Chapter 1 – Definition of a Dinosaur
What is a Dinosaur?
Reptile-like or Bird-like
Animal
different from modern
reptiles, but share common ancestors
anatomical and behavioral
characteristics of birds, and birds are dinosaur descendents
If you consider living birds to be dinosaurs, then the definition is for non-avian
dinosaurs
Mastodons are mammals and so
are not dinosaurs
Dimetrodon is a mammal ancestor and so
is not a dinosaur
Upright (erect) posture
legs directly beneath torso
Contrasts with sprawling or semi-erect posture, where limbs project to the side of the torso,
like modern amphibians and reptiles
bipedal and quadrupedal
stances
Dinosaurs among the first animals to habitually
walk on two legs, as shown
by tracks and anatomy
Not all dinosaurs were bipedal, but even four-legged dinosaurs were upright, as shown by tracks and anatomy
Why?
More efficient movement on land
Lived on land
Did not fly or swim
Pterosaurs flew and so are
not dinosaurs
Plesiosaurs swam and so are
not dinosaurs
Ranged widely in SIZE
Some were the largest animals
to have lived on land
Many Smaller than humans
Smallest were the size of
chickens
Lived only during the
MESOZOIC ERA
Fossils found in rocks formed
during the last of the Triassic, the Jurassic and the Cretaceous Periods (230
– 65 million years ago)[see Geologic Time Scale handout]
No dinosaurs prior to 230 million years ago or
since 65 million years ago
No dinosaurs lived with humans, who only evolved about 4 million years ago
Classification/Taxonomy of
Dinosaurs
Traditional method
developed by C. Linnaeus (in 1758) [real name is Carl von
Linné]
Referred to as Linnaean
classification and is based on hierarchical grades
Kingdom, Phylum, Class, Order, Family, Genus, species
Increasingly more exclusive categories based on
a standard set of anatomical characteristics & stratified from groups with many members to those with fewer
Phylum Chordata Chordata
Subphylum Vertebrata Vertebrata
Class Reptilia Mammalia
Subclass Diapsida Theria
Infraclass Archosauria Eutheria
Superorder Dinosauria n/a
Order Saurischia Primate
Suborder Theropoda Anthropoidea
Family Tyrannosauridae Hominidae
Genus Tyrannosaurus Homo
species rex sapiens
New & more popular
method applied to dinosaurs since 1984
Referred to as phylogenetic classification,
or cladistics, and is based on synapomorphies, or shared, evolutionarily
derived (new or novel) anatomical characteristics with organisms placed within
clades
Characteristics are observed, not inferred
Explanations of evolutionary
relationships summarized with Cladograms
Clades nested within one another
Branches on a bush, rather than rungs on a ladder
(Chapter 11) (Chapter
12) (Chapter
13) (Chapter
15) (Chapter
14)
\______________ / \_______________ |___________________ /
| |
\_______________________________________ /
|
|
Chordata Chordata
Vertebrata Vertebrata
Gnathostomata Gnathostomata
Sarcopterygia Sarcopterygia
Tetrapoda Tetrapoda
Amniota Amniota
Reptilia Synapsida
Diapsida Therapsida
Archosauriformes Mammalia
Archosauria
Ornithodira
Dinosauria
Saurischia/
Ornithischia
Same names used by both
systems
Dinosaur paleontologists
usually referring to clades now
Species
A set of organisms that can interbreed and produce offspring
that can also reproduce with one another
Note: IN NATURE; closely related species have been interbred in
captivity
Mules (donkeys and horses); Ligers and tions (lions
and tigers)
Binomial nomenclature
Genus (general name) and species (trivial name)
Major dinosaur clades (see
Table 1.1)
Saurischia
Theropoda: Late Triassic to Late Cretaceous; generally bipedal; grasping hands; hollow bones; generally carnivorous; <1 to 16 meters long
Ceratosauria – Abelisaurus, Ceratosaurus, Coelophysis, Dilophosaurus
Tetanurae – Allosaurus, Compsognathus, Oviraptor, Tyrannosaurus
Sauropodomorpha: Late Triassic to Late Cretaceous; both bipedal (a few early forms) and quadrupedal (most others); relatively small heads and long
necks; herbivorous; 2 to 38 meters long
Prosauropoda – Plateosaurus, Lufengosaurus, Coloradisaurus, Riojasaurus
Sauropoda – Apatosaurus, Argentinosaurus, Brachiosaurus, Camarasaurus
Ornithischia
Ornithopoda: Early Jurassic to Late Cretaceous; generally bipedal; herbivorous with excellent grinding teeth; 1 to 15 meters long
Hypsilophodontidae – Hypsilophodon, Orodromeus, Othniella
Iguanodontidae – Camptosaurus, Dryosaurus, Iguanodon, Ouranosaurus
Hadrosauridae – Corythosaurus, Edmontosaurus, Hadrosaurus, Saurolophus
Thyreophora: Early Jurassic to Late Cretaceous; quadrupedal; armored with spines and plates; herbivorous; 3 to 12 meters long
Ankylosauria – Ankylosaurus, Hylaeosaurus, Nodosaurus, Pinacosaurus
Stegosauria – Huayangosaurus, Kentrosaurus, Stegosaurus, Tuojiangosaurus
Marginocephalia: Cretaceous only; bipedal in Pachycephalosaurs and generally
quadrupedal in Ceratopsians; herbivorous; 2 to 12 meters long
Pachycephalosauria – Homalocephale, Pachycephalosaurus, Prenocephale, Stegoceras
Ceratopsia – Chasmosaurus, Protoceratops, Torosaurus, Triceratops
The Importance of
Dinosaurs
Dinosaurs in Science and
Education
Sciences used in studying
dinosaurs
Paleontology
Combines biology and geology
Fossils
Body fossils – preserved body parts like bones or
skin (or shells)
Trace fossils – preserved of behavior while
alive like tracks, nests or toothmarks
Taphonomy
Study of HOW fossils are preserved in the geologic
record
Invertebrate paleontology; vertebrate paleontology; micropaleontology; paleobotany
Dinosaur paleontologists are a subset of vertebrate
paleontologists
Ecology vs Paleoecology
Ecology is the study of organisms and their
interactions with environments
An ecosystem is a specific group of organisms
interacting with a specific environment
Paleoecology is the attempt to reconstruct
ancient ecosystems on the basis of fossils and other clues left in rocks
Chemistry, geochemistry,
biochemistry, microbiology, biogeochemistry
Physics, biomechanics,
thermodynamics, geophysics
Mathematics, biometry, allometry
Computer science, geographic
information systems (GIS)
Geography, paleobiogeography
Metric system used (see table
1.3)
Dinosaurs in Popular Culture
and Fiction
Authors
Charles Dickens, Sir Arthur
Conan Doyle, Edgar Rice Burroughs
Films
The Lost World (1925), King Kong (1933), One Million B.C. (1940), Journey to the
Beginning of Time
(1955), The Valley of the Gwangi (1969), Jurassic Park (1993), Lost World (1997), Dinosaur (2000), Jurassic Park 3 (2001), Dinotopia (2002)
Web pages
Dinosaurs in Art
Scientific Illustration
Charles L. Knight, Gregory
Paul
Aesthetics
Beware of Anachronisms
Dinosaur models and
estimating dinosaur weight
Weight equals volume times
density