History of Dinosaur Discoveries Timeline

Beginning in 1852 with a passing mention in Charles Dickens' Bleak House, dinosaurs have been featured in large numbers of fictional works.

Image source: Bleak House

Public enthusiasm for dinosaurs first developed in Victorian England, where in 1854, three decades after the first scientific descriptions of dinosaur remains, a menagerie of lifelike dinosaur sculptures was unveiled in London's Crystal Palace Park.

Image source: Crystal Palace Dinosaurs

Jules Verne's 1864 novel Journey to the Center of the Earth was one of the early notable examples of dinosaur appearances in fiction.

Image source: Journey to the Center of the Earth

Sir Arthur Conan Doyle's 1912 book The Lost World became one of the most famous fictional works featuring dinosaurs.

Image source: The Lost World (Doyle novel)

The 1914 animated film Gertie the Dinosaur featured the first animated dinosaur, becoming a landmark in both animation history and dinosaur popular culture.

Image source: Gertie the Dinosaur

The iconic 1933 film King Kong featured memorable dinosaur sequences and cemented dinosaurs as staples of popular entertainment.

Image source: King Kong (1933 film)

The 1954 film Godzilla and its many sequels made dinosaur-inspired monsters icons of cinema and popular culture worldwide.

Image source: Godzilla (1954 film)

Michael Crichton's best-selling 1990 novel Jurassic Park and its 1993 film adaptation brought dinosaurs to a massive global audience and renewed public fascination with paleontology.

Image source: Jurassic Park

A village in Henan, central China was reported in 2007 to have spent the previous several decades excavating and using real dinosaur bones as 'dragon bones' for traditional Chinese medicine purposes.

Image source: Long gu

In 1858, William Parker Foulke discovered the first known American dinosaur in marl pits in the small town of Haddonfield, New Jersey. Hadrosaurus was one of the first nearly complete dinosaur skeletons found (the first was in 1834, in Maidstone, England), and it was clearly a bipedal creature.

Image source: Hadrosaurus

Amphicoelias fragillimus, known only from a now lost partial vertebral neural arch, was described in 1878. Recent size estimates in 2023 have this sauropod reaching lengths of up to 44 m (144 ft) long and placed in a colossal weight range of around 110000–170000 kg (240000–370000 lb).

Image source: Amphicoelias

The first potential evidence for herding or flocking as a widespread behavior common to many dinosaur groups was the 1878 discovery of 31 Iguanodon, ornithischians that were then thought to have perished together in Bernissart, Belgium, after they fell into a deep, flooded sinkhole and drowned.

Image source: Iguanodon

Among ornithischians, in 1884 Jacob Wortman found skin impressions on the first known specimen of Edmontosaurus annectens, which were largely destroyed during the specimen's excavation. Owen and Hooley subsequently described skin impressions of Hypsilophodon and Iguanodon in 1885 and 1917.

Image source: Edmontosaurus annectens

Dinosaur fossils with scaly skin impressions have been found since the 19th century. Samuel Beckles discovered a sauropod forelimb with preserved skin in 1852 that was incorrectly attributed to a crocodile; it was correctly attributed by Marsh in 1888.

Image source: Samuel Beckles

The longest complete dinosaur is the 27 meters (89 ft) long Diplodocus, which was discovered in Wyoming in the United States and displayed in Pittsburgh's Carnegie Museum of Natural History in 1907.

Image source: Diplodocus

Important dinosaur remains were discovered in Tanzania between 1907 and 1912, yielding some of the most famous giant sauropods known to science.

Image source: Tendaguru Formation

From a behavioral standpoint, one of the most valuable dinosaur fossils was discovered in the Gobi Desert in 1971, preserving a predator and prey locked in combat.

Image source: Fighting Dinosaurs

Bob Makela and Jack Horner's 1978 discovery of a Maiasaura ('good mother lizard') nesting ground in Montana demonstrated that parental care continued long after birth among ornithopods.

Image source: Maiasaura

A specimen of the oviraptorid Citipati osmolskae was discovered in a chicken-like brooding position in 1993, which may indicate that they had begun using an insulating layer of feathers to keep the eggs warm.

Image source: Citipati

Cannibalism amongst some species of dinosaurs was confirmed by tooth marks found in Madagascar in 2003, involving the theropod Majungasaurus.

Image source: Majungasaurus

A 2009 review indicated that non-avians used visual displays and possibly non-vocal sounds, such as hissing, jaw-grinding or -clapping, splashing, and wing-beating (possible in winged maniraptoran dinosaurs).

Image source: Dinosaur

A 2016 study concludes that some dinosaurs may have produced closed-mouth vocalizations, such as cooing, hooting, and booming. A 2016 estimate also put the number of dinosaur species living in the Mesozoic at 1,543–2,468.

