Dinosaur Information
 Last Updated    2/27/2003     2/26/2003

Dino Count  Current total number of "Official" Dinosaurs.

What does modern science have to say about the dinosaurs? Are they truly obsolete, long-extinct relics of a more primitive and experimental stage in the history of life, or is there more to the Dinosauria than meets the eye?

Dinosaurs are animals that evolved into many sizes and shapes. Dinosaurs were and are quite diverse, and often one person will think of an animal like a long-necked sauropod, while another person will think of a large, fierce meat-eater like Tyrannosaurus rex. It should be clear then that the term "dinosaurs", or the scientific version "Dinosauria", is describing a diverse group of animals with widely different modes of living. The term was invented by Sir Richard Owen in 1842 to describe these "fearfully great reptiles", specifically Megalosaurus, Iguanodon, and Hylaeosaurus, the only three dinosaurs known at the time. The creatures that we normally think of as dinosaurs lived from late in the Triassic period (about 225 million years ago) until the end of the Mesozoic era (about 65 million years ago); but actually they live on today as the birds.

Dinosaur Myths
The term "dinosaur" has had a long history of misrepresentation. A few simple points must be kept in mind when discussing these animals:

Not everything big and dead is a dinosaur.

All too often books written for a popular audience include animals such as mammoths, mastodons, plesiosaurs, ichthyosaurs, and the sail-backed Dimetrodon. Dinosaurs are a specific subgroup of the archosaurs, a group that includes crocodiles and birds, whereas mammoths and mastodons are mammals. Other archosaurs included the pterosaurs, relatives of dinosaurs but not true dinosaurs. More distantly related to true dinosaurs were the marine plesiosaurs and ichthyosaurs. These were marine reptiles, not dinosaurs or even close relatives of them. Dimetrodon is neither a reptile nor a mammal, but a basal synapsid -- that is, an early relative of the ancestors of mammals.

Not all dinosaurs lived at the same time.

Different dinosaurs lived at different times. Despite the portrayals in movies like Fantasia and Jurassic Park, no Stegosaurus ever saw a Tyrannosaurus, because Tyrannosaurus wasn't alive for another 80 or so million years. Ditto for Apatosaurus (a.k.a. "Brontosaurus").

Dinosaurs are not extinct.

Technically. Based on features of the skeleton, most people studying dinosaurs consider birds to be dinosaurs. This shocking realization would make even the smallest hummingbird a legitimate dinosaur. Rather than refer to "dinosaurs" and birds as discrete, separate groups, it is best to refer to the traditional, extinct animals as "non-avian dinosaurs" and birds as, well, birds are birds, or avian dinosaurs. Whatever works for you. It is incorrect to say that dinosaurs are extinct, because they have left living descendants in the form of cockatoos, cassowaries, and their pals -- just like modern vertebrates are still vertebrates even though their Cambrian ancestors are long extinct. Yes, even birds have ancestors, funny looking as birds may be.

Dinosaurs represent failure and extinction.

Rather, dinosaurs are the best examples of success and adaptation. They ruled the Earth longer than any other land animals (over 150 million years), and gave rise to BIRDS.

Dinosaurs and "humans" coexisted.

The death of the last dinosaur and the appearance of the first "human" (genus HOMO) was separated by about 62 million years.

Dinosaurs were either all hot-blooded or all cold-blooded.

Mesozoic dinosaurs were not "warm-blooded" like modern mammals, nor were they "cold-blooded" like modern lizards. Most specialists believe that dinosaurs were "dinosaur-blooded", a condition that combines certain aspects of "warm-bloodedness" with a changing metabolism over the animal's lifetime.

The word dinosaur means "terrible-lizard."

Actually it was originally defined to mean "fearfully-great lizard", by Richard Owen in 1842. The greek word "deinos", when used as a superlative, means "fearfully-great" (as used by Homer in THE ILIAD). It became simplified over time, as a simple adjective, to mean "terrible". Dinosaurs are neither terrible nor are they lizards!

