The Meaning of Fossils
Dinosaur fossils have been weathering out of the rock since LONG before humans evolved, yet "Dinosauria" was not recognized until 1842. Why did it take this long?

Before scientists could recognize the existence of dinosaurs, they had to recognize that fossils were the remains of dead (not alive), unknown, extinct (not living anywhere) organisms.

Traditional cultures around the world noticed fossils, but assumed they were remains of supernatural creatures (giants, trolls, mammuts (a Siberian [Yakut] legendary race of "earth dwellers": the name is now transferred to fossil elephants!), unicorns, dragons, etc.).

During the Renaissance and Enlightenment in Europe, many thinkers began to abandon a view of the mythic past that included monsters and dragons. So what might fossils be? Some explanations included:

• "Lessons" put there by God, or "tricks" by Satan
• "Sports of nature": rocks that just happened to look like animal and plant parts
• Products of the "vital force" of nature (at this time, many people believed that living things were produced by spontaneous generation)

Nicolas Steno, a 17th Century naturalist, came up with a simple solution: fossils really WERE parts of dead animals and plants! Steno was one of the first people to recognize that rocks were not eternal, but were formed during the history of the Earth. So fossils were the remains of living things buried as those rocks formed. But what sort of animals were represented by fossils?

Baron Georges Cuvier (France) and contemporaries examined many fossils in the late 1700s/early 1800s:

• Had access to a wide variety of modern animal specimens as well as fossils
• Developed comparative anatomy: detailed descriptions of the equivalent parts of different living things
• Recognized fossils were remains of unknown organisms: that is, they were not examples of known living species
• Explained them being unknown because they were extinct organisms
• Examples of unusual extinct vertebrates described by Cuvier and contemporaries in the late 1700s and early 1800s included:
  • Palaeotherium, an early relative of tapirs and horses
  • Megatherium, a giant ground sloth
  • Mastodons and mammoths
  • The "Great Animal of Maastricht", a giant marine reptile eventually recognized by Cuvier as a huge sea lizard, and now named Mosasaurus: the first giant fossil reptile known to Science!
  • Other marine fossil reptiles, such as long necked Plesiosaurus and dolphin-like Ichthyosaurus
  • The flying reptile Pterodactylus

First major dinosaur discovery, in Britain, by Oxford geologist Reverend William Buckland:

• Megalosaurus ("big lizard")
• Formally described it in 1824
• Thought it to be a giant version of the modern monitor lizard

Next major discovery, in the Weald region of southern England, by husband and wife team Dr. Gideon and Mary Ann Mantell:

• Teeth were leaf-shaped, reminiscent of the modern Iguana, a primarily herbivorous reptile
• Called it Iguanodon ("iguana tooth")
• Formally described it in 1825
• Imagined it to be an immense version of the iguana lizard

Third major discovery, also in the Weald region and also by the Mantells:

• Very large spikes were found arranged along the skeleton: first evidence of giant armored reptiles
• Called it Hylaeosaurus ("lizard of the Weald")
• Described in 1833
• Pictured it as a giant spiky lizard

Other discoveries were made on the European continents in the 1830s and 1840s.

In 1841, Sir Richard Owen gave public talks about the fossil reptiles of Britain. Concluded that Megalosaurus, Iguanodon, and Hylaeosaurus formed their own distinct group. Proposed the name Dinosauria ("fearfully great lizards") for this group when he wrote up talk (in 1842)

In the 1850s the Great Exposition. Benjamin Waterhouse Hawkins sculpted Megalosaurus, Iguanodon, and Hylaeosaurus (and other non-dinosaurs) under Owen's guidance. (A recent photo of those models.) Dinosaurs became popular subjects for popular science, political cartoons, etc.

But even at this point, still no complete dinosaur skeletons.

Early North American discoveries:

• Three toed footprints in the Connecticut River Valley, thought to be giant bird tracks
• Fragmentary skeleton (also from Connecticut), thought to be "Indian skeleton"
• Dinosaur teeth and bones found by explorers in western territories (now Montana):
  • Described in 1856 by first American vertebrate paleontologist Joseph Leidy
  • Recognized some to be similar to Iguanodon, others to be similar to Megalosaurus, still others to be some sort of lizard
  • Represented the first material from the New World recognized AS dinosaurs

In 1858, first major North American dinosaur fossil:

• Discovered near Haddonfield, New Jersey
• Described by Leidy, who named it Hadrosaurus ("heavy lizard")
• Teeth and bones were similar to Iguanodon, but fossil was more complete
• Front leg was much smaller and more slender than hindlimb, indicating it was bipedal (two legged)
  • Suggested that Iguanodon was bipedal, too

First recognition of bipedal dinosaurs. In 1866, another New Jersey discovery (this time of bipedal meat-eater) described by Edward Drinker Cope of Philadelphia. Eventually named Dryptosaurus.

Major important rivalry between Cope and Othniel Charles Marsh of Yale University. Conflict (primarily over fossils of dinosaurs and mammals from American West) during the 1870s and 1880s: "The Bone War". Among these were some of the first relatively complete dinosaur fossils, revealing body shapes unlike previously known animals, living or extinct! The vast numbers of fossils discovered formed the central collections of major museums and greatly increased the knowledge of extinct life (including some of the first complete dinosaur fossils).

(If you wish to watch a full-length TV PBS documentary about the Bone Wars, go here.)

In Europe, new discoveries were also being made:

• First complete Iguanodon skeletons
• First small dinosaurs (Compsognathus, Hypsilophodon)

Beginning of 20th Century, new, wealthy museums sponsored major expeditions to American and Canadian West: the Royal Ontario Museum (Toronto), the National Museum of Canada (now the Canadian Museum of Nature, Ottawa), the Carnegie Museum of Natural History (Pittsburgh), the United States National Museum (aka the Smithsonian Institution) (Washington), the Field Columbian Museum (now the Field Museum of Natural History, Chicago), and most especially, the American Museum of Natural History (AMNH) (New York) under the leadership of vertebrate paleontologist Henry Fairfield Osborn

Also, the AMNH and various European museums began the era of imperial paleontology (major expeditions to foreign lands, to bring fossils back to the home institution)

• Most famous AMNH expeditions: the Central Asiatic Expeditions of the 1920s
• From 1907-1912, German expedition to Tendaguru, German East Africa (now Tanzania)
• Various digs in other parts of the world by other museums (e.g., Germans in Egypt, various U.S. and Canadian museums in Alberta, etc.)

Also, dinosaur science began to lose its scientific appeal.

In 1960s, John Ostrom of Yale University:

• Reinterpreted horned and duckbill dinosaurs as sophisticated feeders
• In 1964, discovered Deinonychus ("terrible claws") (named in 1969)
  • Sickle-like claw on foot indicated active leaping predator
  • Later comparisons between Deinonychus and the primitive bird Archaeopteryx caused Ostrom to revive idea that dinosaurs were bird ancestors

1970s: Beginning of the Dinosaur Renaissance. New (or revived) topics of dinosaur research:

• Were they cold-blooded or warm-blooded?
• How fast did they move?
• Did they have complex family structures?
• How did they communicate?
• How were the different types of dinosaur interrelated?
• What was the relationship between dinosaurs and birds?
• How did dinosaurs fit into their ecosystems?
• How did the dinosaurs go extinct?

• Now discoveries made from every continent
• Discoveries often done by international teams, included paleontologists from local populations

Remainder of the course represents the work of Ostrom's colleagues and students during the "Dinosaur Renaissance".

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Last modified: 4 September 2013