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Home Dr. Hembree Research Continental Ichnology Laboratory Students Publications Courses News and Opportunities Links
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Welcome to the
Continental Ichnology Research Laboratory. The purpose of the CIRL is to
investigate the behaviors and biogenic structures (burrows, nests, tracks,
trails) produced by modern continental organisms in order to better interpret
trace fossils preserved in continental deposits throughout geologic time. |
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Goals of the CIRL |
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Research in the CIRL focuses on the burrowing behavior and
biogenic structures of extant terrestrial animals for application to the
study of ichnofossils. Ichnofossils provide
a critically important in situ record
of paleoenvironmental and paleoecological change that has become an essential
aspect of sedimentology, stratigraphy, and paleontology. By studying the behavior
of continental tracemakers, the morphology of their burrows, nests, tracks,
and other traces may be correlated to continental environmental factors such
as temperature and precipitation, depositional environments, and such
substrate characteristics as soil consistency, moisture level, and organic
content. In addition, if trace morphology can be linked to specific taxa or
body morphologies, then these traces may be used in lieu of body fossils to
determine the geographic and temporal range of different groups of organisms. |
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Current Laboratory
Research Animals |
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Small (10-15 cm long) millipedes that spend the majority of their
lives in the subsurface. They construct long-term dwelling structures in a
wide variety of soils and are capable of excavating very dense sediment. These millipedes inhabit semi-arid regions
but still require high moisture.
Construction of permanent burrows allows these millipedes to construct
microhabitats with high humidity. |
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Giant African Millipedes (Archispirostreptus gigas) One of the largest extant millipedes in the world (18-25 cm
long). Giant African millipedes produce sinuous burrows related to foraging
behaviors. If humidity drops too low, however, these millipedes will
construct U-shaped and W-shaped, temporary dwelling structures. Giant African
millipedes will only burrow into loose sediment and are unable to penetrate
compacted or clay-rich soils. |
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Ocala Scrub Millipedes (Narceus gordanus) Medium-sized millipedes (6-10 cm long) from Florida that move
from the subsurface to the soil surface during the night to feed. This
continuous movement acts to churns the soil, disrupting primary sedimentary
structures and leaving behind multiple irregular, open burrow segments and
chambers resulting in increased porosity and permeability. The bioturbation
of these millipedes overturns the soil moving organic material from the soil
surface to the subsurface. |
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Emperor Scorpions (Pandinus imperator) One of the largest scorpion species, P. imperator reaches 15-20 cm in length as adults. They inhabit
the floor of tropical rain forests in West Africa and exhibit communal
behavior, living in groups of several individuals within large burrows.
Emperor scorpions will construct burrows within a few days if no other
shelter is available. These initial burrows are shallow, simple ramps, but
they are made deeper and more complex over time. Burrows produced by two or
more individuals may have multiple entrances and tunnels that are typically
much larger in diameter than the scorpions themselves. |
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Malaysian Forest Scorpion (Heterometrus spinifer) A large scorpion (10-15 cm) that inhabits tropical forests of
Malaysia and Thailand. These scorpions exhibit some communal behavior but
tend to be more territorial and aggressive than P. imperator. H. spinifer is a nocturnal predator that constructs
simple steeply dipping ramp-style burrows with varying depth, although they
do not burrow as actively as P.
imperator. Two or three individuals may occupy a burrow for short
intervals of time. |
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Arizona Hairy Desert Scorpion (Hadrurus arizonensis) One of the largest scorpion species in North America, H. arizonensis reaches 14-15 cm in
length. The species is found in the North American southwest (Sonoran and
Mojave deserts) and is adapted to hot and dry conditions. Hairy desert scorpions are solitary
nocturnal predators. They can construct elaborate spiral and U-shaped
dwelling burrows in consolidated sandy soil (some >2 m deep) that are used
as temporary to permanent dwellings. |
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Dune Scorpions (Smeringurus mesaensis) A small- to medium-sized (5-10 cm) scorpion that inhabits desert
environments with loose, shifting sand in Arizona and California. These
scorpions are well-adapted to dry climates and obtain all of their water from
their prey. S. mesaensis
is a solitary nocturnal predator that constructs simple, shallow burrows in
loose sand or sandy soil. |
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Northwestern Forest Scorpions (Uroctonus mordax) A small- to medium sized (5-10 cm) scorpion that inhabits the
California coast and montane forests of the Cascades
and Sierras at elevations up to 1900 m. While they are most commonly found
beneath rocks or logs, these scorpions will also produce simple, steeply
dipping ramp-style burrows in sandy soils. |
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Giant Vinegaroons
(Mastigoproctus giganteus) These arthropods, also referred to as whip scorpions, are 2-9 cm
in length. They inhabit the southern and southwestern United States. They are nocturnal predators with poor vision
but the first two walking legs are modified as sensory appendages.
