Ostrom's interest in the dinosaur-bird connection started with his study of what is now known as the Haarlem "Archaeopteryx". Discovered in 1855, it was actually the first specimen recovered but, incorrectly labeled as "Pterodactylus crassipes", it languished in the Teyler's Museum in the Netherlands until Ostrom's 1970 paper (and 1972 description) correctly identified it as one of only eight "first birds" (counting the solitary feather).