Whatever you read in the latest "dinosaur book" or see on T.V. or in the movies must be true.

Popular books, movies, and TV specials need not be 100% accurate. They often contain errors and outdated information, and may reflect the personal bias of the writer. (Most dinosaur books and TV scripts are not reviewed by professional dinosaur paleontologists).

Dinosaurs all lived and died at the same time.

The distance in time between Tyrannosaurus and Apatosaurus (formerly called "Brontosaurus") is more than the time between Tyrannosaurus and your parents, about 65 million years. Of the (approximately) 900 named species of Mesozoic dinosaurs, only two or three dozen species faced the final extinction in North America.

Mammals arose after the dinosaurs, and helped drive the dinosaurs into extinction by eating dinosaur eggs.

Mammals and dinosaurs both appeared in the Late Triassic Period. There is no evidence that dinosaurs went extinct because of predation on their eggs.

An asteroid (or comet) killed the dinosaurs.

The controversy over the cause of the dinosaur extinction continues among paleontologists. However, evidence from a deep sea core drilled off the coast of Florida proves that an asteroid hit the Earth at the end of the Cretaceous which caused the dinosaur extinction. Most dinosaur specialists are willing to accept that an asteroid hit the Earth, but do not think that it was the sole cause of the Mesozoic extinctions. Instead, the fossil record reveals that dinosaurian diversity was already in decline by the end of the Cretaceous. The asteroid impact may have been "the straw that broke the camel's back."

All big reptiles from the prehistoric past ["Monsters"] are dinosaurs.

Dinosaurs represented less than 10% of the 40 groups of reptiles from the Mesozoic Era (Pterodactyls, sea-serpents, giant lizards, pelycosaurs, and other BIG prehistoric beasts are NOT dinosaurs). "Monsters" and Dragons are the products of fiction and mythology. Dinosaurs are better because they are real!!

Archaeologists dig up dinosaurs.

Archaeology and paleoanthropology (subdivisions of Anthropology) only deals with man and covers the last 3-4 million years. Paleontology (a combination of Geology and Biology), deals with all fossils and covers the last 3.5 billion years!

      1824 - Buckland published the first description of a dinosaur called Megalosaurus[4].

 1825 - Dr Gideon Mantell[3] published a description of Iguanodon which was found in a quarry at Cuckfield, Sussex, England.
 1841 - Sir Richard Owen, of the Natural History Museum London, suggested that these reptiles be called the Dinosauria (the `terrible lizards').

1809 - A lower shin- bone of a large unknown animal was collected at Cuckfield by William
Smith ("Father of English Geology"). This fossil was deposited at the British Museum in London and years later was identified as that of Iguanodon.

 1818 - Bones of Megalosaurus were discovered at Stonefield, Oxfordshire in England, but were not described till years later.
 1822 - Mrs Mary Ann Mantell found the teeth of an unknown animal near Lewes, Sussex (described in 1825 by her husband as those of Iguanodon[3]).

Dinosaur fossils had been known for centuries as "dragon bones" or the remains of giants, but it wasn't until Dean William Buckland of Oxford, England described the carnivorous "lizard" Megalosaurus (in 1824) that they were formally studied as an extinct group of giant reptiles. The English country doctor Gideon Mantell described Iguanodon in 1825, and today there are more than 800 known types of non-avian dinosaurs (plus some 10,000-plus birds).

The term "Dinosauria" was invented by Sir Richard Owen in 1842 to describe these "fearfully great reptiles", specifically Megalosaurus, Iguanodon, and Hylaeosaurus, the only three dinosaurs known at the time. The irony of Owen's invention of Dinosauria is that he devised the taxonomic group as an argument against progressive evolution, but actually had presented evidence supporting evolution.

