Introduction to the Study of Dinosaurs

Anthony J. Martin


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Paraphyletic group of primitive ornithiscian dinosaurs, most closely aligned with clade Ornithopoda.
All of the characteristics imparted by an environment to its sediment at approximately the same time; can be represented by biofacies (organismal remains), ichnofacies (traces left by organismal behavior), and lithofacies (composition and proportions of sediments).
Phenomenon that has an actual, objective existence, regardless of whether it was observed or not.
Integument associated with avian and known in a few non-avian theropods, which can function as flight or downy feathers but also is used for display and insulation. Consists of central shaft with barbs emanating from it, forming a vane in flight feathers.
Mappable unit of rock, given a formal name that typically refers to a place with a type section of the formation.
Fractional change in the amount of stable isotopes, where one becomes depleted while the other is enriched.


Sex cell (egg or sperm) containing a haploid complement of chromosomes, that for better or worse will combine with another (complementary) gamete to form a zygote.
Literally “stomach stones,” refers to stones ingested by a vertebrate to use for either digestion or ballast. The fossil equivalent of this is a trace fossil.
Node-based clade that includes clades Thyreophora and Ornithopoda.
Nucleotide sequence in a DNA molecule that provides a code for a protein or part of a protein. Can be either dominant or recessive.
Sum total of genes, conveyed in a DNA molecule and encompassing coding for all of an organism’s proteins. Represents the genetic potential of an organism.
Genetic expression of an organism. A pair of genes at a locus on a chromosome. Contrast with phenotype.
Name applied as first part of binomial nomenclature used in species name. Can be used by itself but also represents a broader category that may include several species.
Study of chemistry in regarding how it pertains to earth processes and geologic media.
Geographic Information Systems (GIS)
Computer programs, facilitated through computer hardware, that integrate spatial data with other forms of information. Geography Study of the earth’s surface, typically facilitated through the use of maps.
Geologic Map
Graphical, two-dimensional representation of the outcrop patterns of rock units (formations) on the land surface. Typically has topographic information, (such as elevation changes) superimposed on it.
Geologic Time Scale
Standard description of time intervals in the history of the earth, based on a combination of relative dating and absolute dating criteria. Geophysics Study of how basic physical principles are used to better understand the earth, particularly its interior.
Muscular organ anterior of the stomach in the alimentary canal. In herbivorous dinosaurs, former presence is indicated by gastroliths.
Levels applied to classifying organisms, which are, (in order of most to least inclusive,) kingdom, phylum, class, order, family, genus, and species. In botany, the equivalent grade to a phylum is a division.
Classification system that places organisms into grades (levels) that become more inclusive based on anatomical similarity.
Gravitation, (Theory of)
Generally accepted explanation for observations of the attraction of matter for matter.


Clade of ornithischian dinosaurs, placed with clades Ornithopoda, Euornithopoda, and Iguanodontia, characterized by a minimum of the following traits: long and wide anterior portion of skull (“duckbill”), well-developed dental batteries, loss of antorbital and surangular fenestrae, increase of vertebrae to at least 8 sacral and 12 cervical vertebrae, loss of digit I on the manus, development of prominent unguals on the pes, and long forelimbs relative to hindlimbs.
Half of the normal complement of chromosomes in a somatic (body) cell. Characteristic of a gamete.
Herbivory; (Herbivorous)
Study of amphibians and reptiles.
Clade of saurischian dinosaurs, often placed within clade Theropoda but sometimes placed outside of the Dinosauria. Consists of a minimum of the following traits: long pubis with relation to its femur, three sacral vertebrae, semiperforate to open acetabulum with a well-developed medial wall, femur length nearly twice that of the humerus, elongate skull nearly equal in length with its femur, serrated and recurved conical teeth, long and equally sized metatarsals I and V on the pes, and manus with five digits but digits IV and V reduced and without unguals. Considered one of the more primitive clades of dinosaurs.
Dentition that shows a variety of teeth adapted for different functions. Heterodontosauridae Clade of ornithischian dinosaurs, placed with clades Ornithopoda, and limited to the Early Jurassic of South Africa. Identified by heterodont dentition.
Clade of ornithischian dinosaurs, placed with clade Marginocephalia and Pachycephalosauria. Often known as “flat-headed” dinosaurs.
Animal that maintains a near-constant internal body temperature, regardless of whether it is endothermic or ectothermic.
Body parts that are the same in different animals, although they may have a different morphology because they have been modified with descent as adaptations.
Physics of water flow. Important for interpreting sedimentary environments and taphonomy.
Conditional explanation of an observation or series of observations that typically proposes a cause for the observations. Must be testable and falsifiable.
Paraphyletic group of ornithischian dinosaurs within clade Ornithopoda and Euornithopoda. Among first dinosaurs to achieve pleurokinesis, a jointing between the premaxilla and the rest of the skull (including the premaxilla) that caused the maxilla to shift outward when the mouth closed.


Resultant patterns or texture imparted to a substrate (either unconsolidated or solid) as a result of organismal behavior, such as trampling of sediment by dinosaurs.
Study of traces left by organisms as a result of their behavior.
Name given to a trace fossil on the basis of its form (not its tracemaker). A type of parataxonomy, where binomial nomenclature is used for both ichnogenera and ichnospecies.
Igneous Rock
Rock formed from originally molten material (magma), can be either plutonic (cooling far below the earth’s surface) or volcanic (cooling on or near the earth’s surface). Minerals from these rocks often are used for calculating radiometric ages.
Clade of ornithischian dinosaurs, placed with clades Ornithopoda and Euornithopoda. Includes Hadrosauridae.
One of the hip bones, paired and lateral to the sacral vertebrae of the axial skeleton.
Inclusions, (Principle of )
Basic geologic principle used in determining relative ages of rocks; particles of a pre-existing rocks incorporated into a sediment must be older than the rock including them.
Insectivory; (Insectivorous)
Insect-eating habit. Considered as a hypothetical feeding strategy for some theropods (therizinosaurs).
Skin and its derivatives, such as scales or feathers.
Between different species, such as in most parasitic or predator-prey relations.
Within the same species, such as in intraspecific competition for mates.
One of the hip bones, posterior to both the pubis and ilium.
Variation on atomic weight of an element, can be either radioactive (undergoing decay) or stable (not decaying).


Jurassic Period
Time interval in the geologic time scale spanning about 206 to 140 million years ago. Middle period of the Mesozoic Era.


Anatomical reference to the side of an organism, or of any body part, farther away from a midline.
“Line of descent,” defined by populations that went through generations, from ancestors leading to descendants.
Lines of Arrested Growth (LAG’s)
Lines recorded in dinosaur bones that represent periods of interrupted growth, which can be attributed to yearly cycles in growth and thus suggestive of ectothermy.
Linnaean Classification
Hierarchical classification system of organisms based on grades (levels), also known as gradistics. Defined by Carl von Linnz, (also known as Carolus Linneaus).
Cool, rigid exterior of the earth that incorporates the crust and upper part of the mantle. Composes plates (which can have continents) that interact with one another as a result of processes emanating from the asthenosphere.