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INTRODUCTION

     The study of dinosaurs is a branch of Vertebrate Paleontology.  Paleontology is the study of fossils and other geologic information to decipher the nature of ancient life.  Vertebrates are animals with backbones and include the modern classes: Agnatha (jawless fishes), Chondrichthyes (cartilaginous fishes), Osteichthyes (bony fishes), Amphibia, Reptilia, Aves (birds), and Mammalia.  Dinosaurs are members of the Reptilia, however, they are very closely related to birds (as we will see as this course procedes).  In fact, dinosaurs are thought to be more closely related to birds than to other living (extant) reptiles (you say......How can that be if they are reptiles?  Well....we will see later in the course.)  Some dinosaur paleontologists go so far to say that birds are living dinosaurs!  However, when we use the word dinosaur in this course we will be referring to nonavian dinosaurs.

     The dinosaurs were rulers of the land for more than 160 million years and most of the Mesozoic Era.  The word "dinosaur" (from the Greek deinos meaning terrible and sauros meaning lizard or reptile) is usually taken to mean "Terrible Reptiles or Terrible Lizards".  However, as originally coined by Sir Richard Owen (a leading British

     Dinosaurs evolved about 230 million years ago (the oldest dinosaur fossils have been found in rocks that have been dated at 228 million years before present), near the beginning of the Late Triassic Epoch of time.  Dinosaurs evolved from archosauriforms (the name means "ruling reptile forms").  Archosauriforms are a group of reptiles whose ancestors arose during the Permian Period (from about 286 to 250 million years ago) and include several groups of archosauriforms (sometimes called Thecodonts, although this is not the best term to use, basal archosauriforms is a better term), the dinosaurs, the pterosaurs, and modern crocodiles.  Although most archosauriforms of Late Permian and Early Triassic were sprawling, crocodile-like animals called proterosuchians ("earlier crocodiles"), some archosauriforms of the Early to Middle Triassic were well on their way to becoming dinosaurs.  Although small, they were agile and lightly built with small forelimbs and were capable of bipedalism (walking on their back legs), but were primarily quadrapedal (walking on four legs) except when running.  These small primitive archosauriforms were carnivorous predators and closely resemble the first dinosaurs of Late Triassic time. Euparkeria is an example of an archosauriform that may be closely related to dinosaurs and other archosaurs (crocodiles and pterosaurs) (see Parrish, 1997 for a discussion of the difference between archosauriforms and archosaurs).

     The oldest dinosaurs are from Late Triassic deposits in South America.  The two oldest and most primitive dinosaurs dating to about 228 million years ago are Eoraptor (see:  Introduction to Eoraptor  ) and Herrerasaurus (see:  Introduction to Herrerasaurus ) {More on this later in the course}.

     The dinosaurs evolved rapidly in Late Triassic time and by the end of the Triassic Period were the dominant vertebrates on land.  They dominated the land throughout the remainder of the Mesozoic Era, until becoming extinct 65 million years ago (for nonavian dinosaurs).  After the dinosaurs were gone, the mammals (which also had evolved in Late Triassic time) quickly evolved into the niches vacated by the dinosaurs and became the dominant land vertebrates during the Cenozoic Era.
 

BRIEF HISTORY OF DINOSAUR HUNTING

     Certainly, dinosaur bones and tracks have been found by man since ancient times.  However, the first published accounts of dinosaur bones come from England in the early 1800s.  William Buckland, professor of mineralogy and geology at Oxford University was the first to describe a dinosaur in publication.  He described teeth and bones of a giant carnivorous reptile, which he named Megalosaurus ("great lizard"), in 1824.  Shortly thereafter (1825), Gideon Mantell, and English physician-surgeon, described teeth and bones of a giant beast that he name Iguanodon ("Iguana toothed").   Other names were given to other large extinct reptiles found in England and other parts of Europe prior to Owen defining Dinosauria in 1842 (Sarjeant, 1997)).

     In North America, the first dinosaur fossils were described by Philadelphian anatomist Joseph Leidy (1823-1891)

     The real revolution in dinosaur hunting took place between about 1870 and 1900 with the western North American "dinosaur bone rush",  fueled by the bitter scientific feud (Here is a good link to the Fossil Feud: The Great Feud - Full Text: August '98 American History Feature ) between Edward Drinker Cope and Othniel Charles Marsh.  Both Marsh and
 

Othniel Charles Marsh (1831-1899)  (From: http://www.peabody.yale.edu/people/whoswho/MarshOC.html)  GO TO THIS LINK AND READ ABOUT MARSH:   Yale Peabody Museum: People - O. C. Marsh