The First Discoveries

 The clade Dinosauria was originally defined by Sir Richard Owen in 1842, in a two hour speech that reportedly held the audience captivated. The original dinosaurs of this new group were Megalosaurus, Iguanodon and Hylaeosaurus. However, each of these animals was known only from fragmentary specimens. It wasn't until the discoveries of dinosaurs in North America in the mid-19th century that people began to get a clearer picture of what dinosaurs looked like.

It is generally accepted that the first discovery of dinosaur remains in North America was made in 1854 by Ferdinand Vandiveer Hayden during his exploration of the upper Missouri River.

Near the confluence of the Judith and Missouri Rivers (shown above) Hayden's party recovered a small collection of isolated teeth which were later described by the Philadelphia paleontologist Joseph Leidy in 1856, in the Proceedings of the Academy of Natural Sciences of Philadelphia.

An important, more complete specimen

A short two years later, Leidy had the honor of describing the first reasonably complete dinosaur skeleton the world would know, Hadrosaurus foulkii. Named after its discoverer William Parker Foulke,  this specimen was recovered during quarrying of a sand pit in Haddonfield, New Jersey.

The real significance of this specimen was in its limb proportions. For the first time scientists studying these animals could see that some dinosaurs were bipedal, walking on two legs instead of on all fours. Bipedalism was a revolutionary thought for a reptilian posture.

This specimen, now on display at the Academy of Natural Sciences of Philadelphia, was originally mounted in a free-standing bipedal pose by Benjamin Waterhouse Hawkins in 1868.

The records for attendance at the Academy show that visitation increased three-fold with this new exhibit, testimony to the public's long-standing and intense fascination with dinosaurs.


For many years, Hadrosaurus foulkii was the only dinosaur on public display. Duplicate casts of the skeleton were made for other institutions both in the United States and in Europe.

Events surrounding the discovery of the Bushmans River dinosaur.

1845 - Dr WG Atherstone and Mr AG Bain discovered the fossil of "Cape Iguanodon" in the Bushmans River valley near Dassieklip[1].

1849 & 1853
- Bain sent collections of SA fossils to the Natural History Museum in London for identification by Sir Richard Owen. This material included the lower jaw of the "Cape Iguanodon" from Bushmans River[5,6].

1857
- Dr WG Atherstone[1] published the account of their trip to the Bushmans River valley and the discovery of this fossil.

1871
- Dr WG Atherstone[7] mentioned that the "Cape Iguanodon" had still not been identified and that it was still housed in the Natural History Museum in London.

1876
- Sir Richard Owen published an illustrated description of the fossil of "Cape Iguanodon" and named it Anthodon serrarius[8]
         
1890 - Richard Lydekker[6], a curator of palaeontology at the British Museum of Natural History in London, corrected Owen's mistake regarding the locality yet failed to distinguish them as separate species - Anthodon serrarius, a pareiasaur and "Cape Iguanodon" a dinosaur.

1909
- Dr Robert Broom visited the British Museum of Natural History and examined the Bushmans River material. He concluded that the fossil was in fact from a herbivorous dinosaur and noted that "..... when we compare the teeth with those of Cretaceous reptiles of other parts we find that they are strikingly similar to those of some herbivorous Dinosaurs"[9]. Broom noted a striking similarity between the Bushmans River teeth and a tooth of Palaeoscincus costatus, an ankylosaur which is now regarded as a close relative of the stegosaurs. He went on to suggest that as the Bushmans River teeth were so similar to those of the ankylosaur Palaeoscincus costatus it was probable that they belonged to the same genus. He recommended that the Bushmans River specimen be provisionally named Palaeoscincus africanus, emphasizing that it was definitely not the pareiasaur Anthodon serrarius and pretty certainly dinosaurian.

1913
- Prof. E.H.L. Schwarz and students from Rhodes University revisited the discovery site and they found more fossil bone, including a heavy femoral head, the head of a tibia, some vertebra and numerous smaller fragments[10]. These specimens (a total of 22 fragments) are housed in the Albany Museum. In describing this material Schwarz, however, did not adopt the name proposed by Broom and persisted with the mistaken name Anthodon serrarius. Recent examination of this material suggests that it may not be from a stegosaur but rather from some large sauropod dinosaur. This material was however collected in the general area where Atherstone found the stegosaur.

