Era: 251-65.5 Million Years Ago
Cretaceous Period: 145.5-65.5 MYA
Idaho, Utah & Wyoming
a tree fern genus represented by permineralized false trunks.
The genus is an important index fossil for the Cretaceous. Click
word Tempskya for
a printable version of our article.
Chippy Creek, Idaho
7.5 cm x 6 cm x 0.8 cm thick
Tempskyaceae are an extinct family of Mesozoic ferns represented
by the single genus Tempskya (Tidwell, 2002,
Tempskya occurs as the
silicified false trunk of a Cretaceous aged tree fern. Tempskya is
referred to as a false trunk because internally it is composed
numerous small branching stems and petioles embedded
in a mat of adventitious
roots (Brown, 1936, p. 48). The ropelike mass of the false trunk
is often club-shaped, straight or conical when found
intact. The mass
of intertwined roots gives the exterior a rope or cable-like appearance,
see Figure 1. The flattened conical shape of the Tempskya specimen
in Figure 1 is referred to as a “Cardinal’s Cap” by
collectors and may represent the apex of a false trunk.
1: Tempskya “Cardinal’s Cap” or
Apex of False Trunk.
Dakota Sandstone Formation, Cretaceous. Utah.
species of Cretaceous aged Tempskya have been reported from North
America, eight or possibly ten from Europe, one
from Japan, one
from Argentina, and one from Australia (Tidwell & Wright, 2003, pp
141-143; Clifford & Dettmann, 2005, p. 71). Tempskya species are
defined primarily by differences in the arrangement and makeup of tissues
within the stems of the false trunks. The purpose of this paper is to
help collectors explore the general anatomy of the Tempskya false trunk
in transverse section.
False trunks of some Tempskya species reach diameters
of 30 centimeters and lengths of 3 meters (Tidwell, 1998, p. 190).
Thus, evidence suggests
that Tempskya was a short to medium height tree fern (Andrews,
1943, p. 136; Andrews & Kerns, 1947, p. 155). Internally, the
trunks are composed of stems, petioles and roots. Figure 2 represents
Tempskya false trunk cut in the transverse plane. The stems
making up the false trunk appear as circular or lobe-shaped structures
roughly 1 cm in diameter. The roots are mostly circular and measure
around 1 mm in diameter. Figure 3 gives us a closer look at the stems,
leaf traces or petioles and roots.
2: Tempskya. Lower Cretaceous, Wyoming.
Specimen 24.5 cm x 17
3: Tempskya. Close-up Showing Stems,
Leaf Traces or Petioles
transverse sections of varying sized false trunks have been used
to determine the supposed mode of growth for Tempskya as
well as examination of in situ specimens, those found in
growth position (Seward, 1924, pp. 489-491; Andrews & Kern, 1947,
pp. 134-138; Tidwell & Hebbert, 1992, p. 528). The base of in
exhibit three to nine lobes each containing a stem. Thus, several
stems initiated the growth of the tree fern and branched dichotomously
in a uniform profuse manner throughout life, producing both the
apical and lateral growth of the false trunk. Roots, emerging from
the sides of stems, branched profusely filling in voids, tying
the mass of stems together forming the false trunk. Roots, greatly
outnumbering the stems provided the structural support for the
false trunk. Stems produced leaf traces or petioles frequently.
Petioles of leaves, small in size, are close to their point of
origin on stems indicating small leaves that persisted for only
a short time. The false trunks of Tempskya tapered from
base to apex. Unlike other tree ferns Tempskya was not
crowned with large leaves; rather, leaves at the apex were small
in size. The false
trunk also bore small leaves for a considerable distance downward
from the apex (Andrews & Kern, 1947, p. 129).
Roots growing down ruptured stems and petioles. Upper portions of
stems continued to be nourished by emerging adventitious roots. Consequently,
transverse sections near the base of the false trunk have few stems
and many roots while transverse sections towards the apex of the false
trunk have many stems embedded among the roots, see Figures 5 and 6.
4: Tempskya. Lower Cretaceous.
Greenhorn Mountain, Oregon.
Specimen 12 cm. Image courtesy of Frank Daniels
specimen pictured in Figure 4 exhibits many stems embedded among numerous
roots and most likely represents
a transverse section higher
up on the false trunk (Daniels, 2009, p. 153). The specimen pictured
in Figure 5 has very few stems embedded among the adventitious roots,
which indicates it came from the base of the trunk. In general, there
is an increase in the number of stems from base to apex on the false
trunks of most Tempskya species. T. minor from Utah
seems to be different from other Tempskya species in that specimens
possess very few stems throughout the length of the false trunk (Tidwell & Hebbert,
Figure 5: Tempskya. Lower Cretaceous.
