Glossary of Ichnological and Geological Terms
J & H PaleoScience: Vertebrate Ichnology. Fossil foot prints and track ways from Massachusetts MA, Connecticut CT, New York NY, New Jersey NJ, Pennsylvania PA, Maryland MD

Alluvial - Pertaining to material deposited by a stream, river, or running water away from the original source leading to the formation of an alluvial fan such as in a delta at the end of a river.

Amber - A fossilized resin formed from coniferous trees. It is usually yellow, orange, red or brown; and transparent when not oxidized. Amber has the ability to entrap and enclose insects and other organisms and preserve them for millions of years. Amber is found in alluvial soils and lignite beds and on some seashores. Marcasite is also frequently found in the lignite beds with the amber.

Ankylosaur - Armored quadrupedal ornithischian with ankylosed, or fused plates.

Apatosaurus - Previously known as Brontosaurus, is a genus of sauropod dinosaurs that lived about 140 million years ago, during the Jurassic Period. They were some of the largest land animals that ever existed, about 15 feet tall at the hips, with a length of up to 70 feet and a mass up to 40 tons.

Argillite - A compact rock, derived from mudstone or shale but more highly indurated than either of those rocks. It lacks the fissility of shale or the cleavage of slate. Argillite is a product of weak metamorphism.

Arkose - A feldspar-rich sandstone, typically coarse grained and pink or red in color, derived from the rapid disentigration of granite or granitic rocks which often resembles them. Quartz is the main mineral and feldspar making up at least 25%. Also included is the matrix material including clay and iron oxide which gives it a reddish coloring.

Arkosic sandstone - A sandstone with over 25% feldspar and less than 20% of matrix made of clay, sericite and chlorite.

Basalt - A dark colored igneous rock commonly extrusive (formed from lava on the surface of the Earth) and composed primarily of calcic plagioclase and pyroxene also known as the fine grained equivalent of gabbro.

Bed - A single layer of sedimentary rock or a single stratum

Bedding Plane - The planar surface that exists between two beds of rock or layers of strata.

Biostratigraphy - The dating and zoning of strata using fossils.

Bioturbation - Disturbances of soils and substrates by an animal or plants which also includes inverebrate burrowing as well as tracks and traces from vertebrates.

Biped - Describes an animal walking on its two hind feet.

Body Fossil - Part of the actual remains of an animal such as a tooth or bone material. Occasionally mummified skin or tissue may be a body fossil.

Brontosaur - The dinosaur genus originally known as Brontosaurus is now officially designated Apatosaurus. The name "Brontosaurus" is regarded as a synonym.

Brownstone - A brown or reddish-brown sandstone whose grains are generally coated with an iron oxide. Most brownstone is from the Triassic age and made of ferruginous quartz sandstones found in many of the rift valleys of the Northeastern United States.

Carnosaur - A robust type of carnivorous theropod.

Cast - The negative replica of a fossil impression or mold.

Ceratopsian - Horned Cretaceous quadrupedal ornithischian.

Coelurosaur - Gracile, hollow boned theropod.

Coprolite - Fossil dung, feces, or spoor. Not necessarily found with tracks.

Coquina - A detrital limestone composed of broken shell fragments which is weakly to moderately cemeneted together usually occurring in relatively recent deposits.

Core Sample - A cylindrical section of rock usually 5 to 10 cm in diameter and several feet in length that has been extracted from the earth by a core bit for further examination in the laboratory showing cross sections of the strata from depth.

Deposit - Generic term for a sedimentary deposit such as sandstone, mudstone, or limestone which is laid down or deposited into a particular area either small or large in area.

Desiccation Crack - A crack formed in sediment by the drying or evaporation of water. Desiccation cracks are often preserved in sedimentary rocks.

Diabase - An intrusive rock (formed inside the Earth from magma) consisting mostly of labradorite and pyroxene and characterized by an ophitic texture. Excellent example is the Palisade Sill along the Hudson River in NJ/NY.

Digit - An individual finger or toe.

Digitigrade - Refers to walking on the digits only.

Dinosaur - Any reptile of the subclass Archosauria distinguished from other reptiles by the features of the pelvic bones. May be herbivores, carnivores, bipedal, or quadripedal and range from the Triassic period to the Cretaceous period.

Dinoturbation - The trampling and disturbances of soils and substrates by dinosaurs.

Dipodichnites - Animal tracks with 2 feet.

Drag Mark - A long groove or striation produced by an object dragged across a soft sedimentary surface. Examples are tail marks toe marks, and claw marks. Often preserved in sedimentary rocks in the geological record at dinosaur track sites.

Facies - Term denoting sedimentary deposit of a particular character or genesis such as deltaic facies, playa lake facies.

Fauna - The entire animal poplulation either living or a fossil of a specific area, environment, geological formation or time span.

Flora - The entire plant poplulation either living or a fossil of a specific area, environment, geological formation or time span.

Flagstone - A hard sandstone usually micaceous and fine grained that occurs in thin beds with shale It splits uniformly and is widely used as a slabs for sidewalks, retaining walls, and driveways.

Fluvial - Pertaining to rivers and the conditions produced by the actions of a stream or river.

Footprint - The impression made by the foot into a soft sediment.

Fossil Footprint - Occurs when a footprint made in soft sediment later turns to rock through lithification to preserve it as a fossil.

Gait - Types of progression of an animal such as walking, running, or trotting.