1929
- Frans Baron Nopsca[11], apparently unaware of the name proposed by Broom, studied the Bushmans River fossil at the British Museum of Natural History and named it Paranthodon oweni recognizing that it was in fact a stegosaur. He introduced the new stegosaur genus Paranthodon into the literature.

1972
- Walter P. Coombs examined the fossil and requested that it be prepared for detailed study[2].

1981
- Peter M. Galton and Walter P. Coombs tied up most of the loose ends of this saga and establish the taxonomy of this specimen in their paper entitled "Paranthodon africanus (Broom) - A Stegosaurian Dinosaur from the lower Cretaceous of South Africa"[2] .

Remains of Dinosaurs

If the diverse and numerous dinosaurs (except birds) are extinct, then how can we better understand they lived? Despite the fact that the great dinosaurs of the Mesozoic are gone, they have left us many clues about what they looked like and how they lived. This is because dinosaur fossils are not limited to bones, but include skin, eggs, nests, footprints, and other special kinds of fossils that give us clues about their lifestyles.

Dinosaur Nests

 The news has recently carried several stories of wonderful finds of nesting dinosaurs, and it is true that an explosion of data on dinosaurian nesting and social behavior has been uncovered in the past 20 years. Some of the most well known and compelling evidence comes from Dr. Jack Horner's (Museum of the Rockies) ongoing work at the "Egg Mountain" site in Montana, where he has documented evidence of a large nesting area used by hadrosaurian (duckbill) dinosaurs. These dinosaurs were named Maiasaura, "good mother reptile," referring to the closely packed nests that contain fossilized eggs, embryos, and juveniles (such as the one pictured at right). This is one case where we can be fairly confident that parental care was involved in these dinosaurs' lifestyle. Actually, this is not a surprising assertion, because both crocodilians (their closest living relatives) and birds (their living descendants), both show some degree of parental care and extensive nest building.

Other dramatic finds of dinosaur nests include theropod dinosaurs (Oviraptor and Troodon) that apparently died while brooding their nests, and abundant nests of the early ceratopsian dinosaur Protoceratops. An interesting story about Oviraptor: the so-called "egg stealer" was so named because it was found atop a clutch of eggs that were assumed to belong to Protoceratops. This idea held for some 70 years until a find in the 1990s showed an Oviraptor embryo inside one of those eggs... Egg stealer exonerated!

 Dinosaur Footprints  

We know of literally thousands of non-avian dinosaur footprints scattered around the globe, from Late Triassic to Late Cretaceous age. You might not think that a footprint, or a sequence of footprints (called a trackway), could tell us much, but actually it can tell us some general things about the biology of dinosaurs.

From trackway data, we can tell that (1) some non-avian dinosaurs travelled in large groups; (2) non-avian dinosaurs moved with their feet held underneath their body (as birds and mammals do); and (3) some non-avian dinosaurs moved rather quickly, but some plodded along at a more leisurely pace -- see our section on dinosaur speeds for more info. See Dinosaurs Tracks

Dinosaur Diet

Dinosaurs, living and extinct, have varied diets. We have some strong evidence of exactly what the diets of some of the extinct dinosaurs was, and we can observe birds directly to learn about their diets. Dentition (tooth structure) is one of the most abundant lines of evidence useful for determining dinosaur diets. Most ornithischian and sauropodomorph dinosaurs had rather simple, short stubby crenellated teeth, which are similar to those of living herbivores, and clearly not too good for eating much meat.

 Theropod teeth, on the other hand, retain the primitive archosaurian characteristic of being recurved, serrated, laterally -compressed, and knife-like. There is some variation in tooth structure among extinct theropods, but most are fairly similar and obviously related to a carnivorous diet.

