Gerhard Heilmann

Gerhard Heilmann (1859–1946) was a Danish artist, paleontologist and writer of the Origin of Birds, an influential account of bird evolution.

Life
Heilmann was born in Skelskør, Denmark and studied medicine. In 1883, he abandoned medicine and became an artist's apprentice, later becoming a painter at Royal Copenhagen. He also designed Danish banknotes and became a book ilustrator.

The Origin of Birds
Heilmann published a number of papers in Danish on the evolution of birds between 1913 and 1916, which were published in the Journal of the Danish Ornithological Society (Dansk Ornitologisk Forenings Tidskrift or DOFT). They were collected in 1916 as Vor Nuværende Viden om Fuglenes Afstamning. He revised this and published it in English 1926 as the The Origin of Birds. Like Thomas Huxley, Heilmann compared Archaeopteryx and other birds to an exhaustive list of prehistoric reptiles, and also came to the conclusion that theropod dinosaurs like Compsognathus were the most similar. However, Heilmann noted that birds possessed clavicles fused to form a bone called the furcula ('wishbone'), and while clavicles were known in more primitive reptiles, they had not yet been recognized in theropod dinosaurs. A firm believer in Dollo's Law, which states that evolution is not reversible, Heilmann could not accept that clavicles were lost in dinosaurs and re-evolved in birds, so he was forced to rule out dinosaurs as bird ancestors and ascribe all of their similarities to convergence. Heilmann stated that bird ancestors would instead be found among the more primitive 'thecodont' grade of reptiles. Heilmann's extremely thorough approach ensured that his book became a classic in the field and its conclusions on bird origins, as with most other topics, were accepted by nearly all evolutionary biologists for the next four decades, despite the discovery of clavicles in the primitive theropod Segisaurus in 1936. Clavicles and even fully developed furculae have since been identified in numerous other non-avian dinosaurs.

In 1940, Heilmann published a successful book on Darwinian evolution, the Univers og traditionen (Universe and Tradition, in Danish).

His work was introduced to D'Arcy Thompson by R. W. Shufeldt and this led to the two exchanging ideas on morphological evolution.

The bird-like dinosaur species Scansoriopteryx heilmanni was named in honour of Gerhard Heilmann in 2002.