In 2021, the best preserved specimen of a dinosaur's cloacal vent exterior was described for Psittacosaurus, demonstrating lateral swellings similar to crocodylian musk glands used in social displays by both sexes and pigmented regions which could also reflect a signalling function.

Image source: Psittacosaurus

The possibility that dinosaurs were the ancestors of birds was first suggested in 1868 by Thomas Henry Huxley. Brought to light just two years after Charles Darwin's seminal On the Origin of Species (1859), its discovery spurred the nascent debate between proponents of evolutionary biology and creationism.

Image source: Thomas Henry Huxley

In 1896, Marsh calculated ratios between brain weight and body weight of seven species of dinosaurs, showing that the brain of dinosaurs was proportionally smaller than in today's crocodiles, and that the brain of Stegosaurus was smaller than in any living land vertebrate.

Image source: Othniel Charles Marsh

As later discoveries showed, clavicles (or a single fused wishbone) were not actually absent in dinosaurs; they had been found as early as 1924 in Oviraptor, but misidentified as an interclavicle. This evidence was key to debates over the bird-dinosaur link.

Image source: Oviraptor

Through most of the 20th century, before birds were recognized as dinosaurs, most of the scientific community presumed dinosaurs to have been sluggish and cold-blooded. Bakker, an early proponent of dinosaur endothermy, published an influential paper on the topic in 1968.

Image source: Robert T. Bakker

John Ostrom discovered the bird-like dromaeosaurid theropod Deinonychus and described it in 1969, revolutionizing views of dinosaurs as active animals and reviving the bird-dinosaur connection.

Image source: Deinonychus

In 1972, Bakker expanded on his arguments based on energy requirements and predator-prey ratios, supporting the idea of warm-blooded, active dinosaurs.

Harry Jerison, in 1973, showed that proportionally smaller brains are expected at larger body sizes, and that brain size in dinosaurs was not smaller than expected when compared to living reptiles.

Image source: Humanoid

Bakker published a series of studies that argued for active lifestyles in dinosaurs based on anatomical and ecological evidence, which were subsequently summarized in his 1986 book The Dinosaur Heresies.

Various mineralized structures that likely represented red blood cells and collagen fibres had been found by Schweitzer and others in tyrannosaurid bones as early as 1991. In 2005, Schweitzer and colleagues reported that a femur of Tyrannosaurus preserved soft, flexible tissue within, including blood vessels, bone matrix, and connective tissue that had retained their microscopic structure.

Image source: Mary Higby Schweitzer

Large meat-eating dinosaurs had a complex system of air sacs similar to those found in modern birds, according to a 2005 investigation led by Patrick M. O'Connor. In 2008, scientists described Aerosteon riocoloradensis, the skeleton of which supplies the strongest evidence to date of a dinosaur with a bird-like breathing system.

Image source: Aerosteon

In 2009, Schweitzer and colleagues reported that a Brachylophosaurus femur preserved similar microstructures, and immunohistochemical techniques demonstrated the presence of proteins such as collagen, elastin, and laminin.

Image source: Brachylophosaurus

In 2015, Sergio Bertazzo and colleagues reported the preservation of collagen fibres and red blood cells in eight Cretaceous dinosaur specimens that did not show any signs of exceptional preservation, indicating that soft tissue may be preserved more commonly than previously thought.

Image source: Ivaldo Bertazzo

The bolide impact hypothesis, first brought to wide attention in 1980 by Walter Alvarez, Luis Alvarez, and colleagues, attributes the K-Pg extinction event to a bolide (extraterrestrial projectile) impact.

Image source: Chicxulub crater

Just before the K-Pg extinction event, the number of non-avian dinosaur species that existed globally has been estimated at between 628 and 1078. In 1984, Dale Russell carried out an analysis to account for biases and found no evidence of a decline; another analysis by David Fastovsky and colleagues in 2004 even showed that dinosaur diversity continually increased until the extinction.

Image source: Cretaceous–Paleogene extinction event

The actual impact site remained elusive until a crater measuring 180 km (110 mi) wide was discovered in the Yucatán Peninsula of southeastern Mexico, and was publicized in a 1991 paper by Alan Hildebrand and colleagues.

In 2000, Spencer Lucas and colleagues reported the discovery of a single hadrosaur right femur in the San Juan Basin of New Mexico, and described it as evidence of Paleocene dinosaurs surviving past the K-Pg boundary.

Before 2000, arguments that the Deccan Traps eruptions—as opposed to the Chicxulub impact—caused the extinction were usually linked to the view that the extinction was gradual. In 2020, Alfio Chiarenza and colleagues suggested the Deccan Traps may even have had the opposite effect: long-term warming from its carbon dioxide emissions may have dampened the impact winter from the Chicxulub impact.

Image source: Deccan Traps