Edward Drinker Cope (1850-1897) (From: http://www.turnpike.net/~mscott/cope.htm) GO TO THIS LINK AND READ ABOUT COPE:  Rocky Road: Edward Drinker Cope

Cope were born into wealthy families, although they spent most of the money they inherited on dinosaur hunting.  Cope was from a wealthy Quaker family of Philadelphia and was a protege of Joseph Leidy (Lucas, 2000).  Cope was primarily self-educated, although he did spend some time in Europe studying paleontology.  Marsh was the nephew of the wealthy entrepreneur, George Peabody, who financed the education of Marsh at Yale and in Europe.  Marsh become the first professor of Paleontology at Yale University and founded the Peabody Museum of Natural History at Yale (funded by George Peablody).

     Early in their paleontological careers, Marsh and Cope developed an extreme dislike for each other which manifested itself as a bitter personal rivalry.  News of abundant dinosaur bones being found in the American West in the early 1870s spurred Marsh and Cope to hire crews to exploit this wealth of paleontological resources.  This resulted in a mad frenzy of dinosaur collecting with rushed publications to name new genera and species of dinosaurs, with both Marsh and Cope trying to out-do the other.  This resulted in a wealth of new genera and species (some of which were later invalidated) and a much more complete understanding of dinosaurs (many partial and fairly complete skeletons were found).  Many of the well known genera of dinosaurs  were discovered as a result of the Marsh-Cope feud, particurlay the Jurassic dinosaurs (primarily from Marsh) Brontosaurus (now known as Apatosaurus), Stegosaurus, and Allosaurus from Upper Jurassic deposits of the Morrison Formation (go to this link for a description of the Morrison Formation Ecosystem). MRI Results

     Not all dinosaur research was confined to North America during the "Golden Age".  Two major expeditions took place in the early 1900s that greatly enhanced dinosaur paleontology.  The first of these took place between 1907 and 1912 at Tendaguru Hill in what was then the German Protectorate East Africa (present-day Tanzania).  Werner Janensch (1878-1969), a fossil reptile expert at the Berlin Museum in Germany, was in charge of the expeditions.  Janensch and his associates identified two major dinosaur fossil bone horizons at Tendaguru, both of which were determined to be Late Jurassic (Kimmeridgian) in age.  The deposits here were ancient coastal plain deposits that intertongued with marine Jurassic deposits, thus a fairly accurate relative age could be determined by studying associated marine invertebrate fossils.  The total weight of fossil dinosaur bones (and associated rocks and other fossils) shipped backed to Berlin from the digging at Tendaguru amounted to 235 metric tons (Hans-Dieter Sues, 1997; Lucas, 2000).  The Jurassic dinosaurs found at Tendaguru are very similar to some of the Jurassic dinosarus of Western North America, notably Brachiosaurus, which was found in both regions.

     The second series of great dinosaur expeditions were the Central Asiatic Expeditions of the American Museum of Natural History.  These dinosaur expidetions were to the Gobi desert of Mongolia and China during the 1920s (1922-1930) and were organized and lead by Roy Chapman Andrews (1884-1960) (a zoologist with the AMNH and a real life Indiana Jones).  Although promoted by Andrews, the expeditioins were blessed by dinosaur paleontologist Henry Fairfield Osborn (1857-1935) (also of the AMNH and discoverer of the type specimen of Tyrannosaurus rex, Montana, 1905, now on display at the Carnegie Museum).  The main target of the first expedition was to find evidence of the oldest human ancestors (thought by Andrews and Osborn to be in Central Asia).  However, important discoveries of new Cretaceous dinosaurs were made and the discovery of the first dinosaur eggs (to be identified as dinosaur eggs) in Cretaceous deposits at the "Flaming Cliffs" of Bayn-Dzak, Mongolia.  Not far from where the eggs were found, over 100 skeletons and skulls of the small Cretaceous dinosaur Protoceratops were found (representing all growth stages of Protoceratops, i.e. representative skeletons to construct and complete ontogenetic sequence, the first such find).  At the time it was assumed that the eggs were those of Protoceratops, however, we now know the eggs belonged to Oviraptor ("egg stealer") (a theropod dinosaur also found at the Flaming Cliffs and thought at the time to be the stealer of the eggs of Protoceratops).  Other dinosaurs found during these expeditions were the theropods Sauronithoides and Velciraptor and the so called "parrot dinosaur", Psittacosaurus.