Ghost Print - (a.k.a. "undertrack" or "underprint") The deformation of the underlying layer of strata by the impression of a footprint. Depending on the consistency of the soft sediment and the underlying layer of strata, the ghost print may appear as very similar to the true footprint or could be very different, but will never have skin impressions.

Hadrosaur - Usually refers to late Cretaceous duckbill dinosaurs belonging within ornithopoda and probably descended from the iguanodontids.

Ichnolite - A track in stone.

Ichnology - The study of trace fossils which includes tracks and other impressions and traces.

Index Fossil - A fossil that identifies and dates the strata in which it was found. Common index fossils include graptolites and ammonites.

In Situ - Referring to a rock, fossil, or other object found in the exact location or natural position in which it was formed or deposited.

Lacustrine - Pertaining to, produced by, or inhabiting a lake or lakes.

Lacustrine Cycle - A series of rises and falls of water levels preserved in sedimentary layers showing periods of dry and wet conditions. See also Van Houten Cycle.

Leptodactyli - Slender toed track.

Lithification - The conversion of a newly deposited layer of sediment transferred into a solid rock by processes of cementation, compaction and crystallization from heat and pressure.

Manus - Refers to the front feet (or hands) in four footed animals which may not necessarily be used for walking

Megatracksite - A very large or regionally extensive tracksite associated with a particular layer of strata. This layer may be broken up by erosion and topography with a series of smaller tracksites.

Marker Bed - A rock unit with a stratigraphic feature that is very distinctive and can be traced over long distances and can usually be seen in many different outcrops that can be assumed as one and the same.

Matrix - The rock or sediment surrounding or encased around a fossil, mineral, or other object.

Natural Cast - The lithified infilling of a footprint or trace fossil.

Ornithichnites - Signifying stony bird tracks.

Ornithichnology - Study of stony bird tracks.

Ornithischian - A bird hipped dinosaur.

Ornithoidichnites - Those resembling the track of a bird.

Ornithopod - Means bird foot which includes bipedal ornithischians like the iguanodontids and hadrosaurs.

Outcrop - The part of a geological formation that appears at the surface of the earth and usually exposed along a highway roadcut or cliff face.

Overprint - When an animal partially or completely overprints or overlaps its own front footprints with its hind footprint.

Pace - A single step, left foot to right or right to left. It can also imply speed of progression as in slow or fast paced.

Pace Angulation - The angle made by steps relative to the direction of progression. Angle made in the V drawn between a left, a right, and another left footprint (L-R-L) or a right, a left, and another right footprint (R-L-R).

Pachydactyli - Thick toed track.

Pes - Refers to hind feet in four footed animals.

Plantigrade - Walking with digits flat and part or all of the ankle and wrist also on the ground.

Progression - A forward movement in a particular direction.

Polypodichnites - animal tracks with more than 4 feet.

Quadruped - An animal that walks on all fours.

Redbeds - Sedimentary strata composed largely of sandstone, siltstone, and shale that are predominantly red due to the high content of ferric oxide coating the individual grains of sand.

Rift - A long, narrow continental trough bounded by normal faults often associated with volcanic activity.

Rift Valley - A valley that has developed along a tectonic rift. Rift valleys can be found throughout the northeastern United States in the Newark Supergroup.

Ripple Rock - A preserved condition in rock showing subparallel ridges and troughs formed by loose sand by wind, water currents, or waves. Patterns may vary.

Run - A fast progression in which an animal's feet leave the ground for a short phase between each step.

Saurischian - Reptile or lizard hipped dinosaur

Sauroidichnites - Those resembling the track of a saurian or lizard.

Sauropod - Means reptile foot and refers to Jurassic and Cretaceous long necked, long tailed herbivorous saurischians. Well-known genera include Apatosaurus (formerly known as the Brontosaurus), Brachiosaurus and Diplodocus.

Spoor - The feces, tracks, and trails left by modern animals.

Strata - Layers or beds of sedimentary rock easily distinguished from ones below and above.

Stratigraphy - The study of stratified sedimentary rock sequences.

Stride - Two steps right -left-right (R-L-R) or left-right-left (L-R-L) that is the distance between one footprint and the next footprint made by that same foot.

Substrate - The ground on which an animal walks or progresses. It can be soft (incompetent) or hard (competent) and on land and even underwater.

Tetrapod - A four legged or four limbed vertebrate that may use all legs for walking but may also be bipedal or show other adaptations.

Tetrapodichnites - Animal tracks with 4 feet.

Theropod - Bipedal, carnivorous saurischians which includes gracile coelurosaurs and robust carnosaurs.

Trace Fossil - A sedimentary structure consisting of a fossilized track, trail, burrow, tube, or other impressions or depressions left from the life activities of an animal, plant, insect, or natural force that has been preserved in soft sediment and lithified to solid rock.

Tracksite - A location where tracks are found.

Trackway - Two or more consecutive footprints belonging to a particular animal progressing in a given direction.

Trail - Sometimes used to denote a trackway but more commonly used to indicate the continuous marks made by invertebrates like worms, snails, etc where no footprints exist.

Underprint - see "ghost print"

Undertrack - see "ghost print"

Van Houten Cycle - A Van Houten cycle, as defined by Olsen (1986), records a complete cycle of the lake-level rise (division 1), lake high-stand (division 2), and lake-level fall (division 3).

Walk - A slow progression in which the leading foot touches the ground before the trailing foot lifts off the ground.


Tracking Dinosaurs, 1991 by Martin Lockley

Dictionary of Geological Terms, The American Geological Institute, by Robert L. Bates and Julia A. Jackson, Editors

John McCauley - who added many terms and definitions of his own

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