Plant Fossil Exercise- For all specimens look at and describe the mode of
preservation
SEEDLESS PLANTS –VASCULAR
Lycopods- These plants have leaves with one vein and represent the earliest land plant
lineage still in existance.
Stems- Sigillaria (#1A, 1B) and Lepidodendron (#2A, 2B). Draw and label the leaf scars
and smaller inner scars where a single vein was present. How are the shapes different?
Roots- Stigmaria (#3A, 3B). Draw the round rootlet scar. Rootlets were derived from
leaves? What does this mean in terms of the origin of the roots?
Sphenophytes- Calamites (#4). Draw the ribbed stem. Can you see the node where
leaves are attached? Hint, it appears as a straight line perpendicular to the ribs on the
stem.
GYMNOSPERMS SEED PLANTS
Archaeopteris (#5)- One of the first gymnospersms, often grouped with the earliest,
Devonian aged gymnosperms called Progymnoperms. Draw the leaves.
Cordaites (#6a, 6b)- The long, strap-like leaves of this plant have numerous veins. Draw
them. Cordaites is part of a lineage that gave rise to modern conifers, including pines.
Ginko- Ginkos have pollen and “sperm”-swimming cells. They were found worldwide
and during the K and first part of the Cenozoic were abundant in Northern Hemisphere
forests. Draw the veination in a leaf (#7)? Can you find and draw a seed (#8)?
#9 is a true fruit from a tree in the walnut family (see flowering plants), draw this fruit.
Seed ferns- Seed ferns have foliage that looks like that of ferns and seeds. They went
extinct at the K-T boundary. Draw the leaves of Neuropteris(#10). Do you think the
veination looks like an unwanted insect you may have seen in someone’s (never your
own) house?
Compare #10 with Alethopteris (#11), draw this sample as well.
Can you see any difference between the seed fern foliage (#12) and a true fern foliage
(#13), draw both samples?
FLOWERING PLANTS
Paleobotanists use fossil leaves to determine past patterns in temperature and
precipitation. If a flora has many leaves with toothed margins it was probably growing in
a climate that was coller than a flora with more leaves with entire margins.
Can you tell what the margins are like on the leaves found in the light clay (#14A-C)?
Do you think they represent a cooler or warmer flora?
For #15 why is it so hard to see the veins and margin compared to the different samples
of #14? Draw this sample as well.