Before (and even after) Darwin, naturalists sometimes saw species as part of a ranked hierarchy in which newer forms were somehow better than what came before. This isn’t just a matter of splitting hairs erminology shapes our ideas and the way dramatic changes in the course of life are interpreted. Paleontologists often prefer the term “transitional form” or “intermediate form,” because they imply that these species are parts of an ever-changing continuum. NMNH Paleobiology Dept / Smithsonian By Any Other Nameīut what to call “strange beings ‘a la Darwin' like Archaeopteryx, whales with legs, and humans that look like apes? But that term obscures the reality of how evolution works. That’s why paleontologists have come to abhor the term: it obscures the true pattern of evolutionary change.Īrchaeopteryx has long been considered a "missing link" between birds and dinos. The chain metaphor that “missing link” implies would have us looking for straight lines, when the reality of evolution is much more discursive. Not every fossil creature can be slotted in as a direct ancestor to something alive today. Instead, evolution “produces a tree-like branching pattern with multiple descendants of an ancestor species existing at the same time, and sometimes even alongside that ancestor species.” “To me, the idea of a ‘missing link’ implies a linear chain of one species evolving into another, evolving into another, and so on,” says Smithsonian Human Origins Program anthropologist Briana Pobiner. As Nicholas Pyenson, Smithsonian National Museum of Natural History curator of fossil marine mammals, puts it: “Life is really a tree, not a chain.” But there’s good reason not to use the phrase-which Darwin himself knew. It certainly checks a lot of boxes for an animal that seems between what were thought to be two distinct categories of organism. Today, some still refer to Archaeopteryx as that long-sought “missing link” between birds and dinosaurs.
“Had the Solenhofen quarries been commissioned-by august command-to turn out a strange being ‘a la Darwin,'” he wrote his friend, “it could not have executed the behest more handsomely-than in the Archæopteryx.” The feathers left no question that the Jurassic Archaeopteryx was a bird, but the creature also had a suite of saurian traits that pointed to a reptilian ancestry.įalconer could hardly contain his glee. This extraordinary fossil -bearing feathers as well as teeth, claws, a bony tail and other reptilian traits -was just the sort of creature that Darwin’s theory of evolution by natural selection predicted should exist. On January 3rd, 1863, Charles Darwin received a letter from his paleontologist friend Hugh Falconer with news of a tantalizing find: Archaeopteryx. Less than two years after the publication of Origins, he got his wish. Though the term never once appears in the book, Darwin knew that his claims could benefit greatly from paleontological evidence of a species transition-an intermediate species connecting, for instance, humans to apes and monkeys. When Darwin published Origin of Species, one thing was missing from his argument: a “missing link.”
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