     After the "Golden Age" of the first part of the 20th century, dinosaur exploration and research went into somewhat of a "Dark Age" during the 1930s and 1940s.  During this time, although some dinosaur exploration and research was still going on, there was more emphasis by vertebrate paleontologists on the therapsids (sometimes referred to as "mammal-like" reptiles).  The therapsids were thought to be on the mainstream of evolution, while dinosaurs were off the main line of evolution (Colbert, 1997) (of course, this view is not held today - both are important groups in terms of evolutionary studies).  However, there were important discoveries during this period, particularly the discovery of hundreds of skeletons of the small meat eating dinosaur Coelophysis from Upper Triassic rocks of Northern New Mexico by Edwin Colbert and crews from the American Museum of Natural History.  Other discoveries of Triassic dinosaurs in Argentina and Brazil and new Cretaceous dinosaurs from Mongolia and China helped with the understanding of dinosaur anatomy and distribution and the climate and environment in which dinosaurs lived, but did not alter the basic view of dinosaurs as a sideline reptilian evolutionary branch (Lucas, 2000).

     After World War II and into the 1950s, a new breed of dinosaur paleontologists emerged.  Older studies of dinosaurs had mostly been descriptive aimed at interpretation of morphologic anatomy and taxonomic relationships (Colbert, 1997).  Studies during the late 1940s and into the 1950s are exemplified by paleontologists such as John Ostrom of Yale, who realized that dinosaur skeletons could reveal much more information with studies of bone structure and bone histology which could have implications concerning dinosaur physiology (Colbert, 1997).  Ostrom's discovery of the small meat eating (theropod) dinosaur, Deinonychus in the 1960s (in Cretaceous deposits of Montana) and the interpretation that this dinosaur was an intelligent, active hunter that was probably warm-blooded (endotherimic) was the beginning of a Renaissance in dinosaur studies and research.  The idea of dinosaurs as slow, sluggish, dim-witted reptilian brutes was starting to fade.

     The real Renaissance in dinosaur paleontology occurred in the early 1970s, when Robert Bakker (a student of Ostrom at Yale) challenged orthodox dinosaur paleontology by suggesting that dinosaurs were warm-blooded, active creatures that were much more bird-like in anatomy and physiology than traditonally thought.  He, and others, contended that dinosaurs are much more closely related to birds than to modern reptiles.  Bakker started a revolution in dinosaur paleontology that is still occurring today (Lucas, 2000).

     From the 1970s to the present, renewed interest in collecting dinosaurs from all parts of the globe; restudying dinosaur bones in museums; new technologies of study (such as catscans); new interpretations of dinosaur phylogney (based on cladistic analysis); new discoveries of dinosaur nests, eggs, and babies; new discoveries and new interpretations of dinosaur footprints and trackways; new evidence supporting causes of dinosaur extinction and new discoveries of bird-like (possibly feathered) dinosaurs from China are changing our perceptions of dinosaurs and the study of dinosaur paleontology.  We are truely in a Renaissance of dinosaur exploration and research.

WHAT ARE DINOSAURS?

     Dinosaurs are not  mammoths, mastodons, saber-toothed tigers, nor "mammal-like reptiles" like Dimetrodon, a pelycosaur.  They are not extinct flying reptiles (pterasaurs) like Pteranodon nor extinct swimming reptiles, like the pleisosaurs and icthyosaurs.

      Dinosaurs are extinct reptiles having an upright posture (legs underneath the body, not sprawling out to the side like an alligator or crocodile) and a hole in the hip socket (dinosaur paleontologists would say "they have a perforated acetabulum).  They first evolved about 228 million years ago in the Late Triassic and became extinct 65 million years ago, at the end of the Cretaceous Period.  Birds are now thought to be living descendants of dinosaurs.
However, dinosaurs do have reptilian skeletal features and it appears the most (if not all) dinosaurs (like modern reptiles and birds) layed eggs.

     Not all dinosaurs were giants.  Many were small, some the size of chickens.  In fact, some had skeletal features in common with chickens (birds).
 

WHEN AND WHERE DID DINOSAURS LIVE?

     Dinosaurs lived on the Earth for about 160 million years.  Humans have lived on the Earth for, at most, 3 to 4 million years.  Therefore, dinosaurs lived on the Earth 40 to 50 times longer than humans have occupied the Earth.
Humans and dinosaurs are separated in time by about 60 million years, so movies and cartoons which depict cave men as living along side dinosaurs are grossly inaccurate.

     Dinosaurs lived during most of the time called the Mesozoic Era (248 million years ago {mya} to 65 million years ago).  The Mesozoic Era is divided into three periods, the Triassic Period (248 mya to 208 mya), the Jurassic Period (208 mya to 144 mya), and the Cretaceous Period (144 mya to 65 mya).  Dinosaurs lived from Late Triassic (about 228 mya) to the end of Cretaceous time (65 mya).