Greenhorn Mountain, Oregon.
Specimen 12 cm.
You can explore and learn the general anatomy of the stems and roots
with a loupe or dissecting microscope. A 10x loupe can be used to differentiate
stems, petioles and roots; however, a 20x loupe or dissecting microscope
with 30x or 40x allows one to study the tissues that make up these organs.
Most of the roots and stems of Tempskya grow in parallel indicating an
upright structure. The stems are larger than the roots. Depending on
the species, stems may have a diameter of 2.5 mm to 1.5 cm. Roots are
generally 1 mm in diameter or less. Roots are often circular in transverse
section while stems are circular or lobed. The circular stem pictured
in figure 6 is viewed at 30x.
6: Tempskya Circular Stem at 30x.
Stem measures 4 mm in diameter
or lobes on stems represent the formation of leaf traces or petioles.
In Figure 7 an outgrowth of
the stem represents the early
stages of leaf trace formation. Tissue from the stem will form the new
leaf trace. Figure 8 shows a leaf trace that has formed. The water conducting
tissue (xylem) of the leaf trace or petiole forms a characteristic horseshoe
or c-shape when viewed in cross-section. In many species the stem forms
a second petiole, see Figure 9. In Figure 9 we can see that the c-shaped
xylem in the petiole was derived from a portion of the ring-shaped xylem
in the stem. Once the leaf trace has formed the stem’s xylem will
once again form a ring-shape. Many of the petioles are formed oriented
to the outside of the stem. In many false trunks that are found complete
it has been observed that stem branching is numerous, and that the trunk
is radially symmetrical with respect to the departure of leaf traces
(Andrews & Kern, 1947, p. 126). Some specimens exhibit dorsiventral
symmetry with respect to leaf traces. Some have suggested that such specimens
represent false trunks that grew horizontal along the ground before growing
upright, while others believe these specimens are just partial false
trunks that were in fact radial in symmetry when complete (Tidwell & Hebbert,
1992, p. 524).
Figure 7: Tempskya Stem Forming Leaf Trace at 40x
Figure 8: Tempskya Stem
and Newly formed Petiole at 20x. Stem & petiole
9: Tempskya Stem Forming Second Petiole.
Idaho specimen pictured in Figure 10 possesses stems that measure 3 mm
and roots that measure 1 mm or less in diameter. A second leaf trace
is in the process of forming. Roots surround the stem and leaf traces.
Using a loupe or dissecting microscope one can learn to identify tissues
that make up the stems, petioles and roots of the false trunk.
Figure 10: Tempskya Stem,
Leaf Traces & Roots.
consist of a pith centered in a ring of xylem tissue (water conducting
tissue) surrounded inside and out by phloem
tissue). Cortex tissue surrounds the pith, xylem and phloem. The stem
pictured in Figure 11 measures 6 mm in diameter, while the roots measure
1 mm or less. Two leaf traces have formed and the xylem in the stem is
once again forming a ring-shape. The characteristic c-shaped xylem strands
of the leaf traces or petioles are clearly visible in this Wyoming specimen.
Figure 11: Tempskya Stem,
Leaf & Root Traces.
In cross section the xylem in Tempskya roots forms a cross.
Phloem surrounds the primary xylem filling in the remaining area at the
of the root. Cortex tissue surrounds the vascular tissue of the root,
see Figure 12. It is the cortex of the roots, which provides most of
the structural support for the false trunk. In fact the cable-like structure
of the Tempskya false trunk was composed mostly of roots. Figure
12 is the same large root trace pointed to in the picture above. As mentioned
earlier the transverse sections taken close to the base of the false
trunk may be composed entirely of roots. Stems lower in the plant were
ruptured by invading roots growing downwards. Disintegrated stems were
replaced by roots. Figure 13 shows a root growing through a stem. The
root with the characteristic cross-shaped xylem can be seen below and
adjacent to the pith of a stem. The pith of the stem has a somewhat pear
shape as it was in the process of forming a leaf trace.
Figure 12: Tempskya Root at 40x.
Root Measures 1.2 mm in Diameter
Figure 13: Tempskya Root Grows Through Stem.
Specimen from Idaho.
Galleries filled with fecal pellets in roots, stems and leaves provide evidence
of at least three different kinds of insects feeding on various Tempskya species
(Tidwell & Hebbert, 1992, pp. 521 & 524; Tidwell, 2002, pp. 154-157).
Fecal pellets of an unidentified insect can be seen in the roots of an Idaho
specimen, see Figure 14.
Figure 14: Fecal Pellets in Tempskya Roots at 40x.
resembling mycorrhizal fungi have been found associated with the roots
of some Tempskya specimens
possibly revealing a symbiotic relationship
(Tidwell & Hebbert, 1992, p. 524). Andrews and Kerns (1947) reported
that Tempskya fossils in Idaho and Wyoming are associated with cycadeoids,
conifers, angiosperm dicots, dinosaur bones, and possibly tropical ferns.
