Fossils (from Latin fossilium “that which is dug up”) are the physical remains of past life and its activities preserved in the rock record.

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.

Many cultures in the world live in regions where fossils can be found. In most, they are explained as traces of the mythic past (an ancient time when monsters and gods roamed the Earth) or of supernatural beings (dragons, trolls, thunder birds and thunder horses, etc.).

In western Europe after the Enlightenment the belief many natural historians questioned the literal reality mythic pasts of European culture (Genesis, Classical mythology, and Germanic and Celtic folklore). Some other explanation was needed.

Were fossils really remains of animals and plants?

Alternative explanations offered

• Supernatural Causes: side effects of Creation; failed diabolic attempts at making life
• Mechanistic Causes: perhaps some vis plastica (shaping force) similar to that which produced regularly shaped crystals made bone-, leaf-, and shell-shaped rocks
• However:
  • Did not simply have the shape of bones, leaves, shells, etc., but retained even microscopic features
  • Were not found in all kinds of rocks, but only in those formed in the same surface conditions and environments in which animals and plants live (and die)

Were fossils the remains of known animals and plants?

• At first, people assigned fossils to known species (humans, horses, elephants, etc.)
  • (In)famous example: lower part of a carnivorous dinosaur thigh bone called Scrotum humanum after its resemblance to, well…
  • Another example: a fossil was named Homo diluvii testis (“human who witnessed the Flood”) because it seemed to resemble a human skull and spinal column
  • And another: a skull and partial skeleton of a large marine animal from Maastricht (Netherlands), thought to be either a whale or a very large crocodile
• However, science of comparative anatomy was developed
  • Animals and plants from across the world were brought back to the museums and zoos of the imperial powers of the 1600s and 1700s (France, England, Russia, etc.)
  • Natural historians studied these discoveries, catalogued the similarities and differences between different species
  • Baron Georges Cuvier (France) “father of comparative anatomy” examined many fossils in the late 1700s/early 1800s
    • Discovered the Homo diluvii testis was a giant salamander similar (but not identical) to the giant salamander of Asia
    • Recognized that the marine animal from Maastricht was a giant seagoing lizard similar to modern monitor lizards, later named Mosasaurus
    • Also recognized the newly found Pterodactylus was a flying reptile unknown except for the fossil

How could animals like Mosasaurus or Pterodactylus or the mammoth and mastodon remain unknown?
Were they hiding in parts of the world as yet unexplored by Europeans?

• Thomas Jefferson (yes, the 3rd U.S. President) described fossils of the mastodon and giant ground sloth from the eastern U.S.
  • Suggested these giant beasts still lived in the west, ordered Lewis & Clark to look for living examples during their expeditions
• Cuvier argued that these creatures were extinct:
  • Too much of the world had been mapped with no sign of such animals
  • The further back in time the rock record went, the less the animals and plants resembled the modern, suggestion a series of previous “worlds” of now-extinct organisms in the past

The stage was now set for the recognition of dinosaurs.

First major discovery, in Britain, by Reverend William Buckland:

• A jawbone, backbones, hip bones, leg bones, and other fragments of a large reptile
• Teeth were blade-like, with serrations down the front and back, indicating it was a carnivore
• Called it Megalosaurus (“big lizard”), formally described it in 1824
• Thought it to be a giant version of the modern monitor lizard

First good evidence of giant terrestrial (land dwelling) reptiles in the ancient past

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

• A series of teeth, jaw bones, limb bones, hip bones, and more of a large terrestrial reptile
• 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
• Spike-like bone found with the skeleton was of uncertain anatomical position; hypothesized it to be a horn as in the modern rhinoceros iguana

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

• Similar to Iguanodon in some features
• 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 (British Museum of Natural History, the “British Cuvier”) gave public talks about the fossil reptiles of Britain. Concluded that Megalosaurus, Iguanodon, and Hylaeosaurus formed their own distinct group:

• Large body size
• Terrestrial rather than aquatic (as in mosasaurs, ichthyosaurs, plesiosaurs)
• Upright limbs (like mammals) rather than sprawling to the side (like most reptiles)
• Extra hip vertebrae (as in mammals)
• Possibly warm-blooded (as in mammals)

In the 1850s the Great Exposition (a “world’s fair” to highlight the achievements and discoveries of the British Empire under Queen Victoria) was planned. The Natural History Museum’s exhibit was to be a journey through geologic time, showing life-sized replicas of prehistoric animals and plants.

Benjamin Waterhouse Hawkins sculpted Megalosaurus, Iguanodon, and Hylaeosaurus (and other non-dinosaurs) under Owen’s guidance. When the display opened up, millions saw dinosaurs (as then conceived) for the first time: quickly became popular subjects for popular science, political cartoons, etc.

