaf example, fossils 1-4 are all dicot leaves with petioles attached outside the margin. They
are unlobed and the primary vein is pinnate. Fossils 1 and 2 have a toothed margin
but fossils 3 and 4 are smooth. Thus the fossils are split into two groups.
Fossils 1 and 2 have toothed margins, agrophic veins and the secondaries veins are
semicraspedodromous so they go to bin 15. Fossils 3 and 4 have smooth margins, no
agrophic veins, brochidodromous secondary veins and an elliptic shape. Thus they
both go to bin 24.
3. Subdivide the specimens in each bin: Once the fossils are grouped
into bins, it is much easier to separate them by higher-order venation pattern and
tooth type [see LAWG 1999, Hickey 1973, 1979 and Hickey and Wolfe, 1975]. Here's
the breakdown for our example flora:
Bin 7: Although they are both ferns, fossil 5 and 6 are different ferns. Therefore
fossil 5 will be labeled 7.1 (first morphotype in bin 7) and fossil 6 will be labeled
7.2 (second morphotype in bin 7).
Bin 15: Although minor differences can be noted, fossils 1 and 2 are examples of
the same morphotype. They will both be labeled morphotype 15.1 and fossil 1 will
be designated the holomorphotype. Fossil 2 is just another example of the morphotype.
Bin 24: Fossils 3 and 4 are different from each other. The angle of the secondary
veins is steeper on fossil 3 and the brochidodromous loops occur closer to the margin
on fossil 4 than fossil 3. Thus, fossil 3 becomes 24.1 and fossil 4 becomes 24.2,
both are holomorphotypes.
One major distinction between holotype specimens (the single specimen
that bears a Linnaean name) and holomorphotype specimens (the informal
numbering-bearing specimen in this system) is that holotypes are permanent where
holomorphotypes are informal and may be replaced with better specimens or sunk into other morphotypes.
4. Describe the morphotpyes: The next step is to completely describe
the diagnostic features of the morphotype. (We use the terminology found in the Manual of Leaf Architecture as
a guide.) This is typically done by designating a single quarry
holomorphotype that best represents all of the characteristics of the morphotype
and describing how to distinguish it from other morphotypes found at this quarry. In the process of morphotyping a flora,
you may discover that some morphotypes are not easily represented by a single holomorphotype
because of the range of variation exhibited by the specimens. In this case, a holomorphotype
is still designated but the description of the morphotype is expanded
using additional specimens that show clear overlap in their morphological characters
with the holomorphotype specimen, to completely describe the morphotype.
Learning how to look at venation patterns takes practice. To highlight the characters
that differentiate the fossils within your bins, it is very helpful to sketch and/or
photograph the holomorphotypes and note diagnostic features and the range of variation.
It is useful to print photos or scanned slides as full page images that can be mounted
on the wall of you work area. This increases familiarity with the various morphotypes.
5. Comparing leaves from multiple localities: At DMNS, we try to
collect a minimum of 300 leaves from a single quarry (more if the flora is very
diverse). With this data, we can estimate paleoclimate and diversity parameters
for each locality without needing to name the fossils.
To manage all of these fossils, we use the bin system to sort the fossils from a
single quarry. Thus, multiple quarries can have a fossil labeled 24.1 even though
they do not represent the same morphotype across quarries. This has two advantages.
The first is that students can participate in the process by morphotyping a single
locality without needing to have mastered of all of the existing fossils in the
basin. The second is that the morphotypes can then go through a second filter (called
the Holomorphotype Quality Index) which further separates the quarry holomorphotypes based
on their completeness and quality of preservation. This helps to sort fossils which are well
enough preserved to be named from fossils which provide data for paleoclimate analysis but not
taxonomy. The fossils which pass this quality
filter are called Basin Morphotypes and a Basin Holomorphotype is designated, usually
with a two letter prefix followed by a three digit number. (For example DB016.)
6. Holomorphotype Quality Index (HQI): Score your dicot leaf holomorphotypes, giving one
point for the presence of lobes, complete base, peltate base, complete apex, margin,
3rd order veins, 4th order veins and 5th order veins. The maximum a leaf can score
is 7. Note that all of these characters must be present on one
single specimen (the holomorphotype).
If a fossil scores a "4" or higher, it is usually well-enough preserved to describe
it completely, so it is assigned a basin holomorphotype number. In some cases, when over 60 examples
of a fossil are present at a quarry and no single leaf meets the "4" standard but
several leaves can be put together to meet the standard, we would elevate this fossil
to basin holomorphotype status based on the large numbers of
specimens. In this way, fossils can be compared across a large
geographic area without needing to be placed in the Linnaean system. Only fossils
that meet the basin holomorphotype standard are included in the on-line Paleobotany
Project. Basin morphotype numbers consist of a two letter prefix followed by three
numbers. DMNS keeps the master list of morphotype numbers.
Complete apex or peltate base (yes, base is being scored twice in this case but
this is a very distinctive feature and often these leaves do not have an apex.)
7. Formally naming fossil plants: This is a difficult and time consuming
process. To formally name a fossil, first, you need to research the literature to
make sure that it has not been named before. For the purpose of submitting fossils
to the DMNS Paleobotany Project, you can assign a published name to your fossil
and include the reference where the name was published. To produce a monograph of
a flora, you would need to do the following additional steps.
Case 1 – the fossil has been described before:
If you find a description (and hopefully a picture) of your fossil in the literature,
you need to show that your fossil shares the characteristics that demonstrate biological
affinity with the previously named species. Then, you need to verify that the name
is valid, meaning that it’s been correctly published in accordance with the International
Code of Botanical Nomenclature (ICBN). If you determine that the name is incorrect,
you need to rename the fossil following the rules described in the ICBN. In the
process of doing this research, you will create a synonymy, which documents each
instance when a scientist changed the name as well as any historical fossils that
match your fossil and were misidentified.
Case 2 - the fossil is new to science:
To determine that your fossil represents a novel species, you first need to distinguish
your fossil from other species that have been previously described and share similar
characteristics. Next, you designate a type specimen, which will bear the new name.
Unlike the basin holomorphotypes discussed previously, this fossil is only one specimen
and can never be replaced. It must be reposited in a recognized public institution
and be accessible to future researchers. The name is a Linnaean binomial (genus
species) in Latin. To be valid, the name must be published with an illustration of the type
specimen, a written description and a diagnosis. A diagnosis describes the elements
that are essential for identification of the new species and they are repeated in
the description. Although it’s not necessary to place the fossil into a full taxonomic
framework, researchers typically strive to document as much of the higher taxonomy
guide in PDF format