     As previosly stated, dinosaurs were one of the most succesful groups of organisms of all time, they were long lived, widely distributed (on all the continents, even Anarctica where they were discovered in 1989), extremely varied in form, and occupied many habitats and niches.  In fact, it was not until the dinosaurs were extinct that the mammals took over the land (the mammals evolved about the same time as the dinosaurs).
 

WHY STUDY DINOSAURS?

     Certainly, we study dinosaurs because they are extremely interesting.  But even more, they represent an important part of the evolutionary history of life on the Earth.  By studying dinosaurs (as with any group of living or extinct organisms) and their interactions with each other, other living creatures of the time, and with their environment, we learn more about how the environment and climate of the world can change (sometimes rapidly and drastically) and how life adapts to these changes.  By studying dinosaurs we better understand how Earth systems interact.  By an understanding of various  past Earth cycles and system interactions, we are better able to understand modern Earth systems and perhaps will be able to predict future changes in Earth system interactions.
 
 

Colbert, Edwin H., 1997, North American Dinosaur Hunters, in The Complete Dinosaur (Farlow, James O. and Brett-Surman, M. K., eds.): Indiana University Press, Bloomington and Inianapolis, p.p. 24-33

Lucas, Spencer G., 2000, Dinosaurs The Textbook (3rd ed.): The McGraw-Hill Companies, Inc., 278 p.

Parrish, J. Michael, 1997, Evolution of the Archosaurs, in The Complete Dinosaur (Farlow, James O. and Brett-Surman, M. K., eds.): Indiana University Press, Bloomington and Inianapolis, p.p. 191-203.

Sarjeant, William A. S., 1997, The Earliest Discoveries, in The Complete Dinosaur (Farlow, James O. and Brett-Surman, M. K., eds.): Indiana University Press, Bloomington and Inianapolis, p.p. 3-11.

Richard Owen (1804-1892): http://www.ucmp.berkeley.edu/history/owen.html

Speer, Brian R., 1997, Introduction to Euparkeria: http://www.ucmp.berkeley.edu/diapsids/euparkeria.html

Speer, Brian R., 1997, Introduction to Herrerasaurus: http://www.ucmp.berkeley.edu/diapsids/herrerasaurus.html

Speer, Brian R., 1997, Introduction to Eoraptor: http://www.ucmp.berkeley.edu/diapsids/eoraptor.html

Levins, Hoag, 1996-2000, Finding the Bones in 1858: http://www.levins.com/bones.html

Levins, Hoag, 1996-2000, Hadrosaurus foulkii: Discovering the World's First Full Dinosaur Skeleton, Haddonfield, N.J., USA, 1858: http://www.levins.com/dinosaur.html

Huntington, Tom, 1998, The Great Feud - Full Text: August '98 American History Feature: http://www.thehistorynet.com/AmericanHistory/articles/1998/0898_text.htm

 Yale Peabody Museum: People - O. C. Marsh: http://www.peabody.yale.edu/people/whoswho/MarshOC.html (last revision May 12, 2000)

Michon Scott, Michon, 1996-2001, Rocky Road: Edward Drinker Cope: http://www.turnpike.net/~mscott/cope.htm

Turner, Christine E, et al, 1995, Morrison Research Results -  LATE JURASSIC ECOSYSTEM RECONSTRUCTION DURING DEPOSITION OF THE MORRISON FORMATION AND RELATED BEDS IN THE WESTERN INTERIOR OF THE UNITED STATES: http://www.colostate.edu/%7Ecwis70/results.html (last revision December 1998)

Jurassic: (Text and imagery adapted from: "A Guide to the Age of Reptiles (2nd Edition)," by John H. Ostrom, Leo J. Hickey, and Theodore Delevoryas, (C) 1987 Peabody Museum of Natural History; and "The Great Dinosaur Mural at Yale: The Age of Reptiles," by Vincent Scully, Rudolph F. Zallinger, Leo J. Hickey, and John H. Ostrom, (C) 1990 Peabody Museum of Natural History.): http://www.peabody.yale.edu/mural/jurassic/(last revision March 17, 1998)

Berlin Brachiosaurus, 1937: Linda Hall Library, Kansas City, Missouri (Source: Janesch, Werner. "Skelettrekonstruktion von Brachiosaurus brancai aus den Tendaguru-Schichten Deutsch-Ostafrikas," in: Deutsche Geologische Gesellschaft. Zeitschrift, vol. 89 (1937), pp. 550-552.): http://www.lhl.lib.mo.us/pubserv/hos/dino/jan1937.htm