Stomach contents are another line of evidence, somewhat more direct but also a bit more tricky to interpret accurately. Well-preserved dinosaur skeletons sometimes have traces of apparent food items preserved in their abdominal cavity, where it's safe to assume that they had a stomach. This includes pine cones and/or needles in some herbivores' guts, and traces of some vertebrates in some theropods' guts. So this independent line of inquiry substantiates the data from tooth morphology. Also, some sauropodomorph stomachs contain well- rounded stones, caled gastroliths, that were probably used to grind food in a muscular crop or gizzard, like some birds (and crocodilians) do.

The general hypothesis that most ornithischians and sauropodomorphs were largely, if not completely herbivorous, and that theropods (at least before the origin of birds) were mostly carnivorous, thus holds. More specific hypotheses have been proposed and supported by data, while others have fallen by the wayside. It is likely that new discoveries will illuminate more about dinosaur diets as the global "dinosaur renaissance" continues.

You can learn more about the diets of sauropods from our page on that subject.

Dinosaur Classes

With the discovery of many new species since the 1840s, the Dinosauria now contains two major groups of dinosaurs: the Ornithischia, or "bird-hipped" dinosaurs, and the Saurischia, or "lizard-hipped" dinosaurs. The division between the two groups was made by H.G. Seeley in 1888. The etymology behind the two names ("bird-hipped" vs. "lizard-hipped") is not very accurate, since some saurischians had bird-like hips, and ornithischians' hips were somewhat birdlike due to convergent evolution, not due to direct ancestry. In fact, birds are saurischians!  Goto Dinosaur Groups  to see examples.

Saurischia contains two main groups:  

Ornithischia contains several groups of herbivorous dinosaurs, including several basal groups, but primarily three large ones:

Geologic Time Scale


Dinosaurs and other Mesozoic Animals


  

 Acrocanthosaurus   

Icthyosaurus
Icthyosaurus

 

 Albertosaurus 

Coelophysis

Iguanodon

 Thecodontosaurus 

Allosaurus
Allosaurus

Compsognathus   

 Maiasaura

Thescelosaurus   

Anchisaurus

Corythosaurus

 

Triceratops

     

Tsintaosaurus

Ankylosaurus

Deinonychus

Muttaburrasaurus

Troodon

     

Tuojiangosaurus

Apatosaurus

Dilophosaurus
Dilophosaurus

  Ornithomimus

 Tyrannosaurus

    Archaeopteryx  

Oviraptor 

 
   

Pachyrhinosaurus

 
   Bagaceratops  

Parasaurolophus

 

Barosaurus

Diplodocus

Plateosaurus

Velociraptor

    

Polacanthus

 

Brachiosaurus

 Edmontosaurus 

 Procompsognathus

 
 Brachyceratops 

Elasmosaurus

Prosaurolophus  
 Camarasaurus   Protoceratops
Protoceratops
 
 Camptosaurus

Eoraptor

Psittacosaurus  
    Pterosaur
Pterosaur
 

 Centrosaurus

Euoplocephalus

Saltopus

 

Ceratosaurus

Hadrosaurus

 Saurolophus

 
  Heterodontosaurus

Sauroposeidon

 
   

Scelidosaurus

 

 

 

Stegosaurus

 


  DinoData Dinosaur Index
  Exhibits A-Z
  Dinosaur Types
  Jurassic Dinosaurs
  Cretaceous Dinosaurs

Extinction
Go to Blast From the Past
  To see the Asteroid Theory of Extinction

Sixty-five million years ago the curtain came down on the Age of Dinosaurs when a cataclysmic event led to mass extinctions of life. This interval of abrupt change in Earth's history, called the "K/T Boundary", closed the Cretaceous (K) Period and opened the Tertiary (T) Period.

A recently recovered deep-sea core provides convincing support to the hypothesis that an asteroid collision devastated terrestrial and marine environments world-wide. It shows a record of flourishing marine life before the event, followed by mass extinction and then evolution of new species and slow recovery of surviving life forms after the event.