The Great Exposition introduced dinosaurs to the general public, but complete dinosaur fossils were still unknown. Dinosaurs were still thought to be essentially lizard-like, except for a few mammal-like features. This would change with later discoveries in North America.

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 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

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:

• Described by Leidy’s protégé, Edward Drinker Cope of Philadelphia
• Teeth, jaw bones, and limb bones were similar to Megalosaurus, but fossil was more complete
• Front limb was VERY small, but hindlimb was long, indicating it (and probably Megalosaurus) was bipedal
• Was later named Dryptosaurus

Major important rivalry between Cope and Othniel Charles Marsh of Yale University:

• Although started as friends, became bitter enemies
• Both very wealthy, used resources to find new fossils in the “Wild West” in the 1870s-1890s
• Tried to be first to discover and name the different species of extinct animals
• Their rivalry actually aided paleontology:
  • The vast numbers of fossils discovered formed the central collections of major museums
    • Cope: the Academy of Natural Sciences in Philadelphia and the American Museum of Natural History in New York
    • Marsh: the Peabody Museum of Natural History at Yale University, New Haven, CT and the Smithsonian Institution in Washington, D.C.
    • Dinosaurs became the main feature of Natural History museum halls
  • Their discoveries greatly increased the knowledge of extinct life
  • Their discoveries included some of the first complete dinosaur fossils
    • Revealed that dinosaurs did not resemble either mammals OR lizards, but were (in many cases) very unlike any living creature
    • Because of the completeness of the fossils, dinosaur diversity, history and ecology was better understood
    • Many of the most famous dinosaurs were discovered and named: Triceratops, Stegosaurus, Allosaurus, “Brontosaurus” (properly Apatosaurus), and more
• Envisioned dinosaurs as dynamic creatures comparable to, but different than, mammals
• Marsh (and European colleagues) thought dinosaurs might have been ancestors of birds
• Eventually their rivalry and politicking exhausted their resources, in time for a new generation of paleontologists

In Europe, new discoveries were also being made:

• First complete Iguanodon skeletons
  • From Bernissart, Belgium
  • Showed that Iguanodon was a Hadrosaurus-like biped
• First small dinosaurs (Compsognathus, Hypsilophodon)

Beginning of 20th Century, new, wealthy museums (such as Pittsburgh’s Carnegie Museum of Natural History and the American Museum of Natural History (AMNH), under Cope’s student Henry Fairfield Osborn) began to sponsor major expeditions to American West.

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
  • Led by “Indiana Jones”-like Roy Chapman Andrews, a zoologist and adventurer
  • Included paleontologists, geologists, botanists, zoologists, anthropologists, archaeologists, etc.
  • Important dinosaur discoveries
    • First remains of Velociraptor and other small bird-like carnivores
    • First definite dinosaur nests (although dinosaur eggs found in France in 1800s)
    • Many, many new species
• From 1907-1912, German expedition to Tendaguru, German East Africa (now Tanzania)
  • Dinosaurs similar to, but not identical with, Cope & Marsh Jurassic discoveries
  • Team lead by handful of German specialists and hundreds of local workers
  • Limited British expeditions after region became part of Empire after WWI, but no large scale expeditions since: great potential for new discoveries
• 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.)

• Popularity of dinosaurs convinced many that dinosaurs were just “kids’ stuff”
• Useful as showcases for getting people into museums, so that admission fees could support “real science”
• Since Dinosauria was a “dead end” branch of the Tree of Life, dinosaurs were not important to understanding modern animals
• Other groups of vertebrates (most especially mammals and their ancestors) became primary focus of vertebrate paleontology

By mid-1900s, only a couple of active dinosaur researchers worldwide

However, dinosaur research did continue, and some other important discoveries were made.

In 1960s, John Ostrom of Yale University began looking for dinosaurs in rocks from the early part of the Cretaceous Period (a “twilight zone” for dinosaurs) in Montana and Wyoming.

• In 1964, discovered (on way back to camp on last day of expedition) a claw of a small meat-eating dinosaur
• Rest of skeleton was found the next summer, proved to be a new type of dinosaur
  • Claw did not come from hand, but from foot
    • Could only use claw while standing on one foot, or leaping up to attack
    • Clearly for attack, but to do so required expert balance and a higher level of activity than found in typical crocs, lizards, etc.
    • Suggested dinosaurs might have been warm-blooded
  • Named dinosaur Deinonychus (“terrible claws”) in 1969
    • The dinosaur incorrectly called Velociraptor in Jurassic Park (true Velociraptor is a smaller dinosaur)
  • 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:

• Dinosaur paleontology became very active aspect of research
• New (or revived) topics of dinosaur research
  • Were they cold-blooded or warm-blooded?
  • 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 the dinosaurs go extinct?
• New discoveries from many parts of the world
  • Now discoveries made from every continent
  • Discoveries often done by international teams, included paleontologists from local populations
  • New techniques to find, uncover, prepare, and describe fossils

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