Trace Fossils Flashcards
are the biogenic sedimentary structures that record biological activities such as burrowing, walking, and feeding
Trace fossils ( ichnofossils)
Trace fossil genera = ichnogenera
species = ichnospecies
trace preserved on the top of the bed
Epirelief
Entire trace preserved in three dimensions with sediments
Full Relief
trace preserved on the lower surface of the bed
Hyporelief
Collapsed burrow or trace formed on the surface of the bedding plane
Semirelief
which are traces produced on the upper surface of a sediment then preserved by being quickly covered by a sediment of a different lithology
Epigene Traces
which are structures filled within the host sediment, and therefore are homogeneous with the casting medium. The sediment infilling may have occurred either actively (by the organism itself) or passively (by some other process, after the organism has created the structure);
Endogene traces
which are endogenic structures formed at a lithological interface or the junction between two beds
Intergene traces
are found on the top of the strata of origin, being those ridges and grooves that
were formed by benthic organisms or infaunal burrows that have been exposed
by erosion
Epichnia
are those traces that are found wholly within the casting medium, and therefore
can only have been made by an
infaunal organism.
Endichnia
are ridges and grooves found on the soles of the beds of origin at their interfaces with other strata, representing the opposite of epichnia.
Hypichnia
are traces that are made of material that is different from the surrounding medium, having either been actively filled by an organism or eroded out and re-covered by an alien sediment
Exichnia
Resting or hiding traces formed during a
temporary pause in locomotion. Rather
than resting, the traces usually represent
feeding by stationary feeders or refuge
Usually as casts on the bottom of beds.
Morphology reflects the nature of the
undersurface of the resting organism
Cubichnia
Dwelling traces formed by burrowing or
boring into the substrate. Traces represent
the long-term home of an animal that is
stationary in the burrow
Deep excavations of varying shape
found within beds. Usually form an
anastomosing tubular structure, or a
straight or a U- shaped burrow
Domichnia
Escape structures formed when animal
moves rapidly upward to prevent burial by
a sudden influx of sediment or, more
rarely, laterally to avoid predators
Usually within beds in association with
domichnia. Sediment at proximal end of
burrow is reworked and lamination is
disturbed
Fugichnia
Adjustment traces formed by infaunal
animals maintaining the position of their
burrow with respect to a gradually
agrading or degrading sea floor
Occurs within beds in association with
domichnia. Distinct laminations formed
parallel with the main burrow
Equilibrichnia
Locomotion traces that represent directed
movement (from A to B). Includes walking,
crawling, tunneling, and running
Found as casts on the bottom of beds or
as epireliefs. Characteristically
continuous, elongate trails, sometimes
revealing motion of limbs
Repichnia
Grazing traces formed by systematic
exploitation of a particular area of the
sediment for food
Horizontal traces found on or beneath the
bedding plane. Distinctive furrowed trails
with sinuous, meandering form but paths
rarely cross
Pascichnia
Traps and farming traces formed by
animals that trap food particles or grow
algae. Structures represent feeding and
dwelling in a fixed area
Complicated horizontal network of
burrows with multiple openings to
surface. Usually preserved as hyporeliefs
on bottom bed surface
Agrichnia
Traces which represent two functions:
deposit feeding and dwelling. Excavations
are made as the organism eats the
sediment and digests the food within it
Three-dimensional form usually found
within the bed. Generally horizontal but
more complex forms can have branched
networks of burrows
Fodinichnia
indicative of substrate
found in fully lithified substrates, such as rocky coastlines and hard grounds
Trypanites ichnofacies
generally developed in shallow water in the near -shore environment.
* it is typical of higher energy conditions associated with well
-sorted shifting sand. Deep, vertical, and
U
-shaped tubular hallows characterize the
ichnofacies
Skolithos ichnofacies
reflects shallow water, lower energy conditions between the outer edge of the surf zone and storm wave base.
commonly developed in estuarine, lagoons, or in shelf environments.
it is a high diversity ichnofacie with crawling, deposit
feeding and shelter traces dominating organisms.
Cruziana ichnofacies
- indicates deep water environments and is developed from the deep shelf to upper continental slope.
- associated with low oxygen environments and the low diversity in these ichnofacies may reflect oxygen-stressed
conditions
Zoophycos ichnofacies
- developed on the abyssal plain * reflects quiet, moderately well
-oxygenated conditions - most traces are found within the lower surface of beds
and show a systematic grazing of the seafloor for food
and detritus
Nereites ichnofacies
defines the base of the Cambrian.
It is the feeding trace of a worm-like animal
Treptichnus pedum