There have been LOTS of extinctions that affected animals besides dinosaurs. There were even some that the dinosaurs lived through and survived.
 

  1. Cretaceous-Tertiary extinction, about 65 million years ago - loss of land animals including dinosaurs.  probably caused or aggravated by impact of several-mile-wide asteroid that created the Chicxulub crater now hidden on the Yucatan Peninsula and beneath the Gulf of Mexico. Some argue for other causes, including gradual climate change or flood-like volcanic eruptions of basalt lava from India’s Deccan Traps. The extinction killed 16 percent of marine families, 47 percent of marine genera (the classification above species) and 18 percent of land vertebrate families, including the dinosaurs. 
  2. End Triassic extinction, roughly 199 million to 214 million years ago - loss of marine animals.  most likely caused by massive floods of lava erupting from the central Atlantic magmatic province -- an event that triggered the opening of the Atlantic Ocean. The volcanism may have led to deadly global warming. Rocks from the eruptions now are found in the eastern United States, eastern Brazil, North Africa and Spain. The death toll: 22 percent of marine families, 52 percent of marine genera. Vertebrate deaths are unclear. 
  3. Permian-Triassic extinction, about 251 million years ago - loss of land species: animals, plants, insects.  Many scientists suspect a comet or asteroid impact, (scientist estimates the object was 9 to 12 miles (15 to 20 kilometers) wide.) although direct evidence has not been found. Others believe the cause was flood volcanism from the Siberian Traps and related loss of oxygen in the seas. Still others believe the impact triggered the volcanism and also may have done so during the Cretaceous-Tertiary extinction. The Permian-Triassic catastrophe was Earth’s worst mass extinction, killing 95 percent of all species, 53 percent of marine families, 84 percent of marine genera and an estimated 70 percent of land species such as plants, insects and vertebrate animals.  Recent analysis of South African rocks reveals that rivers suddenly became clogged with sediments 251 million years ago, indicating Earth’s worst mass extinction wiped out many trees and other plants that held soil in place. Sedimentary rocks from that time show that large meandering rivers throughout South Africa’s Karoo Basin took on a braided, multichannel appearance, resembling streams in areas devastated by Mount St. Helens’ big eruption or areas logged by clear-cutting. That supports the notion of a global die-off of land plants, including extinction of Glossopteris trees and bushes, which resembled modern ginkos. Ward said a variety of ferns, seed ferns and early pine trees also went extinct.  In July, Doug Erwin of the Smithsonian Institution’s National Museum of Natural History published a study in Science in which marine rocks from China revealed the Permian-Triassic extinction happened in less than 160,000 years.  And in July’s issue of the journal Geology, a study of seafloor rocks now in the Austrian Alps concluded the extinction happened in less than 60,000 years and perhaps in less than 8,000 years.
  4. Late Devonian extinction, about 364 million years ago - loss of marine animals cause unknown. It killed 22 percent of marine families and 57 percent of marine genera. Erwin said little is known about land organisms at the time. 
  5. Ordovician-Silurian extinction, about 439 million years ago - loss of marine animals caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted. The toll: 25 percent of marine families and 60 percent of marine genera 




Earth.gif - 6650 Bytes Webs Sites

Dinosauria On-Line Dinosaur Omnipedia

Dinosaurium    Hooper Virtual Natural History Museum.  The Department of Earth Sciences, Carleton University, Ottawa, Ontario, Canada

Dinosaur List    This page lists all known Dinosaur genera.

Dinosaur News     Here you will find all the latest bits of dinosaur news. New discoveries, theories, statements, research, etc. Be the first to find out.

Dinosauria Translation and Pronunciation Guide A   Pronunciation, meaning, and information of all dinosaur species.

Dinosaurs End, The Gravitational Process

Earth's Geologic Time Line   

Journal of Dinosaur Paleontology

Oceans of Kansas Paleontology: Fossils From the Western Interior Sea

Official State Dinosaur Page