They picture a tropical habitat for Tempskya. Andrews and Kerns also
point out that although the leaves of Tempskya were small, large numbers
were distributed over a considerable portion of the false trunk possibly
making it ideal for browsers.
Tempskya fossils are found reworked in younger gravels or reworked
within the formations in which they were preserved. The only in situ Tempskya specimens are found in an upright growth position embedded
in undisturbed carbonaceous shale southeast of Castle Dale, Utah
(Tidwell & Hebbert,
1992, p. 525). The carbonaceous shale suggests Tempskya grew in swamps
on flood plains, similar to the Mississippi Delta or the Florida
Everglades. T. judithae described from Australia is associated with
and angiosperms. The depositional environment represents the broad
alluvial plain of a riverine/lacustrine system. Clifford and Dettmann
(2005) postulate a flood plain habitat with mild temperatures and
periodically moderate to high precipitation (p. 83).
Isolated spores and several sporangial remains have been found associated
with Tempskya but none with definite attachment to the plant (Taylor,
Taylor & Krings, 2009, p. 459). Transverse sections of leaves
have been reported associated with T. wyomingense (Tidwell & Hebbert,
1992, p. 521). The restoration of the probable habit of Tempskya by Andrews and Kern uses Anemia type foliage (Andrews & Kern,
1947, pp. 139 & 140). Interestingly, fronds of Anemia fremontii have been collected as compressions in the coalified sediments around
the base of in situ Tempskya false trunks (Tidwell & Hebbert,
p. 516). Discovery of complete Tempskya leaf structures and fertile
remains attached to the false trunk would be both exciting and
The false trunk of the tree
fern Tempskya is intriguing with its intertwined
rope or cable-like structure of roots, stems and petioles. The extensive
distribution of Tempskya in the Northern Hemisphere and
its discovery in the Southern Hemisphere provide evidence of its
One can imagine the highly evolved herbivorous dinosaurs of the Cretaceous
seeking out the foliage growing along the false trunks of Tempskya.
The profuse branching of stems and roots as well as the frequent formation
of leaf traces, frozen in time by silica, provides dynamic evidence
of ancient growth in most Tempskya specimens. For collectors, knowledge
of Tempskya anatomy may provide insight into specimens within their
collection. What part of the false trunk does the specimen represent?
Is there evidence of insect feeding? Can one identify a stem or root
dividing, petioles forming or roots invading stems? Permineralized
specimens with excellent cellular preservation can provide a snapshot
of ancient plant growth. Imagination fueled by empirical evidence;
a true joy of science.
wish to thank Jim Mills for sharing his in-depth knowledge of Tempskya and
his feedback on earlier versions of this article. I would also
like to thank Frank Daniels for his generosity in sharing his excellent
photograph of the Tempskya specimen from Oregon (figure 4
in this article, figure 5 in the pdf version). Finally, I would like
to thank my son Thomas Viney for his editing expertise.
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Vol. 29, No. 1 pp. 133-136.
H.N & Kern, E.M. (1947). The Idaho Tempskyas and Associated
Fossil Plants. Annals of the Missouri Botanical Garden, 34, pp.
Brown, R.W. (1936). Field identification of the fossil ferns called
Tempskya. Journal of the Washington Academy of Sciences Vol. 2, No
2, pp. 45-52.
Clifford, T.H. & Dettmann, M.E. (2005). First record from Australia
of the Cretaceous fern genus Tempskya and the description of a new
species, T. judithae. Review of Palaeobotany & Palynology.
134, pp. 71-84.
Daniels, F.J. and Dayvault, R.D. (2006). Ancient Forests:
A Closer Look at Fossil Wood. Western Colorado Publishing Company: Canada.
Seward, A.C. (1924). On a New Species of Tempskya from Montana:
Tempskya Knowltoni, sp. nov. Annals of Botany Vol. 38, pp. 485-507.
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M. (2009). Paleobotany: The Biology and Evolution of Fossil
Plants [2nd Ed]. New York:
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N., (1992). Species of the Cretaceous tree fern Tempskya from
Utah. International Journal of Plant Science.
153, pp. 513-528.
Tidwell, W.D. (1998). Common
Fossil Plants of Western North America.
[2nd Edition]. Smithsonian Institution Press: Washington, pp. 214-215.
W.D. (2002). Tempskya-a Unique Fern from the Cretaceous. In Dernbach,
U. & Tidwell, W.D. Secrets of Petrified Plants:
Fascination from Millions of Years (pp. 153-159). Germany: D’ORO