Vinegaroons use their pedipalps to excavate loose to compacted soils and
construct a diverse array of burrows from horizontal shafts, U-shaped
burrows, helical burrows, and interconnected burrow networks. |
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Red Trapdoor Spider (Myrmekiaphila sp.) This genus of trapdoor spiders inhabits the southeastern United
States. They are 3-8 mm in length and yellowish-red to dark-reddish brown in color.
These spiders construct silk-lined burrows covered by a silken trap door. The
burrows consist of networks of interconnected vertical shafts and horizontal
tunnels. In shallow soils the majority of the burrow may be composed of
horizontal tunnels with several chambers and trap doors at the surface. |
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African Trapdoor Spider (Gorgyrella sp.) Large (3-5 cm) trapdoor spiders that inhabit southern Africa. Gorgyrella
constructs simple vertical shafts with a single, large silken trapdoor at the
surface. |
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Florida Giant Centipede (Scolopendra alternans ) Originating from the West Indies, these centipedes are now common
in Florida. They are very aggressive
predators but also spend a significant amount of time in the subsurface. Scolopendra alternans produces dense
networks of vertical and horizontal cross-cutting burrows. They burrow by wedging their bodies through
the sediment. Sediment is displaced
horizontally and compacted but very little is transported to the surface. |
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Tiger Salamanders (Ambystoma tigrinum) Terrestrial salamanders, typically 15-25 cm in length, with a
wide range across eastern North America from the Gulf Coastal Plain to the
Midwest. A. tigrinum
is characterized by a robust body with four, short well-developed limbs, a
broad head, and a bluntly rounded, broad snout. The tiger salamander is an
active burrower and utilizes burrows as permanent dwellings. Field studies of
these burrows have shown that the burrows may be up to 60 cm below the
surface. |
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Marbled Salamanders (Ambystoma opacum) Terrestrial salamanders, typically 5-10 cm in length, distributed
across the eastern United States from New England to Florida and as far west
as eastern Texas. A. opacum is characterized by a small body, short limbs,
and a broad head with a blunt snout. These salamanders spend most of their
time in shallow burrows which are primarily constructed by enlarging holes
and cracks already present in the soil. |
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Ocellated Sand
Skinks (Chalcides ocellatus) This medium-sized skink (15-30 cm long) inhabits arid
environments from southern Europe, northern Africa, and western Asia. C. ocellatus
is a generalist sand swimmer that is found in sand dunes, gravel plains, and
river beds. Sand skinks burrow by “swimming” through loose sand. While this
behavior does not produce open burrows, it does disrupt primary sedimentary
structures and produces distinctive biogenic structures. |
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Red-Sided Skink (Mabuya sp.) Medium-sized, generalist skinks (15-30 cm long) that inhabit a
wide variety of environments. Mabuya burrow by excavation of the substrate to produce
open burrows in sandy soils. |
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Field Research |
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In addition to laboratory work, research on burrowing organisms
in their natural environments is critical to interpreting continental trace
fossils. Soils are complex assemblages of biotic and abiotic elements each capable
of masking or potentially highlighting the other. In order to make accurate
paleoecological interpretations based on continental ichnofossils and
paleosols, these modern communities must be studied in the field. My field-based neoichnological research to date has involved
modern soil communities in floodplains and wetlands of eastern Kansas as well
as the badlands and prairies of northeastern Colorado. Based on some initial
observations while in Alaska, I am also interested in pursuing research on
the tundra subsurface ecosystems of southern Alaska. |
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Arctic Ground Squirrel (Spermophilus parryii) These small mammals are prolific in the tundra of Alaska. This
individual was in the Polychrome Pass area of Denali National Park. Arctic
ground squirrels construct maze-like, permanent burrow complexes with several
openings. In the winter these openings are sealed and the burrows are used
for hibernation. These highly successful animals provide an excellent example
of the use of burrows by mammals to survive extreme environmental conditions.
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Coming Soon… |
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This site will contain high quality digital images of biogenic
structures produced in the CIRL.
Please check back later for more details. |
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Copyright © 2007 Daniel Hembree Last revised: 5/2011 |
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